CN111172408A

CN111172408A - Equipment for continuously and deeply purifying zinc sulfate solution to remove nickel, cobalt and germanium and control method

Info

Publication number: CN111172408A
Application number: CN202010067985.5A
Authority: CN
Inventors: 张旭; 耿惠; 段志勇; 沈庆峰; 崔鹏
Original assignee: Kunming Hanchuang Technology Co Ltd
Current assignee: Kunming Hanchuang Technology Co Ltd
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-05-19
Anticipated expiration: 2040-01-20
Also published as: WO2021147803A1; CN111172408B

Abstract

The invention relates to equipment for continuously purifying a zinc sulfate solution by two stages to remove nickel, cobalt and germanium and a control method. The method is characterized by comprising 2-5 serially connected continuous stirring reactors commonly used in the zinc hydrometallurgy industry, and on the basis of the existing purification equipment, the intermittent addition of zinc powder and an activating agent in the existing continuous purification reactor is changed; zinc powder, activating agent containing copper and antimony are intermittently added into the reactor No. 1. For the first-stage copper and cadmium removal liquid containing 2-100 mg/l of cobalt, 0-6 mg/l of nickel and 0.02-0.3 mg/l of germanium, the second-stage purified liquid can reach the cobalt content of less than 0.1mg/l, the germanium content of less than 0.02mg/l and the nickel content of less than 0.1mg/l, and the consumption of the cobalt-removal zinc powder is 50-70% of that of the prior art. The deep purification of the cobalt and the deep purification of the germanium and the nickel are realized, the concentration range of the germanium, the nickel and the cobalt contained in the front liquid is greatly widened, and the consumption of zinc powder is reduced. The purification equipment and the operation mode of the zinc powder and the activating agent are suitable for a zinc sulfate liquid purification system of the existing wet zinc refinery.

Description

Equipment for continuously and deeply purifying zinc sulfate solution to remove nickel, cobalt and germanium and control method

Technical Field

The invention belongs to the field of nonferrous metallurgy, mainly relates to a zinc hydrometallurgy continuous purification device and an operation method, in particular to a device for removing nickel, cobalt and germanium from liquid after copper and cadmium are removed at one section and a control method, and aims to overcome the defects of the structure and the operation method of the traditional continuous purification reactor.

Background

The classical wet electrolysis process for the production of metallic zinc consists of the following processes: a first leaching step, in which the zinc oxides containing impurities are leached with sulphuric acid from the electrolytic recovery.

The end point of the leaching solution is about pH5.4, so that proper amount of Fe is added³⁺And arsenic, iron, germanium and some other elements are deposited by coprecipitation, and a neutral zinc sulfate leachate containing impurities is obtained by the method.

However, some unhydrolyzed impurities, such as cadmium, copper, thallium, cobalt, nickel, etc., are still present in the zinc sulfate solution. These impurities are harmful to zinc electrolysis not only because they co-deposit with zinc at electrolysis, contaminating the cathodic deposits (cadmium, copper, thallium), but also because of the reduced hydrogen overvoltage, allowing hydrogen to evolve on the cathode without evolving zinc (Ge, Sb); but also redissolves zinc (Co Ni) as the anode due to the formation of the microbattery.

Usually, the solution is purified in three stages as shown in figure 1, one stage of purification uses zinc powder to replace and remove copper and cadmium, the other impurities such as nickel and cobalt are removed in the second stage of purification, then a small amount of zinc powder is added in the third stage to remove a small amount of residual impurities, and then the purified solution is electrolyzed to produce metallic zinc.

For the purification of neutral zinc sulfate leaching liquid, a zinc powder replacement method is the oldest method, but the method is simple and feasible, so that the method is still the main purification method for zinc sulfate purification. The replacement of one section of copper, cadmium and thallium is simple, 55-75 ℃ of copper, cadmium and thallium can be carried out at low temperature (the temperature of neutral leachate), an activating agent is not required to be added, the process is mature, and the required control index can be achieved by adjusting process parameters in industrial practice.

Because the special behavior of cobalt in the zinc powder replacement process causes the difference between the cobalt removal process and the copper-cadmium replacement process to be larger, the known cobalt removal process needs to be carried out under the condition of adding a certain activating agent, but the product form of cobalt in the cobalt removal process and the action mechanism of the activating agent and how to accurately control the cobalt removal operation according to solutions with different compositions are not completely clear so far. For this reason, numerous technicians have conducted long-term studies disclosing numerous patents aimed at improving the cobalt removal efficiency of zinc powders, a process which has been carried out for over 100 years. The earliest patents were traced back to uk patent GB831948A in 1918. These patents can be divided into two broad categories in general terms: the first method is to add different activators and optimize the addition amount of the activators to remove cobalt. The second is that other metal elements are added into zinc powder to improve the activity or replacement capability of the zinc powder, but the rule of removing cobalt is not completely mastered so far, which results in poor adaptability of purification to raw materials and high consumption of zinc powder in the production practice of zinc hydrometallurgy. With the development of the technology and the complication of raw materials, higher requirements are put on zinc hydrometallurgy, and obviously, the adoption of less zinc powder to realize higher purification depth is the direction of the technical progress. At the same time, the complexity of the raw materials also puts higher demands on the purification method, i.e. the purification process must be adaptable to different raw materials to stably produce a purification solution suitable for the electrolysis needs. The related patents are introduced in chronological order below.

In 1918 British patent GB138948A, a method for purifying and removing cobalt from lead dioxide or manganese dioxide is disclosed, which comprises the step of oxidizing cobalt into Co by using a mixture of manganese dioxide and lead dioxide at 80-100 DEG C₂O₃Or Co₃O₄The mixture is removed by precipitation, and the method is not used in a purification system because manganese in the solution is also removed when cobalt is removed.

1930 U.S. patent 1920442 discloses a method for removing cobalt, cadmium and germanium in the presence of Te and Cu by using zinc powder. It is clear that Te is an expensive rare metal.

U.S. Pat. No. 2503479 of 1946 discloses that the index of the purified liquid containing 2.2mg/l of cobalt is realized by adding tartaric acid, copper sulfate and lead acetate and removing cobalt with zinc powder, which is an earlier patent of antimony salt purification method.

Australian patent AU-B-90737/82 in 1952 discloses the addition of antimony and zinc powder in the presence of cadmium to remove cadmium, cobalt and nickel, at a temperature of 65 ℃ to the boiling point. The antimony adding amount is 0.5-10 mg/l, the adopted zinc powder is alloy zinc powder containing 0.1-2.0% of lead, the adding amount of the two-stage cobalt and lead removing salt is 20-100 mg/l, and antimony is antimony oxide, antimony sulfide, metal antimony and the like. The second stage temperature is 75 ℃, but the cadmium-cobalt slag produced by the method is easy to oxidize, and the method is characterized in that the method can remove cobalt by adding a small amount of antimony without adding copper, but the cadmium concentration required for removing cobalt is higher, so that a large amount of cadmium is circulated in the process. Typical examples thereof show that cadmium concentrations of around 500mg/l are required. Modern research has shown that leaching of cadmium slag requires a high acidity at which cobalt in the slag is largely dissolved out, which makes this patent unsuccessfully used in modern industry.

In 1968, U.S. Pat. No. 3672868 discloses a method for removing cobalt by using distilled zinc powder containing lead and antimony or atomized metal zinc powder, wherein the method comprises the steps of adding 2g/l of zinc powder containing lead and 3% antimony to 20mg/l of cobalt-containing zinc sulfate solution at 75-85 ℃ to achieve almost 100% cobalt removal, and the cobalt content of the purified solution is below 0.1mg/l after 120 minutes. Although this patent gives good results, cobalt can be removed without adding copper by adding only a small amount of an alloyed zinc powder containing antimony and lead. However, until now, the industrial practice proves that the defect of only adding the lead-antimony-containing alloy zinc powder to remove cobalt exists, and in order to realize better cobalt removal effect, copper and antimony are added when the alloy zinc powder is adopted.

UK patent 1393606 in 1972 discloses a method for removing cobalt by adding antimony compounds and alloyed zinc powder, which does not add copper. 4 different zinc powders A were compared: lead-free distilled zinc powder, B: distilled zinc powder containing 0.91% lead, C atomized metallic zinc powder containing no lead, D atomized metallic zinc powder containing 0.97% lead. For a zinc sulfate solution containing cobalt and 48-50 mg/l, the addition amount of antimony oxide is 1.2mg/l, the amount of zinc powder is 4g/l, and two groups of lead-containing zinc powder B and D respectively realize the cobalt content of the post-solution to be less than 0.1mg/l in 2 hours and 4 hours at 90 ℃. And the lead-free A and C have poor cobalt removal effect. Using zinc powder D, a cobalt-containing solution of 56mg/l at 90 ℃ with an antimony addition of 2mg/l, a zinc powder addition of 5g/l, a lead sulfate addition of 100mg/l gave results of less than 0.1mg/l of the cobalt-containing solution after 2 hours.

This patent shows that the amount of lead added has a significant effect on the removal of cobalt from zinc powder. Further increasing the amount of antimony oxide, adding antimony and lead with atomized lead-free zinc powder C, confirming that adding 5g/l zinc powder achieves cobalt content of less than 0.5mg/l and cobalt content of less than 0.05mg/l in 2 hours under the condition of adding 3.6mg/l antimony oxide and 50mg/l lead (lead acetate), which indicates that adding lead can improve the cobalt removal rate. On the other hand, the invention recognizes that the use of alloyed zinc powders containing lead also requires the addition of antimony compounds for cobalt removal to achieve good results. Obviously, the amount of zinc powder used in this patent is too large, reaching 5 g/l.

From the above patent, it can be seen that the purified zinc powder consumption is mainly used for cobalt removal, and the slag produced by cobalt removal has high zinc content, and numerous flow combinations and patents are proposed to reduce the zinc powder consumption.

Canadian patent 1046288A in 1975 discloses a process for reducing zinc dust consumption using a two-stage slag return for one-stage cleaning. The method adopts three-stage purification, antimony compound and copper compound are added in the two-stage purification to remove cobalt, the used antimony compound is antimony oxide, the obtained two-stage slag is returned to the first stage to reduce the consumption of zinc powder, the electrolysis waste liquid is added to control the pH value of the second stage to be 4.1-4.7, and a purification result with the cobalt content being less than 0.1mg/l is obtained in a continuous state. However, the method has too large slag return amount, and a large number of thickeners and cyclones are adopted to separate and purify slag for realizing slag return, so that the equipment is complex. The obtained first-stage slag contains zinc and almost all harmful impurities such as copper, cadmium, cobalt, nickel and the like, the slag treatment process is complex for recovering the valuable elements, and the main difficulty is that a large amount of cobalt is re-dissolved into the solution in the acid leaching process, and the cobalt has to be removed for the second time, so that the treatment cost is high.

In 1975, Canadian patent 1075912 carried out improvement research and discloses a method for removing cobalt by using a copper-antimony activating agent, wherein the amount of copper added is optimized, the purification process adopted comprises the steps of removing copper and cadmium in one stage and removing cobalt by adding copper and antimony in the second stage, and the inventor tries to find out the relationship between the cobalt content of a solution and the amounts of copper, antimony and zinc powder added. In the invention, the problem of great difference of cobalt removal effect caused by different addition amounts of copper and antimony in an antimony salt purification method is described in detail, and a large number of experiments suggest that to obtain good cobalt removal effect, the proportion of the added copper amount to the cobalt amount in a solution must be at least 0.2, the maximum copper concentration is not more than 200mg/l, the added antimony amount is 1-2 mg/l, and the zinc powder is at least 1 g/l. The antimony compound is antimony potassium tartrate, the zinc powder is atomized metal zinc powder containing 0.5-2.5% of lead, and the level of cobalt content in the solution is less than 0.1mg/l after 2 hours at 80 ℃. The patent does not, however, identify relationships for different cobalt concentrations and only relies on extensive experimentation to give a rough optimization.

For stable cobalt removal, U.S. Pat. No. 4252622 in 1980 discloses a continuous cobalt removal process using a copper arsenic compound, which employs four stages of purification. 1. Adding fine zinc powder to precipitate copper. 2. Adding coarse zinc powder, dilute sulfuric acid and copper arsenate to remove most of cobalt. 3. Coarse zinc powder and dilute acid were added to remove the cobalt to 1 mg/l. 4. Coarse zinc powder is added to remove the cobalt to below 0.1 mg/l. Obviously, the process adopts an activating agent containing arsenic, the produced slag inevitably contains a large amount of arsenic, and acid is added in the purification process, so that toxic gas is easily generated.

In order to further improve the cobalt removal efficiency, canadian patent 1133228 in 1980 discloses a method for removing cobalt by using atomized alloyed zinc powder containing aluminum and lead. The alloy contains 0.001-0.031% Al alloy, 0.05-1.0% Pb alloy, and the balance of Zn, and 0.02-0.1% Cu alloy can be added. However, the reaction time of the cobalt-removed solution was 2 hours, and the reaction temperature was only 1mg/l or less at 75 ℃.

Canadian patent 1122229 in 1980 discloses a method for using pentavalent antimony as an activator for adding antimony compounds, which comprises oxidizing trivalent antimony into pentavalent antimony by potassium permanganate added with potassium antimony tartrate, and adding the obtained pentavalent antimony aqueous solution into a first-stage solution after copper and cadmium are removed. For a solution containing 1.6mg/l of cobalt and 200mg/l of cadmium, under the condition of adding 36mg/l of copper and 0.75mg/l of pentavalent antimony, 4g/l of zinc powder is added, under the condition of 75 ℃, the cobalt can be removed to be below 0.1mg/l within 2 hours, but the cobalt is not removed to be below 0.1mg/l by a solution without adding cadmium. It is clear that the patent adds a relatively large amount of zinc powder, but from this invention it can be seen that the difficulty of achieving deep purification of the low cobalt solution is seen.

French patent 2550805 in 1983 proposes a method for removing cobalt by using zinc-magnesium alloy zinc powder, which realizes that the cobalt is removed to the level of 0.2mg/l at the low temperature of 65 ℃, but the magnesium content of the alloy is 6-47%, a large amount of magnesium is brought into the solution, and the alloy zinc powder is not easy to prepare.

In 1983, the improvement of the conical bottom tank purification equipment with the expansion section is proposed in the U.S. Pat. No. 4637832, and although the examples show better indexes for reducing the consumption of zinc powder, the industrial practice is not reported so far because the equipment is greatly changed.

In 1986, Canadian patent 1324724 proposes a high-pressure cobalt removal method to accelerate the cobalt removal speed, and the cobalt removal temperature is 120-150 ℃. For 8-12 mg/l cobalt-containing solution, 2mg/l antimony oxide, 0-5 mg/lCu and 2-3 g/l zinc powder are added in the embodiment, and the cobalt content of the solution is below 0.1mg/l after 60 minutes. The reaction speed of cobalt removal is obviously better than that of normal pressure, but the high-pressure cobalt removal equipment is expensive, the operation is complex and the energy consumption is high.

In 1987, in order to stabilize the cobalt removal effect, a method for monitoring the oxidation-reduction potential in the purification cobalt removal process is proposed in German patent 3819020A1, which plays an auxiliary role in stabilizing the indexes of the cobalt removal process, but does not solve the core problem of the process, namely how to adjust zinc powder and an activator in cobalt removal.

Japanese patent Sho 63-312991 in 1988 also proposed the use of a method of controlling the redox potential to improve the stability of cobalt removal by the arsenate method.

Russian patent 2186131C2 in 2000 proposed that zinc alloy zinc powder containing 0.6-0.9% of lead and 0.003-0.5% of iron was used to remove cobalt and nickel, so as to achieve the effect of reducing zinc powder, but obviously, the iron in the solution will be increased.

2012's us patent 8545690B1 discloses a method for removing cobalt and nickel by pressure purification, nitrogen is introduced into a reaction tank, the temperature is maintained at 85-130 ℃, the pressure is 0.2-0.6 MPa, 2.8g/l of atomized metallic zinc powder is added, 60 minutes later, purified liquid of cu0.062mg/l, cd1.17mg/l, co1.0mg/l and ni0.24mg/l is obtained, copper and antimony are not added in the purification process, and the purification effect is slightly worse than that of the depth of cobalt content of 0.1mg/l obtained in canadian patent 1324724, which is obtained in 60 minutes.

2010 Chinese patent CN101988155A discloses that arsenic-antimony smoke dust is used as a cobalt removal activator, arsenic-containing antimony smoke dust is used for replacing antimony trioxide, under the coordination of chalcanthite, 50-72 mg/L of cobalt-containing zinc sulfate solution is added with 100mg/L of chalcanthite at 80-85 ℃, and the purified solution containing cobalt for 1 hour is obtained<As a result, 1mg/l was obtained, which was effective in reducing the cost of the activator and the amount of the activator added. However, the activator contains arsenic, which causes difficulty in purifying slag and may produce highly toxic AsH₃。

2010 Chinese patent CN102021339A discloses an additive for reducing cobalt redissolution, which reduces cobalt redissolution in the purification process by adding lead sulfate after size mixing. However, the patent does not provide the scope and effect of the addition of lead sulfate.

2014 Chinese patent CN103966443A discloses an activator, zinc powder, lead sulfate, chalcanthite and antimony potassium tartrate are added into the solution after copper and cadmium are removed at one section, the temperature is controlled to be 80-95 ℃ under the condition of continuous stirring for 60-90 minutes, and the new solution obtained after stirring and filtering is sent to recycle electrolytic zinc. The zinc powder added for removing nickel and cobalt in the two-stage purification is atomized metal zinc powder, the zinc content of the atomized metal zinc powder is greater than 98%, the effective metal zinc content of the atomized metal zinc powder is greater than 95%, and the particle size of the atomized metal zinc powder is 65-75 microns. In the process of secondary purification and removal of nickel and cobalt, under the condition that 3.634-9.98 g/L of atomized zinc powder and a certain amount of the activating agent are added into 52mg/L of cobalt-containing zinc sulfate solution, the deep purification solution with the cobalt content of 0.03mg/L of the purified solution is obtained, and meanwhile, the cobalt content of the obtained purified nickel and cobalt slag is 0.62-0.79%. Although the method meets the requirement of deep purification, the added zinc powder is excessive, and the cobalt content of the slag is low.

2016 Chinese patent CN106893872A discloses a purification and cobalt removal method, which is characterized in that zinc powder is adopted to remove copper and cadmium in the first section, and common zinc powder and Zn are adopted in the second section: 50-60%, manganese: 30-49%, magnesium: 0.05-2%, aluminum: 0.05-2 percent of alloy zinc powder containing 0.9-3 percent of lead, antimony salt and antimony white, wherein the temperature is 85-90 ℃, 1-3.5 g/l of common zinc powder and 2-3 g of antimony salt are added into each cubic solution of a No. 1 purification tank and a No. 2 purification tank, and 0.3-1 Kg/M of common zinc powder and 0.3-1 Kg/M of antimony salt are added into a No. 3 purification tank³The 3# groove is simultaneously added with 0.15-2 g/M of alloy zinc powder³The reaction time of the activator consisting of antimony salt and antimony white is 2.5-3 hours. In the embodiment, 35-52 mg/l of middle supernatant is used for continuous purification, the cobalt content of the second-stage purification solution is 0.12-0.18 mg/l, and obviously, the preparation of the alloy zinc powder is difficult. The patent adopts a plurality of means described in the patent, which is concretely represented by adopting alloy zinc powder containing a plurality of elements; antimony white and antimony salt were added to a plurality of purification tanks, but from the results of the examples, the cobalt content of the purified liquid was not yet 0.1mg/l or less.

From the numerous patents relating to cobalt removal by zinc dust displacement described in chronological order above, it is evident that, as early as a century ago, it has been found that the cobalt removal process is different from the copper-cadmium displacement process, in which the cobalt removal process must be carried out with the addition of an activator and at a higher temperature (greater than 70 c), and an excess of zinc dust must be added. In addition, a considerable amount of copper needs to be added, and the activator currently used is antimony (Sb)₂O₃Or antimony potassium tartrate) and arsenic (As)₂O₃) The compounds of (1) are classified into an antimony salt purification method and an arsenic salt purification method according to the addition of an activator.

The arsenic salt purification method is used by a small number of manufacturers at present due to the reasons of environmental protection and production safety, and the mainstream process at present is basically the antimony salt purification method. The development of various methods for purifying cobalt is summarized below.

1. In the aspect of improving the efficiency of the activator, a plurality of activators are proposed to improve the cobalt removal activity of zinc powder by replacement, and the activators comprise Te salt and Sn salt, but finally the combination of copper and arsenic or copper and antimony is adopted to obtain better effect, the arsenic salt purification method is better than the antimony salt purification method in terms of cobalt removal depth, the technology is mature, however, because of the harm of arsenic to the environment and environment, the cobalt removal of the prior electrolytic zinc plant is mainly performed by the combination of copper and antimony activators, in the aspect of improvement of the antimony salt purification method and the use method, although a great deal of research and patent disclosure are made, however, there is no consensus that copper addition can improve the cobalt removal rate, and as mentioned above, Canadian patent 1046288A suggests that the amount of copper added must be 0.2 or more by weight of Cu/Co during the cobalt removal process, and the amount of antimony added is only 1 to 2 mg/l. The inventor believes that when antimony oxide and antimony potassium tartrate are added in a large amount, there is a possibility that antimony exceeds the standard for controlling the antimony content of the purified solution by electrolysis.

2. Antimony salts employ different compounds, mainly antimony potassium tartrate and antimony oxide, but there is no patent comparing the two, most of the patents use antimony compounds of antimony oxide and the rest are antimony potassium tartrate, and only one patent (canadian patent 1122229) proposes the use of pentavalent antimony salt to remove cobalt. The added antimony amount is considered to be enough to complete the cobalt removal process by adding 1-5 mg/l of antimony from the numerous patents, most of the patents only add 1-2 mg/l, excessive antimony addition is considered to be unnecessary, and excessive antimony addition is considered to cause overhigh antimony content in the purified liquid, so that the phenomenon of plate burning during electrolysis due to overhigh solution impurities and large amount of hydrogen cathode precipitation during electrolysis is known to occur due to the fact that the antimony content in the solution is overhigh, but most of electrolytic zinc plants adopt three-stage purification at present, and a small amount of antimony can be removed in a third stage without influencing electrolysis.

3. In order to improve the replacement speed of the zinc powder, the driving force and the reaction speed of the replacement are improved by adopting different zinc powder, and the other direction of the development of purifying and removing cobalt is provided. For the zinc powder preparation process, two types of zinc powder are mainly used, one is distilled zinc powder and the other is atomized metal zinc powder. The distilled zinc powder can be divided into pure metal zinc or alloy distilled zinc powder and metal zinc powder obtained by adopting zinc-containing material to directly reduce in an electric furnace and condensing gas products. The atomized metal zinc powder is obtained by directly melting zinc ingots and then directly blowing liquid zinc into fine-grained zinc powder by gas or water.

The distilled zinc powder is characterized by fine granularity, the general grain size is less than 2-5 microns, the electric furnace zinc powder also belongs to the zinc powder, only the impurities such as lead are higher, the effective zinc is lower than that of the distilled zinc powder of pure metal, the effective zinc of the general electric furnace zinc powder is 85-90%, the effective zinc of the distilled zinc powder prepared from the pure metal zinc can reach more than 95%, and the use effect is that the electric furnace zinc powder has fine granularity and large reaction surface area, so the cobalt removal speed is high.

The atomized zinc powder has thicker granularity and smaller corresponding reaction surface area, and in order to increase the cobalt removing speed of the zinc powder, some patents propose adding some alloy elements to improve the driving force of the reaction, wherein the alloy elements comprise lead, antimony, aluminum, magnesium, manganese, iron, tin and the like. For the use of such alloyed zinc powders, lead-containing metallic zinc powders are used in many cases. However, the effect of deep cobalt removal cannot be achieved by using the alloy zinc powder alone, and in general industrial practice, most factories simultaneously use the alloy zinc powder and the copper-antimony activating agent to remove cobalt. We have also noted that the effect of alloying lead-containing metallic zinc powders can also be achieved by adding lead salts, including lead acetate or lead sulphate, when cobalt is removed using lead-free zinc powders, and it is clear that the addition of lead salts when using purification is simplified compared to the production of alloyed zinc powders, with the amount of lead added being only 1% of the zinc (uk patent 1393606).

In order to improve the activity of the zinc powder, Canadian patent 1046288A proposes adding acid to prevent passivation, the pH value is controlled to be 4.1-4.7 when purifying and removing cobalt, most of other patents do not mention controlling the pH value in the cobalt removing process, and only a small amount of acid is added into the solution after removing copper and cadmium in one section to control the pH value of the solution before removing the cobalt. However, how to control the acid addition amount so that the zinc powder is not passivated and the zinc powder does not consume too much zinc powder becomes a key to how to control the acid addition amount. In order to prevent the generation of basic zinc sulfate in the arsenic salt purification process, a method for controlling the BT value of the solution (US 8021459B2) is proposed instead of controlling the pH during the purification process, but is not seen in the antimony salt purification process. However, obviously, the generation of a large amount of basic zinc sulfate in the antimony salt purification method can influence the purification cobalt removal process, which is also an important reason that the second-stage cobalt removal purification slag has high zinc content and low cobalt content, and thus the second-stage purification slag has high treatment capacity and high cost.

4. In order to stabilize the cobalt removal process, methods for controlling the solution potential during the purification of cobalt have been proposed, and these patents provide a means for controlling the purification process by controlling the redox potential of the slurry during the purification of cobalt, which is obviously only an auxiliary means.

5. In order to improve the utilization rate of the zinc powder, several patents propose a method for returning the second-stage cobalt-removal purification slag to the first-stage, so as to achieve the purpose of reducing the consumption of the cobalt-removal zinc powder. However, it is obvious that the treatment process is difficult because the primary purification slag contains almost all impurity elements, and particularly secondary cobalt removal is required.

6. In the aspect of equipment, the reaction tanks with special structures are adopted to improve the cobalt removal efficiency and reduce the consumption of zinc powder, but the special tank types are inconvenient to use and are mostly not applied industrially; or the use of high pressure to increase the rate of cobalt removal, it is clear that the complexity of the high pressure equipment limits its industrial application.

The patent analysis shows that the old problem of cobalt removal has existed for nearly a century, the complexity and difficulty of the problem are explained, and although a great deal of research is carried out by a great deal of technicians, the technology which is not only suitable for the current increasingly strict environmental protection requirement but also low in the consumption of zinc powder and can meet the deep purification requirement is not fundamentally provided. Although the indexes of cobalt content of the liquid after cobalt removal is less than 0.1mg/l are given in the examples of numerous patents, the purification depth in the production practice is often less than 0.1 mg/l.

Obviously, from the perspective of the above patents, although a large number of patents are disclosed for the antimony salt purification method, there are still many problems in the production practice, which are shown in the following:

and a, the consumption of the two-stage purified zinc powder is large.

And b, the concentration of the purified deep cobalt is not easy to reach the deep purification standard of 0.1 mg/l.

And c, the cobalt in the purification slag is easy to redissolve.

And d, when the concentration of cobalt changes greatly, the zinc sulfate solution is difficult to purify and remove the cobalt.

And e, the slag amount is large, the number of filtering devices is large, the cobalt content in the slag is low, and the slag treatment cost is high.

And f, when the germanium content of the solution is high, the purification requirement is not easy to meet.

Particularly, when the concentration of cobalt and other impurities is changed greatly, the cobalt content of the final purifying liquid is increased due to the fact that the concentration cannot be adjusted in time, the purifying level of an arsenic salt purifying method cannot be achieved by an antimony salt purifying method, a well-controlled factory is generally adopted, and the final purifying liquid can only reach 0.2-0.3 mg/l.

However, the purification of antimony salts is advantageous from the viewpoint of environmental protection and safety of production, which is an important reason why the purification of antimony salts is now adopted in most plants. Further improvements in antimony salt purification to achieve less zinc dust and higher purification depth are the direction of development of antimony salt purification.

Therefore, a great deal of researchers research the cobalt removal process and issue a plurality of papers, which can be roughly divided into two types, wherein one type is to try to find out the better parameters of the cobalt removal process by adjusting the parameters of the cobalt removal process, such as the addition amount of zinc powder, the pH value or the acid addition amount of the solution, the addition amount of an activator (mainly the addition amount of copper and antimony and the proportion thereof), the temperature, different zinc powders and the like; the second type is to study the phenomenon generated in the cobalt removing process from the mechanical layer surface, and provide a basis for proposing a new cobalt removing method. However, most research papers only perform a lot of experiments on a single or small range of cobalt concentration by a lot of experiments to obtain better parameters, and then apply the parameters to industrial production, and production fluctuation is inevitable due to deviation of various parameters from the experimental range in production practice.

On the other hand, for the problem of cobalt redissolution in production, the mechanism of redissolution is unclear, and a method of adding zinc powder is generally adopted to inhibit cobalt redissolution, but this results in more consumption of zinc powder. The more fiery [1] study of Hu shows that when the copper sulfate and the potassium antimony tartrate are used for activating the zinc powder to remove cobalt, the cobalt can be removed to be below 0.1mg/l at the early stage, but the cobalt is obviously re-dissolved at the later stage, so that the consumption of the zinc powder is not easy to reduce in industrial practice by using the copper-antimony activating agent. To avoid cobalt redissolution, too much zinc powder is often added. Obviously, due to the existence of the redissolution problem, more difficulties are encountered in the adjustment of various control parameters and the search of cobalt removal rules, the difficulties are to ensure the cobalt removal depth and prevent the cobalt redissolution, and the search of such rules is more difficult because the cobalt redissolution problem cannot find the reason for a long time.

In addition, many research papers try to optimize the cobalt removal process for reducing the consumption of zinc powder and achieving lower cobalt content in the purified liquid, and deep purification generally requires less than 0.1mg/l of cobalt, but all papers are optimized for a single cobalt concentration or a smaller cobalt concentration range, and do not find the relationship between the cobalt concentration and other impurities and the addition amount of zinc powder and an activator, so that many factories limit the cobalt content in the raw material to ensure the purification effect. From the above patents and research papers, all of them do not refer to the difference between antimony compounds potassium tartrate and antimony oxide, and it is generally considered that both compounds can be used [2 ].

In order to find out the rule of the cobalt removal process, some researchers have conducted some basic researches aiming at disclosing the mechanism of the cobalt removal process, proposing a new activator and a new cobalt removal technology, but so far, only the cobalt product produced by the antimony salt purification method is obviously different from the arsenic salt purification. Tozawa 3. Studies have confirmed that cobalt produced by arsenic salt purification is present as an arsenic-cobalt metal compound, while it is not completely clear in what form cobalt produced by antimony salt purification is present.

Oluf Bockman, Terje Ostvold research showed [4], that cobalt may be replaced in the form of a zinc-cobalt alloy and basic cobalt sulfate, which the authors believe: the presence of basic cobalt sulfate is the main cause of cobalt redissolution. Obviously, the problem of cobalt re-dissolution can be solved if the cobalt precipitation morphology is controlled to form alloys only.

Terje Ostvold, Oluf Bockman [5] studied the effect of tartaric acid on cobalt displacement, and it is believed that high concentrations of tartaric acid reduce the rate of cobalt displacement, whereas potassium antimony tartrate is a commonly used cobalt scavenging compound.

V. van der Pas, D B Dreisinger. [6] showed that cobalt was deposited as a Zn-Co alloy under certain conditions due to underpotential deposition of zinc, which was more positive than zinc. However, the conclusion is that the zinc-cobalt alloy is obtained under the conditions of electrolysis experiments and pH 3-4, and the zinc powder displacement is not proved to be obtained due to the difficulty of detection.

A large number of researchers have studied the mechanism of the cobalt-removing purification process and proposed many possible mechanisms of action. For these findings, a. nelson et al reviewed [7] in 2000, concluding that although numerous studies suggest various cobalt removal mechanisms and explanations, no one can be determined which theory is reliable. This conclusion also illustrates the complexity of the cobalt displacement removal process of the zinc hydrometallurgy antimonate purification process, while the displacement mechanism remains an unsolved problem.

2013A. Nelson et al [8 ]]The influence of the solution components on cobalt replacement in the cobalt replacement process is researched, and a solution containing 30mg/l of cobalt is adopted, and Sb is added³⁺2mg/l(Sb₂O₃) And Cu²⁺30mg/l, the corresponding copper-cobalt ratio is 1, water atomized metal zinc powder (Pb0.7-1%) is used, and the addition amount of the zinc powder is 5 g/l. Research shows that the cobalt removal experiment result without controlling the pH of the solution is better than the experiment with controlling the pH at 4.0, the pH of the reaction slurry is detected in the experiment process, and the research is compared with the purification cobalt removal effect, and the research shows that the solution is not beneficial to cobalt removal under the acidic condition in the replacement process, and the better result is obtained without controlling the pH of the solution, which fully explains the defect of adopting the pH to monitor the purification cobalt removal process. From the antimony addition in this paper it is evident that the antimony addition is substantially the same as 1-2 mg/l antimony addition described in canadian patent 1046288A, the copper addition is also greater than 0.2 in the copper to cobalt ratio proposed in this patent and the maximum copper addition does not exceed 200 mg/l.

In 2018, Toni Karlsson et al [9] studied the kinetics of the cobalt removal process and the morphology of the cleaned product in an attempt to reveal the morphology of cobalt in the product, but the results of the study showed that only cobalt hydroxide was found in the slag and no metallic cobalt was found.

From the above-mentioned patent and research papers, it is obvious that the antimony salt purification method is still a method to be perfected, although it has been continuously improved and practiced in production for nearly 100 years. The concrete points are as follows:

1. the method for adjusting the adding amount of zinc powder and the adding amount of a copper-antimony activating agent in different component solutions, particularly in the case of cobalt change, is lacked.

2. The control of the acid adding amount in the acid adding and adjusting process and the detection means of related parameters in the solution are lacked.

3. There is a lack of a targeted prevention based on the mechanism of cobalt redissolution.

4. There is a lack of reliable theory of cobalt displacement mechanism.

5. The difference research of two common antimony compounds as the cobalt purifying and removing activator is lacked, and the production practice is not easy to adjust according to the production change.

Due to the problems, when the solution components are changed violently in the production process, the impurity concentration of the purified solution fluctuates due to the fact that rapid adjustment cannot be carried out, and the normal operation of electrolysis is affected. Obviously, the existence of the problem is the result of the above complex reasons, and the cobalt removal process is adversely affected by a plurality of factors which are mutually interwoven.

The problem is also further complicated by the variation of cobalt concentration on production, and obviously the problem cannot be solved by a single solution, and the improvement is also made more difficult by the unclear cobalt removal mechanism, which is also the main difficulty in purification in the current zinc hydrometallurgy industry. Obviously, solutions to the existing various problems need to be provided respectively and then integrated into an integral solution, so that the problem of purifying and removing cobalt in the zinc hydrometallurgy production can be solved completely.

As for equipment, in industrial practice, zinc powder and an activating agent are continuously added into a plurality of continuous stirring reactors connected in series in three-stage continuous purification, liquid in the reactors usually flows from top to bottom [10], copper and cadmium are removed by adding zinc powder into one stage, and residual impurities are removed by adding zinc powder into three stages normally. Copper and antimony compounds are added when the cobalt is removed by adopting an antimonite purification method in the two-stage purification cobalt removal process, the copper and antimony compounds are continuously and independently added, the adding place is mostly added in a No. 1 reactor, and when the purification requirement cannot be met, some enterprises also add in No. 2 or No. 3. Production practices show that the equipment and the feeding mode have poor adaptability to the change of the cobalt concentration, low purification depth and large slag quantity. In order to ensure the purification effect, most of the production enterprises adopt large-scale zinc hydrometallurgy enterprises in continuous purification industry, the cobalt content of raw materials is strictly limited, so that the raw material purchase is limited, and the cobalt content of purified liquid is only 0.2-0.5 mg/l. While the accepted standard for deep cobalt removal is that cobalt is less than 0.1 mg/l. Due to the influence of various factors such as a cobalt removal mechanism, various improved methods are tried, but a good purification result is not obtained. The patent and research paper results disclosed above all show that continuous deep purification of zinc sulfate solution is a problem to be solved urgently by zinc hydrometallurgy enterprises.

Cited documents:

1. huzhonghuo, school newspaper of the university of China and south (Nature science edition), 8 months 2012, volume 43, phase 8

2.R.Raghavan，Hydrometallurgy 51(1999)187-206

3.K.Tozawa，Hydrometallurgy,30(1992)445-461

4.Oluf Bockman,Terje Ostvold，Hydrometallurgy 54(2000)65-78

5.Terje Ostvold，Oluf Bockman,Hydrometallurgy 55(2000)107-112

6.V.van der Pas,D.B.Dreisinger，Hydrometallurgy 43(1996)187-205

7.A.Nelson,Mineral Processing and Extractive Metallurgy Review.20(2000)325-356。

8.A.Nelson,Canadian Metallurgical Quarterly,Vol 39,No 2,pp175-186,2000

9.Toni Karlsson，Hydrometallurgy，181(2018)169-179

10.Vakil Singh,Hydrometallurgy 40(1996)247-262

The invention content is as follows:

the invention relates to a method for purifying zinc sulfate aqueous solution to remove nickel, cobalt and germanium, and belongs to the patent of the inventorOne branch of (2). In using Sb proposed in the above patent₄O₅Cl₂On the basis of using chalcanthite as zinc powder replacement cobalt removal activating agent, the device and the operation of the method for removing cobalt by using a continuous purification system consisting of a plurality of continuous stirring reactors are further improved, and the specific objects of the invention are as follows:

the invention aims to provide a method for preparing Sb₄O₅Cl₂+ equipment for continuous purification and removal of nickel, cobalt and germanium with chalcanthite as an activating agent.

The invention also aims to provide a method for preparing the Sb₄O₅Cl₂And the adding mode and the control method of the activating agent for continuously purifying and removing nickel, cobalt and germanium and the zinc powder by taking the chalcanthite as the activating agent.

The invention also aims to provide a control method for adding acid into the solution in a continuous purification state.

The invention also aims to provide a method for preparing Sb on the basis₄O₅Cl₂The zinc powder replacement continuous purification nickel, cobalt and germanium removal device with chalcanthite as an activating agent and the control method thereof realize the continuous deep purification nickel, cobalt and germanium removal of the solution after copper and cadmium removal at one section with different cobalt concentrations.

Specifically, consistent with the claims, the present invention consists of the following processes:

a zinc sulfate solution continuous deep purification removes apparatus and control method of nickel cobalt germanium, the continuous purification apparatus that two-stage purification removes nickel cobalt germanium is by the zinc hydrometallurgy a plurality of continuous stirred tank reactors that are commonly used are connected in series and made up, neutral leachate removes copper cadmium through one section, the back liquid of copper cadmium removal that obtains, carries on two-stage removal nickel cobalt germanium again, the back liquid of copper cadmium removal trickles naturally from No. 1 reactor to the next reactor, until the last reactor, characterized by: adding a certain amount of zinc powder and an activating agent into the reactor No. 1 at the same time according to a certain interval time and interval; continuously adding a proper amount of sulfuric acid or electrolytic waste liquid into the purification system; then, zinc powder and an activating agent continuously flow through the purification system under the conditions of a certain temperature range and continuous stirring to react with the first-stage copper and cadmium removing solution for a period of time, and then cobalt, nickel and germanium are removed; and continuously carrying out liquid-solid separation on the slurry containing the purified slag and the purified liquid flowing out of the last reactor to obtain the purified slag and the purified liquid.

The continuous stirring reactor adopts a lower inlet and an upper outlet; the liquid outlet of the continuous stirring reactor is positioned on the liquid level of the continuous stirring reactor, and the liquid outlet mode is liquid level overflow.

The equipment for continuously and deeply purifying and removing nickel, cobalt and germanium by zinc hydrometallurgy and the control method are characterized in that zinc powder and an activating agent are intermittently added, a certain amount of zinc powder and the activating agent are intermittently added according to a certain interval time, and the interval time is 40-60%, preferably 45-55% of the average residence time of a solution of a section of solution after copper and cadmium removal in a No. 1 reactor; the quantity of the zinc powder and the activating agent added each time is the quantity of the zinc powder and the activating agent required by the solution after the copper and cadmium removal of the continuous purification system flowing into the solution after the copper and cadmium removal of the continuous purification system in the interval time multiplied by the unit volume of the zinc powder and the activating agent. The activator and the zinc powder are added in a solid state and simultaneously added, and the activator at least contains chalcanthite and Sb₄O₅Cl₂。

Continuously adding sulfuric acid or electrolytic waste liquid in the purification process, wherein the adding place is a No. 1-4 continuous stirring reactor, and preferably adding the sulfuric acid or the electrolytic waste liquid in the No. 1 reactor; the adding speed is 5-20% of the adding amount of the zinc powder in unit volume multiplied by the liquid volume after the copper and cadmium are removed in one section flowing in per unit time, the adding amount is the sulfuric acid net content of the sulfuric acid or the electrolytic waste liquid, and OH in the purifying liquid flowing out of the last reactor of the purifying system is controlled^-The concentration is 0.01 to 0.06mol/l, preferably 0.015 to 0.05 mol/l.

Adding an appropriate amount of activator according to the multiplication of the unit volume of the first-stage copper and cadmium removal liquid by the liquid flow rate, wherein the adding amount of the activator of the first-stage copper and cadmium removal liquid in the unit volume is adjusted according to the cobalt concentration of the solution, and specifically, Sb is controlled according to the cobalt concentration according to the copper-cobalt ratio and the antimony-cobalt ratio in a certain range₄O₅Cl₂And the addition amount of the chalcanthite, wherein the copper-cobalt ratio and the antimony-cobalt ratio are as follows: the copper-cobalt ratio is the ratio of the weight of copper contained in the added chalcanthite to the weight of cobalt in the solution, and the antimony-cobalt ratio is the weight of Sb added₄O₅Cl₂The ratio of the weight of antimony in the solution to the weight of cobalt in the solution; when the concentration range of cobalt is 2-120 mg/l, the ratio of copper to cobalt is 1.2-0.32, the ratio of antimony to cobalt is 0.5-0.16, the higher the concentration of cobalt is, the lower the corresponding ratio of copper to cobalt and antimony to cobalt is, and the more or less chalcanthite and Sb are required according to the concentration of cobalt in the post-liquid₄O₅Cl₂The amount added.

The zinc powder required by the unit volume is the adding amount of the whole zinc powder according to the cobalt concentration of the liquid before cobalt removal and the cobalt removal capacity of the zinc powder, the cobalt removal capacity of the zinc powder is the weight (mg) of cobalt removed by the zinc powder in unit weight (g), the adding amount of the zinc powder is 1.5-4.25 g/l when the cobalt concentration range is 2-120 mg/l and the cadmium concentration is below 50mg/l, the corresponding adding amount of the zinc powder is in the cobalt concentration range, the cobalt removal capacity of the zinc powder is 1.33-28.23 mg Co/(g), and the higher the cobalt concentration is, the higher the cobalt removal capacity of the zinc powder is; when the cadmium concentration exceeds 50mg/l, the adding amount of the zinc powder is increased according to the cadmium concentration increase at least according to the theoretical amount of cadmium removal by replacement, and the adding amount of the zinc powder is increased or decreased according to the concentration requirement of the purified liquid cobalt, but the adding amount of the zinc powder cannot be lower than 1.5g/l at least.

The number of the plurality of reactors connected in series is at least 2, and preferably 3-4; the period of time is the average residence time of the liquid after copper and cadmium removal in the continuous purification system and ranges from 90 minutes to 150 minutes; the purification temperature is 80-90 ℃.

The zinc powder for continuously purifying and removing nickel, cobalt and germanium can use electric furnace zinc powder, metal atomized zinc powder and distilled zinc powder, and the activating agent is chalcanthite and Sb₄O₅Cl₂。

The purified liquid can reach Co <0.5mg/l, Ni <0.1mg/l and Ge <0.02mg/l within 90 minutes; co is less than 0.1mg/l, Ni is less than 0.1mg/l, and Ge is less than 0.02mg/l for 120-150 minutes.

To further illustrate the context of the present invention, the following description is made with respect to these processes.

In view of the above-mentioned patents and research papers, most of them do not pay attention to the distinction between intermittent purification and continuous purification, but the two are not considered to be greatly different, but obviously, the two have great difference, which is shown in that under the condition of the same cobalt concentration, the initial concentration of the discontinuous purification is far greater than the cobalt concentration of the continuous purification reactor No. 1, this is caused by the known dilution effect in the continuous purification process, and the research results of the reaction engineering show that to realize the effect of the discontinuous experiment, a plurality of full mixed flow reactors are connected in series, however, the conclusion is deduced by adopting liquid-liquid reaction, and the particularity of the cobalt purifying and removing process is not considered, the comparative research of the continuous cobalt removal purification process and the discontinuous purification cobalt removal process is not reported, which is one of the main reasons that the deep purification is not realized for a long time by adopting an antimonate purification method to remove cobalt in the zinc hydrometallurgy purification.

The inventor considers that: the difference between continuous and discontinuous purification is the key to solving the problem of continuous purification and cobalt removal in the current industrial practice. In intermittent purification, when a copper-antimony compound is used as an activating agent for removing cobalt in a zinc sulfate solution, numerous researches show that most of copper and antimony in the solution are quickly replaced and removed by zinc powder in the initial reaction stage, cobalt is also replaced and removed by most of cobalt in the stage, but long reaction time is needed to meet the requirement of deep purification of cobalt, but the cobalt is easily redissolved if the reaction time is too long, and the effect is not good in industrial practice because the amount of zinc powder is increased or the zinc powder and the activating agent are supplemented in a purification reactor.

The kinetic study of the intermittent purification cobalt removal shows that the cobalt concentration is rapidly reduced in the initial stage of the reaction, but the reduction speed of the cobalt concentration is slowed down in the later stage, and long time is usually needed for achieving deep purification. The examination of the copper-antimony concentration in the solution over time shows that the copper-antimony has been displaced to a lower concentration early in the reaction and that the copper-antimony concentration in the solution is very low later in the reaction, and for this phenomenon, the inventors believe that: the purification of cobalt may consist of two stages: the first stage is that zinc powder, activating agent and impurity elements in the cobalt-removing precursor solution act together to form a high-speed cobalt-removing section of the microcell, in the first stage, the added zinc powder, copper and antimony in the activating agent and metal impurities in the solution such as cobalt and the like react together to form active zinc powder with the surface covered with impurities such as copper, antimony, nickel, cobalt, cadmium and the like, so that the microcell with the metal impurities such as cobalt and the like is formed, and the process of forming the microcell is called as preactivation by the inventor. After the preactivation process is finished, the formed preactivated zinc powder further finishes the deep purification of metal impurities, particularly cobalt, in the subsequent reaction process, and the subsequent removal of impurities such as cobalt and the like is carried out by a micro battery generated in the preactivation section. The inventors refer to this hypothesis of the reaction process as the preactivation cobalt removal hypothesis.

In the intermittent purification process, the process is naturally carried out, namely, the pre-activation of the zinc powder is firstly carried out at the initial stage of the reaction, and the cobalt removal of the activated zinc powder is further completed at the later stage.

In the traditional continuous purification process, the continuous feeding of zinc powder and an activating agent is generally adopted, most of zinc powder and the activating agent in the electrolytic zinc plant are continuously fed in the reactor No. 1, and part of zinc powder and the activating agent are also fed in the

subsequent reactors

2, 3 and 4 in part of the plant. The operation mode is used for removing copper and cadmium at the first stage, and achieves better effect, but the operation mode has poor effect on removing nickel and cobalt at the second stage. In this regard, based on the inventors' analysis of the batch process, the process of continuously feeding zinc powder and activator in reactor No. 1 may suffer from two problems: the first problem is that the concentration of cobalt and other impurities in the solution is greatly diluted in the No. 1 reactor, so that the reaction process speed is reduced, and the activation process of zinc powder is influenced; the second problem is that the action of the continuously added zinc powder and the activator is disturbed, i.e. the added activator does not react only with the newly added zinc powder to form a preactivated zinc powder containing a large number of microcells, but rather a part of it reacts with the already formed microcells, which results in non-uniformity of the microcell components and reduces the utilization of the zinc powder and the activator.

Based on the hypothesis that the cobalt removal process forms a micro battery through the preactivation as described above, and then the deep cobalt removal of the micro battery is performed through the micro battery, the inventor believes that the continuous addition of zinc powder and an activator causes the copper and antimony in the activator to be kept at a low concentration during the continuous purification, that is, the added activator not only acts with the added zinc powder, but also acts with a large amount of slag in a reactor.

Based on the above analysis, the present inventors considered that the existing continuous purification process using a method of continuously adding zinc powder and an activating agent has a disadvantage in that the results of the intermittent experiment are simply directly used in a continuous stirred reactor, and the difference between the two is not considered, and the particularity of the purification cobalt-removing process is not considered.

Obviously, in order to achieve the effect of discontinuous purification in the continuous purification process, the particularity of the cobalt removal process must be considered, that is, certain conditions must be firstly provided in the reactor No. 1 in a continuous state so that the preactivation can be smoothly carried out, and further, the deep purification is realized in the subsequent reactors in series. On the other hand, discontinuous experiments show that the zinc powder is dissolved along with the extension of the reaction time, and the excessive reaction time inevitably causes the re-dissolution of the cobalt in the slag, so that the excessive retention time of the slag in the system in the continuous purification process is avoided to avoid the re-dissolution of the purified slag in the reactor.

According to the hypothesis of preactivation and cobalt removal of the cobalt removal process of the inventor, it is obvious that the process is realized by firstly carrying out intermittent preactivation in one reactor and then continuously feeding preactivated slurry into a continuous reactor, but the experimental result and the attempt of the inventor show that the mode of adopting intermittent preactivation and continuous feeding of reaction slurry has complicated operation connection; the use of a pipeline reactor is another way to achieve the above process, but it is obvious that the pipeline reactor is far more complicated in structure and control than a continuous stirring reactor, which inevitably leads to difficulties in industrial application.

After various combined attempts, the inventors found that: in the existing continuous purification system consisting of a plurality of continuous reactors connected in series, the aim can be achieved by adopting intermittent zinc powder and an activating agent, namely, the existing continuous zinc powder and the activating agent are changed into intermittent zinc powder and the activating agent according to certain interval time. In the adding mode, the concentration of antimony and copper in the solution reaches a peak value quickly in a short time after the zinc powder and the activating agent are added, so that the preactivation reaction of the newly added zinc powder and the activating agent is facilitated, the process is similar to the intermittent purification, after the preactivation of the zinc powder and the activating agent is completed, the zinc powder and the activating agent added into the No. 1 reactor continuously react with the solution to complete the preactivation process and carry out the cobalt removal reaction with impurities in the impurity-containing solution in the subsequent intermittent period, and simultaneously, the generated slag is continuously brought into the subsequent purifying reactor by the added solution, so that the secondary effect of the activated zinc powder and the newly added activating agent in the No. 1 reactor is greatly reduced. The pre-activated slurry continuously flows out of the reactor No. 1, and further cobalt removal is completed in the subsequent reactors No. 2, 3, 4 or 5. When zinc powder and an activating agent are added intermittently, the inventor surprisingly discovers that the concentration fluctuation of the solution cobalt which is worried about originally does not occur, but rather, because the high activity of the preactivated zinc powder well avoids the fluctuation, the cobalt concentration of the reactor No. 1 is lower than that of the reactor with continuous addition of the zinc powder and the activating agent.

For the continuous purification process and the addition of sulfuric acid, another patent application named "a method for purifying aqueous zinc sulfate solution from nickel, cobalt and germanium" filed by the present inventors is known in the patent application₄O₅Cl₂+ when chalcanthite is used as the activator, a small amount of sulfuric acid is added to control the OH of the solution in order to obtain a better cobalt removal effect^-Concentration, in intermittent purge, acid was added before zinc fines and activator, in continuous purge, we found that sulfuric acid was added continuously in or before reactor No. 1 and the OH of the effluent of the last reactor was controlled^-And the concentration can obtain better cobalt purification and removal effects.

The method obviously improves the cobalt removal process in the continuous purification process, and basically achieves the effect of discontinuous purification. Obviously, based on the above hypothesis, zinc powder and activator are preferably added in the continuous purification cobalt-removing process in reactor No. 1 of the continuous purification system consisting of a plurality of continuously stirred reactors. Of course, it is also possible to add small amounts of zinc powder to other reactors during continuous purification, for example, adding small amounts of zinc powder to reaction nos. 3 or 4 can control the concentration of impurities such as cadmium and thallium, but has no effect on cobalt removal.

From the inventors' analysis of the cobalt removal process in reactor No. 1, it is clear that the deposition of excess activated zinc fines in reactor No. 1 is detrimental to the pre-activation process with newly added zinc fines and activator, and the use of intermittent addition solves some of the problems, but in the laboratory we use the same inlet and outlet means as in the industry: when the zinc powder flows in and out from the top, the zinc powder or the active slag is difficult to deposit in the reactor No. 1, so that more zinc powder is left in the reactor No. 1, and the phenomena occur in the reactors No. 2, No. 3 and No. 4 because the flow velocity in the guide pipe is slow, the slag is deposited in the guide pipe, and partial slag is deposited in the reactors. The slag accumulation of the reactor No. 1 increases the secondary reaction of newly added activating agent and accumulated slag, affects the pre-activation process, causes the cobalt removal effect to be poor, and also causes the re-dissolution of part of purified slag caused by excessively long stay in the reactor. Therefore, all continuous stirring reactors in the continuous purification experimental device are changed into downward feeding and upward discharging, and the problem is solved. Obviously, in industry, the phenomenon that the flow rate is large and the flow velocity of liquid in the guide pipe is large can be relieved to a certain extent. When the flow is large, the reactor No. 1 can be used for intermittent continuous purification provided by the invention by adopting an upper inlet and lower outlet mode, based on analysis of the continuous purification process, the reactor can be used as long as the slag in the reactor is ensured not to be deposited and the position of a liquid outlet which flows into the next reactor is favorable, but obviously, the upper outlet mode that the liquid outlet is positioned on the liquid level, namely the liquid level overflow mode is more favorable for discharging the slag as soon as possible, and the lower outlet mode is unfavorable for the slag to rapidly flow out of the reactor, so the liquid level overflow mode is preferably adopted by the invention, namely the liquid outlet is positioned on the liquid level of the reactor.

The activators and the amounts added to them used in the present invention are already present in the present contextThe inventor also applies for the method for removing nickel, cobalt and germanium by purifying zinc sulfate aqueous solution, and the activator adopts Sb₄O₅Cl₂And Chalcanthitum, for specific explanation reference is made to the patent application; and controlling the solution OH by adding acid^-The better cobalt removal effect of purification can be obtained when the concentration is reached, and the related description and the embodiment refer to the application documents of the patent; OH in solution^-The concentration was determined by the method described in the inventor's application entitled "method for determining hydroxide concentration in Zinc sulfate solution". On the basis of the above inventions, the continuous deep purification of cobalt, nickel and germanium under different cobalt concentrations can be realized by adopting the equipment and the intermittent feeding mode provided by the invention.

In order to examine the reaction activity of the reactor slag, the inventor adopts the continuous liquid supply for a period of time, stops the liquid supply, adds the zinc powder and the activating agent, keeps the temperature and continues stirring for 30 minutes, and examines the activity of the reactor slag and the re-dissolution of the cobalt, and surprisingly discovers that all reactors are reduced to be below 0.1mg/l in 30 minutes, but the phenomenon does not occur by adopting the traditional feeding mode of continuously adding the zinc powder and the activating agent, which directly explains the superiority of adopting the intermittent feeding.

Since the method of the present invention is very different from the known continuous antimony salt purification method in terms of the results obtained, and since the antimony salt purification method lacks reliable theoretical support, the various improvements described in the present invention are described only with respect to experimental results, and according to the possible explanations given by the understanding of the process by the present inventors, the mechanism thereof needs to be further studied to confirm the explanations made by the present inventors. In conclusion, on the basis of the activator and the acid addition control method provided by the invention and by matching with a matching solution provided by the inventor, the improved antimony salt purification method can realize continuous deep purification and cobalt removal.

The following experiments are combined to further illustrate the specific contents of the present invention:

drawings

FIG. 1 is a flow chart of a three-stage continuous purification process employed in the present invention.

FIG. 2 is a purification system consisting of a plurality of bottom-in top-out continuous stirred reactors connected in series.

FIG. 3 is a single top-in bottom-out continuous stirred reactor.

FIG. 4 is a single bottom-in top-out continuous stirred reactor.

The reference numbers in the figures: 1-liquid inlet, 2-honeycomb duct; 3-a liquid outlet; 4-a stirrer; 5-a reaction vessel; reactor No. 6-1, reactor No. 7-2, reactor No. 8-3, and reactor No. 9-4.

The noun explains:

(1) up-in-down continuous stirring reactor

In the continuous stirring reactor shown in the attached figure 3, a liquid inlet is positioned at the liquid level of the reaction reactor, a liquid outlet is positioned below half of the height of the liquid level of the reactor, and solution or slurry flowing out of the previous reactor is guided to a liquid level outlet of the reactor to flow out through a guide pipe.

(2) Continuous stirring reactor with lower inlet and upper outlet

In the continuous stirring reactor shown in the attached figure 4, the liquid inlet is positioned above the liquid level of the reaction reactor, the solution or the slurry flowing out of the previous reactor is guided to the position below half of the height of the liquid level of the reactor through the guide pipe and flows into the reactor, and the slurry overflows out of the reactor from the liquid level.

(3) Purification system formed by connecting a plurality of continuous stirring reactors in series

As shown in the attached figure 2, the reactor is formed by combining the two continuous reactors in series, one section of liquid after copper and cadmium removal is added from the No. 1 reactor, the No. 1 reactor is the first reactor with the highest liquid level, the outlet of the No. 1 reactor is connected with the inlet of the No. 2 reactor, the outlet of the No. 3 reactor is connected with the inlet of the No. 3 reactor, the process is repeated until the last reactor is reached, the purified slurry continuously flows out of the last reactor from the last reaction and enters a filtering system, and the purified liquid and the purified slag are obtained after continuous filtering.

In order to further illustrate the content of the present invention, the following description is given with reference to the examples.

Detailed Description

The leachate (middle supernatant) produced by leaching has the following general solution components according to different raw material components:

100-190 g/l Zn, 5-25 g/l Mg, 2-10 g/l Mn, 50-2500 Mg/l Cd, 10-1500 Mg/l Cu, 1-10 Mg/l Ni, 2-120 Mg/l Co, 0.1-0.5 Mg/l Ge. After copper and cadmium are removed by replacing zinc powder in one section, the liquid after copper and cadmium removal in the first section comprises the following components:

100-190 g/l Zn, 2-120 Mg/l Co, 5-25 g/l Mg, 2-10 g/l Mn, less than 1Mg/l Cu, 1-100 Mg/l cadmium, 1-6 Mg/l nickel, 0.1-0.3 Mg/l germanium, and cobalt, nickel and germanium as impurities mainly influencing electrolysis. The industry accepted standards for deep purification are Co <0.1mg/l, Ni <0.1mg/l, Ge <0.02 mg/l.

The solution used in the embodiment and the experiment of the invention adopts the actual second-stage purified solution of a zinc hydrometallurgy plant, and then dilute sulfuric acid solution of analytically pure reagents of cobalt sulfate and cadmium sulfate, nickel sulfate and germanium dioxide is added to adjust the impurity concentration. The antimony compound is antimony potassium tartrate and Sb₂O₃And Sb₄O₅Cl₂The amount of copper-antimony metal added is controlled to be the same. The molecular formula of the potassium antimony tartrate is C₄H₄KO₇Sb·1/2H₂O, purity 97%, antimony content 35.37%, Sb₂O₃The antimony content is 81.86% for technical grade product (98%), and Sb is Sb in the specification unless otherwise stated₄O₅Cl₂Is named as Sb applied by the inventor in the inventor laboratory₂O₃Direct preparation of Sb with aqueous hydrochloric acid₄O₅Cl₂The process described in the patent application document, antimony content 76.5%. The copper compound adopts chalcanthite, and the molecular formula is CuSO₄·5H₂And O, the purity is industrial grade (98%), the copper content is 24.95%, the copper content is weight percent, and the antimony copper content in the specification is calculated according to the copper and antimony content of the compound. The sulfuric acid added in the specification is the net content of sulfuric acid, and 98% (weight percent) of industrial sulfuric acid is adopted. In the actual process, the electrolytic waste liquid can be added instead of adding industrial sulfuric acid, and the addition amount is converted according to the content of the sulfuric acid in the electrolytic waste liquidThe content of sulfuric acid in the electrolysis waste liquid is 150-200 g/l, and the content of zinc is 40-60 g/l.

Example 1

This example is a comparative experiment of intermittent purification and continuous purification in different modes of 10mg/l cobalt-containing zinc sulfate solution, the experimental temperature is 80 ℃, and the first-stage after copper and cadmium removal solution comprises the following components: zn160g/l, Co 10mg/l, Cd30 mg/l. The amount of the test solution was 1 liter.

Intermittent experimental equipment: the constant temperature water bath with the heating and temperature control device is used for carrying out the experiment in a beaker with the effective volume of 2 liters, the amount of the experiment solution is 1 liter, and a polytetrafluoroethylene mechanical stirring paddle is used for stirring.

Intermittent experimental procedures: heating the cobalt removal precursor solution to a specified temperature, adding a proper amount of sulfuric acid, adding zinc powder and an activating agent at the same time, maintaining the temperature, carrying out a cobalt removal experiment under a stirring state, wherein the reaction time is 180 minutes, starting to sample after reacting for 60 minutes to measure the cobalt concentration, and sampling 20ml each time at an interval of 30 minutes until 180 minutes.

The zinc powder used was electric furnace zinc powder, the composition of which is shown in Table 1.

TABLE 1 Zinc powder composition of electric furnace

Total Zn%	ZnO％	Effective zinc	Pb％	Cd％
					88.46	6.11	82.25	1.25	0.33

The contents in the table are weight percentages, and the solid contents are weight percentages unless otherwise specified in this specification.

First, a batch experiment was conducted, experiment No. 1 a.

Calculating the adding amount of zinc powder and an activating agent: the activator is chalcanthite and Sb₄O₅Cl₂(simultaneous addition of solids), copper 10.3mg/l, antimony 2.8mg/l, corresponding copper to cobalt ratio of 1.03 and antimony to cobalt ratio of 0.28. The adding amount of Chalcanthitum is 10.3/0.2495 ═ 41.28(mg), Sb₄O₅Cl₂The addition amount is 2.8/0.765 which is 3.66mg, and the chalcanthite and Sb are added in the following examples in the description₄O₅Cl₂The amounts of addition of (A) are calculated in the same manner and will not be described.

Calculating the adding amount of the zinc powder and the adding amount of the sulfuric acid: the addition amount of sulfuric acid is 2.0 × 0.15 and 0.3(g/l), respectively, when the addition amount of sulfuric acid is 2.0g/l and the addition ratio of sulfuric acid is 0.15. The results obtained are shown in Table 1A.

TABLE 1A

And (3) measuring the concentration of cobalt in the solution by adopting an anodic voltammetry stripping method, wherein the equipment is Switzerland VA797, and the detection limit is 0.005mg/l, which is the same as the following.

As can be seen from Table 1A, with intermittent purging with the above-described activator, a depth of purging of cobalt <0.1mg/l was achieved in 120 minutes without redissolution in 180 minutes.

The continuous purification experiment was carried out on the basis of the above intermittent experiment, using a solution of the same composition as the intermittent experiment, with experiment number 1b, and the same temperature and intermittent experiment.

Continuous purification equipment: the device adopted in the continuous cobalt removal experiment adopts a continuous purification system formed by connecting 4 glass continuous stirring reactors with effective volume of 1 liter in series, the solution inlet and outlet modes of the 4 reactors are all that the solution enters and exits from the bottom as shown in the attached figure 2, and each reactor is provided with an independent automatic temperature control device and a stirring device. The solution is continuously added by a peristaltic pump according to a given flow rate, and the zinc powder and the activating agent are manually added in fixed time and quantity.

The calculation method of the continuous purification experiment parameters comprises the following steps:

firstly, setting a liquid supply speed according to experimental requirements, and then calculating the total average residence time of the solution according to the continuous purification system, wherein the calculation formula of the total average residence time of the continuous purification system is as follows:

then setting an interval proportion according to experimental requirements, and calculating the feeding interval time according to the proportion, wherein the calculation formula is as follows:

the interval ratio in this equation is the ratio of the feed interval time to the average residence time of the solution in reactor No. 1. In this example, the number of reactors was 4, the volume of a single reactor was 1 liter, and the liquid feed rate was 2 liters/hour, and the total average residence time of the solution was 4 × 1 liter/(2 liters/hour) 2 hours, and the interval ratio was set to 50%, and the feed interval time was (2 hours/4) × 50%: 0.25 hours and 15 minutes.

Then, the adding amount of the zinc powder and the activating agent is calculated according to the liquid flow rate and the obtained adding interval time. First, the volume of the solution flowing into the purification system in the intermittent time is calculated according to the formula:

in this example, based on the above calculations, the time between dosing is 15 minutes, and the volume of solution flowing into the purification system during this time is: 2 l/hr × 15 min/60-0.5 (l). The charging interval times in the following examples are calculated by this method, and the calculation of the charging interval times will not be described.

The total average residence time is calculated according to the liquid supply speed and is 4 multiplied by 1 liter/(2 liters/hour) and 2 hours, the acid is pre-adjusted to 0.2g/l after the copper and the cadmium are removed in one section, and the adding amount of the zinc powder and the activating agent in unit volume is calculated according to the adding amount of the intermittent experiment.

The amounts of zinc powder and activator added were then calculated at 15 minute intervals by first calculating the amount of solution flowing into the reactor over 15 minutes, and when the addition interval was 15 minutes, the volume of solution flowing into the purification system No. 1 reactor over 15 minutes was 2 liters/hour x (15 minutes/60) was 0.5 liters.

According to the results of intermittent experiments, the adding amount of zinc powder per liter of solution is 2g, the volume of the flowing solution in 15 minutes is 0.5 l, and the zinc powder to be added is 0.5 l multiplied by 2 g/l-1 g, namely the adding amount of the zinc powder is 1g each time. In the same manner, the Chalcanthitum addition for the intermittent test was 41.28 mg/L, Sb₄O₅Cl₂Is 3.66mg, 0.5 l of solution is added: chalcanthitum 0.5L × 41.28 mg/L-20.64 mg, Sb₄O₅Cl₂The weight was 0.5 l × 3.66 mg/l, 1.83 mg. The following examples, which all show only the time between charges and the amount of activator and zinc powder added per unit volume of solution, do not describe the physical amount of each charge.

The continuous experimental procedure was: firstly, slotting, adding the copper and cadmium removing solution with the same intermittently purified components into a reactor, heating the solution to a specified experimental temperature, adding 1.5 times of the adding amount of the zinc powder, the activating agent and the sulfuric acid into the reactor, reacting for 1 hour, completing slotting, and sampling in a No. 4 reactor to determine the cobalt concentration. After the grooving is finished, the first stage of copper and cadmium removing solution is continuously fed into the reactor No. 1 at a liquid feeding speed, which is 2L/h in this example.

After the continuous liquid supply is started, sampling is started after one hour, the cobalt is sampled and measured from a reactor No. 1-3 every hour, and the reaction No. 4Determination of cobalt concentration and OH in reactor effluent^-Concentration, after the liquid is supplied for 6 hours, stopping supplying the liquid, keeping the temperature and stirring for 30 minutes, stopping the experiment for 6.5 hours, measuring the cobalt concentration of the No. 1 to No. 4 reactors to evaluate the activity of the slag in each reactor, and measuring OH of the No. 4 reactor^-And (4) concentration. And (4) after the test is finished, filtering all slurry in each reactor, washing, drying and weighing the slag, and then carrying out elemental analysis.

The results of the solution are shown in Table 1B, and the results of the 6.5 hour cobalt slag are shown in Table 1C, wherein the contents of the elements in the purified slag in Table 1C are all in weight percent, and the contents of the elements in the purified slag in the other examples in this specification are all in weight percent.

The slag ratio in Table 1C was calculated by dividing the weight of slag in the vessel at 6.5 hours by the amount of zinc powder charged per hour, and the slag ratio in this specification was calculated in this manner.

As can be seen from tables 1B and 1C, the results obtained in the continuous purification experiment are basically the same as those obtained in the intermittent experiment, the cobalt content of the effluent of the reactor No. 4 after being filtered reaches the requirement of less than 0.1mg/l within 120 minutes of the retention time, the cobalt concentration of the effluent of the intermittent experiment is basically consistent with that of the effluent of the reactor No. 4 after being filtered, and the cobalt concentration of the effluent of the reactor No. 3 and the reactor No. 4 after being stopped and stirred for 30 minutes is consistent with that of the effluent of the intermittent experiment after being kept warm for 150 minutes. And the cobalt in each reactor is not redissolved and is rapidly reduced to be below 0.1mg/l, which shows that the slag in each reactor keeps higher activity in the continuous operation process.

TABLE 1B

Injecting: OH-in the table is OH-concentration in the effluent of reactor No. 4, as follows.

TABLE 1C

Component (%)	Slag weight (g)	Slag rate%	Zn％	Co％	Cd％
						No. 1 reactor	1.5437	77.19	82.29	0.89	3.29
No. 2 reactor	1.074	53.70	70.68	1.76	4.90
						No. 3 reactor	0.7085	35.43	67.85	1.80	6.14
No. 4 reactor	0.6771	33.86	66.89	2.03	6.17

To compare the effect of continuous addition of zinc powder and activator, which is common in industry, experiment number 1 c. Under the same conditions of the experiment, grooving is completed, zinc powder and the same activating agent are continuously added into the solution commonly used by a zinc hydrometallurgy enterprise, the added activating agent is dissolved in a section of solution after copper and cadmium removal, which is added with 0.2g/l of sulfuric acid, the zinc powder adopts a small amount of solution after cobalt removal, slurry is mixed (50 g/l of zinc powder), the zinc powder is continuously added into a reactor No. 1 by a peristaltic pump under the stirring state, the adding speed of the zinc powder is 2 liters/(hour). times.2 grams/liter is 4 grams/(hour), the cobalt concentration is detected by sampling from the reactor No. 1-4 per hour, the liquid supply is stopped after 6 hours of continuous liquid supply, the liquid supply is stopped, the temperature is continuously maintained, and the stirring is carried out for 0.5 hour. And after the test is finished, all slurry in each reactor is filtered, washed and dried by slag, weighed and subjected to element analysis. The results of the obtained solution are shown in Table 1D, and the results of the 6.5 hour cobalt slag are shown in Table 1E.

TABLE 1D

TABLE 1E

Component (%)	Slag weight (g)	Slag rate%	Zn％	Co％	Cd％
						No. 1 reactor	0.812	40.60	53.30	1.25	6.12
No. 2 reactor	0.5345	26.73	40.72	2.06	8.75
						No. 3 reactor	0.4516	22.58	32.12	2.79	10.15
No. 4 reactor	0.3334	16.67	29.34	2.80	10.33

As is apparent from the results in tables 1D and 1E, the purification effect of <0.1mg/l cobalt was not obtained with the conventional continuous addition of zinc powder and activator. The results obtained in tables 1D and 1E are compared with those in tables 1B and 1C, and the difference is large, and the cobalt content of the reactor No. 4 in experiment 1C gradually increases with time, and the reactor is in an unstable state. Meanwhile, after the liquid supply and the heat preservation are stopped for a half hour, the cobalt concentration of each reactor is only slightly reduced, but is not reduced to be below 0.1mg/l, which indicates that the activity of the slag is low. Since the experiment only changes the addition mode of the activator, it can be seen that the traditional continuous addition of zinc powder and the activator are not beneficial to purifying and removing cobalt under the condition of adding a small amount of acid, and the results in table 1E also show that: the slag rate and the zinc content of the slag are lower than those of the experiment 1b, which shows that the method causes more zinc powder to be dissolved.

Comparing the results of the experiments in tables 1B and 1D, it was surprisingly found that when the batch addition of zinc powder and activator was used (experiment 1B), the cobalt concentration in reactor No. 1 did not fluctuate in cobalt concentration, resulting in an increase in cobalt content, but was lower than in the continuous addition of zinc powder and activator (experiment 1 c); the cobalt concentration of the rest 3 purification reactors in the intermittent feeding experiment is obviously lower than that of the traditional operation method for continuously adding the zinc powder and the activating agent, and when the intermittent addition of the zinc powder and the activating agent is adopted after the liquid supply heat preservation stirring is stopped for half an hour, the cobalt concentration of each reactor is reduced to be below 0.1mg/l, which shows that the cobalt removal efficiency of the zinc powder is greatly improved by adopting the intermittent addition of the zinc powder and the activating agent, the activity of each purification reactor keeps better activity, but the experiment (experiment 1c) adopting the continuous addition of the zinc powder and the activating agent does not have the phenomenon, which shows the superiority of the intermittent addition of the zinc powder and the activating agent mode provided by the inventor, and also proves that the inventor analyzes the cobalt removal process from a preactivation section and a micro-battery deep cobalt removal section.

The results of experiment 1c also confirm that the conventional continuous addition of zinc powder and activator is the main cause of poor cobalt removal effect in production practice, and the present inventors have considered that continuous purification by this operation commonly used in the industry is insufficient. Obviously, the intermittent feeding mode has obvious advantages.

For comparison, the antimony compounds of potassium antimony tartrate and Sb commonly used in industry are compared under the condition of adding zinc powder and activating agent intermittently₂O₃The two kinds of common antimony are adopted respectively for the applicability of cobalt removal in a continuous stateAmount of metal such as compound substituted for Sb used in experiment 1b₄O₅Cl₂The amount of copper antimony metal added to the activator was the same as in the experiment listed in Table 1B (experiment 1B), and the experimental equipment and procedure were the same as in experiment 1c, and a batch-wise addition purification cobalt removal comparative experiment was performed.

The antimony compound in the activator is changed into antimony potassium tartrate, and the experimental number is 1 d. The results of the obtained solution are shown in Table 1F, and the results of the residue are shown in Table 1G.

TABLE 1F

TABLE 1G

Component (%)	Slag weight (g)	Slag rate%	Zn％	Co％	Cd％
						No. 1 reactor	1.1176	55.88	81.39	0.95	6.27
No. 2 reactor	0.6744	33.72	78.43	1.41	8.59
						No. 3 reactor	0.5845	29.23	69.3	1.6	9.02
No. 4 reactor	0.5134	25.67	69.02	1.86	10.32

As can be seen from tables 1F and 1G, even when the continuous purification for removing cobalt is performed by the intermittent feeding method proposed by the present inventors, the cobalt concentration in the reactor No. 4 gradually increases with time, and the cobalt re-dissolution occurs in the reactor No. 4 after the liquid supply is stopped for 30 minutes, using antimony potassium tartrate and chalcanthite as the activators. The antimony potassium tartrate and the chalcanthite are used as activating agents, and a small amount of acid is added to control the OH of the solution^-Under the condition of concentration, good purification results can not be obtained, which probably is the reason that the acid is not added in the industrial continuous purification, and the results are consistent with the results of the intermittent experiment which is named as a method for purifying the nickel, cobalt and germanium from the zinc sulfate aqueous solution and is applied by the inventor.

To compare Sb₂O₃As the effect of the antimony source of the activator, the antimony compound in the activator is changed into Sb₂O₃Experiment number 1 e. The amounts of copper and antimony added were the same as those in the experiment listed in Table 1B (experiment No. 1B), and the same applies to the experimentThe intermittent addition is adopted, the addition intermittent time and the addition amount of the zinc powder and the activating agent each time are completely the same as those in experiment 1b, the experimental equipment and the procedure are completely the same as those in experiment 1b, the change results of the obtained solution are shown in Table 1H, and the slag results are shown in Table 1I.

TABLE 1H

TABLE 1I

Component (%)	Slag weight (g)	Slag rate%	Zn％	Co％	Cd％
						No. 1 reactor	1.2084	60.42	82.79	2.08	4.62
No. 2 reactor	0.8476	42.38	79.91	2.38	5.95
						No. 3 reactor	0.6140	30.70	76.85	2.49	6.21
No. 4 reactor	0.5214	26.07	76.24	2.87	5.65

As can be seen from the results in Table 1H and Table 1I, Sb was used₂O₃As antimony source and chalcanthite as activating agent, when the intermittent feeding mode proposed by the inventor is adopted to continuously purify and remove cobalt, the cobalt concentration does not reach the standard similar to the experiment adopting potassium antimony tartrate and chalcanthite<The result of the 0.1mg/l standard and the phenomenon of re-dissolution of the cobalt concentration in the reactor No. 4 is identical with the result of the intermittent experiment which is named as a method for purifying the zinc sulfate aqueous solution to remove the nickel, the cobalt and the germanium and is applied by the inventor. It is evident from the purified slag obtained in tables 1G and 1I that there is still a relatively large amount of zinc remaining in the slag, but after the liquid supply is stopped, re-dissolution of the cobalt slag occurs, which may be caused by the unstable structure of the microbattery formed by these two common antimony compounds.

It is obvious from the experiments in this example that the continuous adding of zinc powder and activator in the prior continuous purification process is performed by using Sb provided by the inventor₄O₅Cl₂The continuous purification operation of the chalcanthite activator is not sufficient because the particularity of the cobalt removal process in the intermittent purification and the continuous purification process is not considered. Taking into account the particularity of intermittent and continuous cleaningThen, the zinc powder and the activating agent are added intermittently and Sb provided by the inventor is adopted₄O₅Cl₂+ Chalcanthitum activator obtained a purification effect with a cobalt content of less than 0.1mg/l in the post-treatment solution (experiment number 1 b). Meanwhile, Sb₂O₃And antimony potassium tartrate re-dissolution of cobalt occurs in the reactor No. 4 even if the intermittent addition mode of the invention is adopted, which fully explains that antimony potassium tartrate and Sb₂O₃The two common antimony compounds have defects in continuous purification, and the Sb provided by the invention is also illustrated₄O₅Cl₂+ the superiority of chalcanthite as a replacement cobalt removal activator.

Example 2

This example is a time between charges experiment. It is clear that the key to the intermittent addition of zinc powder and activator is the time interval between feeds, for which different feed interval experiments were carried out using the same equipment as the continuous purification plant described in experiment No. 1b of example 1. The components of the solution used in the experiment are Zn170g/l, Cd30mg/l and Co 20 mg/l. The feeding intervals were calculated as the interval ratios of 40, 45%, 50%, 55%, and 60%, and the calculation procedure was the same as in example 1, and the corresponding feeding intervals were 12 minutes, 13.5 minutes, 15 minutes, 16.5 minutes, and 18 minutes, and the following are experimental results.

First, a batch experiment, which is designated experiment 2a, was conducted. The experimental equipment and procedure were the same as in experiment 1a of example 1.

The zinc powder used was an electric furnace zinc powder as listed in Table 1, the zinc powder addition was 2.25g/l, the sulfuric acid addition rate was 0.15 times and 0.34g/l, and the activators were Chalcanthitum and Sb₄O₅Cl₂(simultaneous addition of solids), copper was added in an amount of 15.6mg/l and antimony was added in an amount of 5.6mg/l based on the solution, and the results obtained are shown in Table 2A.

TABLE 2A

Experiment number	Time in minutes	0	60	90	120	150	180
								2a	Co mg/l	20	1.321	0.231	0.06	0.014	0.011

As can be seen from Table 2A, for the solution containing 20mg/l of cobalt, 0.06mg/l was reached at 120 minutes and 0.011mg/l was reached at 180 minutes.

On the basis, continuous purification cobalt removal experiments with different feeding intervals are carried out. The experimental equipment and experimental procedure were the same as in experiment 1b of example 1.

Adding the copper and cadmium removing solution with the same components for intermittent purification into each reactor, heating the solution to 80 ℃, adding the zinc powder, the activating agent and the sulfuric acid according to the addition amount of 1.5 times of the addition amount of the intermittent experiment, reacting for 1 hour, and finishing slotting. And a sample was taken from reactor No. 4 to determine the cobalt concentration, which was counted as the start time for the continuous purge.

After the grooving is completed, the 20mg/l of the copper and cadmium removing solution is continuously fed into the reactor No. 1 by a peristaltic pump at a set flow rate of 2 liters/hour, the feeding amount of the zinc powder and the activator per unit volume is the same as that of the intermittent experiment, and the corresponding zinc powder and the corresponding activator are added at different feeding intervals, the corresponding calculation mode is shown in example 1, and the following experiment results are shown.

12 minute addition interval experiments, run number 2B, with results shown in Table 2B.

As can be seen from the data in tables 2B, 2C, 2D, 2E, and 2F, at 12 minutes (Table 2B), the cobalt content of the effluent from reactor 4 was higher than 0.1mg/l after filtration, and when the time was extended to 13.5 minutes (Table 2C), the goal of less than 0.1mg/l cobalt content of the effluent from reactor 4 was achieved, and when the time between feeds was extended to 16.5 minutes (Table 2E), the cobalt content of the effluent from reactor 4 was less than 0.1mg/l after filtration. The addition interval was further extended to 18 minutes (Table 2F) and the cobalt content rose to above 0.1mg/l after filtration of the reactor effluent No. 4.

TABLE 2B

13.5 minute addition interval time experiment, run number 2C, results are shown in Table 2C.

TABLE 2C

15 minutes addition interval time experiment, run number 2D, results are shown in Table 2D.

TABLE 2D

16.5 minute addition interval experiments with run number 2E results are shown in Table 2E.

TABLE 2E

The 18 minute addition interval experiment, run number 2F, results are shown in Table 2F.

TABLE 2F

From the above results, it can be seen that a better cobalt removal effect can be obtained within a feeding interval of 13.5-16.5 minutes, and the cobalt removal effect is reduced due to too short or too long feeding interval time, and the corresponding better feeding interval proportion is 45-55%.

To further examine the effect of extended purge time on cobalt removal, the total residence time was increased to 2.5 hours, the feed time was (2.5/4) × 0.6 × 60 ═ 22.5 minutes calculated as 60% of the residence time of the solution in reactor No. 1, the volume of the solution flowing in during this time was 22.5/60 × 2.5 ═ 0.9375 (liters), the amounts of zinc powder and activator added each time were adjusted accordingly based on the volume of the solution, the first 3 reactor tank samples and reactor No. 4 effluent were taken every hour and tested for cobalt, test No. 2G, and the results of the solutions are shown in table 2G.

TABLE 2G

As can be seen from Table 2G, at longer intervals of 22.5 minutes, the effect of purifying cobalt was less effective than the 15 minute intervals, but slightly better than the 18 minute intervals, the 2 hour total residence time (Table 2F), but the cobalt concentration in reactor No. 4 increased with time due to the longer intervals, indicating that increasing the residence time is advantageous for cobalt removal, consistent with the results of the batch experiments.

From the experiment on the feeding interval time, it can be seen that the feeding interval time is from 12 to 22.5 minutes, after the reaction stops supplying liquid and the stirring is continued for 30 minutes in all the experiments, the cobalt does not redissolve, and the concentration in all 4 reactors is reduced to be below 0.1mg/l, which further proves that the activity of the zinc powder for removing the cobalt can be fully ensured by adopting the intermittent feeding of the zinc powder and the activating agent, and the result is far superior to the existing process adopting the continuous feeding of the zinc powder and the activating agent. The purification target that the cobalt content of the post-liquid is less than 0.1mg/l can be realized within the range of 45-55% of the average residence time of the No. 1 reactor at the feeding interval. The feed interval defined according to the invention is therefore 40% to 60%, preferably 45% to 55%, of the mean residence time of the reactor No. 1. It can also be seen that increasing the reaction residence time (table 2G) also achieved better cobalt removal when the batch feed method was used, which is clearly consistent with the results of the batch experiments with prolonged cobalt concentration reduction. The retention time of the solution in the purification system is 120-150 minutes, and the index that the cobalt content of the purified solution is less than 0.1mg/l can be realized.

Obviously, the mode of discontinuously adding zinc powder and the activating agent provided by the invention solves the problem of difference between discontinuous purification and continuous purification, and realizes deep purification in continuous purification.

Example 3

This example is a continuous purification of a 2mg/l cobalt-containing zinc sulphate solution, with a test liquid flow of 2 litres/hour and a test temperature of 80 ℃. The equipment and procedure for the batch experiment were the same as in experiment 1a, experiment number 3a, example 1. The cobalt removal front liquid comprises the following components: zn160g/l, Co 40mg/l, Cd30mg/l, Ni 2mg/l, Ge 0.3 mg/l. The activator adopts Sb₄O₅Cl₂The copper addition, measured as a solution, of Chalcanthitum was 6mg/l, the antimony addition was 2mg/l, the corresponding copper-cobalt ratio was 1.2, the antimony-cobalt ratio was 0.4, the zinc powder addition was 1.75g/l, and the acid addition was 0.15 times the weight of the zinc powder and was 0.26g/l, and the results of the intermittent cleaning shown in Table 5A are shown in Table 3A.

TABLE 3A

As can be seen from Table 3A, when the above activating agent is used for intermittent purification, the purification depth of cobalt is less than 0.1mg/l, the purification depth of nickel is less than 0.1mg/l, and the purification depth of germanium is less than 0.02mg/l within 120 minutes, and the cobalt is removed, and simultaneously, the nickel and the germanium all meet the deep purification requirement.

A continuous decontamination experiment was performed on the basis of experiment 3a, experiment number 3 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were the same as in experiment 1b of example 1, and the remaining experimental parameters such as liquid flow rate and time between additions were the same as in experiment 1b of example 1. The results for cobalt in the solution are shown in Table 3B, for nickel and germanium in the solution in Table 3C, and for cobalt residue at 6.5 hours in Table 3D.

TABLE 3B

TABLE 3C

TABLE 3D

Component (%)	Zn％	Co％	Cd％
				No. 1 reactor	81.80	1.95	3.52
No. 2 reactor	78.53	2.63	5.72
				No. 3 reactor	77.03	2.70	7.18
No. 4 reactor	75.39	2.75	8.09

From the results obtained in example 3, it can be seen that under the conditions of cobalt concentration up to 40mg/l, nickel concentration of 2mg/l and germanium concentration of 0.3mg/l, the purification effects of cobalt content of less than 0.1mg/l, nickel content of less than 0.1mg/l and germanium content of less than 0.02mg/l can still be achieved by using the present invention.

Example 4

This example is a continuous purification of Co120mg/l zinc sulphate solution containing cobalt with zinc dust in an electric furnace, the experimental liquid flow rate being 2 litres/hour and the experimental temperature being 80 ℃. The equipment and procedure for the batch experiment were the same as in experiment 1a, experiment number 4a, example 1. The cobalt removal front liquid comprises the following components: zn 175g/l, Co120mg/l, Cd 50mg/l, Ni 4mg/l, Ge 0.1 mg/l. The activator adopts Sb₄O₅Cl₂Copper is added in 43.2mg/l, antimony is added in 19.4mg/l, corresponding copper-cobalt ratio is 0.36, antimony-cobalt ratio is 0.16, zinc powder is added in 4.0g/l, acid is added in 0.15 times of the weight of the zinc powder and is 0.60g/l, the zinc powder is the electric furnace zinc powder listed in Table 1, and the zinc powder is the electric furnace zinc powder listed in Table 1Zinc powder, results of intermittent experiments are shown in table 4A.

TABLE 4A

A continuous decontamination experiment was performed based on experiment 4a, experiment number 4 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. Experimental equipment and procedure as in example 1, experiment 1b, with a liquid flow of 1.6 litres/hour, a total mean residence time of 150 minutes, a feed interval of 19 minutes, and the remainder of the conditions copper example 1, experiment 1 b. The results for cobalt in the solution are shown in Table 4B, the results for nickel germanium in the solution are shown in Table 4C, and the results for cobalt residue at 6.5 hours are shown in Table 4D.

TABLE 4B

TABLE 4C

TABLE 4D

Component (%)	Slag weight (g)	Zn％	Co％	Cd％
					No. 1 reactor	4.3610	85.36	3.15	2.66
No. 2 reactor	2.5428	79.55	4.44	3.81
					No. 3 reactor	2.4680	73.91	4.98	4.79
No. 4 reactor	2.3494	70.47	5.67	6.85

From the results of example 4, it can be seen that, in the case where the cobalt concentration of the solution before cobalt removal is as high as 120mg/l, the purification effects of cobalt content of the solution after purification being less than 0.1mg/l, nickel content of the solution after purification being less than 0.1mg/l, and germanium content of the solution after purification being less than 0.02mg/l can be achieved by using electric furnace zinc powder in 150 minutes.

Example 5

This example is a continuous purification experiment of 2mg/l zinc sulphate solution containing cobalt with distilled zinc metal powder, the experimental liquid flow rate is 2 liters/hour and the experimental temperature is 80 ℃. The equipment and procedure for the batch experiment were the same as in experiment 1a, experiment number 5a, example 1. Cobalt-removing front liquidThe components are as follows: 100g/l Zn, 2mg/l Co, 30mg/l Cd, 2mg/l Ni, 0.1mg/l Ge. The activator adopts Sb₄O₅Cl₂The copper addition, calculated as the solution, of the chalcanthite is 6mg/l, the antimony addition is 2mg/l, the corresponding copper-cobalt ratio is 1.2, the antimony-cobalt ratio is 0.4, the zinc powder addition is 1.75g/l, the acid addition is 0.15 times of the weight of the zinc powder and is 0.26g/l, the zinc powder is distilled metal zinc powder listed in Table 6, and the results of intermittent experiments are listed in Table 5A.

TABLE 5A

A continuous decontamination experiment was performed on the basis of experiment 5a, experiment number 5 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were the same as in experiment 1B of example 1, the other experimental parameters such as liquid flow rate and feeding interval were the same as in experiment 1B of example 1, and the results of cobalt content in the solution are shown in Table 5B. The results of cobalt content in the solution are shown in Table 5B, and the results of cobalt residue at 6.5 hours are shown in Table 5C.

The results for cobalt in the solution are shown in Table 5B, the results for nickel germanium in the solution are shown in Table 5C, and the results for cobalt residue at 6.5 hours are shown in Table 5D.

TABLE 5B

TABLE 5C

TABLE 5D

Component (%)	Slag weight (g)	Zn％	Co％	Cd％
					No. 1 reactor	1.5815	91.56	0.36	3.24
No. 2 reactor	1.0995	89.90	0.51	4.22
					No. 3 reactor	1.0605	87.51	0.59	5.33
No. 4 reactor	0.8697	84.87	0.74	6.34

As can be seen from tables 5B and 5C, the results of the cobalt content of the post-treatment solutions being <0.1mg/l, nickel <0.1mg/l and germanium <0.02mg/l were also obtained using electric zinc dust for the lower concentration zinc sulfate solution of 2mg/l, except that the amount of zinc dust added and the amount of activator added were not significantly reduced from the cobalt-containing solution of 10 mg/l.

Example 6

This example is a continuous purification of atomized zinc metal powder from a 10mg/l zinc sulphate solution containing cobalt. The zinc powder components used are shown in Table 6.

TABLE 6

Kind of zinc powder	Total Zn%	ZnO contains zinc%	Effective zinc%	Pb％	Cd％	Particle size
							No. 1 atomized metal zinc powder	99.7	0.15	98.55	0.05	0.01	<5-50 um accounts for 95%
No. 2 atomized metal zinc powder	98.9	0.41	98.40	0.55	0.01	<5-20 um accounts for 95%
							Distillation of metallic zinc powder	98.8	0.37	97.55	0.15	0.35	<2um accounts for 97 percent

The main objective of this experiment was to examine the applicability of different lead-containing atomized metallic zinc powders to continuous purification and cobalt removal, and the zinc powders used were the atomized metallic zinc powders nos. 1 and 2 listed in table 6, and the following results are the cobalt removal results of the atomized metallic zinc powders.

The equipment and procedure for the batch experiment were the same as in experiment 1a, experiment number 6a, example 1. The cobalt removal front liquid comprises the following components: zn150g/l, Co 10mg/l, Ni 2mg/l, Ge 0.3mg/l, activator Sb₄O₅Cl₂The copper addition amount calculated by the solution of the chalcanthite is 10.3mg/l, the antimony addition amount is 2.8mg/l, and the corresponding copper-cobalt ratio is 1.03 and the antimony-cobalt ratio is 0.28. The zinc powder was added in an amount of 2, 2.25g/l and the acid in an amount of 0.10 times the weight of the zinc powder, 0.2, 0.23g/l, respectively, and the results of the intermittent experiments are shown in Table 5A. Different amounts of lead (in the form of lead sulfate) were added during the experiment, and the experimental numbers of the atomized metallic zinc powders No. 1 listed in table 6 were 6A, 6b, and 6c, and the results are listed in table 6A; the results of the intermittent test of atomized zinc powder No. 2, test Nos. 6d and 6e, are shown in Table 6B.

TABLE 6A

TABLE 6B

As can be seen from tables 6A and 6B, a small amount of lead (in the form of lead sulfate) needs to be added into both the two atomized metal zinc powders, the lead addition amount is 5-10 mg/l, and the good effect can be obtained, and when no lead is added, the cobalt redissolves in 180 minutes. There was little difference in the cobalt removal effect compared to the cobalt removal experiment using electric furnace zinc powder (see table 1A). But the amount of zinc powder added is slightly increased, which is probably due to the reduction in the reaction surface area caused by the coarser particle size of the zinc powder.

From the results of two kinds of zinc powders, the difference of cobalt removal is very small, and a continuous experiment is carried out by selecting No. 1 atomized metal zinc powder (containing no lead), wherein the experimental conditions are that 10mg/l of lead is added according to the experimental condition 6c, the adding amount of zinc powder is 2.25g/l, the experimental condition is 6f, and the device adopted in the continuous experiment is the same as the continuous purification device described in the experimental condition 1b in the example 1. Adding the copper and cadmium removing solution with the same components for intermittent purification into each reactor, heating the solution to 80 ℃, adding 1.5 times of the zinc powder, the activating agent and the sulfuric acid according to the addition of the intermittent experiment, reacting for 1 hour, finishing slotting, and sampling in a No. 4 reactor to determine the cobalt concentration.

After the grooving is finished, liquid supply is started continuously, the liquid supply speed is 2 liters/hour, the liquid is pre-adjusted to 0.23g/l after copper and cadmium are removed for one section, and the adding amount of zinc powder and an activating agent in the solution per unit volume is calculated according to the adding amount of an intermittent experiment. The zinc powder and the activator were intermittently added at intervals of 15 minutes, the lead addition was 10mg/l, and the addition was intermittently calculated for 15 minutes, the zinc powder and the activator were added at 15 minutes, the purification process temperature was 80 ℃, and the rest of the experimental procedures were the same as those of experiment 1b of example 1. In the experiment of No. 1 atomized metallic zinc powder, the concentration results of cobalt in the solution are shown in Table 6C, the concentration of nickel and germanium in the No. 4 reactor is shown in Table 6D, and the concentration of cobalt slag in 6.5 hours is shown in Table 6E.

TABLE 6C

TABLE 6D

TABLE 6E

Component (%)	Slag weight (g)	Zn％	Co％	Cd％
					No. 1 reactor	2.2616	90.22	0.67	2.52
No. 2 reactor	1.5985	89.17	0.97	3.57
					No. 3 reactor	1.2212	87.54	1.11	4.06
No. 4 reactor	0.9861	85.41	1.41	5.06

And (3) selecting No. 2 lead-containing atomized metallic zinc powder to carry out continuous experiments, wherein the experiment number is 6G, the lead adding amount is 5mg/l, the rest experiment conditions are the same as those of experiment 6F, the concentration result of the solution cobalt is listed in a table 6F, the concentration result of the No. 4 reactor germanium nickel is listed in a table 6G, and the cobalt slag after 6.5 hours is listed in a table 6H.

TABLE 6F

TABLE 6G

TABLE 6H

Component (%)	Slag weight (g)	Zn％	Co％	Cd％
					No. 1 reactor	1.7047	89.41	1.01	2.69
No. 2 reactor	1.4969	89.19	1.03	3.10
					No. 3 reactor	1.4533	86.70	1.15	3.91
No. 4 reactor	1.0821	84.78	1.30	4.65

As can be seen from tables 6A, 6B, 6C and 6F, both the two kinds of metal zinc powders are suitable for the continuous purification proposed by the present invention, and both cobalt removal effects of cobalt content of the post-solution of less than 0.1mg/l, nickel content of less than 0.1mg/l and germanium content of less than 0.02mg/l are obtained.

Example 7

This example is an up-in-down extended continuous purification experiment for a Co-containing 20mg/l solution containing Zn170g/l, Cd30mg/l, run number 7 b. The results of the batch experiments are shown in Table 2A of example 2 (experiment 2A) and the zinc powders are those listed in Table 1.

Adopt above-mentioned solution to carry out the purification experiment in succession, the equipment that removes the cobalt experiment in succession adopts 4 effective volumes to be the continuous clean system that the continuous stirring of 8.5 liters purifies reactor series connection and constitutes, and the solution business turn over liquid mode of 4 reactors all adopts and goes in and out from the top, and each reactor all has independent heating automatic temperature control device and agitating unit. The solution is continuously added by a peristaltic pump, and the zinc powder and the activating agent are manually added in fixed time and quantity.

Adding the copper and cadmium removing solution with the same components for intermittent purification into each reactor, heating the solution to 80 ℃, adding 1.5 times of the zinc powder, the activating agent and the sulfuric acid according to the addition of the intermittent experiment, reacting for 1 hour, finishing slotting, and sampling in a No. 4 reactor to determine the cobalt concentration.

After the grooving is finished, the liquid supply speed is 17 liters/hour, the total retention time is 2 hours, the liquid after the copper and cadmium removal in the first section is continuously supplied, namely the liquid after the copper and cadmium removal in the first section is pre-adjusted to 0.2g/l, and the adding amount of the zinc powder and the activating agent in unit volume is calculated according to the adding amount of the intermittent experiment. The average residence time of the solution in the reactor No. 1 is 120/4-30 (minutes), the interval time is calculated according to the interval proportion of 50 percent and is 15 minutes, and the adding amount of the zinc powder and the activating agent is calculated according to the volume of the solution added in 15 minutes each time. The temperature was maintained at 80 ℃ during the purge and the rest of the experimental procedure was the same as in example 1, experiment 1 b. The results of the solution are shown in Table 7A, and the results of the 6.5 hour cobalt slag are shown in Table 7B.

TABLE 7A

TABLE 7B

As can be seen from tables 7A and 7B, similar effects are obtained by adopting the electric furnace zinc powder and adopting the upper inlet and the lower outlet in an 8.5-liter purification system, but the cobalt concentration at the outlet of the No. 4 reactor is close to 0.1mg/l, the effect is slightly poor, which is probably the influence of the upper inlet and the lower outlet, and the liquid inlet and outlet mode of the solution can adopt the upper inlet and the lower outlet, also can adopt the lower inlet and the upper outlet, and preferably adopts the liquid surface overflow mode of the lower inlet and the upper outlet.

Example 8

This example is a zinc sulphate solution containing 2mg/l cobaltThe atomized metal zinc powder is subjected to a continuous purification experiment at the temperature of 80 ℃. The cobalt removal front liquid comprises the following components: zn 100g/l, Co 2mg/l, Cd30 mg/l. The activator adopts Sb₄O₅Cl₂Adding activator with chalcanthite according to the ratio of copper to cobalt being 1.2 and antimony to cobalt being 0.4, wherein the adding amount of copper is 6mg/l and the adding amount of antimony is 2 mg/l. The adding amount of the zinc powder is 1.75g/l, the adding amount of the acid is 0.15 time of the weight of the zinc powder, namely 0.26g/l, and the zinc powder is atomized metal zinc powder No. 1 listed in Table 6. The batch experiment, batch equipment and procedure were the same as in experiment 1a of example 1, with an amount of 1 liter of experimental solution and an experimental number of 8A, and the results are shown in Table 8A.

TABLE 8A

Experiment number	Time in minutes	0	60	90	120	150	180	OH^-mol/l
									5a	Co mg/l	2	0.365	0.069	0.023	<0.005	<0.005	0.0364

A continuous decontamination experiment was performed based on experiment 8a, experiment number 8 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were the same as in experiment 1B of example 1, the other experimental parameters such as liquid flow rate and feeding interval were the same as in experiment 1B of example 1, and the results of cobalt content in the solution are shown in Table 8B. The results of cobalt content in the solution are shown in Table 8B, and the results of cobalt residue at 6.5 hours are shown in Table 8C.

TABLE 8B

TABLE 8C

Component (%)	Zn％	Co％	Cd％
				No. 1 reactor	92.15	0.32	3.25
No. 2 reactor	90.36	0.48	4.32
				No. 3 reactor	87.25	0.54	5.76
No. 4 reactor	84.37	0.71	6.10

As can be seen from tables 8B and 8C, for the lower concentration zinc sulfate solution of 2mg/l, the results of the cobalt content of the post-solution being <0.1mg/l were also obtained with atomized metallic zinc powder, except that the amount of zinc powder added and the amount of activator were not significantly reduced from the 10mg/l cobalt-containing solution.

Example 9

This example is a 40mg/l zinc sulphate solution containing cobalt and an atomized metallic zinc powder continuous purification experiment. The discontinuous experimental equipment and experimental procedure were the same as in experiment 1a of example 1, the volume of the experimental solution was 1 liter, the temperature was 80 ℃, and the components of the solution before cobalt removal were: zn160g/l, Co 40mg/l, Cd30mg/l, lead addition (lead sulfate form) 10 mg/l. The activator adopts Sb₄O₅Cl₂The copper addition amount is 26.8mg/l and the antimony addition amount is 9.6mg/l based on the solution of the chalcanthite. The zinc powder adopts No. 2 atomized zinc powder listed in Table 6, and the addition amount is 3.0 g/l; the adding amount of the sulfuric acid is 0.10 time of the weight of the zinc powder and is 0.3 g/l; experiment number 9A, and results of intermittent purge are shown in Table 9A.

TABLE 9A

As can be seen from Table 3A, with intermittent purification using atomized zinc metal powder, a purification depth of <0.1mg/l cobalt was achieved in 120 minutes for a zinc sulphate solution containing 40mg/l cobalt, without redissolution in 180 minutes.

A continuous purge experiment was performed based on experiment 9a, experiment number 9 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were the same as in experiment 1B of example 1, the other experimental parameters such as liquid flow rate and feeding interval were the same as in experiment 1B of example 1, and the results of cobalt content in the solution are shown in Table 9B. The cobalt-containing results of the solution are shown in Table 9B.

The results of cobalt content in the solution are shown in Table 9B, and the results of cobalt residue at 6.5 hours are shown in Table 9C.

TABLE 9B

TABLE 9C

From the results obtained in example 3, it is seen that under the condition of a cobalt concentration of 40mg/l, a purification effect of less than 0.1mg/l of cobalt in the purified solution can be achieved by using atomized metallic zinc powder, and the solution is not redissolved within 180 minutes.

Example 10

This example is a continuous purification cobalt removal experiment of 120mg/l cobalt-containing zinc sulfate solution atomized metal zinc powder, the experiment temperature is 90 ℃, and the number of the intermittent experiment is 10 a. The batch apparatus was the same as in example 1, experiment 1a, the amount of the test solution was 2 liters and the procedure was the same as in example 1. Cobalt removal front liquid composition: 150g/l of Zn, 15g/l of Mg15g, 5.2g/l of Mn5.2g/l, 30Mg/l of Cd, and 120/l of Co120 Mg. The zinc powder is atomized metal zinc powder No. 1 listed in Table 6, the adding amount is 4.25g/l, the adding amount of sulfuric acid is 0.43g/l calculated according to 0.10 time of the amount of the zinc powder, 10mg/l lead (in the form of lead sulfate) is added in the experiment, and the activating agent is Sb₄O₅Cl₂The copper addition and the antimony addition were 43.2mg/l and 19.4mg/l, respectively, corresponding to a copper to cobalt ratio of 0.36 and an antimony to cobalt ratio of 0.16, based on the solution. The procedure of the batch experiment was the same as that of experiment 1a of example 1, and the cobalt removal results of the obtained solution and OH of the 180 minute solution were obtained^-The concentrations are shown in Table 10A.

TABLE 10A

As can be seen from Table 10A, when the cobalt concentration reached 120mg/l in the purification with the atomized metallic zinc powder, a purification depth of cobalt <0.1mg/l was achieved in 120 minutes without re-dissolution in 180 minutes.

A continuous purge experiment was performed based on experiment 10a, experiment number 10 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were as in experiment 1b of example 1, except that the parameters liquid flow rate was 1.6 liters/hour, total average residence time was 150 minutes, the feed interval was 19 minutes, and the conditions were otherwise as in experiment 1b of example 1. The remaining conditions were the same as in experiment 1B of example 1, and the results of cobalt content in the solution are shown in Table 10B.

TABLE 10B

As can be seen from Table 10B, with continuous purification using atomized metallic zinc powder, a purification depth of <0.1mg/l of cobalt was achieved in 120 minutes without re-dissolution in 180 minutes at a cobalt concentration of 120 mg/l.

Example 11

This example is a purification experiment of a liquid-distilled metallic zinc powder containing 50mg/l of cobalt after removing copper and cadmium at 85 ℃ under the intermittent experiment No. 11 a. The solutions Zn 175g/l and Cd30mg/l, the experimental equipment and experimental procedure were the same as in example 1, the added activator had a copper concentration of 33mg/l, an antimony concentration of 10mg/l, a corresponding copper-to-cobalt ratio of 0.66, an antimony-to-cobalt ratio of 0.2, and the zinc powder was distilled metallic zinc powder as listed in Table 6, and the amount of zinc powder was 2.5 g/l. 10mg/l of lead (in the form of lead sulfate) was added, the ratio of addition of sulfuric acid was 0.10 times the amount of zinc powder, the amount of addition was 0.25g/l, and the results of intermittent experiments are shown in Table 11A.

TABLE 11A

As can be seen from Table 11A, the use of distilled metallic zinc powder can achieve the requirement of deep purification of less than 0.1mg/l after 120 minutes and no re-dissolution within 180 minutes for the first-stage copper and cadmium removal solution of Co 50 mg/l.

A continuous purge experiment was performed based on experiment 11a, experiment number 11 b. The solution with the same components and the obtained zinc powder, the activating agent and the acid are added in the intermittent experiment at the same temperature for continuous purification experiment. The experimental equipment and procedure were the same as in experiment 1B of example 1, and the other experimental parameters such as liquid flow rate and feeding interval were the same as in experiment 1B of example 1, and the results of cobalt content in the solution are shown in Table 11B. The cobalt-containing results of the solution are shown in Table 11B.

TABLE 11B

As can be seen from Table 11B, deep purifications with <0.1mg/l cobalt were achieved for solutions containing 50mg/l cobalt using distilled metallic zinc dust.

Example 12

This example is a test of purifying and removing cobalt from distilled metallic zinc powder containing 120mg/l cobalt in zinc sulfate solution, the test temperature is 85 ℃, and the number of the intermittent test is 12 a. The batch apparatus was the same as in example 1, experiment 1a, the amount of the test solution was 1 liter, and the procedure was the same as in example 1. Cobalt removal front liquid composition: 150g/l Zn, 15g/l Mg, 5.2g/l Mn, 30Mg/l Cd, 120Mg/l Co. The zinc powder is distilled metal zinc powder listed in Table 6, the adding amount is 4.25g/l, the adding amount of sulfuric acid is calculated according to 0.10 time of the zinc powder, and the activating agent is Sb₄O₅Cl₂The copper addition and the antimony addition were 43.2mg/l and 19.4mg/l, respectively, corresponding to 0.36 for copper and 0.16 for antimony and cobalt, respectively, based on the solution. 10mg/l lead (in the form of lead sulfate) was added for the experiment. Cobalt removal results for the interrupted test solution and OH of the 180 minute solution^-The concentrations are shown in Table 12A. Serial No. 12b

TABLE 12A

As can be seen from Table 12A, for a 120mg/l cobalt-containing zinc sulfate solution, the cobalt concentration can be <0.1mg/l in 120 minutes.

A continuous decontamination experiment was performed on the basis of experiment 12a, experiment number 12 b. And carrying out continuous purification experiments by adopting the solution with the same components and the obtained zinc powder, the activating agent and the acid in the intermittent experiments. Experimental Equipment and procedure the same as in experiment 1B of example 1, with a liquid flow rate of 1.6 liters/hour, a total mean residence time of 150 minutes, and a time interval of 19 minutes between additions, and the rest of the experimental conditions for experiment 1B of copper example 1, the results for cobalt in the solution are shown in Table 12B.

TABLE 12B

As can be seen from Table 12B, continuous deep purification with <0.1mg/l of cobalt can be achieved for a solution containing 120mg/l of cobalt using distilled metallic zinc dust.

The data from the above examples show that the cobalt content of the pre-solution can be varied from 2 to 120mg/l, and that by using the method of the present invention and four serially connected continuous stirred reactors, a purified solution level of <0.5mg/l cobalt content can be achieved in 90 minutes (3 reactors), and a purified solution level of <0.1mg/l cobalt content can be achieved in 120 to 150 minutes. The stable cobalt removal under the continuous purification state is realized.

As is evident from the above examples, the method of continuously adding sulfuric acid in a certain proportion into the No. 1 reactor and adding OH at the outlet of the No. 4 reactor^-The concentration is below 0.05mol/l, so that the generation of a large amount of basic zinc sulfate is avoided; the intermittent feeding mode is adopted, and the cobalt removing effect of intermittent purification is realized within the range that the feeding interval time is 45-55% of the average residence time of the No. 1 reactor; the problem of cobalt slag redissolution is solved by adopting a liquid level overflow mode. On the basis of adopting the various methods, various zinc powders can achieve better cobalt removal effect.

Obviously, the cobalt concentration of the above examples already covers the cobalt concentration range of the first-stage copper and cadmium removal liquid of most electrolytic zinc plants, but when the cobalt concentration is beyond the range, the method proposed by the present invention can also be used when the second-stage purified liquid with low cobalt is adopted to dilute the cobalt removal front liquid to the cobalt concentration range described in the present patent; for the difficulty of cobalt removal and cobalt removal of zinc sulfate liquid with low cobalt concentration, a small amount of zinc sulfate liquid with high cobalt concentration can be added into the supernatant to increase the cobalt concentration to a cobalt concentration range with relatively high cobalt removal efficiency, and the adjustment mode obviously can avoid the frequent adjustment of the zinc powder, an activating agent and the addition of sulfuric acid by a production system, but the appropriate cobalt concentration range can be selected after the technical and economic indexes of each plant are comprehensively analyzed. It is clear that the wide adaptability of this patent to cobalt concentrations provides a large selection range for such adjustments.

Finally, the above embodiments and the accompanying drawings are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail through the description and the above embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present invention as defined by the claims.

The beneficial and unexpected effects produced by the present invention are:

as is apparent from the above examples, the zinc powder and Sb were intermittently charged₄O₅Cl₂And Chalcanthitum as activator, and adding small amount of sulfuric acid into the solution to obtain purified solution containing cobalt<As a result of the purification of 0.1mg/l, deep continuous purification of cobalt was achieved. By using the method of the present invention, the following beneficial and unexpected effects are achieved.

1. Generally, the more uniform and stable the continuous addition of zinc powder and activating agent in the continuous purification process, the better the cobalt removal effect, therefore, the zinc hydrometallurgy plant adopts electromagnetic oscillation feeder, electronic belt scale and other equipment or zinc powder size mixing, then zinc powder and activating agent are continuously added into No. 1 purification reactor, and the solution after copper and cadmium removal is added into No. 2, No. 3 and No. 4 stirring reactors sometimes a small amount of zinc powder and activating agent is also added. The experimental result of the inventor shows that in the purification process, by adopting the operation mode, the concentration of cobalt and the activator in the solution is always kept at a lower level, which is not beneficial to cobalt removal, and the zinc powder is more dissolved, and the cobalt slag is easy to redissolve. The intermittent addition of zinc powder and activator is favorable for forming the micro-battery with better cobalt removal activity, the formed micro-battery further reacts with the cobalt-containing solution after the pre-activation is completed and continuously flows out of the No. 1 stirring reactor, and the secondary action of the formed micro-battery and the activator is reduced. The cobalt concentration can reach 120mg/l, and the deep purification can be realized, and the result is far superior to the conventional mode of continuously adding zinc powder and an activating agent, and the unexpected result is obtained.

2. Generally, it is considered that, because the zinc powder and the activating agent are added intermittently in the reactor No. 1, the concentration of impurities in the solution of the whole continuous purification system is inevitably fluctuated, which is not beneficial to realizing a stable purification process, and continuous zinc powder and activating agent feeding equipment is often used in industrial production. Surprisingly, although the reactor No. 1 adopts intermittent addition of zinc powder and an activating agent, the activity of the microcell formed by the reactor No. 1 is improved, the fluctuation caused by the intermittent addition of the zinc powder and the activating agent is well balanced, the cobalt concentration of the reactor No. 1 does not fluctuate greatly, the cobalt concentration of each reactor keeps small fluctuation, and the cobalt concentration of the reactor No. 1 in the continuous purification process is lower than that of the traditional continuous purification in which the zinc powder and the activating agent are continuously added. Unexpectedly, after the liquid supply is stopped, the cobalt concentration in all the purification reactors is reduced to below 0.1mg/l within 30 minutes, which fully shows that the intermittent feeding mode of the invention has better anti-redissolution performance and improves the stability of the whole system.

3. The cobalt removing process is easy to adjust, and is suitable for the fluctuation of cobalt, nickel and germanium in a larger solution, and the requirement of intermittent feeding on a control system, particularly equipment for continuously adding the zinc powder and the activating agent, is relaxed only by adding the zinc powder and the activating agent regularly and quantitatively due to the greatly improved impurity removing rate, particularly the greatly improved cobalt and germanium removing rate. Meanwhile, when impurity fluctuation occurs in the cobalt removal front liquid, timely adjustment can be made.

4. The antimony salt is believed to be less different from the antimony trioxide in the purification and cobalt removal of the antimony salt by adopting potassium antimony tartrate, but the inventor discovers through a large number of experiments that the antimony compound and the chalcanthite are matched when the method is adopted and the Sb is adopted₄O₅Cl₂When compared with the continuous purification and cobalt removal of the activator prepared by the chalcanthite, the activator can remove cobalt, but the purification depth is far lower than that of Sb₄O₅Cl₂And the cobalt removal depth of the activator prepared by the chalcanthite, which is an important and beneficial result for improving the purification depth of the antimony salt purification method.

5. By adopting the method of the invention, the requirement on the germanium content of the front liquid is greatly relaxed, the germanium content of the first-stage liquid after copper and cadmium removal can be allowed to reach 0.3mg/l, the germanium content of the liquid after cobalt removal can be less than 0.02mg/l, and the requirement on germanium deposition during neutral leaching is reduced, which is another beneficial effect of the invention.

6. In general plant practice, the stirred reactor is internally provided with a liquid supply mode of feeding liquid from top to bottom, which is beneficial to improving the retention time of slag, but the invention finds that better results can be obtained by adopting the mode of feeding liquid from bottom to top, which can reduce the excessive retention time of part of deposited slag to cause the re-dissolution of cobalt, and obviously provides better guarantee for the stability of industrial production.

7. It is generally believed that the addition of acid results in more dissolution of the zinc powder and therefore the amount of acid added is less for the industrial antimony salt purification process, but the present invention utilizes solution OH^-After the acid adding amount is controlled by the concentration, in a continuous state, in a certain range, the acid adding amount is improved, so that the cobalt removing speed is favorably improved, the consumption of zinc powder is less, the generation of basic zinc sulfate is further reduced, the slag amount is reduced, the filtering equipment is reduced, the cobalt content of the second-stage purification slag is greatly increased, and the next-step treatment of the cobalt slag is favorably realized. This is an important and beneficial result.

From the above, it is obvious that the invention will obviously promote the technological progress of continuous purification and cobalt removal of zinc hydrometallurgy.

Claims

1. The equipment for continuously and deeply purifying the zinc sulfate solution to remove nickel, cobalt and germanium and the control method are characterized in that: the continuous purification equipment for the second-stage purification and removal of nickel, cobalt and germanium is formed by connecting a plurality of continuous stirring reactors commonly used for the zinc hydrometallurgy in series, the neutral leaching solution is subjected to first-stage copper and cadmium removal to obtain a solution after copper and cadmium removal, then the second-stage nickel, cobalt and germanium removal is carried out, the solution after the first-stage copper and cadmium removal naturally flows from the No. 1 reactor to the next reactor until the last reactor,

heating the first-stage copper and cadmium-removed liquid to a specified temperature range, adding a proper amount of zinc powder and an activating agent into the No. 1 reactor according to the unit volume of the first-stage copper and cadmium-removed liquid multiplied by the liquid flow rate, and adding the zinc powder and the activating agent intermittently at certain intervals; continuously adding a proper amount of sulfuric acid or electrolytic waste liquid into the purification system; then, zinc powder and an activating agent continuously flow through the purification system and react with the first section of solution after copper and cadmium removal to remove cobalt, nickel and germanium in a certain time under the condition of continuous stirring in a certain temperature range; and continuously carrying out liquid-solid separation on the slurry containing the purified slag and the second-stage purified liquid flowing out of the last reactor to obtain the purified slag and the purified liquid.

2. The equipment for continuously and deeply purifying the zinc sulfate solution to remove the nickel, the cobalt and the germanium is characterized in that the continuous stirring reactor adopts a lower inlet and an upper outlet; the liquid outlet of the continuous stirring reactor is positioned on the liquid level of the continuous stirring reactor, and the liquid outlet mode is liquid level overflow.

3. The zinc hydrometallurgy continuous deep purification nickel cobalt germanium removing device and the control method thereof according to claim 1, characterized in that the zinc powder and the activator are added intermittently, a certain amount of zinc powder and the activator are added intermittently according to a certain interval time, and the interval time is 40-60%, preferably 45-55% of the average residence time of a section of solution after copper and cadmium removal in the reactor No. 1; the quantity of the zinc powder and the activating agent added each time is the quantity of the zinc powder and the activating agent required by the solution after the copper and cadmium removal of the continuous purification system flowing into the solution after the copper and cadmium removal of the continuous purification system in the interval time multiplied by the unit volume of the zinc powder and the activating agent.

4. A zinc hydrometallurgy continuous purification plant and method as claimed in claim 1 or 2, wherein activator and zinc powder are added in solid form and simultaneously, said activator comprising at least chalcanthite and Sb₄O₅Cl₂。

5. The continuous purification equipment and the control method for zinc hydrometallurgy according to claim 1, characterized in that sulfuric acid or electrolytic waste liquid is continuously added in the purification process, and the adding place is a No. 1-4 continuous stirring reactor, preferably the adding place is a No. 1 reactor; the adding speed is 5-20% of the adding amount of the zinc powder in unit volume multiplied by the liquid volume after the copper and cadmium are removed in one section flowing in per unit time, the adding amount is the sulfuric acid net content of the sulfuric acid or the electrolytic waste liquid, and OH in the purifying liquid flowing out of the last reactor of the purifying system is controlled^-The concentration is 0.01 to 0.06mol/l, preferably 0.015 to 0.05 mol/l.

6. The continuous purifying apparatus and control method for zinc hydrometallurgy according to claim 1, characterized in that a proper amount of activator is added according to the unit volume of the first-stage solution after copper and cadmium removal, the addition amount of the activator of the first-stage solution after copper and cadmium removal in the unit volume is adjusted according to the cobalt concentration of the first-stage solution after copper and cadmium removal, specifically, Sb is controlled according to the cobalt concentration according to the copper-cobalt ratio and antimony-cobalt ratio in a certain range₄O₅Cl₂And the addition amount of the chalcanthite, wherein the copper-cobalt ratio and the antimony-cobalt ratio are as follows: the copper-cobalt ratio is the ratio of the weight of copper contained in the added chalcanthite to the weight of cobalt in the solution, and the antimony-cobalt ratio is the weight of Sb added₄O₅Cl₂The ratio of the weight of antimony in the solution to the weight of cobalt in the solution; when the concentration range of cobalt is 2-120 mg/l, the ratio of copper to cobalt is 1.2-0.32, the ratio of antimony to cobalt is 0.5-0.16, the higher the concentration of cobalt is, the lower the corresponding ratio of copper to cobalt and antimony to cobalt is, and the more or less chalcanthite and Sb are required according to the concentration of cobalt in the post-liquid₄O₅Cl₂The amount added.

7. The continuous purification equipment and the control method for zinc hydrometallurgy according to claim 1, characterized in that a proper amount of zinc powder is added into the liquid after copper and cadmium removal in unit volume and liquid flow rate according to the concentration of liquid cobalt after copper and cadmium removal in a section and the addition amount of zinc powder is adjusted according to the cobalt removal capacity of the zinc powder, the cobalt removal capacity of the zinc powder is the weight (mg) of cobalt removed by the zinc powder in unit weight (g), when the cobalt concentration is in the range of 2-120 mg/l, and when the cadmium concentration is below 50mg/l, the corresponding addition amount of zinc powder is in the cobalt concentration range, the addition amount of zinc powder is 1.5-4.25 g/l, the cobalt removal capacity of the zinc powder is 1.33-26.6 mg Co/(g zinc powder), the higher the cobalt concentration is, the higher the cobalt removal capacity of the zinc powder is, the cadmium concentration exceeds 50mg/l, the addition amount of zinc powder is increased according to the increase of cadmium concentration by at least the, and the adding amount of the zinc powder is increased or reduced according to the concentration requirement of the purified liquid cobalt, but the minimum adding amount of the zinc powder cannot be lower than 1.5 g/l.

8. The continuous purification equipment and the control method for zinc hydrometallurgy according to the claim 1, characterized in that the number of the plurality of reactors in series is at least 2, preferably 3-4; the average residence time of the copper and cadmium removed liquid in the continuous purification system is within the range of 90-150 minutes; the specified temperature range is 80-90 ℃.

9. The continuous purifying apparatus and controlling method of claim 1, wherein the zinc powder is selected from the group consisting of electric furnace zinc powder and metal atomized zinc powder.

10. The continuous purification equipment and the control method for zinc hydrometallurgy according to the claims 1-10, characterized in that the purified liquid can reach Co <0.5mg/l, Ni <0.1mg/l, Ge <0.02mg/l within 90 minutes; co is less than 0.1mg/l, Ni is less than 0.1mg/l, and Ge is less than 0.02mg/l for 120-150 minutes.