CN111254292B

CN111254292B - Method for removing nickel, cobalt and germanium by zinc sulfate aqueous solution purification

Info

Publication number: CN111254292B
Application number: CN202010068126.8A
Authority: CN
Inventors: 张旭; 耿惠; 段志勇; 张云彭; 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: 2022-06-28
Anticipated expiration: 2040-01-20
Also published as: WO2021147816A1; CN111254292A

Abstract

The invention relates to a method for purifying a zinc sulfate aqueous solution. The method comprises the steps of removing copper and cadmium from the supernatant by using zinc powder, adding the zinc powder and a copper-antimony activator at a temperature of 80-95 ℃ to purify and remove cobalt, nickel and germanium, adding the copper-antimony activator, the zinc powder and a small amount of sulfuric acid or electrolytic waste liquid according to the concentration of cobalt in a solution, and adding a copper-antimony activator, the zinc powder and a small amount of sulfuric acid or electrolytic waste liquid into a section of copper and cadmium removing solution containing 2-120 mg/l of cobalt, 0.02-0.3 mg/l of germanium, 0.02-4 mg/l of nickel and 5-120 mg/l of cadmium, wherein the purifying effects of cobalt content of the solution being less than 0.1mg/l, germanium content of the solution being less than 0.02mg/l and nickel content of being less than 0.1mg/l can be realized within 90-150 minutes, and the deep purification of the solution can be realized by using different zinc powders.

Description

Method for removing nickel, cobalt and germanium by zinc sulfate aqueous solution purification

Technical Field

The invention belongs to the field of non-ferrous metallurgy, mainly relates to a method for purifying and removing nickel, cobalt and germanium by zinc hydrometallurgy, in particular to a method for purifying and removing nickel, cobalt and germanium by removing copper, cadmium and liquid at a first section, and aims to overcome the defects of the traditional method for purifying and removing cobalt.

Background

The classical wet electrolytic process for the production of zinc metal consists of the following processes: a first leaching step, in which zinc oxides containing impurities are leached with sulphuric acid from 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 by a three-stage process as shown in figure 1, wherein zinc powder is used for displacement in the first stage to remove copper and cadmium, zinc powder is used for displacement in the second stage to remove other impurities such as nickel and cobalt, 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 research and have disclosed 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 type 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.

British patent GB138948A in 1918 discloses a method for purifying and removing cobalt from lead dioxide or manganese dioxide, which is implemented by 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 because the method is used for removing cobalt, manganese in the solution is also removed, and the method is not used in a purification system.

1930 U.S. patent 1920442 discloses a method for removing cobalt, cadmium and germanium by using zinc powder in the presence of Te and Cu. 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. A typical example shows that cadmium concentrations 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 or atomized zinc powder containing lead and antimony, wherein the method comprises the steps of adding 2g/l of zinc powder containing lead and 3-0.02-0.1% of antimony at 75-85 ℃ into 20mg/l of cobalt-containing zinc sulfate solution to achieve almost 100% of 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 zinc powder containing no lead, D atomized 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.

The patent states that the amount of lead added has a significant effect on the cobalt removal of zinc powder. Further, the amount of antimony oxide was increased, and the addition of antimony and lead to atomized lead powder C containing no lead demonstrated that the addition of 5g/l zinc powder achieved a cobalt content of <0.5mg/l and <0.05mg/l over 2 hours with the addition of 3.6mg/l antimony oxide and 50mg/l lead (lead acetate), indicating that the addition of lead increased the rate of cobalt removal. On the other hand, the invention considers that the use of alloyed zinc powder containing lead also requires the addition of antimony compound for cobalt removal to obtain good results. Obviously, the amount of zinc powder used in this patent is too large, reaching 5 g/l.

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

Canadian patent 1046288A of 1975 discloses a process for reducing zinc dust consumption by using a two-stage slag return and one-stage purification. The method adopts three-stage purification, wherein an antimony compound and a 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 pH value of the two stages is controlled to be 4.1-4.7 by adding electrolysis waste liquid, and a purification result with the cobalt content of less than 0.1mg/l is obtained in a continuous state. However, the method has too large slag return amount, and a large amount 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 activator, wherein the method focuses on optimizing the amount of copper and antimony added, 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 roughly one optimum result.

For stable cobalt removal, 1980, U.S. Pat. No. 4252622 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 alloy contains 6-47% of magnesium, so that 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 device 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, no industrial practice report is found so far due to the larger modification of the device.

In 1986, Canadian patent 1324724 provides a high-pressure cobalt removal method to accelerate the cobalt removal speed, the cobalt removal temperature is 120-150 ℃, for a solution containing 8-12 mg/l of cobalt, 2mg/l of antimony oxide, 0-5 mg/l of Cu and 2-3 g/l of zinc powder are added in the embodiment, and the cobalt content of the solution after 60 minutes is below 0.1 mg/l. The reaction speed of cobalt removal is obviously better than that of normal pressure, but 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 canadian patent 1324724, which is obtained 60 minutes, and the cobalt content of 0.1mg/l is achieved.

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 AsH ₃。

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 zinc powder, the zinc content of the atomized zinc powder is more than 98%, the effective metal zinc content of the atomized zinc powder is more than 95%, and the particle size of the atomized 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 zinc sulfate solution containing cobalt, 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 tank ³Adding 0.15-2 g/M of alloy zinc powder into a No. 3 groove at the same time³The 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 related to cobalt removal by zinc powder displacement described in chronological order, it is evident that, as early as a century ago, it has been found that the cobalt removal process and the copper-cadmium displacement process were not the sameMeanwhile, in the process of purifying and removing cobalt, an activating agent must be added and the purification and the removal are carried out at a higher temperature (more than 70 ℃), and excessive zinc powder needs to 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 only 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 an 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 replacement, and the activators comprise Te salt and Sn salt which are all tried to be used, but finally the better effect is obtained by adopting the combination of copper and arsenic or copper and antimony, the arsenic salt purification method is better than the antimony salt purification method in terms of the depth of cobalt removal, the technology is mature, however, because of the harm of arsenic to the environment and environment, the cobalt removal of the current zinc electrolysis plant is mainly based on the combination of copper and antimony activators, in the improvement of the antimony salt purification process and the method of use thereof, although a great deal of research and patent is being conducted and published, however, there is no consensus but one of the main ideas is that the addition of copper can increase the cobalt removal rate, and as described above, canadian patent 1046288A proposes 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 considered to be 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 are made of different compounds, mainly antimony potassium tartrate and antimony oxide, but there is no patent comparing them, 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 salts for removing cobalt. The amount of antimony added is seen from the numerous patents, 1-5 mg/l of antimony is considered to be enough to complete the cobalt removal process, most of the patents are only added with 1-2 mg/l, excessive antimony is considered to be unnecessary, and excessive antimony is considered to cause overhigh antimony content in the purified liquid, so that the phenomenon of plate burning during electrolysis due to overhigh impurity in the solution is known to cause the precipitation of a large amount of hydrogen at the cathode during electrolysis, but most of the electrolytic zinc plants adopt three-stage purification at present, and a small amount of antimony can be removed in the third stage without influencing the 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 powders 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. Atomized 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 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 electric furnace zinc powder has fine granularity and large reaction surface area in terms of using effect, 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 removal speed of the zinc powder, some patents propose adding some alloy elements to increase the reaction driving force, 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 mostly used. 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 to add acid to prevent passivation, the pH value is controlled to be 4.1-4.7 when the cobalt is removed through purification, most of other patents do not mention the pH value control in the cobalt removal process, and only a small amount of acid is added into the solution after copper and cadmium are removed in one section to control the pH value of the solution before the removal. However, how to control the acid adding amount is the key to control the acid adding amount, so that the zinc powder is not passivated, and the zinc powder does not consume too much zinc powder. 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 patent 8021459B2) is proposed instead of the method for controlling the pH during the purification process, but it is not shown to be adopted in the antimony salt purification process. However, obviously, the generation of a large amount of basic zinc sulfate in the antimony salt purification method affects the purification cobalt-removing process, which is also an important reason that the second-stage cobalt-removing purification slag has high zinc content and low cobalt content, and thus the second-stage purification slag has large treatment capacity and high cost.

4. In order to stabilize the cobalt removal process, methods for controlling the potential of the solution 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 two-stage cobalt removal purification slag to the first stage, so that the aim of reducing the consumption of the cobalt removal zinc powder is fulfilled. However, it is obvious that the primary purification slag contains almost all impurity elements, so that the treatment process is difficult, and particularly secondary cobalt removal is required.

6. In the aspect of equipment, the reactor with a special structure is adopted to improve the efficiency of cobalt removal and reduce the consumption of zinc powder, but the special groove type is inconvenient to use and is mostly not industrially applied; 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 many patents give an index of cobalt content of the cobalt-removed liquid less than 0.1mg/l in examples, the purification depth in production practice is often less than 0.1 mg/l.

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

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

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 redissolution mechanism is unclear, and a method of adding more zinc powder is usually adopted to inhibit the cobalt redissolution, but the method results in more consumption of the zinc powder. The 1 research of Huzhonghuo 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 in the early stage, but the cobalt is obviously redissolved in the later stage, so that the consumption of the zinc powder is not easy to reduce in industrial practice by using the copper antimony activator. To avoid re-dissolution of the cobalt, too much zinc powder is often added. Obviously, due to the existence of the problem of re-dissolution, more difficulties are encountered in the adjustment of various control parameters and the search of the cobalt-removing rule, the difficulties are to ensure the cobalt-removing depth and prevent the cobalt re-dissolution, and the problem of cobalt re-dissolution cannot find the reason for a long time, so the search of the rule is more difficult.

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 point of view, all patents do not refer to the difference between antimony compounds potassium tartrate and antimony oxide, and it is generally believed 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. The K.Tozawa. [3] study confirmed that cobalt produced by the arsenic salt purification process existed in the form of cobalt arsenic metal compound, while it was not completely understood in what form cobalt produced by the antimony salt purification process existed.

The study of Oluf Bockman, Terje Ostvold showed [4], that cobalt may be replaced by 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.

Studies in V.van der Pas, D.B.Dreisinger [6] have shown that cobalt is deposited as a Zn-Co alloy under certain conditions due to zinc underpotential deposition, which is 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 purification and removal process, and a plurality of possible action mechanisms are proposed. From these findings, a.nelson et al reviewed [7] in 2000, concluding that although numerous studies suggest various cobalt removal mechanisms and explanations, it is uncertain which theory is reliable. This conclusion also illustrates the complexity of the cobalt removal process of hydrometallurgical zinc antimonate purification by displacement, while the displacement mechanism remains an unsolved problem.

Nelson et al, A.2013 [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 of controlling the pH to be 4.0, and the experiment process is better for the cobalt removal experiment resultThe pH value of the reaction slurry is detected, and compared with the purification cobalt removal effect, 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 if the pH value of the solution is not controlled, which fully explains the defects of the purification cobalt removal process by adopting pH monitoring. 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.

2018, Toni Karlsson et al [9] studied the kinetics of the cobalt removal process and the morphology of the purified product in an attempt to reveal the morphology of cobalt in the product, but the results of the study obtained 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 the related parameters in the solution are lacked.

3. There is a lack of 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.

Citations

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. Zhao Tian Yuan, antimony, Metallurgical Press, 1987, p572-573

The invention content is as follows:

according to the above patents and research documents and the current production situation, aiming at the defects of the prior antimony salt purification method, the invention aims to:

1. provides a new activator consisting of a new antimony compound and chalcanthite to obtain better cobalt removal effect and avoid re-dissolution of cobalt in the purification process.

2. A method for controlling the solution to reduce or avoid the generation of basic zinc sulfate in the purification process is provided.

3. Provides a control method for adjusting the adding amount of zinc powder and an activating agent according to the change of cobalt concentration.

4. Provides a method and an activator for realizing deep purification of germanium while ensuring cobalt replacement of germanium when the concentration of germanium in a solution is higher.

5. On the basis of the method, the method for realizing deep purification by using various zinc powders is further provided.

6. Further providing a basis for the improvement of the continuous purification process.

Based on the discovery, the neutral leaching solution of the wet zinc smelting plant adopts three-stage purification process, wherein in the first stage, the copper and cadmium in the solution are removed by adopting the traditional method for removing the copper and cadmium by using zinc powder to obtain a first-stage solution after the copper and cadmium are removed, then the second-stage purification is carried out to remove the nickel, the cobalt and the germanium, and in the third stage, a small amount of zinc powder is added to remove the residual impurities. For said two-stage purification, in accordance with the claims, the invention consists of the combined use of several processes and methods:

a method for removing nickel, cobalt and germanium by zinc sulfate aqueous solution purification is characterized in that neutral leachate is subjected to first-stage copper and cadmium removal to obtain first-stage copper and cadmium removal back liquid, and then the second-stage purification is performed to remove nickel, cobalt and germanium, and the method comprises the following steps: in the second-stage purification, proper amount of chalcanthite and antimony compound is added according to the components of the first-stage copper and cadmium removing liquid_、Proper amount of zinc powder and proper amount of sulfuric acid are added, and the antimony compound is Sb ₄O₅Cl₂And zinc powder, chalcanthite and Sb are added₄O₅Cl₂And (3) the slurry is in a solid form, the nickel, cobalt and germanium are removed by reacting for a period of time within a certain temperature range, and the second-stage purified slurry with the nickel, cobalt and germanium removed is subjected to liquid-solid separation to obtain second-stage purified liquid.

The proper amount of sulfuric acid is added according to a certain multiplying power of the adding amount of the zinc powder, and according to OH in the final solution when the purification process is finished^-The amount of acid added is adjusted for concentration.

Adding appropriate amount of chalcanthite and Sb according to the components of the first-stage copper and cadmium removing solution₄O₅Cl₂The cobalt concentration of the solution after copper and cadmium removal is adjusted according to the first stage of the process₄O₅Cl₂The amount of (a) added; the addition of a proper amount of zinc powder is based on one-stage copper removalAnd adjusting the adding amount of the zinc powder according to the cobalt concentration and the cadmium concentration of the cadmium post-solution.

The proper amount of sulfuric acid is added according to a certain multiplying power of the adding amount of the zinc powder, and according to OH in the final solution when the purification process is finished^-The amount of acid added is adjusted for concentration. The proportion is 0.05-0.2 time of the weight of the added zinc powder, the sulfuric acid is industrial sulfuric acid or electrolytic waste liquid, and the added sulfuric acid accounts for the net sulfuric acid content of the industrial sulfuric acid or the electrolytic waste liquid; according to the OH in the final solution at the end of the purification process^-The addition amount of the concentration adjusting acid is that OH in the solution is obtained after 90-180 minutes in the two-stage purification process ^-Concentration of this OH^-The concentration is 0.02-0.05 mol/l.

The chalcanthite and the Sb are adjusted according to the cobalt concentration of the liquid after the first-stage copper and cadmium removal₄O₅Cl₂In an amount of Chalcanthitum and Sb₄O₅Cl₂The addition amount of the catalyst is that Sb is controlled by calculating the ratio of copper to cobalt and the ratio of antimony to cobalt according to the concentration of the cobalt₄O₅Cl₂And 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 of cobalt is 2-120 mg/l, the ratio of copper to cobalt is 0.36-1.5, and the ratio of antimony to cobalt is 0.16-0.5; the higher the cobalt concentration is, the lower the corresponding copper-cobalt ratio and antimony-cobalt ratio are, and the cobalt concentration of the purified liquid is required to increase or decrease the chalcanthite and Sb₄O₅Cl₂The amount added.

The adding amount of the zinc powder is adjusted according to the cobalt concentration of the first-section solution after copper and cadmium removal and according to a certain zinc powder cobalt removal capacity, and the zinc powder consumed by cadmium is calculated, wherein the zinc powder cobalt removal capacity is the weight (mg) of cobalt removed by the zinc powder in unit weight (g), the cobalt concentration range is 2-120 mg/l, when the cadmium concentration is below 50mg/l, the corresponding adding amount of the zinc powder is in the cobalt concentration range, the adding amount of the 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 adding amount of the zinc powder is increased at least according to the theoretical amount of replacement and cadmium removal according to the increase or decrease of the cobalt concentration of the purified solution, but at least not below 1.5 g/l.

And the two-stage purification is carried out in a reaction period within a certain temperature range, wherein the certain temperature range is 80-90 ℃, and the reaction period is 90-180 minutes.

The zinc powder added with the proper amount of sulfuric acid is added with zinc powder, chalcanthite and Sb₄O₅Cl₂Previously added.

The two-stage purification is to heat the first-stage copper and cadmium removing solution to 80-90 ℃, add sulfuric acid or electrolytic waste liquid according to 0.05-0.2 times of the amount of the added zinc powder, and rapidly add zinc powder and Sb in a solid state within 1 minute₄O₅Cl₂Adding Chalcanthitum to the first-stage copper and cadmium-removed solution, adding zinc powder and Sb₄O₅Cl₂And reacting the slurry of the chalcanthite for 90-180 minutes at 80-90 ℃ under a stirring state, removing nickel, cobalt and germanium in the solution, and carrying out solid-liquid separation on the slurry from which the nickel, cobalt and germanium are removed to obtain a second-stage purified liquid and purified slag.

In the two-stage purification, the added zinc powder can be electric furnace zinc powder, atomized metal zinc powder or distilled metal zinc powder, and the particle size is preferably below 50 micrometers when the atomized metal zinc powder is used.

In the second-stage purification, when the cobalt concentration in the solution after copper and cadmium removal is within the range of 2-120 mg/l, the cobalt concentration of the solution after the second-stage purification is less than 0.5mg/l within 90 minutes and less than 0.1mg/l within 120 minutes; the germanium content in the liquid is less than 0.02mg/l after cobalt removal for 90-120 minutes; the concentration of nickel in the cobalt-removed liquid in the nickel-cobalt-germanium removing process is less than 0.1mg/l in 90-120 minutes.

For OH in solution as described in the above procedure^-The concentration was measured by the method described in the patent entitled "method for measuring hydroxide concentration in Zinc sulfate solution" filed by the present inventors.

Sb described for the above procedure₄O₅Cl₂Conventional hydrolysis may be employedPreparation by the method [10 ]]And the cobalt removal effect can reach the index of the invention. However, this preparation process generates a large amount of waste water containing dilute hydrochloric acid, and for this reason, the present inventors have conducted Sb₄O₅Cl₂The improvement of the preparation method provides a new preparation named as' a compound of Sb₂O₃Direct preparation of Sb with aqueous hydrochloric acid₄O₅Cl₂Method of (1)', Sb prepared by the method of this patent₄O₅Cl₂The same cobalt removal effect can be obtained. In the present specification, the Sb of the present inventors' application is used unless otherwise specified₄O₅Cl₂Sb obtained by preparation method₄O₅Cl₂。

On the basis of the methods, different zinc powder can be adopted in the purification and cobalt removal process, such as electric furnace zinc powder, distilled metal zinc powder and atomized metal zinc powder which can be used for purifying and removing cobalt, and the deep purification of nickel, cobalt and germanium can be realized.

In order to better understand the present invention, several methods and processes described in the above invention are further described below.

In order to solve the problems of the antimony salt purification method, the present inventors considered that: the key to the problem is to find a feasible method for preventing cobalt redissolution, and related rules can be found only on the premise of ensuring that cobalt in the slag is not redissolved. We found that:

1. in order to solve the problem of cobalt redissolving during the purification process, the search for new activators, in particular new antimony compounds, is an alternative. The difference and effect of antimony oxide and potassium antimony tartrate which are commonly used in industry in the cobalt removal process are firstly researched, and the result shows that the two compounds have obvious defects, and the inventor considers that the difference and effect is the main reason of instability of the purification and cobalt removal of the existing antimony salt purification method. The defects are mainly shown in that the cobalt removal speed is slow when antimony oxide is adopted, the cobalt removal speed is fast when antimony potassium tartrate is adopted, and the cobalt is easy to redissolve when a small amount of acid is added into the antimony oxide and the antimony potassium tartrate to avoid the generation of basic zinc sulfate and keep the activity of zinc powder. We have unexpectedly found that: using Sb₄O₅Cl₂Replacing the two common antimonyWhen the compound is used, the phenomenon is avoided, the cobalt is not easy to redissolve, and the cobalt content of the purified liquid can be stably less than 0.1mg/l, which is the basis of the invention.

2. The control of the generation of basic zinc sulfate is another key for solving the problems, a good cobalt removal effect can be obtained only under the condition of inhibiting the generation of the basic zinc sulfate, and obviously, the generation of the basic zinc sulfate can be inhibited by adding acid. One control parameter commonly used in zinc hydrometallurgy is the pH of the solution, and we have found that all the purification cobalt removal experiments had a pH (25 ℃) of 5.0 to 5.3 after 30 minutes of reaction, indicating that the pH cannot be used as a process control parameter. We have found that with increasing reaction time, the OH in solution^-The concentration is gradually increased, so that OH in the solution is adopted^-Concentration may be used as a means of monitoring this process. For preventing the generation of basic zinc sulfate, we find that sulfuric acid or electrolytic waste liquid can be added according to a certain proportion of the added zinc powder, and simultaneously, OH in the solution is controlled^-The concentration ensures that the solution is in a neutral environment, and excessive zinc powder consumption is avoided.

3. With respect to the amount of zinc powder added, we have found that the weight of cobalt removed per unit weight of zinc powder increases with increasing cobalt concentration at the appropriate amount of copper antimony activator added, which provides a basis for adjusting the amount of zinc powder added to the production process according to the change in cobalt concentration.

4. We have found that a small amount of nickel and germanium in the solution has an accelerating effect on cobalt removal, and under the condition of adopting the activator and the matching method of the invention, the cobalt removal speed of the solution containing a small amount of germanium and nickel is faster, and the cobalt removal and the removal of the two elements can be simultaneously carried out to the concentration level required by electrolysis.

5. Based on the method found out above, we find that the better cobalt removing effect can be obtained by adopting electric furnace zinc powder, distilled metal zinc powder, and atomized metal zinc powder containing lead or not containing lead when removing cobalt, and only when the atomized metal zinc powder is adopted, a small amount of lead (in the form of lead sulfate) needs to be added, which provides various choices for purchasing the zinc powder in a wet zinc refinery.

As described above, the purification and cobalt removal processIn the process, how to prevent the re-dissolution of cobalt is the premise of realizing deep purification by purifying and removing cobalt. It is believed that two antimony compounds commonly used in industry, antimony oxide and potassium antimony tartrate, can be used for removing cobalt, and the difference is mainly in price, potassium antimony tartrate is obviously expensive, and most plants using antimony oxide have no research comparison on the use of the two antimony compounds. We note that there is a large difference in solubility between the two compounds, antimony oxide is slightly soluble in water, whereas antimony potassium tartrate is readily soluble. The inventor finds that when zinc powder is used for removing cobalt, although the two compounds and the chalcanthite are matched to remove cobalt, antimony potassium tartrate has higher cobalt removal speed and slower antimony oxide; on the other hand, when a small amount of acid is added to prevent the passivation of the zinc powder, the two antimony compounds have cobalt redissolution phenomena with different degrees, the phenomenon is not obvious when more zinc powder is added, the redissolution is intensified when the addition amount of the zinc powder is small, and the redissolution is inhibited to a certain degree but the depth of cobalt removal is lower when the acid is not added for cobalt removal experiments. In further search for alternative antimony compounds, we have unexpectedly found that Sb is used ₄O₅Cl₂When replacing these two common antimony compounds, the cobalt removal process has an unexpected change in that the cobalt is less likely to re-dissolve during the purification process and is less re-soluble when a small amount of acid is added. These findings lay the foundation for our search for better conditions for cobalt removal processes.

As to the reason why cobalt is not easily re-dissolved by the proposed method, the present inventors considered that: further, the present inventors thought that under the condition of adding acid, not only the generation of basic zinc sulfate but also the generation of basic cobalt sulfate is suppressed, and thought that in the present invention, cobalt may be mainly replaced in the form of a zinc-cobalt alloy in which cobalt mainly exists in a solid solution state, and since the standard reduction potential of cobalt is higher than that of zinc, the zinc in the zinc-cobalt alloy prevents the re-dissolution of cobalt, there has been made a study [6 ]]The results obtained by the patent are in accordance with the conclusion of the research, which shows that cobalt is possibly replaced in the form of zinc-cobalt alloy in the process of removing cobalt by replacing zinc sulfate solution. On the other hand, the zinc in the zinc powder is used as a sacrificial anode pairThe formed zinc-cobalt alloy also plays a role in protection. This provides a double protection for the cobalt that has been replaced, thereby solving the problem of cobalt redissolution. Obviously, when the zinc in the zinc powder is consumed, the protection effect is weakened, and only the cobalt protected by the zinc in the zinc-cobalt alloy is redissolved, and when the zinc in the zinc-cobalt alloy is completely dissolved, the cobalt is redissolved. However, the conventional antimony salt purification method lacks the control means of acid addition amount and the antimony compound used is insufficient, so that part of cobalt in the purification slag exists in the form of basic cobalt sulfate, and the research proves that [4 ] ]The basic cobalt sulfate is the main reason for re-dissolving the cobalt slag. In addition, the addition mode and sequence of the activating agent also have great influence on the re-dissolution of the cobalt, and the cobalt is easy to re-dissolve when the activating agent is added firstly. In the cobalt removing process, the nickel and the germanium are also found to play an accelerating role in the cobalt removing process and are simultaneously purified, and the inventor thinks that the reason is that the germanium and the nickel play a role similar to a copper-antimony activator. As for the two kinds of antimony compounds commonly used in the industry, this effect cannot be achieved, and the present inventors considered that this is Sb proposed in the present invention₄O₅Cl₂The differences in the products formed as a result of the differences in the cobalt removal process and the various physical and chemical properties of the two antimony compounds described above, and the mechanisms in depth have yet to be further investigated.

The problems of zinc powder passivation caused by basic zinc sulfate generated in the replacement cobalt removal process and cobalt redissolution caused by the generation of basic cobalt sulfate are solved. As can be seen from the foregoing patents, acid addition adjustment is a well-known method, but how to control the amount of acid added to the process is not addressed. The core of the problem is to adjust the acid adding amount according to the parameters and control the generation of the basic zinc sulfate by adopting the parameters in the reaction process, thereby adjusting the acid adding amount to ensure that the zinc powder is not passivated and controlling the generation amount of the basic zinc sulfate in the process. Obviously, adding an excess of acid would inevitably lead to excessive consumption of zinc powder. It is common knowledge that basic zinc sulfate in a solution is generated by reacting zinc hydroxide and zinc sulfate in the solution at a high temperature. As previously mentioned, this cannot be accurately achieved by controlling the pH of the solution, and controlling the solution to a slightly acidic environment reduces the cobalt removal rate [8 ].

We have found that the OH in the solution can be controlled^-The concentration can control the generation of basic zinc sulfate, and the control is based on OH in the solution^-And (4) measuring the concentration. For this reason the inventors have invented OH in zinc sulphate solution^-The method of (4). Using this assay, the present inventors found that: in the process of purifying and removing cobalt, under the condition of adding a small amount of acid, after the zinc powder and the activating agent are added, the pH value of the solution is quickly increased to 5-5.3 and is not increased any more, and OH in the solution^-The concentration is continuously increased along with the time, and the OH of the solution is not controlled^-At concentration, white basic zinc sulfate often appears in the slurry, apparently with the control solution OH^-The method of concentration is superior to monitoring the pH of the solution. OH in solution^-After controlling the concentration in the proper range, we unexpectedly found that: in the application of Sb provided by the invention₄O₅Cl₂The replacement of two antimony compounds commonly used in industry by the combination with chalcanthite can avoid the occurrence of cobalt redissolution, which may be in proper OH^-The concentration range reduces or avoids the generation of basic cobalt sulfate. We have further found that in such an OH group^-Within the range, cobalt is not easily redissolved and zinc powder consumption is less.

OH in solution^-The reason for this is another important problem, and during the process of removing cobalt by replacing zinc powder, the zinc powder can have the following reactions:

The first reaction is the reaction of zinc dust and an aqueous solution of zinc sulphate.

Zn+2H₂O＝H₂+Zn(OH)₂ (1)

The second reaction is a reaction of zinc oxide contained in zinc powder and added sulfuric acid as follows

ZnO+H₂SO₄＝ZnSO₄+H₂O (2)

Obviously, the acid in solution may also be dissolved in the form of the following reaction:

Zn+H₂SO₄＝H₂+ZnSO₄ (3)

but is well known as H₂The overvoltage of the precipitation on the zinc is large, the reaction (3) is inhibited, and because the reaction 1 is rapidly carried out, the acid in the solution is quickly consumed, and the solution is converted from acidity to neutrality, the reaction (3) is not the main reaction of the zinc in the process of adding acid to remove cobalt. By purifying OH in the front liquid and the rear liquid in the cobalt removal process^-The change in concentration, we have found that the dissolution of zinc is mainly due to reaction (1), apparently, OH in solution^-The increase of the amount of the zinc powder is closely related to the amount of the added zinc powder and the amount of the activating agent, and the amount of the zinc powder is increased through OH in the solution^-The concentration is measured, and the rule is found and applied to the purification and cobalt removal process. The specific implementation method is to calculate the added acid amount according to the zinc powder adding amount according to a certain proportion.

It is well known that zinc hydroxide in solution has a certain solubility in zinc sulphate solution at high temperature if the Zn (OH) in the solution is to be added₂The concentration is controlled below the saturation solubility at the temperature, so that the slurry containing the purification slag at the high temperature is kept clear, no or little basic zinc sulfate is generated, and the slurry contains Zn (OH) ₂The pH of the zinc sulphate solution is maintained substantially constant, and it is believed that the solution contains Zn (OH)₂And ZnSO₄Forms a certain buffer system, and researches show that OH in zinc sulfate solution^-And Zn²⁺Form (ZnOH)⁺The reaction of such a buffer system may be as follows:

if, for the reason of reaction (4), a certain amount of OH is present in the solution after addition of a small amount of acid^-The pH of the solution is substantially unchanged and the addition of acid merely reduces the pH of the solution (ZnOH)⁺The concentration of (3) is controlled only by controlling the amount of acid added to the presence of Zn (OH) in the solution₂The generation of basic zinc sulfate can be controlled when the concentration is not more than the saturated solubility at the temperature, so that the activity of the zinc powder is further ensured, and if excessive acid is added, the solution is inevitably acidified, so that more zinc powder is consumed. It is apparent that such a Zn (OH) exists₂The concentration range within which neither acidification of the solution nor the formation of basic zinc sulphate occurs. This is the basis for our control of the amount of acid added.

By measuring OH of the solution during cobalt removal^-In a variation, we have found that the zinc powder is mostly consumed due to the formation of Zn (OH)₂And H₂The Cu and Sb consumed in the replacement of Co, Ni and Cd and the activator only account for a small part, which is also the main reason of large consumption of the zinc powder in the cobalt removal purification process. Further we have found that to obtain good displacement cobalt removal, especially with the addition of an activator, the hydrogen generation is substantially simultaneous with the cobalt removal process and it is not possible to obtain both rapid cobalt removal and no hydrogen generation. Based on the above findings, we propose to control Zn (OH) in the solution by adding acid in a certain proportion according to the amount of zinc powder added ₂Concentration and by detecting OH in the solution^-The method controls the acid adding amount, and OH of the solution is added^-The concentration range provides guarantee for the smooth operation of the cobalt purification and removal process.

Regarding the temperature for purifying and removing cobalt, the inventor finds that the temperature is lower than 80 ℃, for example, 75 ℃, the purifying and removing cobalt can not reach the requirement that the deep purifying contains less than 0.1mg/l of cobalt. In the temperature range of 80 ℃ to 95 ℃, although the activator and the matching method can realize rapid cobalt removal, the invention further finds that overhigh temperature, such as 95 ℃, can accelerate the dissolution of zinc powder and increase the consumption of the zinc powder, and on the other hand overhigh purification temperature can increase the energy consumption, and the more suitable purification temperature is 80-85 ℃.

With regard to the problem of varying the amount of activator added at different cobalt concentrations, we have found that: sb can be controlled according to the cobalt concentration in a certain range of copper-cobalt ratio and antimony-cobalt ratio₄O₅Cl₂And 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 of cobalt is 2-120 mg/l, the ratio of copper to cobalt is 0.36-1.5, and the ratio of antimony to cobalt is 0.16-0.5; cobalt concentration The higher the copper-cobalt ratio and the antimony-cobalt ratio, the lower the corresponding copper-cobalt ratio and antimony-cobalt ratio, and the higher or lower the contents of chalcanthite and Sb according to the cobalt concentration requirement of the purified liquid₄O₅Cl₂The amount of the addition.

Regarding the addition amount of zinc powder, the inventor unexpectedly finds that when the cobalt removal method proposed by the inventor is adopted, the cobalt removal weight of the zinc powder per unit weight, namely the cobalt removal capacity of the zinc powder, is higher, the cobalt removal capacity of the zinc powder is larger, the cobalt removal efficiency of the zinc powder is higher, and the cobalt removal speed is accelerated as the cobalt concentration is higher; the lower the cobalt concentration, the smaller the cobalt removal capacity of the zinc powder, and the lower the cobalt removal efficiency of the zinc powder. When the cobalt concentration in the solution after the copper and cadmium removal in the section is greatly changed at 2-120 mg/l, the requirement that the cobalt concentration of the purified solution is less than 0.1mg can be achieved within 120 minutes, and for the phenomenon, the inventor thinks that the phenomenon is caused by the fact that the contact probability of zinc powder and cobalt is increased when the cobalt concentration is higher, and the phenomenon accords with the general rule of chemical reaction kinetics. However, the adding amount of the zinc powder is influenced by a plurality of factors, wherein the factors are mainly hydrogen generation reaction which is a main reason causing large consumption of the zinc powder, so the consumption of the zinc powder cannot be too low, and the experimental result shows that the adding amount of the zinc powder is less than 1.5g/l, the residual slag amount is too small, and the cobalt is easy to redissolve.

Because the number of influencing factors in the cobalt removing process is large, screening experiments of the addition amounts of the activating agent and the zinc powder are carried out, the addition amount of the activating agent given in the specification is a moderate result obtained by carrying out screening experiments on the addition amounts of the activating agent and the zinc powder under the condition that the method provided by the invention sets the screening standard, the standard of the screening experiments is that the cobalt concentration is less than 0.1mg/l in 120 minutes, and the cobalt is not redissolved in 180 minutes. The results of the screening for various cobalt concentrations are shown in the examples.

With respect to the problem mentioned in some patents and research papers that higher antimony concentrations in the purified liquid tend to occur when higher antimony is added, we have found that the Sb proposed in this patent is used₄O₅Cl₂+ Chalcanthitum as activator and control of OH in solution^-Under the condition of concentration, the problem of overhigh concentration of the antimony in the post liquid does not occur.

Since the results obtained by the method of the present invention are very different from those obtained by the known antimony salt purification method, and since the conventional antimony salt purification method lacks reliable theoretical support, the various modifications described in the present invention are described only with respect to experimental results, and possible explanations are given according to the understanding of the process by the present inventors, and 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, the antimony salt purification method can be used for realizing deep purification for cobalt removal after being matched with a matching solution provided by the inventor. The processes of the present invention are described in detail above and further illustrated below with reference to examples.

Drawings

FIG. 1 shows a conventional purification process for producing zinc metal from zinc sulfate.

Figure 2 is an improved purification process for zinc sulfate production of zinc metal.

Detailed Description

In an electrolytic zinc plant, according to different raw materials and slag treatment processes, the neutral leaching solution mainly comprises the following components:

100-190 g/l Zn, 2-20 g/l Mg, 2-8 g/l Mn, 50-3000 Mg/l Cd, 50-2000 g/l Cu, 2-100 Mg/l Ni, 1-120 Mg/l Co, 0.1-1 Mg/l Ge, after removing copper and cadmium by first-stage displacement, the Cu in the solution is basically displaced to less than 1Mg/l Cd, the Cd can be controlled below 100Mg/l, most of Ni and Ge are displaced in the first-stage purification copper and cadmium removal process, and the typical first-stage displacement solution comprises the following components: 100-190 g/l Zn, 2-20 g/l Mg, 2-8 g/l Mn, 10-100 Mg/l Cd, 0-1 Mg/l Cu, 2-10 Mg/l Ni, 2-120 Mg/l Co, 0.05-0.3 Mg/l Ge, the following examples are basically the excellent purification results obtained by experiments in such a range. Since Mg and Mn have no influence on the purification process and the influence of Zn is small, only the components of Zn, Co, Ni, Ge and Cd in the solution after Cu and Cd removal are given in the following examples.

The first-stage copper and cadmium removing liquid adopted by the invention is the actual copper and cadmium removing liquid from different electric zinc factories, and analytically pure cobalt sulfate and sulfuric acid are added according to different experimental requirementsThe simulated first-stage copper and cadmium removing liquid is obtained from nickel, cadmium sulfate and high-purity germanium dioxide. The activator is antimony compound and chalcanthite, in the examples of the specification, the antimony compound is antimony potassium tartrate and Sb respectively₂O₃And Sb₄O₅Cl₂. The molecular formula of the potassium antimony tartrate is C₄H₄KO₇Sb·1/2H₂O, the purity is 97%, and the content of antimony is 35.37%; sb₂O₃Is an industrial grade product (98%), antimony content 81.86%, Sb₄O₅Cl₂For the laboratory synthesis of the inventors, the antimony content was 76.5%. The copper compound adopts chalcanthite, and the molecular formula is CuSO₄·5H₂O, purity of industrial grade (98% by weight) and copper content of 24.95%. The content of antimony and copper in the specification is calculated according to the content of copper and antimony in the compound. The amount of the chalcanthite substance is 24.95% of the volume of the solution, and the amount of the antimony compound substance is 24.95% of the volume of the solution per the content of antimony (antimony 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 production process, the electrolytic waste liquid can be added instead of adding industrial sulfuric acid, the addition amount is calculated according to the net content of sulfuric acid in the electrolytic waste liquid, the sulfur acid content of the general electrolytic waste liquid is 150-200 g/l, and the zinc content is 40-60 g/l.

Example 1

In this example, antimony potassium tartrate and Sb were used respectively₂O₃、Sb₄O₅Cl₂And Chalcanthitum as activator for cobalt removal. The test temperature was 80 ℃ and the amount of test solution was 1 liter, test numbers 1a, 1b, 1c, 1d, 1 e.

The experimental equipment is a constant-temperature water bath with a heating and temperature control device, the experiment is carried out in a beaker with the effective volume of 2 liters, and a polytetrafluoroethylene mechanical stirring paddle is adopted for stirring.

The experimental procedure was: firstly, heating the first-stage copper and cadmium removal solution to a set temperature, adding a proper amount of sulfuric acid, simultaneously adding zinc powder, chalcanthite and an antimony compound in a solid form, maintaining the temperature, and carrying out a cobalt removal experiment under a stirring state. After the reaction for 60 minutes, sampling is started to determine the cobalt concentration, each sampling is 20ml, the sampling interval is 30 minutes, and the cobalt concentration is measured until 180 minutesFiltering the rest slurry, and measuring cobalt and OH in 180 min filtrate^-And (4) concentration. And washing and drying the slag to determine the content of elements such as zinc, cobalt, cadmium and the like.

The first-stage copper and cadmium removing liquid comprises the following components: zn150g/l, Cd30mg/l, Co 10mg/l, cu 10.3mg/l, Sb 2.8mg/l, cu-Co ratio 1.03, Sb-Co ratio 0.28, and the actual amount of added chalcanthite (volume of solution × cu concentration mg/l/chalcanthite copper content)% 41.2(mg), in this example, the amount of added chalcanthite (1 liter × 10.3 mg/l)/24.95% > -41.2 (mg), calculated in the same way, Sb ₄O₅Cl₂(v) the amount of antimony added (volume of solution x concentration of antimony added in mg/l in terms of liquid)/Sb₄O₅Cl₂Antimony% in this example, Sb₄O₅Cl₂The amount of Sb added (1 liter. times.2.8 mg/l)/76.5% to 3.66(mg)₂O₃The amount of antimony potassium tartrate added (1 liter × 2.8 mg/l)/81.86% to 3.42(mg) and the amount of antimony potassium tartrate added (1 liter × 2.8 mg/l)/35.37% to 7.92(mg) were calculated as described above in the following examples, and the details are not repeated, and the amount of the activating agent added in the following examples is given only in terms of the concentration of copper and antimony in the solution, and the amount of the substance added is not given. The remaining conditions are shown in Table 2. The zinc powder used was an electric furnace zinc powder listed in table 1, in which the components were all weight%, sulfuric acid was added to the solution in an amount of 0 and 0.15 times the weight of the zinc powder, respectively, and the actual addition amount of sulfuric acid was (zinc powder amount × sulfuric acid ratio)/98%, in this example, when the zinc powder addition amount was 2g/l and the sulfuric acid ratio was 0.15, the sulfuric acid addition amount was (2 g/l × 0.15)/98% was 0.30 (g/l), and the sulfuric acid concentration results in terms of liquid calculated by this calculation method were no longer specified as the actual addition amount of sulfuric acid in the following examples. The reaction time was 180 minutes. The amount of copper-antimony metal added is controlled to be the same. The results are shown in Table 2.

TABLE 1

Total Zn%	ZnO％	Effective zinc%	Pb％	Cd％
					86.27	6.11	80.16	1.914	0.218

TABLE 1A

Injecting: the determination of cobalt adopts anodic stripping voltammetry polarography, the analytical equipment is Switzerland 797VA, and the lower limit of the detection of cobalt is 0.005mg/l, which is the same as the following.

As is evident from table 1A, the activators formulated with different antimony compounds show a clear difference. Adopting antimony potassium tartrate, chalcanthite and Sb₂O₃+ Chalcanthitum activators experiments (1d and 1e) showed a faster cobalt removal rate in the first 120 minutes under acid addition conditions, but a significant cobalt redissolution occurred after 90 minutes. Whereas the experiments (1a and 1b) using the two antimony compounds and the activator formulated with chalcanthite without acid, the activator formulated with potassium antimony tartrate and chalcanthite reached the lowest point in 120 minutes, after which redissolution occurred. Comparing the acid addition experiment, and adopting Sb when no acid is added₂O₃The activator formulated with Chalcanthitum reached a minimum cobalt concentration in 90 minutes, after which redissolution occurred, but after redissolutionThe concentration is lower than that of the acid-adding experiment, which is probably the reason that the purification and cobalt removal are carried out under the condition of not adding acid in industry.

As is apparent from Table 1A, only Sb was used₄O₅Cl₂And the activator of Chalcanthitum has no re-dissolution of cobalt in 180 minutes under the condition of adding acid (experiment number 1c), and the cobalt concentration of the solution after removing cobalt in 180 minutes <0.005mg/l, which indicates the use of Sb₄O₅Cl₂Antimony potassium tartrate or Sb substitute₂O₃Under the experimental condition, cobalt is not redissolved, and the deep purification of cobalt is realized.

To determine the residual zinc in the slag, the reaction slurry from the above experiment was filtered over 180 minutes, the resulting cleaned slag was washed with 100ml of water and 50ml of a pH 4.6 acetic acid-sodium acetate buffer to remove any water soluble zinc and basic zinc sulfate present, and the slag was analyzed for zinc and cobalt after washing. The results of the slag analysis are shown in Table 1B. It should be noted that if the slag is directly analyzed for zinc content by using the filter residue, the zinc content of the slag obtained by the slag analysis is not enough to indicate the amount of the residual metal zinc in the slag due to the existence of a large amount of water-soluble zinc and basic zinc sulfate, and the residual metal zinc in the slag is the basis for estimating the consumption of the zinc powder₄O₅Cl₂And when the chalcanthite is used as an activating agent, only water washing is adopted because the generated basic zinc sulfate is less. It is clear that this is a laboratory evaluation, and that the slag obtained in actual production does not need to be subjected to such treatment.

TABLE 1B

Experiment number	Activator composition	Adding sulfuric acid amount (g/l)	Amount of slag^*g	The slag contains zinc%	The slag contains cobalt%
						1a	Antimony potassium tartrate and Chalcanthitum	0	0.6064	56.3	1.5
1b	Sb₂O₃+ Chalcanthitum	0	0.4518	47.4	2.01
						1c	Sb₄O₅Cl₂+ Chalcanthitum	0.3	0.9572	70.3	1.04
1d	Antimony potassium tartrate + Chalcanthitum	0.3	0.5436	49.3	1.67
						1e	Sb₂O₃+ Chalcanthitum	0.3	0.2174	37.15	4

Injecting: in Table 3, the weight of slag was 180 minutes, and the slag loss due to sampling was increased in proportion to the final weight of slag.

As is evident from table 1B: antimony Potassium tartrate and Sb₂O₃The residual zinc in the residue was increased in the non-acid addition experiments (1a and 1b), which indicated that the combination of antimony potassium tartrate + chalcanthite and antimony oxide + chalcanthite, and the acid addition of Sb₄O₅Cl₂The comparison of the + Chalcanthitum experiment (1c) still consumed more zinc, indicating that the two combinations resulted in more zinc dissolution, fully demonstrating Sb₄O₅Cl₂+ Chalcanthitum combination as a purification cobalt removal activator. In the acid addition experiment, Sb is adopted under the condition that the usage amount of zinc powder is reduced by 0.25g/l₄O₅Cl₂+ Chalcanthitum test (1c) residue with the most available zinc, and the next time with the activator made of antimony potassium tartrate and Chalcanthitum, Sb₂O₃And minimal zinc residue in the activator formulated with Chalcanthitum. Description of the use of Sb₄O₅Cl₂The activator prepared with Chalcanthitum can effectively reduce the consumption of zinc powder, and Sb is used₂O₃Or antimony potassium tartrate and chalcanthite, the residual effective zinc of the active agent zinc is obviously less. In order to reduce the re-dissolution of cobalt and the consumption of zinc powder, Sb is often adopted under the condition of no acid addition in industry ₂O₃Or antimony potassium tartrate and chalcanthite are combined to remove cobalt, but even if no acid is added, the consumption of zinc is high.

In the experiment, the antimony potassium tartrate or Sb is used₂O₃After the reaction time of the activator synthesized with the chalcanthite reaches 90 minutes, the activator has appeared in the slurry for replacing and removing the cobalt in the experiment without adding acidThe obvious white basic zinc sulfate causes the slurry to be whitish, and the filtering speed is obviously reduced. Using Sb₄O₅Cl₂Under the condition of adding acid, cobalt does not redissolve in 180 minutes, slurry is kept clear in 180 minutes, white basic zinc sulfate is not separated out, the residues are more in zinc, the zinc is less dissolved, the filtering speed is higher, the residue amount is less, the problem of filtering the second-stage residue during industrial purification is solved, and meanwhile, the adding amount of the zinc powder is reduced.

During the experiment, we measured the pH of the solution, and for all experiments the pH was above 5 (25 ℃) after 30 minutes of the purification reaction, indicating that the cobalt removal process could not be monitored using pH measurements, for which we measured OH in the solution for 180 minutes^-Concentration according to OH of the solution^-Concentration, converted to the amount of zinc dissolved ═ OH^-concentration/2X 65.38(g/l), the results are shown in Table 1C.

TABLE 1C

OH from the solution listed in Table 1C^-The concentration is obvious, antimony potassium tartrate and Sb are adopted₂O₃And Chalcanthitum as activator, OH in solution^-Higher than Sb₄O₅Cl₂And an activator prepared from Chalcanthitum. The results obtained in Table 1C are consistent with those of Table 1B, indicating that OH is measured in solution^-The method can be used for monitoring the dissolution condition of zinc powder in the cobalt removal process, and OH of the solution^-The concentration change also shows that the dissolution of zinc in the zinc powder is influenced by more factors, wherein the species of antimony compounds is an important influencing factor, and the utilization rate of zinc of the activating agent prepared by different antimony compounds under the same condition has a great difference, which shows that the utilization rate of zinc in the zinc powder can be improved by adopting the invention, thereby reducing the consumption of the zinc powder. OH from Table 1C^-The significant difference in the amount of zinc dissolved by the three different activators is evident from the reduced amount of zinc dissolved, wherein Sb is used₂O₃The most zinc is dissolved as an activator, and the next is antimony potassium tartrate, Sb₄O₅Cl₂The zinc dissolution is minimal. With addition of a small amount of acid, Sb₂O₃And solution OH of the antimony Potassium tartrate test groups (1d and 1e)^-Much higher concentration than Sb₄O₅Cl₂Experimental group (1c), which also shows that the use of these two common compounds results in more zinc powder being dissolved. Note that OH in this solution is ^-The zinc dissolution amount in terms of concentration is not taken into account in the zinc dissolution amount by the addition of the acid, and the actual zinc dissolution amount should be included in this portion. In addition, in the experiment using antimony potassium tartrate or antimony oxide, we found that white precipitation of basic zinc sulfate occurs in the slag, and the precipitation is dissolved by the acetic acid-sodium acetate buffer solution, which is not counted in the slag, and the amount of zinc dissolved in the experiment using the two antimony compounds and the chalcanthite as the activating agents is much larger. As observed from the experimental results and experimental phenomena listed in Table 1C, white OH precipitate of basic zinc sulfate appears^-The highest concentration is 0.0549-0.0568 mol/l, which indicates that the OH is in this condition^-Is already saturated, so the solution OH of the invention^-The upper limit of (2) is controlled to 0.05 mol/l. This example compares Sb from various angles₂O₃And antimony potassium tartrate and Sb₄O₅Cl₂The difference of cobalt removal under the coordination conditions of the three antimony compounds and the chalcanthite is fully demonstrated by the result that: using Sb₄O₅Cl₂When the antimony compound is substituted for other two antimony compounds, the zinc powder is less dissolved, the consumption of the cobalt-removing zinc powder can be reduced, and the cobalt is not easy to redissolve, which is one of the most important results obtained by the invention.

Example 2

This example is an experiment of the influence of the acid addition amount of different zinc powder species on cobalt removal, the experiment temperature is 80 ℃ and the experiment solution amount is 1 liter. The experimental equipment was the same as in example 1.

a. Experiment of acid addition amount of zinc powder in electric furnace

The experiment mainly aims to investigate the influence of the acid adding amount of the electric furnace zinc powder in the cobalt removing process on the cobalt removing process, and the experiment numbers are 2a, 2b, 2c and 2 d. The experimental equipment and experimental procedures were the same as in example 1. Except thatSamples were only run at 90 and 120 minutes and no slag detection was performed. The zinc powder is electric furnace zinc powder listed in Table 1, the addition amount of the zinc powder is 2g/l, and the activating agent is Sb₄O₅Cl₂+ chalcanthite, copper addition 10.3mg/l, antimony addition 2.8mg/l, corresponding copper to cobalt ratio 1.03, antimony to cobalt ratio 0.28. The acid addition rate is 0-0.2 time of the weight of the added zinc powder. The cobalt removal experiment adopted solution components are as follows: zn 150g/l, Co 10mg/l, Cd 30mg/l, experimental time 120 minutes, the rest conditions are shown in Table 2A. The results are shown in Table 2A.

TABLE 2A

As can be seen from Table 2A, under the condition that the adding amounts of zinc powder and an activating agent are consistent, the acid adding multiplying power of 0.1-0.2 can reach below 0.1mg/l within 120 minutes, the concentration of the later liquid cobalt is gradually reduced along with the increase of the acid adding amount, the cobalt removing speed is fastest when the acid adding multiplying power is 0.15, the cobalt removing speed can be fastest when the acid adding multiplying power is below 0.1mg/l within 90 minutes, the optimal value is 120 minutes, the degradation phenomenon appears when the acid adding multiplying power is 0.2, which indicates that the cobalt removing speed is slowed down due to overhigh acid adding amount, and OH corresponding to different acid adding amounts ^-The range is 0.0212-0.0354 mol/l. For the electric zinc powder used in the invention, the amount of acid added is at most 0.2 times the weight of the added zinc powder, and obviously this ratio (times) will vary for different zinc powders, but via the OH in the solution^-The concentration control and the cobalt removal effect evaluation are easy to control the upper limit and the lower limit of the acid adding multiplying power, the acid adding amount is selected by using the screening method of the acid adding amount, and the acid adding amount given in the embodiment is the optimized acid adding amount according to the method.

b. Acid addition amount experiment of atomized metal zinc powder

The experiment mainly aims to investigate the influence of the acid addition amount of the atomized metal zinc powder on cobalt removal in the cobalt removal process, the experiment numbers are 2e, 2f, 2g and 2h, and the experiment procedures and equipment are the same as those in the example 1. Except that sampling was only performed at 90 minutes and 120 minutes and no slag detection was performed. Zinc powder miningThe atomized metallic zinc powder of No. 1 listed in Table 7A was added in an amount of 2.25g/l and the activator Sb₄O₅Cl₂+ chalcanthite, copper addition 10.3mg/l, antimony addition 2.8mg/l calculated as solution. The acid adding multiplying power is 0-0.15 times. The cobalt removal experiment adopted solution components are as follows: zn150g/l, Co10mg/l, Cd30 mg/l. The results are shown in Table 2B.

TABLE 2B

As can be seen from Table 2B, under the condition that the adding amounts of the zinc powder and the activator are consistent, the cobalt concentration with the acid adding multiplying power of 0-0.1 can reach below 0.1mg/l within 120 minutes, the cobalt removing speed is fastest when the acid adding multiplying power is 0.1, the cobalt concentration can be reduced to below 0.1mg/l within 90 minutes, the cobalt concentration is also a better value within 120 minutes, the acid adding multiplying power is 0.15, the degradation phenomenon occurs, and the possible reason that the acid adding amount of the atomized metal zinc powder is lower than that of the electric furnace zinc powder is that the zinc oxide content of the metal zinc powder is lower, so that the better acid adding amount is less.

For the metallic zinc powder used in the present invention, the upper limit of the amount of acid added is 0.15 times the weight of the zinc powder added. The above examples of acid addition amounts fully illustrate that an appropriate amount of acid is necessary to obtain a faster cobalt removal rate. It is noted that the amount of acid added is based on the OH content of the solution^-The pH (25 ℃) of the solution after 30 minutes of reaction is above 5 in all the examples of the present specification, which is not different, and it is sufficient to explain the use of solution OH^-Feasibility and superiority of concentration to replace pH control.

From the results of the acid addition experiments in this example, it was surprisingly found that the addition of an appropriate amount of acid not only facilitated the cobalt removal process but also reduced the zinc powder consumption. For this result, the inventors believe that this is in a suitable solution OH ^-Avoids passivation of zinc powder under the concentrationAnd a combined result of reducing the dissolution of zinc by the reaction of zinc powder and aqueous zinc sulphate.

Example 3

This example is an experiment of the way chalcanthite and different antimony compounds and zinc powder are added. In the patent publications and some research papers, the addition of the activator is not of any particular interest, and the addition of the activator is frequently carried out by dissolving the activator in a solution, adding it to the solution and then adding the zinc powder, which is advantageous for precise control of the amount of reagent added. The inventors have surprisingly found that the activator is added in different ways, and the experimental results are obviously different. Two adding modes are adopted in the experiment, wherein the first mode is that an activating agent is firstly added and is added into the solution heated to the experiment temperature for dissolving for 3 minutes, and then zinc powder is added for removing cobalt; the second addition was made by adding the solid activator and zinc powder simultaneously to a solution heated to the experimental temperature. The experiment adopts solid antimony potassium tartrate, chalcanthite and solid Sb₄O₅Cl₂+ Chalcanthitum and solid Sb₂O₃+ chalcanthite. The experimental temperature was 80 ℃ and the experimental numbers 3a, 3b, 3c, 3d, 3e, 3f, 3 g. The experimental equipment and procedure were the same as in example 1, except that 3a, 3b, 3g were the first addition described above and the other experiments were the second addition described above. The zinc powder used was an electric furnace zinc powder as listed in table 1.

Two sections of solutions with different cobalt concentrations for removing copper and cadmium are adopted in the experiment, and the components and the addition amount of an activating agent are respectively as follows:

first-stage copper and cadmium removing liquid 1: 180g/l of Zn, 10mg/l of Co and 30mg/l of Cd. The addition of the activating agent comprises the following components in percentage by weight: the addition of copper is 10.3mg/l, the addition of antimony is 2.8mg/l, the corresponding copper-cobalt ratio is 1.03, the antimony-cobalt ratio is 0.28, and the addition of sulfuric acid is 0.15 times of the addition of zinc powder by weight.

First-stage copper and cadmium removing liquid 2: zn 160g/l, Co 20mg/l, Cd 30 mg/l. The adding amount of the activating agent is calculated by the solution, the adding amount of the copper is 15.6mg/l, the adding amount of the antimony is 5.6mg/l, the corresponding copper-cobalt ratio is 0.78, the antimony-cobalt ratio is 0.28, and the adding amount of the sulfuric acid is 0.15 times of the adding amount of the zinc powder by weight ratio. The results are shown in Table 3A

TABLE 3A

As a result of Table 3A, it was surprisingly found that Sb was added first₄O₅Cl₂Experiment (3a, 3b) of + Chalcanthitum activator although the early reaction was faster, a clear redissolution appeared after 150 minutes, and the results of experiment (3c, 3d, 3g) of antimony potassium tartrate + Chalcanthitum activator and the first addition of Sb₂O₃+ Chalcanthitum (3g) results are similar. And the solid activator and the zinc powder are added simultaneously (3e and 3f), so that the redissolution phenomenon does not occur, the cobalt removal depth is higher, and the cobalt removal rate at the early stage is lower.

In view of this phenomenon, the present inventors considered that, in the early stage of the cobalt removal process, the addition of Sb is first employed₄O₅Cl₂+ chalcanthite activators or Sb₂O₃After the chalcanthite is dissolved, the concentration of antimony in the solution at the early stage is high, so that cobalt is quickly removed, but the formed micro-battery is structurally changed, so that the cobalt product in the formed micro-battery is unstable, and more zinc powder is dissolved. The adoption of potassium antimony tartrate and chalcanthite activator has the phenomenon that the potassium antimony tartrate is quickly dissolved, and the Sb is firstly added₄O₅Cl₂And adding zinc powder after dissolving the chalcanthite. Apparently, this is a result of the differences in the physical and chemical properties of the different antimony species, which also suggests the use of Sb₄O₅Cl₂Replace antimony potassium tartrate and use the necessity of solid addition. In the tests described below, zinc powder and activator were both added simultaneously in solid form. The above example 1 was also carried out in such a manner that zinc powder and the activator were added simultaneously.

Example 4

This example is 50 mg/l-oneAnd in the experiment of purifying the liquid atomized metal zinc powder after copper and cadmium are removed, the experiment temperature is 85 ℃, and the experiment number is 4 a. The experimental equipment and experimental procedure were the same as in example 1. The solution contained 150g/l zinc and 30mg/l cadmium. The activator is solid Sb ₄O₅Cl₂+ Chalcanthitum. The activator was added at a copper concentration of 33mg/l and an antimony concentration of 10mg/l based on the solution, corresponding to a copper-to-cobalt ratio of 0.66 and an antimony-to-cobalt ratio of 0.2, and the zinc powder used was atomized zinc powder such as No. 1 one listed in Table 7A, and the amount of zinc powder was 2.5 g/l. The amount of lead added was 0.35% by weight of the zinc powder (in the form of lead sulfate), the ratio of sulfuric acid addition was 0.10 times the amount of zinc powder, and the other conditions are shown in Table 4A.

TABLE 4A

As can be seen from Table 4A, although the cobalt concentration was as high as 50mg/l, the zinc powder addition was increased by only 0.5g/l compared with 10mg/l of the cobalt-containing solution. And the cobalt removal rate was higher than 10mg/l, which is a surprising result compared to the cobalt removal experiments with a 10mg/l cobalt-containing solution, the cobalt removal capacity per gram of zinc powder increased from 12.5mg/g zinc powder to 20mg/g zinc powder. 1.044g of cobalt slag, 80.05% of zinc in the slag and 4.75% of cobalt in the slag. The cobalt removal method has higher cobalt removal efficiency on the solution with high cobalt concentration, and can obtain purified slag with higher cobalt content.

Example 5

This example is a 100mg/l first stage experiment for removing copper and cadmium and then purifying zinc powder in a liquid electric furnace, the experimental temperature is 90 ℃, and the experimental number is 5 a. The solution contained 150g/l zinc and 30mg/l cadmium. The activator is solid Sb₄O₅Cl₂+ Chalcanthitum, experimental equipment and experimental procedure are the same as in example 1. The added activator has a copper concentration of 39mg/l and an antimony concentration of 16mg/l, corresponding to a copper-to-cobalt ratio of 0.39 and an antimony-to-cobalt ratio of 0.16, calculated as a solution. The zinc powder was the electric furnace zinc powder listed in Table 1, and the added amount was 3.75 g/l. The addition rate of sulfuric acid was 0.15 times of the amount of zinc powder, and the other conditions are shown in Table 5A, and the experimental results are also shown in Table 5A.

TABLE 5A

As is evident from Table 5A, at cobalt concentrations as high as 100mg/l, deep purification can still be achieved by rapid cobalt removal at the stated activator addition levels, and cobalt is not easily re-soluble. The amount of zinc powder is only 3.75g/l, and the zinc sulfate solution with the concentration can not rapidly remove cobalt once in industry. The cobalt removed per gram of zinc powder rose to 26.67mgCo/g zinc powder. 1.934g of cobalt slag, wherein the cobalt content in the slag is 5.22%, the zinc content is 75.07%, and the cadmium content is 1.51%. The method provided by the invention can realize one-time rapid purification and cobalt removal of the high-cobalt solution, and can obtain purified slag with high cobalt content.

Example 6

This example is an experiment for removing cobalt by purifying zinc powder in an electric furnace containing 2mg/l cobalt sulfate solution, the experimental temperature is 80 ℃, and the experimental number is 6 a. The amount of the test solution was 1 liter. The solution contains 100g/l of zinc and 30mg/l of cadmium, and the experimental equipment and the experimental procedure are the same as those in example 1. The added activating agent is Sb₄O₅Cl₂+ chalcanthite, the added activator has a copper concentration of 3mg/l, an antimony concentration of 1mg/l, a corresponding copper-to-cobalt ratio of 1.5, and an antimony-to-cobalt ratio of 0.5, based on the solution. The amount of zinc powder added was 1.5g/l, the other conditions are shown in Table 6, the zinc powder used was the same as the electric furnace zinc powder listed in Table 1, the sulfuric acid addition rate was 0.15 times the amount of zinc powder, and the experimental results are shown in Table 6A.

TABLE 6A

As can be seen from Table 6, when the cobalt concentration is low, neither the amount of the activator nor the amount of zinc powder added can be reduced too much, which is in accordance with the general chemical reaction rule, i.e., the lower the concentration, the larger the excess factor. For the cleaned slag obtained with the low cobalt concentration solution, the weight of the product slag after washing was 0.617g, the cobalt content was 0.32% and the zinc content was 79.53%.

Example 7

This example is a test of removing cobalt by liquid purification after removing copper and cadmium by distilling a metallic zinc powder at a concentration of 10mg/l, the test temperature being 80 ℃, the test numbers 7a and 7b, the test equipment and the test procedure being the same as those of example 1, and the amount of the test solution being 1 liter. The zinc powders used were distilled metallic zinc powders as shown in Table 7A. The solution contains 190g/l of zinc and 30mg/l of cadmium. The experimental equipment and experimental procedure were the same as in example 1. The addition of copper was 10.3mg/l, antimony was 2.8mg/l, the corresponding copper to cobalt ratio was 1.03 and antimony to cobalt ratio was 0.28 based on the solution. The addition rate of sulfuric acid was 0.10 times of the amount of zinc powder, and the other conditions are shown in Table 7B. The results are shown in Table 7B.

TABLE 7A

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

TABLE 7B

As can be seen from Table 7B, the activator and the method of use of the activator provided by the invention are suitable for removing cobalt from distilled metallic zinc powder. 0.7524g of the residue from experiment 7a was washed with water to give 1.32% cobalt, 78.46% zinc and 3.82% cadmium. 0.8074g of slag produced in experiment 7b, after washing, the cobalt content was 1.28%, the zinc content was 80.94% and the cadmium content was 3.67%. As can be seen from Table 7B, the cobalt removal effect of the distilled metallic zinc powder is inferior to that of the electric furnace zinc powder, and the addition amount of the zinc powder is slightly more (7B), which shows that the electric furnace zinc powder can obtain better cobalt removal effect in terms of the activity of the zinc powder, and the same cobalt removal effect can be realized by replacing the electric furnace zinc powder with the distilled zinc powder and increasing the addition amount of the zinc powder.

Another experiment of this example was a cobalt removal experiment using atomized metallic zinc powders No. 1 and No. 2 as listed in table 7A, experiment nos. 7c, 7d, 7e, 7 f. Experimental equipment and procedure were the same as in example 1, except that the amount of the experimental solution was 1 liter.

The cobalt concentration of the solution is 10mg/l Co Zn190g/l, Cd is 30mg/l, the adding amount of the zinc powder is 2, 2.25g/l, the activating agent is Sb₄O₅Cl₂The copper and the antimony are added at 80 ℃, the adding amount of the activating agent is 10.3mg/l, the adding amount of the activating agent is 2.8mg/l, and the corresponding copper-cobalt ratio is 1.03 and the antimony-cobalt ratio is 0.28. The acid addition amount is 0.1 time of the zinc powder addition amount, the acid concentration is 0.2-0.225g/l, a small amount of lead (in the form of lead sulfate) is added in part of experiments in the experimental process, the lead sulfate, the zinc powder and the activating agent are added simultaneously, the experimental result of the No. 1 atomized metal zinc powder is shown in the table 7C, and the experimental result of the No. 2 atomized metal zinc powder is shown in the table 7D.

TABLE 7C

TABLE 7D

Experiment 7c OH at 180 min^-0.0307mol/l, the cobalt content of the product slag after washing is 1.31%, the zinc content is 80.49%, and the cadmium content is 3.97%. Experiment 7d OH at 180 min^-0.0328mol/l, the cobalt content of the produced slag is 1.08 percent, the zinc content is 85.78 percent and the cadmium content is 3.48 percent after washing; experiment 7e OH for 180 min^-0.0375mol/l, the cobalt content of the produced slag is 1.92 percent, the zinc content is 73.65 percent and the cadmium content is 5.41 percent after only water washing. Experiment 7f OH for 180 min ^-0.0384mol/l, the cobalt content of the product slag after washing is 1.67%, the zinc content is 79.26%, and the cadmium content is 5.09%.

From tables 7C, 7D and OH^-The results of concentration and slag show that the activator of the invention can achieve better cobalt removal effect by using atomized zinc powder, but a certain amount of lead needs to be added, and the results of the above experiments show that the activator is suitable for atomizing zinc powder under the condition of adding a small amount of acidTo remove cobalt, but to prevent re-dissolution of cobalt, a small amount of lead is added. Both metallic atomized zinc powders containing lead and metallic atomized zinc powders not containing lead require the addition of lead to prevent re-dissolution of cobalt. In this regard, the inventors believe that the activator of the cobalt removal process acts to modify the surface of the zinc powder and that cobalt deposition occurs at the active sites of antimony, so that the zinc powder acts only as an anode to provide electrons, and that only the lead on the surface of the zinc powder particles acts to activate it, whereas the lead within the zinc powder does not, and the added lead can participate in this surface modification process to prevent re-dissolution of the cobalt. This experimental result is different from some patents which contain lead-antimony zinc powder, and this may be the result of a series of changes in the conditions of the present invention, including different antimony compounds, the amount of sulfuric acid added, and the use of direct solid addition, among others. However, in view of the amount of zinc powder added, the amount of atomized metallic zinc powder added is slightly more, which may be due to a decrease in reaction rate caused by a coarser particle size and a smaller reaction surface area.

Example 8

In this example, the effect of nickel and germanium additions and different cadmium concentrations on cobalt removal was measured at 80 ℃ and run numbers 8a to 8 k.

In actual production, the solution after copper and cadmium removal usually contains a certain amount of germanium, nickel and cadmium, particularly germanium, and if the purification cannot meet the requirement, the plate is burned, and in order to investigate the influence of the activating agent provided by the invention on nickel and germanium, a comparative experiment for removing cobalt from a solution containing 10mg/l of cobalt and 150g/l of zinc in the presence of nickel, germanium and cadmium with different concentrations is carried out. The experimental equipment and procedure were the same as in example 1, and the amount of the experimental solution was 1 liter. The activator is Sb₄O₅Cl₂The copper addition amount and the antimony addition amount of the added activating agent and the chalcanthite are respectively 10.3mg/l and 2.8mg/l, the corresponding copper-cobalt ratio is 1.03, the antimony-cobalt ratio is 0.28, the zinc powder adopts electric furnace zinc powder listed in Table 1, the addition amount is 2g/l, the experiment time is 120 minutes, the cadmium interference result shows that the components of the solution are changed in Table 8A, and the slag result shows in Table 8B.

TABLE 8A

TABLE 8B

As can be seen from tables 8A and 8B, under the condition that the addition amounts of the activating agent and the zinc powder are not changed, the cobalt removal speed is gradually increased along with the increase of the cadmium concentration, which shows that the cadmium has an accelerating effect on the cobalt removal. 8 a-8 d experiments show that cadmium does not affect cobalt removal substantially when the cadmium does not exceed 40mg/l, the addition amount of the zinc powder is not increased, the cadmium content of the solution after cobalt removal is increased but does not exceed 1mg/l, a large adjustment range of the addition amount of the zinc powder is provided for the cadmium concentration of the solution after a section of copper and cadmium removal process control, obviously, the addition amount of the zinc powder is increased due to excessively high cadmium concentration, and the increase amount of the zinc powder needs to be determined according to experiments. In industrial production, cadmium can be removed to meet the requirements of electrolysis only by adding a small amount of zinc powder during three-stage purification. Nickel interference results the solution composition changes are shown in Table 8C and slag results are shown in Table 8D.

TABLE 8C

TABLE 8D

As can be seen from tables 8C and 8D, the cobalt concentration appeared to decrease first and then increase as the nickel concentration increased, indicating that there was an accelerating effect on cobalt removal at lower nickel, with the lowest point (8e) being reached at 2mg/l nickel. The presence of a small amount of nickel was beneficial for cobalt removal from the 120 minute results, but the depth of cobalt removal decreased with increasing nickel.

Germanium interference results the solution composition changes are shown in table 8E and the slag results are shown in table 8F.

TABLE 8E

TABLE 8F

As can be seen from the results in tables 8E and 8F, the presence of a small amount of germanium favors cobalt precipitation, and germanium can be replaced to less than 0.02mg/l while removing cobalt.

The liquid composition changes of the results of the germanium-nickel composite interference experiments are shown in Table 8G, and the slag results are shown in Table 8H.

TABLE 8G

TABLE 8H

It is apparent from the results in tables 8G and 8H that the cobalt removal was carried out with the activators of the invention when small amounts of nickel and germanium were added to the solution, with the small amount of nickel germanium having an accelerating effect on the cobalt removal, which is similar to that of the copper antimony activators. When cobalt is removed, 0.1-0.3 mg/l Ge is added, under the same zinc powder amount, germanium can stably reach below 0.02mg/l, and nickel can be removed below 0.1 mg/l.

The experimental results of this example show that: the activator of the invention can widen the requirement range of the solution for removing copper and cadmium on cadmium, nickel and germanium, and particularly can reduce the requirement of removing germanium by cleaning in the middle and upper part, which has important significance for reducing burning plates caused by the fact that the concentration of germanium exceeds the control standard in industrial production.

Example 9

This example is a purification experiment of a liquid-atomized metallic zinc powder containing 2mg/l of cobalt after removing copper and cadmium at 80 ℃ under experiment number 9 a. The solution contains 130g/l of zinc and 30mg/l of cadmium. The activator is solid Sb₄O₅Cl₂+ Chalcanthitum, experimental equipment and experimental procedure as in example 1, the amount of experimental solution was 1 liter. The added activating agent has the copper concentration of 3mg/l, the antimony concentration of 1mg/l, the corresponding copper-cobalt ratio of 1.5 and the antimony-cobalt ratio of 0.5 according to the solution. The zinc powder was an atomized zinc powder 1 shown in Table 7A, added in an amount of 1.5 g/l. 5mg/l of lead (in the form of lead sulfate) was added for the experiment, the lead sulfate and zinc powder were added together with the activator, the addition rate of sulfuric acid was 0.10 times and 0.15g/l of the amount of zinc powder, the other conditions are shown in Table 9, and the experimental results are also shown in Table 9.

TABLE 9

As can be seen from Table 9, when the activator of the present invention is used for replacing and removing cobalt by using atomized metallic zinc powder without lead, the low cobalt solution of 2mg/l can reach the requirement of deep purification after 90 minutes, and is not redissolved within 180 minutes. However, the coefficient of zinc powder for removing cobalt as described above is only 1.33mgCo/g zinc powder in terms of the amount of zinc powder added and the ratio of cobalt, and it is more difficult to remove cobalt from a solution having a lower cobalt concentration and a higher cobalt concentration, possibly due to the reaction kinetics.

Example 10

This example is a purification experiment of a first stage of zinc powder containing cobalt 50mg/l, after copper and cadmium removal, by liquid distillation at 85 ℃ under experiment number 10 a. The solutions Zn 175g/l and Cd 30mg/l, the experimental equipment and procedure were as in example 1, the copper concentration of the added activator was 33mg/l, the antimony concentration was 10mg/l, the corresponding copper to cobalt ratio was 0.66, the antimony to cobalt ratio was 0.2, the zinc powder was a distilled metallic zinc powder as listed in Table 7A, and the amount of zinc powder was 2.5 g/l. The addition rate of sulfuric acid is 0.10 times of the amount of zinc powder, the other conditions are shown in Table 10, and the experimental results are also shown in Table 10.

TABLE 10

As can be seen from Table 10, when the activating agent provided by the invention is used for removing copper and cadmium from a section of Co20mg/l under the synergistic effect of zinc powder, the cobalt can reach the requirement of deep purification of less than 0.1mg/l after 120 minutes and is not redissolved within 180 minutes.

Example 11

This example is a purification experiment of a first stage of a liquid distillation metallic zinc powder containing 2mg/l of cobalt after removal of copper and cadmium at a temperature of 80 ℃ under experiment number 11 a. 170g/l Zn and 10mg/l Cd. The activator is solid Sb₄O₅Cl₂+ Chalcanthitum, experimental equipment and experimental procedure are the same as in example 1. The added activating agent has the copper concentration of 3mg/l, the antimony concentration of 1mg/l, the corresponding copper-cobalt ratio of 1.5 and the antimony-cobalt ratio of 0.5 according to the solution. The zinc powder was a distilled metal zinc powder as listed in Table 7A, the addition amount was 1.5g/l, the addition ratio of sulfuric acid was 0.10 times the amount of zinc powder, the other conditions are shown in Table 11, and the experimental results are also shown in Table 11.

TABLE 11

As can be seen from Table 11, the use of distilled metallic zinc powder with the synergistic effect of the activator of the present invention can achieve the deep purification of cobalt in 2mg/l solution after 90 minutes without re-dissolution within 180 minutes.

Example 12

In this example, 120mg/l of zinc sulfate solution containing cobalt is used to purify and remove cobalt from metal zinc powder, the temperature is 85 ℃, and the experimental number is 12 a. The experiment was carried out in a circular reactor heated with polypropylene tape having an effective volume of 8.5l, the amount of the experimental solution was 8.5l, and the stirring was carried out with a teflon mechanical stirring paddle. The experimental procedure was the same as in example 1. Other components of the cobalt-removing precursor liquid: zn185g/l, Cd100 mg/l. The zinc powder used was distilled of a metallic zinc powder as shown in Table 7A, in an amount of 4.5g/l, sulfuric acidThe adding amount is 0.10 times 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 a copper to cobalt ratio of 0.36 and an antimony to cobalt ratio of 0.16, based on the solution. Cobalt removal results for the resulting solution and OH of the 180 minute solution^-The concentrations are shown in Table 12.

TABLE 12

After washing the 180 minutes slag obtained in example 7 with water, 19.35 g of slag were obtained (minus the loss of mass of slag due to sampling), containing 5.16% of cobalt and 70.85% of zinc, calculated on the basis of the amount of slag. It can be obviously seen that the distilled metal zinc powder is suitable for removing cobalt from high-cobalt solution, and purified slag with high cobalt content can be directly obtained, so that the recovery of cobalt and other valuable elements from the cobalt slag in the next step is facilitated.

As can be seen from Table 12, the cobalt removal capacity per unit weight of zinc powder increases significantly with increasing cobalt concentration, and calculated from the data obtained in example 7, for a 120mg/l cobalt-containing solution, 26.6mg/l per gram of zinc powder, calculated as cobalt removed, is significantly higher than the cobalt removal efficiency for a 2mg/l cobalt-containing zinc powder, and a 2mg/l cobalt-containing solution, calculated as cobalt removed, is only 1.33mg Co/g zinc powder per gram of zinc powder, indicating that with the activator of the present invention, the higher the cobalt concentration, the higher the cobalt removal efficiency for the zinc powder. And the lower the cobalt concentration, the lower the cobalt removal efficiency, and the lower the cobalt concentration, the more difficult the purification, which accords with the rules of general chemical reactions.

Example 13

This example is a purification and cobalt removal experiment of 120mg/l cobalt-containing zinc sulfate solution atomized metallic zinc powder, the experiment temperature is 90 ℃, and the experiment number is 13 a. The amount of the experimental solution was 2 liters and the stirring was performed with a teflon mechanical stirring paddle. The experimental equipment and procedure were the same as in example 1. Cobalt removal front liquid component: 150g/l of Zn, 15g/l of Mg15g, 5.2g/l of Mn5, 30Mg/l of Cd and 120 g/l of Co120 Mg. The zinc powder was an atomized zinc powder of No. 1 listed in Table 7A, added in an amount of 4.25g/l and sulfuric acid in an amount of 0.42g/l, calculated as 0.10 times the amount of the zinc powder, to which 10mg/l of lead (in the form of lead sulfate) and sulfuric acid were added in the experiment Adding lead powder, zinc powder and activator at the same time, wherein the activator 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 amount of sulfuric acid added was 0.10 times the amount of zinc powder, and the experimental procedure was the same as in 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 13.

Watch 13

After washing the 180 minutes slag obtained in example 13 with water, 4.2 g of slag were obtained (minus the loss of mass of slag due to sampling), containing 4.75% of cobalt and 80.25% of zinc, calculated on the basis of the amount of slag. It can be obviously seen that the activating agent of the invention is suitable for removing cobalt from the high cobalt solution of atomized zinc powder, can directly obtain purified slag with high cobalt content, and is beneficial to the recovery of cobalt and other valuable elements from the cobalt slag in the next step.

Example 14

In this example, the electric furnace zinc powder high cobalt zinc sulfate solution is purified to remove cobalt, the experimental temperature is 85 ℃, and the experimental number is 14 a. The amount of the test solution was 1 liter. The experimental equipment and experimental procedure were the same as in example 1. Cobalt removal front liquid composition: zn150g/l, Mg 15g/l, Mn 5.2g/l, Cd 30Mg/l, Co 120 Mg/l. The zinc powder is electric furnace zinc powder listed in Table 1, the adding amount is 4.25g/l, the adding amount of sulfuric acid is calculated according to 0.15 time of the zinc powder, and the activating agent is Sb ₄O₅Cl₂The copper addition and the antimony addition were 43.2mg/l, 19.4mg/l, corresponding to a copper to cobalt ratio of 0.36 and an antimony to cobalt ratio of 0.16, based on the solution. Cobalt removal of the resulting solution and OH of the 180 minute solution^-The concentrations are shown in Table 14.

TABLE 14

The 180 minute slag obtained in example 14 was washed with water to give 3.45 g of slag (minus the loss of slag mass due to sampling), and the resulting purified slag had a cobalt content of 6.97% and a zinc content of 76.54%. It can be obviously seen that the method for adjusting the addition amount of the activating agent is suitable for removing cobalt from a high-cobalt solution, and can directly obtain purified slag with high cobalt content, thereby being beneficial to recovering cobalt and other valuable elements from the cobalt slag in the next step. As is apparent from Table 14, the solution containing cobalt up to 120mg/l can obtain better cobalt removal effect by adopting the optimized addition amount of the activating agent, and the cobalt removal capacity of the zinc powder calculated by unit weight of the zinc powder reaches 28.24mgCo/g zinc powder. Obviously, the cobalt concentration of the example exceeds the cobalt-containing range of the liquid after the first-stage copper and cadmium removal of most factories, but the deep cobalt removal can be realized once by adopting the method for controlling the adding amount of the activating agent provided by the invention.

Example 15

This example is an example of purifying and removing cobalt from zinc sulfate solution with different cobalt concentrations of electric furnace zinc powder, aiming at examining the change of antimony concentration of the solution in the purifying and removing cobalt process, the temperature is 80 ℃, and the experiment numbers are 15 a-15 c. The experimental equipment and procedure were the same as in example 1. Cobalt removal front liquid composition: 150g/l of Zn, 30mg/l of Cd and 10mg/l, 40mg/l and 80mg/l of Co respectively, and the amount of the experimental solution is 1 liter. The zinc powder is electric furnace zinc powder listed in Table 1, and the activating agent is Sb ₄O₅Cl₂With respect to chalcanthite, the amount of the activator added was varied according to the concentration of cobalt, and the amounts of copper and antimony added are shown in Table 15A, and the respective copper-cobalt ratios were 1.03, 0.67, and 0.39, and the respective antimony-cobalt ratios were 0.28, 0.24, and 0.16. The results of removing cobalt from the resulting solution are shown in Table 15A, and the results of changing the antimony concentration are shown in Table 15B.

TABLE 15A

TABLE 15B

Injecting: and measuring the concentration of the antimony in the solution by adopting an anodic voltammetry stripping method, wherein the equipment is a Switzerland VA797 voltammetry polarograph, and the detection limit is 0.005 mg/l.

From Table 15B, it can be seen that Sb of the present invention was used₄O₅Cl₂As an activator, when the concentration of antimony added into the solution is changed within a large range of 3.75-12.96 mg/l, the antimony in the solution is less than 0.02mg/l in 120 minutes, which indicates that Sb is₄O₅Cl₂Antimony residues during cobalt removal were low. Also, as can be seen from Table 15A, at 60 minutes, the cobalt concentration was already below 1mg/l, and the corresponding antimony concentration was already below 0.05mg/l, indicating that most of the cobalt and antimony had been displaced in a shorter period of time. This fully illustrates the fact that antimony in the activator proposed by the present invention is added with a small amount of acid to control the OH of the solution^-After concentration, antimony is easily displaced to a lower concentration. It is generally considered that the purified zinc sulfate solution fed to electrolysis can be normally electrolyzed with the antimony content below 0.05mg/l, and the antimony content in most factories is controlled below 0.02-0.03 mg/l. And most enterprises adopt a three-stage purification process as shown in figure 2, and antimony is further reduced in the third stage of purification, so that the purified liquid containing antimony by the method provided by the invention can reach the standard.

Example 16

This example is Sb obtained by hydrolysis₄O₅Cl₂Examples for purifying cobalt.

a、Sb₄O₅Cl₂Preparation of (2)

According to the document [10 ]]The method comprises the steps of firstly adopting hydrochloric acid aqueous solution to dissolve Sb₂O₃Obtaining hydrochloric acid aqueous solution containing stibium, and then adding water to obtain Sb₄O₅Cl₂The specific experiments are as follows:

mixing 300 g of Sb₂O₃(content of>99%) at 30 deg.C, dissolving in 1L 10mol/L hydrochloric acid aqueous solution for 30 min, adding 16L water into the solution, reacting at room temperature for 1 hr, filtering, and oven drying at 100 deg.C for 5 hr to obtain 321 g Sb₄O₅Cl₂And 17 liters of hydrolyzed solution, antimony hydrolysis rate>98 percent. The obtained hydrolysis precipitate contains 76.28% of antimony and 11.23% of chlorine, and the contents of antimony and chlorine are basicallyConform to Sb₄O₅Cl₂Theoretical content of (B), calculated as chlorine₄O₅Cl₂The content was 101.08%.

b. Cobalt removal experiment Sb obtained by adopting preparation method₄O₅Cl₂Cobalt removal was carried out at 85 ℃ and run number 16 a. The experimental equipment and experimental procedure were the same as in example 1. Cobalt removal front liquid composition: cobalt removal front liquid composition: 150g/l of Zn, 15g/l of Mg, 5.2g/l of Mn, 30Mg/l of Cd and 120Mg/l of Co, and the amount of the experimental solution is 2 liters. The zinc powder of the electric furnace listed in Table 1 is adopted, the adding amount is 4.25g/l, the adding amount of the sulfuric acid is calculated according to 0.15 time of the amount of the zinc powder, and the activating agent is Sb ₄O₅Cl₂The copper addition was 43.2mg/l and antimony addition was 19.4mg/l, corresponding to a copper to cobalt ratio of 0.36 and an antimony to cobalt ratio of 0.16, based on the solution, and the results are shown in Table 16A.

TABLE 16A

The 180 minutes slag obtained was washed with water to give 3.38 g of slag (minus the loss of slag mass due to sampling), and the resulting purified slag had a cobalt content of 6.74% and a zinc content of 77.36%.

As is apparent from Table 16A, Table 14A of comparative example 14, Sb prepared by hydrolysis₄O₅Cl₂For removing cobalt, results obtained and Sb produced by the inventor's patent₄O₅Cl₂The effects are basically the same, which shows that Sb prepared by the hydrolysis process₄O₅Cl₂Can also be used for the purification and cobalt removal of the invention.

From the above numerous examples, it is evident that the Sb proposed by the present invention is used₄O₅Cl₂The copper amount and the antimony amount in the added activating agent are increased along with the increase of the cobalt concentration, the copper addition amount is 3-43.2 mg/l, the antimony addition amount is 1-19.4 mg/l, the corresponding copper-cobalt ratio is 0.36-1.5, the antimony-cobalt ratio is 0.16-0.5, and the lower the cobalt concentration is, the phase is formedThe less copper and antimony should be; the higher the cobalt concentration, the more copper and antimony are added. Under the condition of simultaneously adding a small amount of sulfuric acid, the cobalt concentration of 2-120 mg/l can reach the purification standard that the cobalt concentration is less than 0.1mg/l within 120 minutes, and the cobalt is not redissolved within 180 minutes. The adding amount of the zinc powder is adjusted according to the cobalt concentration change in the solution after the copper and cadmium removal of the first section according to the amount of cobalt removed in each gram of the zinc powder, and the adding amount of the zinc powder is at least 1.5-4.25 g/l and at least not less than 1.5g/l within the range of 2-120 mg/l of cobalt concentration. The cobalt removal capacity of the zinc powder per unit weight is 1.33-26.6 mgCo/(g zinc powder), the higher the cobalt concentration is, the higher the corresponding cobalt removal capacity of the zinc powder is, and the lower the cobalt concentration is, the lower the cobalt removal capacity of the zinc powder is. As known in the common knowledge and the specification of the invention, in the cobalt removing process of the zinc powder, the cobalt removing process is facilitated by properly increasing the dosage of the zinc powder. The zinc powder additions given in this description are therefore only moderate zinc powder additions obtained after screening under the conditions described in this description. The zinc concentration of the solution, the purification temperature, and the different purification requirements all affect the amount of zinc powder added, and it is obvious to one skilled in the art that the amount of zinc powder added can be increased or decreased according to the specific purification depth.

From the abundant examples above, we can also see that the Sb provided by the invention is adopted₄O₅Cl₂+ vitriol activator, adding a small amount of sulfuric acid 0.05-0.2 times of the amount of zinc powder, and purifying OH in the solution at 80-90 ℃ for 120-80 minutes^-The concentration is 0.02-0.05 mol/l, and in such a range, good results can be obtained by purifying and removing cobalt. The activating agent of the invention has better effect when different zinc powders are used, which shows that the method provided by the invention is suitable for removing cobalt from various zinc powders.

Obviously, the Sb provided by the invention is adopted₄O₅Cl₂Replace antimony potassium tartrate and Sb commonly used in industry₂O₃As antimony source and chalcanthite, adding small amount of sulfuric acid to control OH content in solution^-Under the condition of concentration, the method is matched with other patents applied by the inventor, and is suitable for deep purification of nickel, cobalt and germanium in zinc sulfate aqueous solution.

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 method for purifying and removing cobalt provided by the invention has the following unexpected and beneficial effects:

1. sb provided by the invention₄O₅Cl₂The method for purifying and removing cobalt provides a selective new antimony compound for purifying and removing cobalt in zinc hydrometallurgy. In the use of Sb₄O₅Cl₂When the nickel cobalt is removed by matching with chalcanthite, the fact that Sb is used for removing nickel cobalt is unexpectedly found₄O₅Cl₂Compared with the method for removing cobalt by using antimony potassium tartrate or antimony trioxide, the method shows great difference, and the cobalt product formed by the chalcanthite and the zinc powder is relatively stable, so that the re-dissolution of cobalt is avoided. And the re-dissolution of cobalt is proved to be related to the species and the adding mode of the adopted antimony compound, so that a novel activator for purifying and removing cobalt, which can avoid the re-dissolution of cobalt, is provided for realizing stable purification and removal of cobalt in production practice.

2. Generally, the addition of acid in the cobalt removing process inevitably leads to the dissolution of zinc powder and the re-dissolution of cobalt, and the adoption of the method for controlling the pH of the solution to be in a weak acid range proves that the defects exist, and the invention controls the OH in the solution^-The method ensures that the solution is neutral and the zinc powder is not passivated, enhances the controllability of the acid adding process, avoids a large amount of basic zinc sulfate from entering slag, avoids the re-dissolution of cobalt, and realizes deep purification by using lower zinc powder. By adopting the method, the cobalt content in the purified slag is greatly improved after washing because the purified slag is basically the water-soluble zinc brought by metallic substances and solutions, the quantity of the second-stage nickel and cobalt removal slag is reduced, and the method is favorable for reducing the filtration equipment for the second-stage nickel and cobalt removal slag and the equipment for treating the second-stage slag.

3. The two-stage purification of the antimonite purification method adopts a copper-antimony activating agent to remove impurity elements such as Ni, Co, Ge and the like by replacement under the action of zinc powder, and because the zinc powder is a main reducing agent for removing cobalt, the driving force of replacement can be improved by increasing the addition of the zinc powder when the depth of cobalt removal does not meet the requirement, but the expected effect can not be achieved frequently. By adopting the method, better purification effect is achieved under the condition of less zinc powder addition, the concentration of the purified liquid cobalt can stably reach below 0.1mg/l, and the deep purification of cobalt can be stably realized, which obviously has important significance for the stable control of industrial production purification.

4. It is generally considered that the higher the cobalt concentration is, the more difficult the cobalt removal is, and the more difficult the high cobalt solution is to be replaced at one time to achieve the deep purification requirement. Unexpectedly, under the activating agent and using conditions of the activating agent, and the related patents applied by the inventor, the deep purification of the high-cobalt solution can be stably realized, the higher the cobalt concentration is, the higher the cobalt removal quality of the zinc powder per unit mass is, and the faster the cobalt removal speed is, and the one-time deep purification cobalt removal is realized under the condition that the cobalt concentration is as high as 120mg/l, and the unexpected result is obtained. Meanwhile, the higher the cobalt concentration is, the higher the cobalt content of the obtained purification slag is, the problem of purification of a high-cobalt solution is solved, and the cobalt slag is beneficial to realizing comprehensive recovery.

In addition, the method of the invention and the calculation of the zinc powder and activator addition based on the cobalt concentration obviously provides an important reference for stable control of industrial production.

5. The activating agent is matched with a small amount of sulfuric acid, so that the activity of zinc powder is improved, germanium is easily replaced and removed by the zinc powder in the process of replacing and precipitating cobalt, the requirement of the middle-upper-clear liquid on germanium content is greatly relaxed, deep germanium removal is realized while cobalt removal is carried out, and the requirement of new electrolytic liquid on cobalt (<0.02mg/l) is met. Unexpectedly, the addition of nickel also produces a similar phenomenon when cobalt is removed more rapidly in germanium-containing solutions than in non-germanium-containing solutions in the presence of small amounts of germanium in the solution, which is an unexpected result.

6. The purification cobalt-removing method provided by the invention has good adaptability to zinc sulfate solutions with various cobalt concentrations, and expands the application range of wet zinc-smelting plants to raw materials, particularly cobalt.

Claims

1. A method for removing nickel, cobalt and germanium by zinc sulfate aqueous solution purification is characterized in that neutral zinc sulfate leaching solution is subjected to first-stage copper and cadmium removal to obtain first-stage copper and cadmium removal solution, and then the first-stage copper and cadmium removal solution is subjected to second-stage purification to remove nickel, cobalt and germanium, and the method is characterized in that: in the two-stage purification, according to the components of the first-stage copper and cadmium-removing liquid, adding proper amount of chalcanthite, antimony compound and proper amount of zinc powder, and adding proper amount of sulfuric acid, wherein the antimony compound is Sb ₄O₅Cl₂And zinc powder, chalcanthite and Sb are added₄O₅Cl₂The solid state is reacted for a period of time within a certain temperature range to remove nickel, cobalt and germanium, and the second-stage purification slurry from which the nickel, cobalt and germanium are removed is subjected to liquid-solid separation to obtain second-stage purified liquid; the certain temperature range is 80-90 ℃, and the certain time is 90-180 minutes;

the proper amount of sulfuric acid is added according to a certain multiplying power of the adding amount of the zinc powder, and according to OH in the final solution when the purification process is finished^-Adjusting the addition amount of acid;

according to the OH in the final solution at the end of the purification process^-The addition amount of the concentration adjusting acid is as follows: in the two-stage purification process, OH in the solution is obtained after 90-180 minutes^-Concentration of this OH^-The concentration is 0.02-0.05 mol/l;

the multiplying power is 0.05-0.2 time of the weight of the added zinc powder;

the adding of the proper amount of zinc powder is to adjust the adding amount of the zinc powder according to the concentration of the cobalt and the concentration of cadmium in the solution after the copper and cadmium are removed;

the adding amount of the zinc powder is adjusted according to the cobalt concentration of the first-stage copper and cadmium removal solution and a certain zinc powder cobalt removal capacity, and the cadmium consumption zinc powder is calculated, wherein the zinc powder cobalt removal capacity is the cobalt weight divided by the zinc powder weight, and the zinc powder weight unit is g; the weight unit of cobalt is mg;

When the cobalt concentration range is 2-120 mg/l and the cadmium concentration is below 50mg/l, the corresponding zinc powder addition amount is in the cobalt concentration range, the zinc powder addition amount is 1.5-4.25 g/l, and the cobalt removal capacity of the zinc powder is 1.33-26.6 mg/g;

the higher the cobalt concentration is, the higher the cobalt removal capacity of the zinc powder is, and the cadmium concentration exceeds 50mg/l, the adding amount of the zinc powder is increased at least according to the theoretical amount of replacing and removing cadmium according to the increase of the cadmium concentration, and the adding amount of the zinc powder is increased or reduced according to the requirement of the cobalt concentration of the purified liquid, but at least the adding amount of the zinc powder cannot be lower than 1.5 g/l;

chalcanthitum and Sb₄O₅Cl₂The addition amount of the Sb is controlled by calculating the ratio of copper to cobalt and the ratio of antimony to cobalt according to the cobalt concentration of the solution after copper and cadmium are removed₄O₅Cl₂And the addition amount of the chalcanthite is 0.36-1.5 of copper-cobalt ratio and 0.16-0.5 of antimony-cobalt ratio when the concentration of the cobalt is 2-120 mg/l.

2. The method of claim 1, wherein: the sulfuric acid is industrial sulfuric acid or electrolytic waste liquid, and the added amount of the sulfuric acid is the net sulfuric acid content of the industrial sulfuric acid or the electrolytic waste liquid.

3. The method of claim 2, wherein: chalcanthitum and Sb₄O₅Cl₂The addition amount of the catalyst is that Sb is controlled by calculating the ratio of copper to cobalt and the ratio of antimony to cobalt according to the concentration of the cobalt₄O₅Cl₂And 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 added ₄O₅Cl₂The ratio of the weight of antimony in the solution to the weight of cobalt in the solution; when the concentration of cobalt is 2-120 mg/l, the ratio of copper to cobalt is 0.36-1.5, and the ratio of antimony to cobalt is 0.16-0.5; the higher the cobalt concentration is, the lower the corresponding copper-cobalt ratio and antimony-cobalt ratio are, and the cobalt concentration of the purified liquid is required to increase or decrease the chalcanthite and Sb₄O₅Cl₂The amount added.

4. The method of claim 1, wherein: the zinc powder added with a proper amount of sulfuric acid is added with zinc powder, chalcanthite and Sb₄O₅Cl₂Previously added.

5. According to the rightThe method of claim 1, wherein: the two-stage purification comprises the steps of firstly heating the first-stage copper and cadmium removal solution to 80-90 ℃, adding sulfuric acid or electrolytic waste liquid according to 0.05-0.2 time of the amount of added zinc powder, and then rapidly adding zinc powder and Sb in a solid form within 1 minute₄O₅Cl₂Adding Chalcanthitum into the first-stage solution after removing copper and cadmium, adding zinc powder and Sb₄O₅Cl₂And reacting the slurry of the chalcanthite for 90-180 minutes at 80-90 ℃ under a stirring state, removing nickel, cobalt and germanium in the solution, and carrying out solid-liquid separation on the slurry from which the nickel, cobalt and germanium are removed to obtain a second-stage purified liquid and purified slag.

6. The method of claim 1, wherein: and in the second-stage purification, the added zinc powder is electric furnace zinc powder, atomized metal zinc powder or distilled metal zinc powder.

7. The method of claim 6, wherein said secondary cleaning employs atomized zinc metal powder having a particle size of less than 50 microns.

8. The method of claim 1, wherein: in the second-stage purification, when the cobalt concentration in the solution after copper and cadmium removal is within the range of 2-120 mg/l, the solution after the second-stage purification reaches Co <0.5mg/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 90-120 minutes.