RU2444574C1 - Method for obtaining cobalt and its compounds - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method for obtaining cobalt and its compounds involves conversion of cobalt from cobalt-bearing raw material to the solution; deposition of cobaltic hydroxide (III) using oxidiser and neutraliser, dilution of cobaltic hydroxide (III) with conversion of cobalt (III) to cobalt (II). Then, the obtained solution is cleaned from impurities and metallic cobalt or its compounds are obtained. Cobaltic hydroxide (III) is diluted with the participation of recovered reduced forms of iron and/or copper salts in the range of oxidation-reduction potential of 300-700 mV relative to silver-chloride comparison electrode and pH 1-3, thus adjusting the temperature of the process by means of evaporation cooling. Recovery of reduced forms of iron and/or copper is performed in a separate unit using the reducer. At insufficient amount of copper and iron in raw material supplied to the process there performed is cleaning of leaching solution from copper by cementation and recirculation of cleaning product to the recovery stage of reduced forms of iron and/or copper.

EFFECT: improving the opening rate of initial raw material and simplifying the process.

12 cl, 2 dwg, 3 tbl, 6 ex

Description

The method relates to hydrometallurgy of non-ferrous metals and can be used in the processing of cobalt-containing polymetallic raw materials.

Known methods for the production of cobalt and its compounds from cobalt-containing raw materials, including the conversion of raw materials into a solution, the precipitation of cobalt (III) hydroxide using an oxidizing agent and a neutralizer, the acid dissolution of cobalt (III) hydroxide with the conversion of cobalt (III) to cobalt (II), cleaning the resulting solution from impurities and obtaining metallic cobalt or its compounds. Depending on the composition of the raw materials and the requirements for the final cobalt product, these methods differ in the operations of dissolution, purification of solutions and obtaining the final product.

So, in particular, when refining rough nickel anodes, cobalt dissolves electrochemically together with nickel, is separated from the nickel solution by precipitation of cobalt (III) hydroxide using chlorine and nickel carbonate. The obtained cobalt (III) hydroxide is dissolved in acid with the conversion of cobalt (III) to cobalt (II) with the participation of a reducing agent. The cobalt-containing solution is purified from impurities, and pure cobalt (III) hydroxide is re-precipitated from it. Metallic cobalt from cobalt (III) hydroxide is obtained by the pyrometallurgical method (Reznik I.D., Sobol S.I., Khudyakov V.M. Cobalt, vol. 2. - M .: Engineering, 1995. - 470 p.).

All known methods for producing cobalt, including the processing of cobalt (III) hydroxide, provide for the acid treatment of this material using reducing agents that convert practically insoluble cobalt oxides of an oxidation state higher than (II) into water-soluble cobalt salts of oxidation state (II), i.e., they are reduced to acid dissolution of cobalt (III) hydroxide with the participation of a reducing agent.

Various mineral or organic compounds are used as reducing agents, which are introduced into the acidic pulp of cobalt (III) hydroxide. So, in particular, according to RF patent No. 2138446 and RF patent No. 2106417, hydroxylamine compounds are used as reducing agents, according to RF patent No. 2094551 - hydrazine, and according to RF patent No. 2141452, hydrogen peroxide is used as a reducing agent. These reducing agents are expensive, toxic or hazardous chemicals. In the metallurgical industry, cheaper compounds of unsaturated sulfur, in particular thiosulfates (ed. St. USSR No. 572433, 1326626) or sulfur dioxide (ed. St. USSR No. 352957), have been used as reducing agents. However, their use is associated with the release of toxic gases, the dissolution process is characterized by a low speed, and determines the formation of sulfate runoff in the production of cobalt metal and its compounds.

To obtain sulfate-free cobalt chloride solutions, chloride compounds, for example hydrochloric acid or mineral chloride salts (ed. St. USSR No. 1708895) can be used as a reducing agent, however, deep dissolution of cobalt (III) hydroxide is achieved at a significantly higher stoichiometric flow rate of hydrochloric acid determining the high acidity of the resulting solution.

The closest technical solution (prototype) is a method of processing cobalt concentrate containing cobalt (III) hydroxide, including pulping, treatment of the pulp with hydrochloric acid and separation of the cobalt-containing solution from the insoluble residue. The concentrate is pulverized in a metal chloride solution, and the pulp is treated at a redox potential of not more than 900 mV in the presence of a reducing agent, which is introduced in excess with respect to the resulting chlorine; a metal selected from the group consisting of nickel, cobalt is used as a reducing agent , iron, copper, aluminum or an alloy containing one or more of these metals, and the metal chloride solution is selected from the group including nickel, cobalt, magnesium, calcium, aluminum (RF patent No. 2080398) .

From the examples of the method implementation, it is seen that, according to the prototype, the dissolution of the concentrate containing cobalt (III) hydroxide is carried out by controlling the redox potential by introducing hydrochloric acid into the pre-prepared pulp of the mixture of the concentrate and reducing agent until its consumption is stopped, which is determined by the final acidity corresponding to a pH of about 0, 5. The described method has the following disadvantages.

1. The low intensity of the process, due to the selected method of the dissolution process by preliminary preparation of the pulp containing cobalt (III) hydroxide concentrate and a reducing agent, followed by feeding hydrochloric acid to the finished pulp according to the value of the redox potential. The simultaneous loading of all solid components with the subsequent gradual introduction of hydrochloric acid by the redox potential determines the zero acidity of the solution for most of the dissolution time. As a result, the possibility of accelerating the process due to the participation of regenerated reduced forms of iron and / or copper salts (mediators) in it is not realized. Even in the presence of copper and iron in the reducing agent and concentrate, the process proceeds in local areas of the acid supply dissolving the precipitated iron (III) and copper (II). The latter, being restored, dissolve the metal, then they are oxidized, reducing cobalt from the hydrated oxide, and, with insufficient acidity, they precipitate. The method is implemented using technical materials in which copper and iron are contained as impurities. The absence of copper and / or iron impurities in the cobalt concentrate, solution, and reducing agent practically excludes the possibility of carrying out the process in the selected modes.

2. The method is carried out in an aqueous suspension of two solid reagents differing in size and density: cobalt hydrate particles and metal particles. The requirement to ensure the uniformity of the pulp significantly limits the fineness of the metal particles and determines the stringent requirements for the mixing device.

3. Inadequate process safety, which is also a consequence of the chosen method of implementation and regulation. The maximum value of the redox potential that ensures the safe conduct of the process should correspond to the presence of mediators of low oxidation state in the metal solution, which for copper or iron ions corresponds to the redox potential of not more than 650 mV. The measured value of the redox potential is characterized by significant fluctuations (throws), and control becomes difficult. Fluctuations in the redox potential may exceed 1200 mV, which meets the conditions for the release of chlorine. In addition, even the partial occurrence of heavier and larger metal particles in a reactor with mechanical stirring leads to heterogeneity of the redox potential along the height of the apparatus, its increase in the upper part up to a value that meets the conditions for the evolution of chlorine.

4. The presence of water supplied with wet cobalt concentrate and with hydrochloric acid, and the formation of water as a result of chemical reactions do not make it possible to obtain concentrated solutions necessary for their further processing without prior evaporation.

The invention is aimed at solving the problem of increasing the intensity of opening of cobalt-containing raw materials and simplifying the regulation of the process, including in the absence of copper and / or iron impurities in the concentrate and reducing agent. The invention also removes the limitations determined by the method of reduction of cobalt (III) hydroxide and the properties of the reducing agent used. In particular, when using a metal reducing agent, significant restrictions on the fineness of metal particles are removed and equipment requirements are simplified. At the same time, the release of chlorine or other toxic products into the gas phase during opening is eliminated, which helps to increase the safety of the process. In addition, the invention provides concentrated solutions required for further processing without additional evaporation.

The technical result is achieved by the fact that in the method for producing cobalt and its compounds from cobalt-containing raw materials, including the conversion of metal components of cobalt-containing raw materials into a solution, precipitation of cobalt (III) hydroxide using an oxidizing agent and a neutralizer, acid dissolution of cobalt (III) hydroxide with the transfer of cobalt (III) ) in cobalt (II), purification of the resulting solution from impurities and obtaining metallic cobalt or its compounds, according to the method, the dissolution of cobalt (III) hydroxide is carried out with the participation of regeneration of reduced forms of iron and / or copper salts with a controlled supply of cobalt (III) hydroxide with a redox potential in the range of 300-700 mV relative to a silver chloride reference electrode and with a controlled supply of acid pH in the range of 1-3.

The reduced forms of iron and / or copper salts necessary for dissolution are regenerated using a sacrificial reducing agent, taken in an amount no less than stoichiometrically necessary for the reduction of cobalt (III) hydroxide, or by electrolysis. The process can be carried out in one stage with combining the reactions of transition of copper and / or iron ions from the reduced form to the oxidized form and vice versa in one apparatus, which supplies cobalt-containing raw materials, acid and a reducing agent, or in two - with the implementation of oxidation and reduction processes in separate apparatuses interconnected by a recycle solution (Figure 1). In an embodiment of the process in two devices in the first stage, the pulp of cobalt-containing raw materials and acid are introduced into a solution containing reduced forms of iron and / or copper salts with a total content of iron and copper ions from 0.5 g / dm ³ to 100 g / dm ³ . The predetermined redox potential is held by supplying the solution from the second stage. In the second stage, reduced forms of iron and / or copper salts in solution are regenerated using a sacrificial reductant or electrolysis. The required concentration of iron and / or copper ions is maintained by dissolving them from cobalt-containing raw materials and a reducing agent, recirculating the solution, or adding from an external source. To dissolve cobalt-containing raw materials, a mineral strong acid, for example hydrochloric, is used.

The two-stage option provides the implementation of the optimal hardware design for each stage of the process, taking into account the selected method of regeneration of reduced forms of iron and / or copper salts. In the electrolysis regeneration method, the reduction of iron and / or copper ions is realized in the cathode space of the electrolyzer. When using toxic gaseous reducing agents, in particular sulfur dioxide, an absorber can be used at the stage of regeneration of the reduced forms of iron and / or copper salts, which allows the digestion to be fully absorbed. When metal or an alloy, for example, technical reduced nickel oxide, is used to regenerate the reduced forms of iron and / or copper salts, it is preferable to organize the fluidization of a dispersed reducing agent in a fluidized bed apparatus. In all variants of the two-stage scheme, the dissolution of the concentrate containing cobalt (III) hydroxide is carried out in a reactor with mechanical stirring. The two-stage scheme allows using the thermal effect of the dissolution reaction for evaporative cooling of the solution recirculating between the devices, which ensures the production of concentrated solutions necessary for their further processing without prior evaporation.

The technical result is also achieved by the fact that the solution after dissolution of cobalt (III) hydroxide is purified from copper by carburizing on a metal from the group of iron, nickel, cobalt or an alloy containing one or more of these metals, and the cement is used as a reducing agent in the stage of regeneration of reduced forms of salts iron and / or copper. This solution provides controlled dissolution of cobalt (III) hydroxide at a high speed when the content of iron and copper in the concentrate and reducing agent is insufficient for the direct-flow process. In this embodiment of the process, a third apparatus is included in the circuit — a fluidized bed apparatus in which the autopsy solution is cleaned of copper by deposition on a dispersed metal or alloy (Figure 2). Copper cement is removed from the technological scheme in an amount equivalent to the supply of copper with the starting products. If iron and copper are absent in the initial products, then the required concentration of copper is ensured by the simultaneous introduction of the required amount of copper-containing material into the process, and the withdrawal of copper cement is excluded.

The high dissolution rate of the concentrate under the indicated limitations of the redox potential and in the presence of free acid is ensured due to the participation of mediators of regenerated reduced forms of iron and / or copper salts by the following mechanism. At the stage of concentrate dissolution, the ions of these metals of the lowest oxidation state restore hydrated cobalt oxide

CoOOH + FeCl ₂ + 3HCl = CoCl ₂ + FeCl ₃ + 2H ₂ O;

CoOOH + CuCl + 3HCl = CoCl ₂ + CuCl ₂ + 2H ₂ O.

At the stage of regeneration of the reduced forms of iron and / or copper salts, the formed ions of mediators of the highest oxidation form are regenerated, for example, by a metal reducing agent, in particular, nickel

2FeCl ₃ + Ni = NiCl ₂ + 2FeCl ₂ ;

2CuCl ₂ + Ni = NiCl ₂ + 2CuCl.

Dissolution mediators are not included in the total equation of the process.

2CoOOH + Ni + 6HCl = 2CoCl ₂ + NiCl ₂ + 4H ₂ O.

The overall rate of the dissolution process with the participation of regenerated reduced forms of iron and / or copper salts is significantly higher than when reducing cobalt hydroxide with a metal reducing agent. The existence of reduced forms of salts of iron and / or copper in a solution is possible only with a redox potential of not more than 650 mV and the presence of free acid excluding hydrolysis. In the presence of free acid and mediators, the limiting stage of the process is the dissolution of the metal, and the total dissolution rate is determined by the surface of the metal phase.

Under the selected conditions, the speed of the process is regulated by the redox potential by the supply of cobalt-containing concentrate. The presence of reduced forms of iron and / or copper salts in the solution is ensured by limiting the redox potential and the supply of free acid in an amount that prevents the hydrolysis of these salts. Unlike the prototype, the value of the redox potential and acidity are independently regulated, and the fluctuations of these values are determined only by the uniformity of supply of the corresponding reagents.

The processes of dissolution of cobalt (III) hydroxide and a metal reducing agent, it is advisable to carry out in optimal from the point of view of their implementation, the apparatus associated with the circulation of the solution (Fig.1, 2). In the first apparatus, cobalt (III) hydroxide is reduced by ions of mediators of a lower oxidation state with their transition to a higher oxidation state. In the second apparatus, the ions of mediators of the highest degree of oxidation are reduced by a metal reducing agent. Both stages correspond to the mechanism described earlier.

To dissolve cobalt (III) hydroxide, it is preferable to use a reactor with mechanical stirring. Such an apparatus is optimal for pulps with a low content of fine solid particles. This apparatus provides effective mixing of the supplied reagents and the uniformity of the parameters controlled in the pulp, in particular the redox potential and acidity. To dissolve the metal, it is preferable to use a fluidized bed apparatus traditional for metal powder. Such an apparatus allows the use of powders with different particle sizes and provides the excess solid phase necessary to maintain a high total process speed. In addition, the apparatus of the fluidized bed provides an exhaust solution with a minimum amount of solid. Then the solution returned to the cobalt concentrate dissolution apparatus does not contain large and heavy metal particles. In particular, under the conditions of obtaining cobalt from rough nickel anodes, it is advisable to use an existing technical product as a consumable metal reducing agent, for example, reduced nickel oxide, which is a powder of partially conglomerated particles of various sizes.

The inventive method allows thermal stabilization of the dissolution of cobalt (III) hydroxide due to evaporative cooling, providing concentrated solutions directly to the dissolution operation using the thermal effect of the dissolution of the concentrate. The thermal effect of the dissolution reaction of cobalt (III) hydroxide with a metal reducing agent is about 500 kcal / kg of oxidizing agent, which is equivalent to the heat of vaporization of approximately 1 kg of water. The use of the thermal effect of the reaction for evaporation during the implementation of the process in one apparatus is difficult, and heat exchangers are necessary for the removal of heat. When organizing the dissolution in separate devices, its thermal stabilization is achieved by installing a vacuum evaporator on the recirculation line, ensuring the maintenance of the water balance of the circuit as a whole (Figure 1, 2).

The autopsy solution is further purified from impurities using liquid extraction. The inventive method, in particular, includes the production of cobalt metal by electroextraction from a purified chloride solution. In this case, chlorine is liberated on an insoluble anode in an equivalent amount of precipitated cobalt. The method involves the use of chlorine released during electroextraction of cobalt as an oxidizing agent during the precipitation of cobalt (III) hydroxide from solutions obtained, for example, by dissolving rough nickel anodes. In addition, anodic chlorine can also be used to strengthen the solutions supplied to the extraction by chlorination of metallized or sulfide intermediates, for example, reduced technical nickel oxide.

The essence and advantages of the proposed method can be illustrated by the following examples. In the examples, various intermediates containing cobalt (III) hydroxide were used, directly obtained by precipitation of cobalt (III) hydroxide using chlorine and nickel carbonate from a solution of refining rough nickel anodes or formed during its further processing. In accordance with accepted terminology, a cobalt (III) hydroxide-containing product isolated directly from refining solutions of rough nickel anodes is called primary cobalt cake. The product after aqueous and acidic repulpations of the primary cobalt cake is called cobalt concentrate, and the product of deep purification of the primary cake or concentrate, including their acid dissolution in the presence of a reducing agent, purification of the solution from impurities and reprecipitation of practically no impurities of cobalt (III) hydroxide, is called commodity hydroxide cobalt (III).

Example 1

In a temperature-controlled reactor with a mechanical stirrer, containing 0.5 l of a chloride solution heated to 75 ° C, g / dm ³ : Ni 90, Fe 9 and HCl 10. In a series of experiments, various amounts of PNK-2K9 nickel powder produced by carbonyl were introduced way. Diluted (1: 1) hydrochloric acid and cobalt concentrate of the composition, diluted with water to a moisture content of 75%, calculated on the dry matter,%: Co 50.8; Ni 2.7; Fe 4.3; Cu 0.06. A constant amount of cobalt concentrate of 88.3 g was used in the experiments. The concentrate was loaded at a rate that ensured that the oxidation-reduction potential was maintained at a given level, while the acid supply kept the required acidity range. The results of dissolution experiments are shown in table 1.

Table 1 The indicators of the process of dissolution of cobalt concentrate with varying the load of the reducing agent, redox potential (ORP) and pH Experience number Download PNA powder, g Powder loading from stoichiometrically necessary,% Continue
solution strength
ny, min pH ORP, mV Fluctuations of ORP in the experiment, mV The degree of dissolution of cobalt,% one 39.0 160 8 0.5-1.0 600 twenty one hundred 2 29.3 120 12 0.5-1.0 600 twenty one hundred 3 25.6 105 twenty 0.5-1.0 600 twenty one hundred four 19.5 80 120 0.5-1.0 600 Up to +1100 85 5 25.6 105 thirty 0.5-1.0 500 twenty one hundred 6 25.6 105 40 0.5-1.0 400 +100 one hundred 7 25.6 105 60 0.5-1.0 300 +200 one hundred 8 25.6 105 120 0.5-1.0 250 +250 90 9 25.6 105 90 0.5-1.0 650 +200 one hundred 10 25.6 105 60 0.5-1.0 700 Up to +1000 one hundred eleven 25.6 105 120 0.5-1.0 750 Up to +1100 90 12 25.6 105 one hundred 1,5 550 250 one hundred 13 25.6 105 120 3.0 550 Up to +1000 one hundred fourteen 25.6 105 120 3,5 550 Up to +1100 fifty fifteen 25.6 105 25 -1.0 550 twenty one hundred 16 25.6 105 25 -1.5 550 twenty one hundred

If the specified level of the redox potential was in the range of 500-600 mV, the pH is 0.5-1.0, and the reducing agent was taken in an amount no less than stoichiometric (ops. 1-3, 5), then during the reagent loading the vibrations are oxidative -reduction potential does not exceed 20 mV, and with a decrease in mixing intensity, the redox potential remains stable. Dissolution time does not exceed 30 minutes.

As the redox potential increases to 700 mV (op. 9, 10) or decreases to 300 mV (op. 6, 7), its oscillations increase. At the same time, the loading speed of cobalt concentrate sharply decreases, the dissolution time increases to 1-1.5 hours.

Fluctuations in the redox potential also increase with increasing pH to more than 1.0 (op. 12, 13), while acidity fluctuations also increase. The retention of redox potential and acidity at a given level is achieved by reducing the load of the reagents, the dissolution time increases to 1.5-2 hours.

An increase in the redox potential of dissolution in excess of 700 mV (op. 11) or its decrease below 300 mV (op. 8), as well as an increase in pH above 3.0 (op. 14) does not allow to stabilize the process parameters even with a significant decrease in the feed rate reagents.

Lowering the pH to below 0.5 does not affect the dissolution, but leads to an additional consumption of acid (op.15-16).

In experiment 4, after loading 70.5 g of the concentrate, the redox potential of the pulp jumped up to a potential of + (1000-1100 mV). The sensor in the aspiration system of the exhaust gases from the reactor detected the release of chlorine. The loading of the remaining pulp practically did not change the value of the redox potential and was not accompanied by an increase in pH.

Example 2

A sample of PNK-2K9 nickel powder was introduced into a temperature-controlled reactor with a mechanical stirrer, containing 0.5 l of the initial chloride solution, composition, g / dm ³ : Ni 90, HCl 10 with a variable iron and copper content from experiment to experiment. . Hydrochloric acid was continuously fed into the stirred pulp and pulped with an acid-free stock solution to a moisture content of 75% pulp containing practically no impurities of commercial cobalt (III) hydroxide. In the experiments, 26.8 g of PNA powder and 92 g of hydroxide containing 53% cobalt were loaded, which corresponded to a 10% excess of reducing agent. The concentrate was loaded at a rate that ensured the maintenance of the redox potential at the level of 550 mV, while the supply of concentrated acid kept the pH in the range of 0.5-1.0. The results of dissolution experiments are shown in table 2.

In experiment 1, immediately after the start of acid supply, the pH of the pulp decreased to a level of 0.3-0.5. Simultaneously with a decrease in pH, an increase in the redox potential to + (1000-1100 mV) was observed. The sensor in the aspiration system of the exhaust gases from the reactor detected the release of chlorine. After the cessation of supply for several minutes, a slow decrease in the redox potential was observed. Simultaneously with a decrease in the redox potential, the pulp pH increased to a level of 1.5. The repeated addition of acid again caused an abrupt decrease in pH and an increase in the redox potential to the potential for chlorine evolution, followed by a decrease in acidity and redox potential after the acid supply was stopped. The process in batch mode lasted for two hours.

table 2 The performance of the dissolution process of commodity cobalt hydroxide with varying concentrations of iron in solution Experience number The content in the solution, g / DM ³ Fluctuations of ORP in the experiment, mV Duration of dissolution, min The degree of dissolution of cobalt,% gland copper one 0 0 +500 120 fifteen 2 0.5 0 150 60 one hundred 3 0 0.5 150 60 one hundred four 0 5,0 thirty thirty one hundred 5 10 0 twenty twenty one hundred 6 fifty fifty 10 eighteen one hundred

The process in batch mode lasted for two hours. When copper and iron salts were introduced into the solution, the dissolution of the hydroxide proceeded at an increasing rate with increasing concentration of copper and iron salts and with smaller potential fluctuations. An increase in the concentration of introduced salts is limited by a decrease in the solubility of cobalt and nickel chlorides.

Example 3

The process was carried out analogously to example 2, but the initial chloride solution in the reactor had the composition, g / dm ³ : Ni 110, Cu 9 and HCl 10. The cobalt (III) hydroxide was pre-pulped to a moisture content of 75% chloride solution of the same composition, but without the addition of acid . Reducer was loaded into the reactor in a 10% excess compared with the stoichiometrically necessary for dissolving a portion of cobalt (III) hydroxide. The reducing agent used was a nickel powder produced by the carbonyl method (experiment 1), and a powder of reduced technical nickel oxide fraction of 0.4 mm, composition,%: Co 2.24; Ni 89.4; Fe 3.15; Cu 3.17 (experiment 2). The loading of cobalt (III) hydroxide was carried out at a rate ensuring the maintenance of the redox potential at the level of 600 mV, and the pH value was kept in the range of 0.5-1.0 units by the supply of acid. The dissolution results are shown in the table.

Table 3 The indicators of the process of dissolution of intermediates based on cobalt (III) hydroxide in a solution containing copper chloride Experience number Amount and type of cobalt raw materials Quantity and type of reducing agent Duration of dissolution, min one 139 g of concentrate, composition according to example 1 47.9 g of technical recovered nickel oxide 25 2 152 g of commodity hydroxide composition according to example 2 44.3 g of reduced technical nickel oxide fifteen

Fluctuations in the redox potential during dissolution did not exceed 20 mV, and with a decrease in mixing intensity, the redox potential remained stable. The hydroxide in both experiments was completely dissolved.

Example 4 (prototype).

In experiment 1, in the initial chloride solution containing 110 g / dm ^{3 of} nickel, without the addition of acid, a pulp of the entire amount of cobalt concentrate and technical reduced nickel oxide, prepared in quantities from the experiment 1 of Example 3, was prepared. Hydrochloric acid was fed into the stirred pulp. The feed rate of the acid was adjusted so as to prevent the growth of the redox potential to a level corresponding to the evolution of chlorine. Even at a low acid delivery rate compared to that realized in the experiments of Example 3, the redox potential varied mainly in the range of 900-600 mV with peak values of up to 1100 mV at the beginning of the process and 600-400 mV at the end of the process. With a short-term decrease in the mixing intensity, the redox potential increased to 1100 mV, and chlorine evolution was recorded in the gases leaving the reactor. Pulp pH gradually decreased from 3-4 at the beginning of dissolution to 0.3-0.5 at the end. A decrease in pH to a level of 0.3 served as a signal to stop the supply of acid. The dissolution time of the cobalt concentrate was 90 minutes. The cobalt concentrate has completely dissolved.

In experiment 2, in the initial chloride solution containing 160 g / dm ^{3 of} nickel, without the addition of acid, a pulp of the total amount of commercial cobalt hydroxide and nickel powder PNK-2K9 was taken, taken in quantities from experiment 2 of Example 3. Immediately after the start of acid supply, the pH decreased to level 0.3-0.5, and the redox potential jumped up to + (1000-1100 mV). The sensor in the aspiration system of the exhaust gases from the reactor detected the release of chlorine. After stopping the supply of acid for several minutes, a slow decrease in the redox potential and an increase in pH to a level of 1.0-1.5 were observed. The repeated addition of acid again caused a stepwise change in pH and the redox potential, followed by relaxation after the supply of acid was cut off. The process in batch mode lasted for two hours. The hydroxide was dissolved by 15%.

Example 5

The process was conducted according to the conditions of experiment 1 of Example 3, but a sulfate solution of the composition, g / dm ³ : Ni 80, Fe (III) 9 and H ₂ SO ₄ 5 was used as the starting one. The cobalt concentrate was charged at a rate that ensured the oxidation reduction potential at 600 mV, and the pH value at the level of 0.5-1.0 was kept by supplying a solution of sulfuric acid. The loading time of cobalt concentrate was 30 minutes. Fluctuations in the redox potential during dissolution did not exceed 20 mV, and with a decrease in mixing intensity, the redox potential remained stable. The cobalt concentrate has completely dissolved.

Example 6

The process was conducted in two stages. 136 g of powder of reduced technical nickel oxide of a fraction of 0.8 mm, composition,%, Co: 2.24; Ni 89.4; Fe 3.15; Cu 3.17. The fluid solution of the fluidized bed apparatus entered a temperature-controlled reactor at 80 ° C with a mechanical stirrer, from which it was returned by a pump to the fluidized bed apparatus. The initial volume of the circulating chloride solution was 0.75 L, and its composition, g / dm ³ : Ni 90, Fe 9, and HCl 10. The diluted (1: 1) hydrochloric acid and cobalt concentrate pulped with water to a moisture content of 75% were continuously fed into the reactor, composition in terms of dry matter,%: Co 50.8; Ni 2.7; Fe 4.3; Cu 0.06. The concentrate pulp was loaded at a rate that ensured the oxidation-reduction potential in the reactor was maintained at 600 mV, and the pH was kept at 0.5-1.0 units by feeding acid. During the experiment, 188 g of cobalt concentrate was loaded into the reactor, which corresponds to 70% of the recovery capacity of nickel powder. Download time was 18 minutes. The cobalt concentrate has completely dissolved.

Example 7

The processing of primary cobalt cake was carried out in three stages in a continuous mode. In the reactor with mechanical stirring, the cobalt cake of the composition was dissolved (in terms of dry matter),%: Co 29.5; Ni 19.4; Fe 2.9; Cu 0.1, in the first of two apparatuses of the fluidized bed, regeneration of the reduced forms of salts of iron and copper was realized, in the second apparatus of the fluidized bed the solution was cleaned of copper. As the reducing agent used powder restored technical nitrous oxide of a fraction of 0.8 mm, composition,%: Co 2.1; Ni 88.4; Fe 3.4; Cu 4.1, initially loaded into both fluidized bed apparatuses. The drain solution from the first fluidized bed apparatus entered the reactor with a mechanical stirrer, from which it returned to the fluidized bed apparatus. Cobalt cake, pulped with a circulating solution to a moisture content of 75%, and hydrochloric acid were fed into the reactor at a rate that stabilized the specified values of the redox potential (600 mV) and pH (0.5-1.0), respectively. To thermally stabilize the dissolution process, a vacuum evaporator was installed on the solution recirculation line between the reactor and the first fluidized bed apparatus. Adjustable vacuum in the evaporator maintained the dissolution temperature in the range of 80-85 ° C. The initial volume of the fluidized bed of the chloride solution circulating between the reactor and the first apparatus is 1 liter, and its composition, g / dm: Ni 90, Fe 9, and HCl 10. The fluctuations of the redox potential in the reactor did not exceed 20 mV.

The cobalt-containing solution cut off from the circulation between the reactor and the first apparatus of the fluidized bed was supplied through an intermediate tank to the second fluidized bed apparatus for copper deposition. In this apparatus, the initial powder loading of reduced technical nickel oxide was periodically replenished by the supply of fresh powder. Part of the cobalt-containing solution purified from copper was used to prepare cobalt cake pulp. The reduction in the height of the fluidized bed in the first apparatus was compensated by the periodic transfer of powder from the second fluidized bed apparatus. Copper cake was periodically removed from the first fluidized bed apparatus.

After stabilization of the process, the raw material costs were: primary cobalt cake 470 g / h, powder of reduced technical nickel nitrous oxide 140 g / h, diluted (1: 1) hydrochloric acid 2.4 l / h. The output of copper cake composition,%: From 1.9; Ni 39.1; Fe 1.1; Cu 28.9 - 18 g / h.

The average flow of the cobalt-containing solution purified from copper removed from the circuit was 2.2 l / h, and its composition, g / dm ³ : Co 63; Ni 130; Fe 12.5; Cu 0.6. From the final cobalt-containing solution by liquid extraction and subsequent re-extraction, a cobalt chloride solution with a cobalt concentration of 100 g / dm ^{3 was} obtained. For liquid extraction, a 30% solution of industrial trialkylamines, fractions of C7-C9 in a mixture of aromatic and saturated hydrocarbons was used, and a cobalt-containing solution with nickel raffinate was mixed before extraction. After the control hydrolytic purification of microimpurities from chlorine and a soda solution by electroextraction, a cathode cobalt corresponding to the K1Au brand according to GOST 123-2008 was obtained from cobalt reextract. For electroextraction, a diaphragm electrolyzer with insoluble titanium anodes with an active coating of ORTA was used. After a control hydrolytic purification with a soda solution, a portion of the cobalt reextract precipitated the main cobalt carbonate, which in chemical composition corresponded to the “chda” brand.

Claims (12)

1. A method of producing cobalt and its compounds from cobalt-containing raw materials, including the conversion of metal components of cobalt-containing raw materials into a solution, precipitation of cobalt (III) hydroxide using an oxidizing agent and a neutralizer, acid dissolution of cobalt (III) hydroxide with the conversion of cobalt (III) to cobalt (II) ), purification of the resulting solution from impurities and obtaining metallic cobalt or its compounds, characterized in that the dissolution of cobalt (III) hydroxide is carried out with the participation of regenerated reduced forms of iron salts and / or copper with a controlled supply of cobalt (III) hydroxide at a redox potential in the range of 300-700 mV relative to a silver chloride reference electrode and with a controlled supply of acid at a pH in the range of 1-3. 2. The method according to claim 1, characterized in that the reduced forms of salts of iron and / or copper are regenerated using a sacrificial reducing agent, taken in an amount not less than stoichiometrically necessary for the reduction of cobalt (III) hydroxide. 3. The method according to claim 1, characterized in that the dissolution of cobalt (III) hydroxide is carried out in a solution with a total content of iron and copper ions from 0.5 g / dm ³ to 100 g / dm ³ . 4. The method according to claim 3, characterized in that the dissolution is carried out in two stages, in the first stage, cobalt (III) hydroxide in the form of pulp and acid are introduced into a solution containing reduced forms of salts of iron and / or copper, and in the second stage regenerate reduced forms of salts of iron and / or copper. 5. The method according to claim 1, characterized in that the dissolution of cobalt (III) hydroxide is carried out using hydrochloric acid. 6. The method according to claim 2, characterized in that the reduced forms of salts of iron and / or copper are obtained using as consumable reducing agent a metal selected from the group of iron, nickel, cobalt, copper, or an alloy containing one or more of these metals. 7. The method according to claim 2, characterized in that the regeneration of the reduced forms of iron and / or copper salts in solution is carried out using technical reduced nickel oxide. 8. The method according to claim 2, characterized in that the solution after dissolving the cobalt (III) hydroxide is purified from copper by carburizing on a metal from the group of iron, nickel, cobalt or an alloy containing one or more of these metals, and the cement is used as a reducing agent on stage of regeneration of reduced forms of iron and / or copper in solution after dissolution of cobalt hydroxide. 9. The method according to claim 1, characterized in that the purification obtained by dissolving the cobalt (III) hydroxide solution from impurities is carried out using liquid extraction. 10. The method according to claim 1, characterized in that during the dissolution of cobalt (III) hydroxide, evaporative cooling is carried out. 11. The method according to claim 5, characterized in that the cobalt metal is obtained by electroextraction. 12. The method according to claim 11, characterized in that the chlorine released during the electroextraction of cobalt is directed to the precipitation of cobalt (III) hydroxide.

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