CN1598013A - Process for removing copper of cobalt electrolytic solution - Google Patents

Abstract

A method of separating and removing impurity in electrolyte when cabalt is produced by electrolysis. The character of this invention using CoS2O3 as copper resistance, adding CoS2O3 in weight proportion of Cu2+:S2O32- =1:8-16 in electrolyte; adding acid and adjusting the pH between 0.5 and 2.0, at the temperature between 70deg.C and 90deg.C, the reaction time is 30-40min, then producing the precipitation of CuS, finally, filtrating and separating the precipitation the process of removing copper is finished. The method effectively overcomes the disadvantage of purifying and removing copper and iron with cobalt positive pole electrolyte, improves the depth of removing copper, decrease the cobalt content in residues, reduces the residues content and increases the straight yield.

Description

Copper removing method for cobalt electrolyte

Technical Field

A copper removing method of cobalt electrolyte relates to a method for separating and removing impurities in the electrolyte, in particular to a method for removing copper impurities when cobalt is produced by electrolysis.

Background

At present, the production of cobalt by electrolysisIn the process, the electrolytic anolyte needs to be purified to remove impurities, particularly impurities such as copper, iron and the like. At present, most of the copper removal processes of cobalt electrolyte in industry adopt a sodium sulfide method, which can basically meet the production requirements, but has the defects of large slag quantity, high cobalt content in slag and large amount of Na brought into the electrolyte⁺And the like. Affecting the quality of the electrolytic cobalt product and the yield of valuable metals.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method which can effectively reduce the amount of slag generated in the impurity removal process and the cobalt content in the slag, and the electrolyte does not contain Na⁺And the like, and effectively improves the quality of the electrolytic cobalt product and the yield of the metal.

The purpose of the invention is realized by the following technical scheme.

The copper removing method of cobalt electrolyte is characterized by adopting cobalt thiosulfate CoS₂O₃The copper removing agent is prepared by the following steps: by Cu in a cobalt electrolyte²⁺∶S₂O₃ ^2-Adding cobalt thiosulfate CoS in the molar ratio of 1: 8-16₂O₃Adding acid to adjust the pH value of the solution to 0.5-2.0, reacting at 70-90 ℃ for 30-40 minutes to generate a CuS precipitate, and filtering and separating the precipitate to finish the copper removal process.

A method for removing copper from cobalt electrolyte is characterized in that the cobalt concentration of the electrolyte for removing copper is 85-95 g/l.

The copper removing method of cobalt electrolyte is characterized by using cobalt thiosulfate CoS₂O₃The copper removing agent is S₂O₃ ^2-The concentration of the aqueous solution is 95-115 g/l.

The reaction rationale of the copper removal process of the method is that cobalt sulfide, copper sulfide and cuprous sulfide are black insoluble substances, and the solubility products of the cobalt sulfide, the copper sulfide and the cuprous sulfide are respectively 1.80 multiplied by 10^-22And 2.4X 10^-35Since the difference between the two is large, in the case of Cu²⁺Adding cobalt thiosulfate CoS into the solution₂O₃The following reaction takes place:

generally, when the pH value of the cobalt electrolyte is 3.5-3.8, under the condition that halogen ions exist, copper ions and cobalt thiosulfate generate cuprous sulfate, the cuprous sulfate is unstable, the cuprous sulfate can immediately react with the cobalt thiosulfate to form cuprous thiosulfate ions, so that cuprous sulfide precipitation is not generated on the copper ions, the solution needs to be further acidified and boiled, and black cuprous sulfide and copper sulfide precipitation are formed. The reaction is as follows:

therefore, since the electrolyte solution contains a large amount of Cl^-If the pH of the solution is reduced to below 2, the solution is maintained at 70-90 ℃ to achieve the purpose of copper removal.

In terms of control of reaction conditions, CoS (cobalt thiosulfate)₂O₃The amount of addition, as can be seen from the test, CoS₂O₃In an amount of Cu²⁺∶S₂O₃ ^2-1: 8-16, in this range, the copper removing efficiency and Cu: Co ratio in copper slag can reach the requirement, CoS₂O₃The copper removal effect cannot meet the requirement with less addition amount; CoS₂O₃The excessive addition of the catalyst can cause SO in the solution₄ ^2-The increase range is large, the consumption is increased, and the copper removal cost is increased.

After adding a certain amount of CoS₂O₃Under the action, the reaction time influences the copper content of the solution after copper removal, and tests show that the copper is gradually reduced along with the increase of the reaction time, the change tends to be gentle after 30 minutes, which indicates that the copper removal reaction is basically finished in 30 minutes and is generally controlled to be 30-40 minutes.

When cobalt thiosulfate is added into a cobalt electrolytic solution, if the temperature is too low, the cobalt thiosulfate can be separated out in a double salt form, the reaction cannot be carried out, no precipitate is generated, the double salt can be decomposed to form a precipitate only by heating to a certain temperature, the reaction speed is accelerated along with the rise of the temperature, the copper removal efficiency is improved, but the temperature is too high, the solution concentration phenomenon is serious, and the copper removal temperature is generally controlled to be 70-90 ℃.

Experiments show that the pH value of the solution is 0.5-2.0, the copper removal rate reaches 98.3%, the pH value of the cobalt electrolytic solution is not controlled, the pH value is usually higher, and the copper removal rate is only about 10% generally.

As can be seen from the test, the lower the cobalt concentration in the cobalt electrolyte solution for copper removal, the better the copper removal effect. According to experiments, the concentration of cobalt in the cobalt electrolyte is preferably controlled to be about 85-95g/l, and the cobalt content of the electrolyte is increased due to cobalt ions introduced by the copper removing agent, so that the requirement of 95-110 g/l of cobalt in the new electrolytic production liquid can be met. The cobalt concentration in the cobalt electrolyte solution for copper removal is higher, the solution after copper removal is higher than 0.002g/l, and the requirement that the copper content Cu in the new solution is less than or equal to 0.002g/l cannot be met.

The copper removal method belongs to a multiphase reaction, the main steps of the reaction depend on chemical reaction and diffusion, and in the experimental process, the copper removal efficiency is not improved along with the increase of the stirring speed.

Compared with the existing method for removing impurities from cobalt electrolyte, the method of the invention adopts soluble cobalt thiosulfate to remove copper, and can show that: with cobalt thiosulphate CoS₂O₃The method replaces sulfide, deeply removes copper from cobalt electrolyte, reacts for about 30 minutes, reduces the copper solution from 0.25g/l to below 0.002g/l, ensures that the Cu/Co ratio in the sediment is 30: 1, ensures that the cobalt content in the sediment is low and the quantity of the sediment is very small, can directly return to a copper system, and removes Na in the copper process⁺No enrichment phenomenon. CoS thiosulfate₂O₃The reaction time for purifying and removing copper from the secondary solution is 20-30 minutes, the copper content in the solution can be reduced from about 2.93g/l to 0.001g/l, the copper removal qualification rate is more than 95%, the Cu/Co ratio in the sediment is up to 58: 1, the cobalt content in the sediment is 0.934%, and the effect is ideal.

The copper removing method of the cobalt electrolyte is characterized in that the preparation process of a copper removing agent cobalt thiosulfate comprises the following steps:

a. first, Na is added₂S₂O₃And BaCl₂The molar ratio of the raw materials is 1: 1, and the mixture is stirred for 10-15min at the reaction temperature of 20-30 ℃ to react to generate BaS₂O₃；

b. According to BaS₂O₃And CoSO₄In a molar ratio of 1: 0.7 in CoSO₄The molar concentration of the CoS is 1.4mol/L, the temperature is 40-50 ℃, the reaction time is 60-80min, and CoS is generated₂O₃A solution;

c. adding CoS₂O₃Liquid-based CoS₂O₃Mixing with ethanol as concentrating agent at volume ratio of 1: 10, crystallizing, standing for 36-42 hr to obtain CoS₂O₃·xH₂And (4) a copper removing agent for the O brown flaky crystals.

The method of the invention can prepare stable cobalt thiosulfate and ensure the product quality of the cobalt thiosulfate. The reaction mechanism for preparing the cobalt thiosulfate is as follows:

due to BaSO₄Ksp of (1.1X 10)^-10And BaS₂O₃Ksp of (1) 8.0X 10^-7. The above reaction is feasible. The method is characterized in that thiosulfate radical ions are directly introduced into a cobalt sulfate aqueous solution to react with the cobalt ions, the reacted solution is separated to remove slag (precipitate), cobalt thiosulfate is separated from the reacted solution, and the cobalt thiosulfate solution and a solid crystal product can be obtained through dehydration and concentration.

a, when preparing the cobalt thiosulfate decoppering agent, firstly, preparing barium thiosulfate. For NaS₂O₃And Bacl₂The ratio of (i.e. NaS)₂O_3·5H₂O and Bacl_2·2H₂The mole ratio of O), the reaction temperature, the stirring time and other experimental conditions, and finding the BaS by adopting an orthogonal experiment₂O₃The best preparation condition is NaS₂O₃And BaCl₂The proportion of the components is 1: 1, the reaction temperature is 20 ℃ (close to room temperature), and the stirring time is 10 min. Washing with hot water with the temperature of about 60 ℃ T for 2-3 times to obtain pure BaS₂O₃。

b for the preparation of liquid cobalt thiosulfate decoppering agent, for BaS₂O₃And CoSO₄Proportioning of (i.e. BaS)₂O₃And CoSO₄Molar ratio of) of (A), CoSO₄The experimental conditions such as the molar concentration, the reaction temperature, the reaction time and the like are discussed, and the orthogonal experiment is adopted to find the liquid cobalt thiosulfate CoS₂O₃The best preparation condition of the copper removing agent is BaS₂O₃And CoSO₄The mixture ratio of (A) to (B) is 1: 0.7, CoSO₄The molar concentration of the catalyst is 1.4mol/L, the reaction time is 60min, and the reaction temperature is 40 ℃. Meanwhile, the concentration of the cobalt thiosulfate decoppering agent and the material concentration (namely CoSO)₄Molar concentration of (d) in a linear relationship.

c for solid cobalt thiosulfate CoS₂O₃Preparation of decoppering agent for liquid CoS₂O₃Proportioning of copper removing agent and concentrating agent (namely liquid cobalt thiosulfate CoS)₂O₃The volume ratio of the copper removing agent to the concentrating agent, the reaction time (namely the standing time of crystallization) and other experimental conditions are discussed, and the experiment is adopted to find solid cobalt thiosulfate CoS₂O₃The best preparation condition of the copper removing agent is liquid cobalt thiosulfate CoS₂O₃The ratio of the copper removing agent to the concentrating agent is 1: 10, and the reaction time is 36 h.

d, confirming the preparation of the solid cobalt thiosulfate CoS by different detection means₂O₃The copper removing agent mainly comprises CoS₂O_3·xH₂O, brown plate crystals.

Barium sulfate has an ion product constant Ksp of 1.1X 10^-10The ionic product constant Ksp of barium thiosulfate is 8.0 x 10^-7. By using a plurality ofThe difference of the ion product, through the conversionreaction of secondary precipitation, the liquid cobalt thiosulfate CoS is synthesized₂O₃Decoppering agent (i.e. cobalt thiosulfate solution)Liquid). The solid copper removing agent is extracted from the copper removing agent by the action of the concentrating agent. The copper removing agent is analyzed, identified and confirmed to be prepared, and the main body is CoS₂O_3·xH₂O, brown flaky crystals with the content of more than 95.89 percent.

The method for removing the copper from the cobalt electrolyte effectively overcomes the defects of the existing method for removing the copper from the cobalt electrolyte by purification, improves the depth of copper removal, reduces the cobalt content in slag, reduces the slag amount and improves the direct recovery rate. Easy operation and loose conditions.

Detailed Description

The copper removing method of cobalt electrolyte adopts cobalt thiosulfate CoS₂O₃As copper-removing agent, in cobalt electrolyte as Cu²⁺∶S₂O₃ ^2-Adding cobalt thiosulfate CoS in the weight ratio of 1: 8-16₂O₃Adding acid to adjust the pH value of the solution to 0.5-2.0, reacting at 70-90 ℃ for 30-40 minutes to generate a CuS precipitate, and filtering and separating the precipitate to finish the copper removal process. The preparation process of the cobalt thiosulfate of the copper removing agent comprises the following steps: a. firstly NAS is adopted₂O₃And BaCl₂The molar ratio of the raw materials is 1: 1, and the mixture is stirred for 10-15min at the reaction temperature of 20-30 ℃ to react to generate BaS₂O₃(ii) a b. According to BaS₂O₃And CoSO₄In a molar ratio of 1: 0.7 in CoSO₄The molar concentration of the CoS is 1.4mol/L, the temperature is 40-50 ℃, the reaction time is 60-80min, and CoS is generated₂O₃A solution; c. adding CoS₂O₃Liquid-based CoS₂O₃Mixing with ethanol as concentrating agent at volume ratio of 1: 10, crystallizing, standing for 36-42 hr to obtain CoS₂O₃·xH₂And (4) a copper removing agent for the O brown flaky crystals.

The present invention will be further described with reference to examples.

Example 1

Preparation of a-barium thiosulfate

Finding BaS by orthogonal experiment method₂O₃Is optimally preparedCondition

Table-factor level table

Note: ratio means NAS₂O_3·5H₂O and BaCl₂·2H₂The molar ratio of O is known from analysis, scheme C₂A₂B₁Is most preferred. Namely:

① the ratio is 1: 1

② temperature 20 deg.C (near room temperature)

③ stirring for 10min

In order to obtain relatively pure BaS₂O₃Mixing BaS₂O₃Rinsing with hot water with T ≈ 60 deg.C for 3 times.

b preparation of liquid cobalt thiosulfate decoppering agent

The optimal preparation condition for preparing the liquid cobalt thiosulfate decoppering agent is found by adopting an orthogonal experiment

Level meter for two factors of table

Note: the ratio is BaS₂O₃And CoSO₄In a molar ratio of

From the analysis, scheme C₁A₁B₁D₃Is most preferred. Namely:

① the ratio is 1: 0.7

② concentration CoSO₄(mol/L)1.4

③ reaction time 60min

④ temperature 40 deg.C

Meanwhile, the concentration of the cobalt thiosulfate decoppering agent and the material concentration (namely CoSO)₄Molar concentration of (d) in a linear relationship.

c preparation of solid cobalt thiosulfate decoppering agent

The best preparation condition for preparing the liquid cobalt thiosulfate decoppering agent is found by adopting an experiment

From analysis, the optimal conditions for the protocol were:

① the ratio is 1: 10

② crystallization time 36h

In the series of crystallization and concentration processes, the concentration of a liquid sample is found to have a certain relation with the purity of the prepared solid product.

Example 2

Firstly, regulating the value of the iron liquid to a preset value by using sulfuric acid, measuring the solution, putting the solution in a beaker, and putting the beaker in an electronic temperature-controlled water bath kettle. And the temperature adjusting controller is preset to a preset temperature, and the stirring is slowly carried out while the temperature is increased. When the temperature of the solution reaches a preset value, adding a proper amount, starting timing, filtering the solution after the reaction is finished, and analyzing the components of the filtrate and the slag.

(2) Copper removal test of cobalt thiosulfate decoppering agent

Condition test

① Effect of the amount of cobalt thiosulfate decoppering agent added

Influence of the amount of cobalt (III) thiosulfate decoppering agent added

Cu2+∶S2O3 2	1∶16	1∶12	1∶10	1∶8	1∶6
						Liquid after copper removal (g/L)	0.0016	0.00175	0.0018	0.002	0.0044

From Table III, CoS₂O₃In an amount of Cu²⁺∶S₂O₃ ^2-1: 8-16, in this range, the copper removing efficiency and the Cu: Co ratio in the steel slag can reach the index requirement, after that, CoS₂O₃The copper removal efficiency of the added amount is less than that of the reaction metering, and the requirement cannot be met, before that, CoS₂O₃The addition amount is greatly excessive, SO that SO in the solution is generated₄ ^2-The increase amplitude is large.

② Effect of reaction time

TABLE IV Effect of reaction time

T(min)	15	20	30	40	50
						Liquid after copper removal (g/L)	0.018	0.005	0.002	0.0018	0.0018

In Table four, the addition of a certain amount of CoS is shown₂O₃Under the action, the reaction time influences the copper content of the solution after copper removal, and as can be seen from data in a table, the copper gradually decreases along with the increase of the reaction time, and the change tends to be gentle after 30 minutes, which indicates that the copper removal reaction is basically finished after 30 minutes.

③ Effect of temperature on copper removal

TABLE V Effect of temperature on copper removal

Reaction temperature (. degree.C.)	60	70	90	Boiling by boiling
					Liquid after copper removal (g/L)	0.034	0.002	0.0018	0.0017

The fifth table lists the influence of temperature on copper removal, when cobalt thiosulfate electrolytic solution is used, the double salt is separated out, no precipitate is generated, the double salt can be decomposed to form precipitate only by heating to a certain temperature, and as can be seen from the table, the reaction speed is accelerated along with the rise of the temperature, the copper removal efficiency is improved, but the solution concentration phenomenon is serious, and the copper removal temperature can be controlled to be 70-90 ℃ generally.

④ Effect of solution acidity

TABLE effects of acidity of the six solutions

pH value	0.5	1.0	2.0
				Liquid after copper removal (g/L)	0.0017	0.0019	0.002

In the copper removal process, acid must be added to adjust the pH value, the copper removal effect is good, experiments under different pH values are respectively carried out, as can be seen from Table 11, the pH value is adjusted in the process of adjusting the pH value at 0.5-2.0, and the copper removal rate reaches 98.3%.

⑤ Effect of cobalt concentration

TABLE influence of cobalt concentration

The solution contains cobalt (g/L)	55	75	85	95	Over 100
						Cobalt (g/L) content after copper removal	58.1	77	91.6	106.4	118.9
Copper-removed liquid Cu (g/L)	0.001	0.0012	0.0016	0.0018	0.0055

The seventh table shows that the lower the cobalt concentration in the solution is, the better the copper removal effect is, and according to experimental data, the cobalt concentration is preferably controlled to be 85-95g/l, because the cobalt content of the new solution in the production is required to be 95-110 g/l, the copper removal agent can meet the requirement after being added, and if the copper in the solution after the copper removal is at the concentration required by the production, the copper in the new solution can only be removed to 0.002-0.008 g/l, and the requirement of the new solution on copper content (Cu is less than or equal to 0.002g/l) cannot be met.

⑥ Effect of agitation speed

TABLE VIII Effect of stirring speed

Stirring speed	Faster (about more than 200 rpm)	Slow speed (about 100-
			Copper-removed liquid Cu2+(g/L)	0.0022	0.0025

The copper removal of cobalt thiosulfate belongs to a heterogeneous reaction, the main steps of the reaction depend on chemical reaction and diffusion, and the copper removal efficiency is not improved along with the increase of the stirring speed in the experimental process.

⑦ Effect of cobalt thiosulfate

TABLE Effect of cobalt Thiosulfate solution concentration

Cobalt thiosulfate solution (g/L)	95	98	110	115	117	118
							The copper removal rate%	97％	97.6％	98％	98.3％	84％	83％

Finding S in the course of experiment₂O₃ ^2-The four batches of reagents with the concentrations of 95g/l, 98g/l, 110g/l and 115g/l have better using effect and contain S₂O₃ ^2-The copper removal effect is poor when the reagent is used in a sulfate system, a large amount of black precipitates are generated after the reagent is used for more than half a month, and the reuse effect is obviously reduced. And (4) conclusion:

① cobalt thiosulfate is used to replace sodium sulfide to deeply remove copper from cobalt electrolyte, reaction is carried out for about 30 minutes, solution copper is reduced to 0.002g/l from 0.25g/l, Cu and Co in sediment are 30: 1, cobalt content in the sediment is low, slag amount is extremely small, the sediment can be directly returned to a copper system, and Na is removed in the copper removing process⁺No enrichment phenomenon.

② the reaction time of the cobalt thiosulfate for purifying and removing the copper from the secondary solution is 20-30 minutes, the copper in the solution can be reduced from about 2.93g/l to 0.001g/l, the copper removal qualification rate is more than 95%, the ratio of Cu to Co in the sediment is up to 58: 1, the cobalt content in the sediment is 0.934%, and the effect is ideal.

③ copper removal in anolyte and secondary solutions, the copper consumption per ton treated was 14.08 tons and 5.29 tons respectively (CoS)₂SO₃Contains S₂O₃ ^2-Concentration of 110 g/l) of the copper remover solution of the invention.

④ the ratio of Co to Cu in the electrolyte containing cobalt is 5000: 1, the ratio of Co to Cu after copper removal by sodium sulfide is 50000-100000: 1, and the ratio of Co to Cu after copper removal by cobalt thiosulfate is 24000-40000: 1.

⑤ comparison of sodium sulfide decoppering with cobalt thiosulfate decoppering

Name (R)	Copper removal from sodium sulfide	The invention discloses a copper removing agent
			Slag quantity (Dry)	200kg/TCo	2.10kg/TCo
Slag contains cobalt (%)	28.0	0.925
			Recovery (%)	98.70	99.58

⑥ the copper-cobalt ratio in the slag is improved if the copper-cobalt ratio in the slag is estimated to be improved.

Claims (3)

1. The copper removing method of cobalt electrolyte is characterized by adopting cobalt thiosulfate CoS₂O₃The copper removing agent is prepared by the following steps: by Cu in a cobalt electrolyte²⁺∶S₂O₃ ^2-Adding cobalt thiosulfate CoS in the weight ratio of 1: 8-16₂O₃Adding acid to adjust the pH value of the solution to 0.5-2.0, reacting at 70-90 ℃ for 30-40 minutes to generate a CuS precipitate, and filtering and separating the precipitate to finish the copper removal process.

2. The method of claim 1, wherein the cobalt concentration of the electrolyte for copper removal is 85-95 g/l.

3. The method for removing copper from cobalt electrolyte as claimed in claim 1, wherein the preparation process of cobalt thiosulfate as copper removing agent is:

a. firstly, RS is firstly₂O₃And BaCl₂The molar ratio of the raw materials is 1: 1, and the mixture is stirred for 10-15min at the reaction temperature of 20-30 ℃ to react to generate BaS₂O₃；

b. According to BaS₂O₃And CoSO₄In a molar ratio of 1: 0.7 in CoSO₄The molar concentration of the CoS is 1.4mol/L, the temperature is 40-50 ℃, the reaction time is 60-80min, and CoS is generated₂O₃A solution;

c. adding CoS₂O₃Liquid-based CoS₂O₃Mixing with ethanol as concentrating agent at volume ratio of 1: 10, crystallizing, standing for 36-42 hr to obtain CoS₂O₃.xH₂And (4) a copper removing agent for the O brown flaky crystals.