Efficient washing method of electro-deposited cobalt anode slime and recycling of washing liquid

Abstract

The present application belongs to the technical field of electrowinning or electrolysis of cobalt (nickel), and discloses a method for efficient washing of electrowinning cobalt anode slime and recycling of washing liquid. Specifically, the electrowinning cobalt anode plate and old electrowinning liquid sequentially pass through a microbial pre-soaking, pickling, lead removal, filter pressing, and microbial deep-soaking washing process, which can be reused. By introducing the microbial pre-treatment soaking and microbial deep-soaking acid supplementing process, the consumption of hydrogen peroxide and exogenous acid is reduced, the production cost is lowered, the cycle washing time is shortened, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrowinning or electrolysis of cobalt (nickel), and particularly relates to a high-efficiency washing method for electrowinning cobalt anode slime and recycling of washing liquid. BACKGROUND

[0002] In the production of electrowinning cobalt, the traditional anode adopts lead-based alloys such as lead-silver (Pb-Ag), lead-calcium (Pb-Ca), and lead-antimony (Pb-Sb). Due to the reasons such as easy deformation, easy passivation on the surface, and large amount of anode slime, the current anode is mainly a titanium-based anode plate, such as titanium plated with lead, titanium plated with ruthenium, and titanium plated with iridium. The main reasons are that the titanium-based anode plate has strong resistance to strong acid corrosion, long service life, low oxygen evolution potential, and high electric energy efficiency. However, the plated layer is prone to fall off, especially during the cleaning operation of the anode slime. The high-pressure water gun washing and knocking are easy to cause the plated layer to fall off, thereby affecting the conductivity and catalytic activity of the anode, increasing the cell voltage, reducing the electric efficiency, and increasing the energy consumption. The uneven distribution of the electric power line affects the quality of the electrowinning cobalt product.

[0003] The common methods for cleaning the anode slime include physical cleaning (such as ultrasonic wave, mechanical brushing, and high-pressure water jet), chemical cleaning (such as dilute sulfuric acid, hydrochloric acid, or citric acid solution), and electrochemical cleaning (such as reverse current electrolysis). The physical cleaning method is easy to cause the plated layer to fall off due to the strong adhesion of the anode slime. The chemical cleaning method has the disadvantages of long cleaning time, incomplete cleaning, and the need for further treatment of the cleaning liquid. The electrochemical cleaning method has not been applied due to the problems of difficult control of the electrolysis parameters, large investment in the washing electrolysis system, and subsequent treatment of the electrolyte. SUMMARY

[0004] 1. Problem to be solved

[0005] In view of the problems of incomplete cleaning of the anode slime, large acid consumption, and difficulty in long-term recycling of the washing liquid in the prior art, the present application provides a high-efficiency washing method for electrowinning cobalt anode slime and recycling of washing liquid.

[0006] 2. Technical solution

[0007] In order to solve the above problems, the technical solution adopted by the present application is as follows:

[0008] The high-efficiency washing method for electrowinning cobalt anode slime and recycling of washing liquid provided by the present application comprises the following steps:

[0009] S1, microbial pretreatment soaking;

[0010] A pretreatment tank containing hot water with a temperature of 60-70℃ is prepared, and a thermophilic sulfur-oxidizing bacteria liquid is added to the pretreatment tank to obtain a pretreatment liquid. The volume ratio of the hot water to the bacteria liquid is 10 cubic meters of hot water to 1 cubic meter of bacteria liquid, and the concentration of the bacteria liquid is 0.5×10 84 x 10 8 CFU / mL, the mass-volume ratio of the bacteria-containing solution in the pretreatment tank is at least 0.5% (g / mL) of elemental sulfur powder; the anode plate with anode mud is placed in the pretreatment solution at a temperature of 70°C for soaking, the volume-mass ratio of the pretreatment solution to the anode plate is 5L:1kg, and the stirring speed is 150-300r / min for 30-60 minutes to preliminarily partially dissolve the oxides in the anode mud to make the anode mud fluffy; after the reaction is completed, the bacteria solution is recovered by filtering through a filter membrane with a pore size of 0.01-0.5μm, and the anode plate is transferred to an acid washing tank;

[0011] In the above steps, the thermophilic sulfur-oxidizing bacteria efficiently oxidize elemental sulfur (S 0 →SO4²⁻) at high temperature (45-70°C) to produce a large amount of H⁺ and SO4²⁻, which not only maintains the acidic environment, but also promotes the stable existence of metal ions in the form of sulfate by increasing the concentration of sulfate in the solution, thereby avoiding the precipitation of hydroxides. At the same time, the production of acid by the thermophilic sulfur-oxidizing bacteria through the oxidation of sulfur powder can achieve the fluffy of the anode mud and the preliminary dissolution of metal oxides such as CoO and PbO, thereby reducing the processing load of the subsequent acid washing process and improving the washing efficiency of the anode mud.

[0012] S2, acid washing process;

[0013] The acid washing solution includes the electrodeposition anode solution and hydrogen peroxide, and the hydrogen peroxide with a mass-volume ratio of 1.5% (g / mL) is added to the electrodeposition anode solution to obtain the acid washing solution, the concentration of the hydrogen peroxide is 30wt%, the addition of the hydrogen peroxide is stopped when the pH of the solution reaches 1.5, the acid washing is performed at a stirring speed of 120-200r / min, the acid washing time is 3 hours, the anode plate after acid washing and the acid washing solution are separated and taken out when the pH of the solution reaches 3.5 to wait for the next operation;

[0014] The main components of the anode mud are metal oxides (such as PbO, CoO, etc.), hydroxides or salts, and neutralization reactions (such as MeO+2H⁺→Me²⁺+H2O) or dissolution reactions occur during acid washing, which consumes H⁺ and leads to a decrease in the acidity of the anode solution after acid washing.

[0015] S3, water washing, lead removal (only the process name is lead removal, but other heavy metal ions are also removed in large amounts) and pressure filtration;

[0016] The anode plate taken out after acid washing is washed with water for 5-15 minutes, 10% of the volume of the water washing water is returned to the pretreatment tank, the acid washing solution is transported to a lead removal tank, 0.2-0.5kg of barium carbonate is added per cubic meter of the acid washing solution in the lead removal tank, the reaction is performed at a stirring speed of 100-150r / min for 0.5 hours, and then the aging reaction is performed for 3 hours; the mixture after the reaction in the lead removal tank is sent to a pressure filter for pressure filtration to obtain a lead removal solution;

[0017] S4, microbial deep soaking to supplement acid;

[0018] The lead-removed solution is connected to the deep soaking tank, and acidophilic sulfur-oxidizing bacteria solution is added to the deep soaking tank to obtain deep soaking solution, the ratio of the volume of the lead-removed solution to the volume of the acidophilic sulfur-oxidizing bacteria solution is 10 cubic meters of treatment solution to 1 cubic meter of bacteria solution, and the concentration of the bacteria solution is 0.5*10 9 ~2*10 9 CFU / mL, and the deep soaking tank contains elemental sulfur powder with a mass-volume ratio of at least 1% (g / mL); the solution is stirred at a stirring speed of 200-300 r / min in an environment of 30°C, and air is introduced at a gas flow rate of 0.1-0.8 m 3 / h per cubic meter of solution, and the reaction time is 1-3 hours; after the reaction is completed, the bacteria solution is recovered through a filter membrane with a pore size of 0.01-0.1 μm, and the remaining filtrate is the new anode solution to be used;

[0019] In the above steps, the acidophilic sulfur-oxidizing bacteria can generate high-oxidation Fe³⁺ by oxidizing ferrous ions (Fe²⁺→Fe³⁺) in the anode mud, indirectly oxidize insoluble metal sulfides (such as CoS and NiS) as "electron carriers", and promote the dissolution of valuable metals such as cobalt and nickel in the form of ions (reaction formula: MeS+2Fe³⁺→Me²⁺+S 0 +2Fe²⁺). At the same time, the acidophilic sulfur-oxidizing bacteria produce sulfuric acid by oxidizing sulfur powder in the acidic environment to supplement the acidity of the anode solution, and the bacteria have tolerance to low-concentration metal ions and can use trace amounts of some metal ions as nutrients, thereby ensuring the stability of microbial activity and maintaining the organic balance required for the electrowinning process.

[0020] It should be noted that deep soaking is only a treatment of the lead-removed solution, and the anode plate has been taken out at this time and will be put into the electrowinning system together after the new electrowinning solution is generated.

[0021] S5, the new electrowinning solution of step S4 and the anode plate washed in step S3 are returned to the electrowinning system for electrowinning of cobalt, and after the electrowinning is completed, the anode plate with anode mud and the electrowinning solution are obtained, and steps S1-S4 are performed to circulate.

[0022] In the traditional process, some washing methods that directly use anode solution for washing without adding external acid will gradually lead to a decrease in the acidity of the anode solution, which cannot meet the acidity requirements of the anode solution for electrowinning of cobalt and the acidity requirements of the anode mud during washing, and some methods directly add H2SO4 or other external acid after the acidity decreases, which undoubtedly leads to a waste of a large amount of external acid, and this simple and rough method of adding acid can only temporarily dissolve part of the anode mud, and cannot effectively remove heavy metal ions in the circulating solution and maintain the organic balance of the acidity.

[0023] The microbial process in the present application converts the energy of the exogenous substrate into the output of acid, so as to ensure that the hydrogen ion concentration of the anolyte is within a stable range during the circulation, that is,

[0024] Substrate (energy source) + microbial metabolism → energy (for microbial growth) + acid (H + ) + metabolic products (such as H2O, CO2).

[0025] Moreover, the organic additives (such as surfactants and organic phosphonates used in the electrodeposition process) that may be left in the anode mud can be decomposed into CO2 and water by the metabolic enzyme system of the bacteria. The extracellular polymeric substance (EPS) produced by the bacteria contains functional groups such as carboxyl and hydroxyl groups, which can adsorb the residual heavy metal ions (such as Pb²⁺ and Zn²⁺) in the solution. Therefore, the microbial process combined with acid washing and lead removal can effectively reduce the content of impurity metal ions in the circulating liquid, and the circulating liquid can still maintain stable acidity after multiple circulations, which not only achieves the effect of waste utilization, Waste ①Old anolyte provides part of the acidity of the acid washing, and Waste ② Anode sludge part of the dissolved cobalt and sulfur ions in the circulating liquid serve as microbial nutrients, thereby improving the purity of the final electrodeposited cobalt product.

[0026] Further, in the S1 and S4 steps, the particle size of the sulfur powder is not greater than 50 microns.

[0027] Further, in the S2 step, the acid washing liquid further comprises the pretreated liquid recovered in step S1. The electrodeposition anolyte is mixed with the pretreated liquid recovered in step S1 at a volume ratio of 3:1 to obtain a mixed liquid. Hydrogen peroxide with a mass volume ratio of 1.5% (g / mL) is added to the mixed liquid to obtain the acid washing liquid.

[0028] Further, the concentration of the thermophilic sulfur-oxidizing bacteria liquid is 10 8 CFU / mL, and the concentration of the acidophilic sulfur-oxidizing bacteria liquid is 10 9 CFU / mL.

[0029] Further, in the S1 step, new sulfur powder with a mass volume ratio of 0.2% (g / mL) is supplemented each time; or 0.1 g / mL of sulfur powder is supplemented at one time in the S1 step, and the same amount is supplemented at one time again after 50 cycles.

[0030] Further, in the S4 step, new sulfur powder with a mass volume ratio of 0.5% (g / mL) is supplemented each time; or 0.25 g / mL of sulfur powder is supplemented at one time in the S4 step, and the same amount is supplemented at one time again after 50 cycles.

[0031] Further, in the S4 step, the acidophilic sulfur-oxidizing bacteria in the deep soaking tank adopt polyurethane foam immobilized carriers, and the microbial loading rate is not less than 50%.

[0032] Further, in the S1 step, the thermophilic sulfur-oxidizing bacteria in the pretreatment tank are supplemented with at least 1% of new bacteria solution in volume per 10 batches of circulation.

[0033] Further, in the S4 step, the acidophilic sulfur-oxidizing bacteria in the deep soaking tank are supplemented with at least 2% of new bacteria solution in volume per 10 batches of circulation.

[0034] Further, in the S4 step, 90% of the filtrate in the obtained new electrodeposition anode liquid is returned to the electrodeposition system, and the other 10% of the filtrate is used as the deep soaking bottom liquid.

[0035] In the above optimization scheme, since the new electrodeposition anode liquid contains sulfur ions and Co 2+ and the like, which can serve as nutrients for microorganisms, 10% of the new electrodeposition anode liquid is separated and stored in the deep soaking tank for use in the next cycle, thereby further improving the activity of microorganisms and reducing the consumption of substrates (sulfur powder).

[0036] 3. Beneficial effects

[0037] Compared with the prior art, the beneficial effects of the present application are:

[0038] (1) The present application reduces the consumption of hydrogen peroxide and exogenous acid by introducing microbial pretreatment soaking and microbial deep soaking acid supplementing processes, reduces production costs, shortens the cycle washing time, and improves production efficiency.

[0039] (2) The present application realizes the recycling of washing liquid, does not need exogenous acid supplement, and the only required additive sulfur powder costs about 0.5-1 yuan per cubic meter, which is greatly reduced compared with the cost of exogenous acid, and in general, a proper amount of sulfur powder can be added at one time to ensure dozens of cycles without the need for further addition, improving resource utilization, reducing production costs and environmental load.

[0040] (3) The two microorganisms of the heat-loving sulfur-oxidizing bacteria and acidophilic sulfur-oxidizing bacteria introduced in the application can be nourished by the substrate + waste (old anode liquid + part of ions dissolved from the anode mud) in each cycle, and the application ingeniously designs the timing of two microbial soaking, such as the first microbial pre-soaking liquid has little heavy metal toxicity, and the second microbial deep-soaking has little heavy metal toxicity because the old anode liquid has completed lead removal, so as to maintain biological activity, and after multiple cycles, the loss is extremely low, such as the heat-loving sulfur-oxidizing bacteria may lose about 1% per 10 batches of cycles, even if a small amount of bacteria is lost, it can be selected whether to supplement according to the demand, achieving the effect of one labor and multiple results, constructing an organic and green recycling of electrowinning cobalt recycling process, which meets the low-carbon and high-efficiency concept of modern metallurgy, and has good environmental friendliness and sustainability. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The anode plate surface schematic diagram after the washing method of the embodiment of the application is washed.

[0042] Figure 2 The anode plate surface schematic diagram before the washing method of the embodiment of the application is washed. DETAILED DESCRIPTION

[0043] The following more detailed description of the embodiments of the application is not intended to limit the scope of the claimed application, but is merely intended to provide an example of how the application can be put into practice, and to describe the features and characteristics of the application in a manner that is sufficient to enable one skilled in the art to carry out the application. It is to be understood, however, that various modifications and changes can be made to the application without departing from the scope of the application as defined by the appended claims. The detailed description is thus to be considered in all respects only as illustrative and not restrictive, and any such modifications and variations that can fall within the scope of the application described herein will be considered to fall within the scope of the application. Furthermore, the background art is intended to provide context for the present technology and should not be used to limit the application or the scope of the application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs; the terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the application.

[0045] The Acidithiobacillus caldus and Acidithiobacillus ferrooxidans in the present application are obtained through a legal, compliant, publicly known and purchasable public channel, belong to a known strain publicly sold by an international preservation center or a domestic agent, and the genetic material or physiological characteristics thereof are not modified, so no preservation number needs to be provided, and the details are as follows:

[0046] (1) Acidithiobacillus caldus: purchased through a domestic agent "Baoebowei Bio", which can be purchased by submitting an inquiry and unit qualification through China Bio-equip (https: / / www.bio-equip.com), and the strain number is ATCC51757.

[0047] (2) Acidithiobacillus ferrooxidans: purchased through the German Microbial and Cell Culture Collection (DSMZ), which can be purchased by placing an order online through the DSMZ website, and the strain number is DSM14882 (model strain, corresponding to ATCC23270).

[0048] The present application will be further described below in conjunction with specific examples.

[0049] Example 1

[0050] The present embodiment provides a method for efficient washing of electrodeposited cobalt anode slime and recycling of the washing liquid, and the anode plate is a titanium-coated lead dioxide anode plate (with anode slime on the surface), which comprises the following steps:

[0051] S1, microbial pretreatment soaking;

[0052] A pretreatment tank containing hot water at a temperature of 70°C is prepared, and Acidithiobacillus caldus liquid is added to the pretreatment tank to obtain a pretreatment liquid, wherein the volume ratio of hot water to bacterial liquid is 10 cubic meters of hot water to 1 cubic meter of bacterial liquid, the bacterial liquid concentration is 1x10 8 CFU / mL, and the pretreatment tank contains elemental sulfur powder with a mass volume ratio of at least 0.5% (g / mL) of bacterial liquid (i.e., at least 0.5 grams of elemental sulfur powder per 100 milliliters of bacterial liquid, and the particle size of the sulfur powder is not greater than 50 microns), and in this embodiment, 0.1 g / mL of sulfur powder is added at one time at the first cycle, which can be recycled for 50 times without additional addition, and in other embodiments, 0.2% (g / mL) of sulfur powder can be added in several times, which will not be described here; the anode plate with anode slime is placed in the pretreatment liquid with a temperature of 70°C for soaking and washing, and the volume mass ratio of the pretreatment liquid to the anode plate is 5L:1kg, and the reaction is carried out at a stirring speed of 150r / min for 30 minutes, which preliminarily partially dissolves the oxides in the anode slime to make the anode slime fluffy; after the reaction is completed, the bacterial liquid is recovered by filtering through a 0.1 μm filter membrane, and the anode plate is transferred to an acid washing tank.

[0053] S2, pickling process;

[0054] The pickling solution comprises the electrodeposition anode liquid, hydrogen peroxide and the pretreatment liquid recovered by filtration in step S1. The electrodeposition anode liquid is mixed with the pretreatment liquid recovered by filtration in step S1 at a volume ratio of 3:1 to prepare a mixed solution. Hydrogen peroxide with a mass-volume ratio of 1.5% (g / mL) is added to the mixed solution (i.e. 1.5 g of hydrogen peroxide is contained in 100 mL of the mixed solution) to obtain the pickling solution. The concentration of the hydrogen peroxide is 30 wt%. The addition of the hydrogen peroxide is stopped when the pH of the solution reaches 1.5. The pickling is performed at a stirring speed of 150 r / min. The pickling time is 3 hours. When the pH of the solution reaches 3.5, the anode plate after pickling and the pickling solution after pickling are separated and taken out for the next operation.

[0055] S3, water washing, lead removal and pressure filtration;

[0056] The anode plate taken out after pickling is water washed for 8 minutes. 10% of the water washing water by volume is returned to the pretreatment tank after water washing. The pickling solution after pickling is delivered to a lead removal tank. Barium carbonate with a mass of 0.4 kg per cubic meter of the pickling solution after pickling is added to the lead removal tank. The reaction is performed at a stirring speed of 100 r / min for 0.5 hours. Subsequently, the reaction is aged for 3 hours. The mixture after the reaction in the lead removal tank is delivered to a pressure filter for pressure filtration to obtain the lead removal solution after lead removal.

[0057] S4, microbial deep soaking and acid supplementing;

[0058] The lead removal solution after lead removal is connected to a deep soaking tank. Acidophilic sulfur-oxidizing bacteria liquid is added to the deep soaking tank to obtain a deep soaking solution. The acidophilic sulfur-oxidizing bacteria in the deep soaking tank are fixed on a polyurethane foam immobilized carrier. The microbial loading rate is not less than 50%. The ratio of the volume of the lead removal solution after lead removal to the volume of the acidophilic sulfur-oxidizing bacteria liquid is 10 cubic meters of the treatment liquid to 1 cubic meter of the bacteria liquid. The concentration of the bacteria liquid is 1×10 9 CFU / mL. The deep soaking tank contains elemental sulfur powder with a mass-volume ratio of at least 1% (g / mL) of the bacteria liquid (i.e. at least 1 g of elemental sulfur powder is contained in 100 mL of the bacteria liquid. The particle size of the sulfur powder is not greater than 50 microns). In this embodiment, 0.25 g / mL of sulfur powder is added at one time at the first circulation. The sulfur powder can be added in several times of 0.5% (g / mL) in other embodiments. The details are not described herein. The deep soaking tank is stirred at a stirring speed of 200 r / min in an environment at 30°C. Air is blown into the deep soaking tank at a blowing rate of 0.5 m 3 / h per cubic meter of the liquid (the concentration of dissolved oxygen is maintained at 2-3 mg / L). The reaction time is 2 hours. After the reaction is completed, the bacteria liquid is recovered through a 0.01 μm filter membrane. The remaining part of the filtrate is the new electrodeposition anode liquid to be used;

[0059] S5, return the new electrowinning anode liquid of S4 step and the anode plate washed by water of S3 step to the electrowinning system to electrowin cobalt, and get the anode plate attached with anode mud and the electrowinning anode liquid after the electrowinning is completed, return to execute S1-S4 steps to circulate.

[0060] In order to verify the technical effect of the embodiment, the concentrations of hydrogen ions, lead ions and cobalt ions in the new electrowinning anode liquid are detected respectively, the concentration of hydrogen ions is 1.56M, the concentration of lead ions is 0.6ppm, and the concentration of cobalt ions is 2.6ppm.

[0061] Example 2

[0062] The embodiment provides a kind of efficient washing and washing liquid recycling method of electrowinning cobalt anode mud, and its specific operation steps are basically same with example 1, main difference is in S4 step, 90% volume of filtrate in the new electrowinning anode liquid obtained is returned to electrowinning system, and 10% volume of filtrate is used as deep soaking bottom liquid, and deep soaking bottom liquid is mixed with lead removal liquid and acidophilic sulfur oxidizing bacteria liquid to obtain deep soaking liquid.

[0063] In order to verify the technical effect of the embodiment, the concentrations of hydrogen ions, lead ions and cobalt ions in the new electrowinning anode liquid are detected respectively, the concentration of hydrogen ions is 1.56M, the concentration of lead ions is 0.6ppm, and the concentration of cobalt ions is 2.6ppm.

[0064] Example 3

[0065] The embodiment provides a kind of efficient washing and washing liquid recycling method of electrowinning cobalt anode mud, and in order to verify its circulation performance, its specific operation steps are basically same with example 1, main difference is in: continue to repeat 9 times of washing+electrowinning (1 time of example 1 is combined, a total of 10 times).

[0066] In order to verify the technical effect of the embodiment, the concentrations of hydrogen ions, lead ions and cobalt ions in the new electrowinning anode liquid after each cycle are detected respectively, and recorded in Table 1.

[0067] Example 4

[0068] The embodiment provides a kind of efficient washing and washing liquid recycling method of electrowinning cobalt anode mud, and in order to verify its circulation performance, its specific operation steps are basically same with example 2, main difference is in: continue to repeat 9 times of washing+electrowinning (1 time of example 2 is combined, a total of 10 times).

[0069] In order to verify the technical effect of the embodiment, the concentrations of hydrogen ions, lead ions and cobalt ions in the new electrowinning anode liquid after each cycle are detected respectively, and recorded in Table 1.

[0070] Table 1, ion concentration comparison in new electrowinning liquid after each cycle of example 3 and 4

[0071]

[0072] Example 5

[0073] The embodiment provides a high-efficiency washing method for electro-deposited cobalt anode slime and recycling of washing liquid. In order to further verify the recycling performance, the specific operation steps are basically the same as those of Example 2, and the main difference lies in that the washing and electro-deposition are repeated for 49 times (a total of 50 times in combination with Example 2).

[0074] In order to avoid data redundancy and verify the technical effect of the embodiment, the hydrogen ion concentration, the lead ion concentration and the cobalt ion concentration of the new electro-deposited anode liquid after the last (i.e. the 50th) cycle are directly detected. The hydrogen ion concentration is 1.45M, the lead ion concentration is 0.86ppm, and the cobalt ion concentration is 3.1ppm.

[0075] As can be seen, the washing method of the embodiment can still ensure stable acidity and heavy metal ion concentration after 50 cycles. Although there is a decrease in acidity and an increase in ion concentration, this may be due to the loss of part of the bacterial species during filtration, resulting in a decrease in overall activity. However, it still meets the requirements of electro-deposited cobalt and anode slime washing. At this time, only sulfur powder needs to be added as a substrate, and whether to add new bacterial liquid can be considered according to user needs. The original activity can be restored by adding 1% volume of new bacterial liquid for each cycle of 10 batches of thermophilic sulfur-oxidizing bacteria and 2% volume of new bacterial liquid for each cycle of 10 batches of acidophilic sulfur-oxidizing bacteria.

[0076] Comparative Example 1

[0077] The comparative example 1 provides a traditional exogenous acid electro-deposited cobalt anode slime washing and recycling method of washing liquid. The specific operation includes: hot water soaking of titanium-coated lead dioxide anode plate (surface attached with anode slime) for 1h; preparation of pickling solution, the pickling solution includes electro-deposited anode liquid + 2% dilute sulfuric acid (i.e. 20kg of anode liquid per side, and the concentration of dilute sulfuric acid is 20wt%); immersion of the hot water soaked anode plate into the pickling solution for pickling, stop adding dilute sulfuric acid when the pickling solution PH is 1.3, pickling time is 4h, and the pickling solution PH is 3 when it is transported to the lead removal tank; water washing of the pickled anode plate, water washing time is 10min, and the anode slime on the surface of the anode plate has been cleaned; lead removal of the pickled solution, 0.5kg of barium carbonate is added to the lead removal tank per side of the pickling solution, the stirring speed is 120r / min, the reaction time is 0.5h, and the aging reaction time is 3h; pressure filtration of the lead-removed solution, and the filtrate is returned to the electro-deposition cycle liquid for use.

[0078] In order to verify the technical effect of the comparative example 1, the hydrogen ion concentration, the lead ion concentration and the cobalt ion concentration of the lead-removed solution are detected. The hydrogen ion concentration is 1.69M, the lead ion concentration is 5.4ppm, and the cobalt ion concentration is 8.0ppm.

[0079] Therefore, this simple exogenous acid washing after lead removal not only wastes a large amount of exogenous acid, but also cannot guarantee the efficient removal of heavy metal ions. If no exogenous acid is added, the acidity may decrease significantly after multiple cycles, which cannot meet the needs of electrowinning cobalt and dissolving anode slime.

[0080] It can be found from Comparative Examples 1-4 and Comparative Example 1 that the washing + electrowinning cycle method of the present application not only can efficiently clean the anode slime on the surface of the anode plate (see Figure 1 and Figure 2 ), but also can ensure that the hydrogen ion concentration of the new anode liquid is maintained within the range of 1.4-1.6 M (i.e. 1.4-1.6 mol / L) without the need for exogenous acid supplementation. Further, Example 2 has little difference in effect after one cycle by using 10% of the new electrowinning liquid as the deep soaking bottom liquid, but after 10 cycles, i.e. Example 4, the hydrogen ion concentration shows a more stable effect compared to the 100% return of the electrowinning liquid of Examples 1 and 3, and the lead ion concentration shows a slow downward trend, which indirectly reflects that the diversion of part of the bottom liquid for microbial deep soaking can improve the activity of the microorganisms, and can actively optimize the properties of the circulating liquid through acid production and lead removal functions, while the change in cobalt ion concentration is not large, which may be because its stability mainly depends on the electrowinning process itself, but even so, the present application can greatly reduce the concentration of cobalt ions.

[0081] The present application has been described in detail in the foregoing by reference to specific example embodiments. It will be appreciated, however, that various modifications and changes can be made without departing from the scope of the present application as defined in the appended claims. The detailed description is to be regarded in an illustrative manner, rather than a restrictive one, and any and all such modifications and variations are to be included within the scope of the present application as described herein. Furthermore, the background is intended to provide an overview of the present technology and its significance, and is not intended to limit the present application or the scope of the application and the field of use of the present application.

[0082] More specifically, although example embodiments of the present application have been described herein, the present application is not limited to these embodiments, but includes any and all embodiments that can be realized by those skilled in the art based on the foregoing detailed description, with modifications, omissions, combinations, adaptations, and / or substitutions of various embodiments. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the foregoing detailed description or during the prosecution of the application, which are to be considered non-exclusive. Any steps recited in any method or process claim can be executed in any order and are not limited to the order recited in the claim. Accordingly, the scope of the present application should be determined by the appended claims and their legal equivalents, rather than by the foregoing description and examples, which are to be considered illustrative only. Claims

[0083] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a contradiction between what is in this specification and what is in the definitions, the definitions in the specification control. Where a range of values is provided, preferred ranges are more highly preferred, and series of upper and lower preferred values are provided, it is to be understood that all ranges formed by any pair of an upper or preferred value and a lower or preferred value are specifically disclosed. For example, a range of 1-50 should be understood to include any number, combination of numbers, or sub-range selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all decimal values between the integers, such as 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, "nested sub-ranges" extending from either end of the range are specifically contemplated. For example, exemplary nested sub-ranges of the range 1-50 can include 1-10, 1-20, 1-30, and 1-40 in one direction, or 50-40, 50-30, 50-20, and 50-10 in the other direction.

Claims

1. A method for efficient washing of a cobalt anode slime from electrowinning and recycling of the washing solution, characterized in that, Includes the following steps: S1. Microbial pretreatment soaking; A pretreatment tank containing hot water at a temperature of 60-70℃ is prepared, and a heat-loving sulfur-oxidizing bacteria solution is added to the pretreatment tank to obtain a pretreatment solution, wherein the volume ratio of the hot water to the bacteria solution is 10 cubic meters of hot water to 1 cubic meter of bacteria solution, and the concentration of the bacteria solution is 0.5×10 8 ~4×10 8 CFU / mL, and the pretreatment tank contains elemental sulfur powder with a mass-volume ratio of at least 0.5% (g / mL); the anode plate with the anode mud is placed in the pretreatment solution at a temperature of 70℃ for soaking and washing, the volume-mass ratio of the pretreatment solution to the anode plate is 5L:1kg, and the reaction is carried out at a stirring speed of 150-300r / min for 30-60 minutes to preliminarily partially dissolve the oxides in the anode mud and make the anode mud fluffy; after the reaction is completed, the bacteria solution is recovered by filtering through a filter membrane with a pore size of 0.01-0.5μm, and the anode plate is transferred to an acid washing tank; S2, pickling process; The pickling solution includes electrowinning anolyte and hydrogen peroxide. 1.5% (g / mL) of hydrogen peroxide is added to the electrowinning anolyte to obtain the pickling solution, with a hydrogen peroxide concentration of 30wt%. When the solution pH reaches 1.5, the addition of hydrogen peroxide is stopped. Pickling is carried out at a stirring speed of 120~200 r / min for 3 hours. When the solution pH reaches 3.5, the pickled anode plate and the pickling solution are separated and removed for the next step. S3, water washing, lead removal and pressure filtration; The anode plates removed after acid pickling are washed with water for 5-15 minutes. After washing, 10% of the volume of the wash water is returned to the pretreatment tank. The acid pickling solution is then transferred to the lead removal tank, where 0.2-0.5 kg of barium carbonate is added per cubic meter of acid pickling solution. The mixture is stirred at 100-150 r / min for 0.5 hours, followed by aging for 3 hours. The mixture after the reaction in the lead removal tank is then filtered through a filter press to obtain the lead-removed solution. S4. Microbial deep soaking for acid replenishment; The lead-removed solution was transferred to a deep soaking tank. Acidophilic sulfur-oxidizing bacteria solution was then added to the tank to obtain the deep soaking solution. The ratio of the volume of the lead-removed solution to the volume of the acidophilic sulfur-oxidizing bacteria solution was 10 cubic meters of treatment solution to 1 cubic meter of bacteria solution, with a bacterial concentration of 0.5 × 10⁻⁶. 9 ~2×10 9 CFU / mL, the deep soaking tank contains at least 1% (g / mL) of elemental sulfur powder in the bacterial solution; stirring is carried out at 200~300 r / min at 30℃, with a concentration of 0.1~0.8 m³ / m³ of liquid. 3 Air is introduced at a puffing rate of / h, and the reaction time is 1~3 hours; after the reaction is completed, the bacterial solution is recovered through a 0.01~0.1μm filter membrane, and the remaining filtrate is the new anolyte to be used. S5. Return the new electrowinning anolyte from step S4 and the anode plate washed with water from step S3 to the electrowinning system for cobalt electrowinning. After electrowinning, an anode plate with anode mud and electrowinning anolyte are obtained. Then, return to the system to perform steps S1 to S4 for recycling.

2. The method according to claim 1, wherein the method is characterized in that, In steps S1 and S4, the particle size of the sulfur powder is no greater than 50 micrometers.

3. The method according to claim 1, wherein the method is characterized in that, In step S2, the pickling solution also includes the pretreatment solution recovered by filtration in step S1. The electrowinning anolyte and the pretreatment solution recovered by filtration in step S1 are mixed at a volume ratio of 3:1 to prepare a mixed solution. Hydrogen peroxide with a mass-volume ratio of 1.5% (g / mL) is added to the mixed solution to obtain the pickling solution.

4. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, The concentration of the thermophilic sulfur oxidizing bacteria is 10 8 CFU / mL, and the concentration of the acidophilic sulfur oxidizing bacteria is 10 9 CFU / mL.

5. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S1, 0.2% (g / mL) of new sulfur powder is added at each cycle; or 0.1 g / mL of sulfur powder is added at once in step S1, and then the same amount is added again after 50 cycles.

6. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S4, 0.5% (g / mL) of new sulfur powder is added at each cycle; or 0.25 g / mL of sulfur powder is added at once in step S4, and then the same amount is added again after 50 cycles.

7. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S4, the acidophilic sulfur oxidizing bacteria in the deep soaking tank are immobilized on a polyurethane foam carrier with a microbial load of not less than 50%.

8. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S1, the thermophilic sulfur-oxidizing bacteria in the pretreatment tank are replenished with at least 1% of the volume of fresh bacterial solution every 10 cycles.

9. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S4, the acidophilic sulfur oxidizing bacteria in the deep soaking tank are replenished with at least 2% of the volume of fresh bacterial solution every 10 cycles.

10. The method for efficient washing and recycling of washing liquid of electrowinning cobalt anode mud according to claim 1, characterized in that, In step S4, 90% of the volume of filtrate from the newly obtained electrodeposited anolyte is returned to the electrodeposition system, and the remaining 10% of the volume of filtrate is used as a deep soaking solution.

Images