Method for efficiently washing electrodeposited cobalt anode slime and recycling washing liquid

Abstract

The invention belongs to the technical field of electrodeposition or electrolysis of cobalt (nickel), and discloses a method for efficiently washing electrodeposited cobalt anode slime and recycling a washing solution. Specifically, an electrodeposited cobalt anode plate and an old electrodeposition solution can be repeatedly used after being subjected to microbial pre-soaking, acid pickling, lead removal, filter pressing and microbial deep soaking washing in sequence, and by introducing microbial pretreatment soaking and microbial deep soaking acid supplementing processes, the consumption of hydrogen peroxide and exogenous acid is reduced, the production cost is reduced, the circulating washing time is shortened, and the production efficiency is improved. And the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the field of electrolytic cobalt (nickel) or electrolysis, and particularly relates to a method for efficiently washing electrolytic cobalt anode mud and recycling washing liquid. Background Art

[0002] In the production of electrolytic cobalt, traditional anodes use lead-based materials such as lead-silver (Pb-Ag), lead-calcium (Pb-Ca), and lead-antimony (Pb-Sb) alloys. Due to reasons such as easy deformation, easy surface passivation, and large amounts of anode mud generated, the current anodes are mainly titanium-based anode plates, such as titanium plated with lead, titanium plated with ruthenium, and titanium plated with iridium. This is mainly due to their strong resistance to strong acid corrosion and long service life; low oxygen evolution potential and high electrical efficiency, but the coating is prone to shedding. Especially during the anode mud cleaning operation, high-pressure water gun flushing and knocking can easily cause the coating to fall off, thereby affecting the anode conductivity and catalytic activity, resulting in increased cell voltage, reduced electrical efficiency, increased energy consumption, and uneven distribution of power lines affecting the quality of electrolytic cobalt products.

[0003] Common methods for cleaning anode mud include: physical cleaning (such as ultrasonic waves, mechanical brushing, high-pressure water jets), chemical cleaning (such as dilute sulfuric acid, hydrochloric acid or citric acid solutions), and electrochemical cleaning (such as reverse current electrolysis). Physical cleaning methods are prone to plating shedding due to the strong adhesion of anode mud. Chemical cleaning methods have disadvantages such as long cleaning time, incomplete cleaning, and the need for further treatment of the cleaning fluid. Electrochemical cleaning methods have not been used due to problems such as the difficulty in controlling electrolysis parameters, the large investment in the washing electrolysis system, and the subsequent treatment of the electrolyte. Summary of the Invention

[0004] 1. Problem to be solved

[0005] Aiming at the problems in the prior art such as incomplete cleaning of anode mud, large acid consumption, and difficulty in long-term recycling of washing liquid, the present invention provides a method for efficiently washing electrolytic cobalt anode mud and recycling washing liquid.

[0006] 2. Technical solution

[0007] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0008] The present invention provides a method for efficiently washing electrolytic cobalt anode mud and recycling washing liquid, which comprises the following steps:

[0009] S1, microbial pretreatment soaking;

[0010] Prepare a pretreatment tank containing hot water at a temperature of 60-70°C, add thermophilic sulfur oxidizing bacteria liquid into the pretreatment tank to obtain a pretreatment liquid, wherein the ratio of the hot water volume to the bacterial liquid volume is 10 cubic meters of hot water to 1 cubic meter of bacterial liquid, and the bacterial liquid concentration is 0.5*10 8~4*10 8 CFU / mL, and elemental sulfur powder with a mass - volume ratio of at least 0.5% g / mL in the pretreatment tank; put the anode plate with anode mud into the pretreatment liquid at 70 °C for soaking and washing. The volume - mass ratio of the pretreatment liquid to the anode plate is 5L:1kg, and react at a stirring speed of 150 - 300 r / min for 30 - 60 minutes to initially partially dissolve the oxides in the anode mud and make the anode mud fluffy; after the reaction, filter and recover the bacterial liquid through a 0.01 - 0.5 μm filter membrane, and transfer the anode plate to the pickling tank;

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

[0012] S2, pickling process;

[0013] The pickling solution includes electrowinning anode solution and hydrogen peroxide. Add hydrogen peroxide with a mass - volume ratio of 1.5% g / mL to the electrowinning anode solution to obtain the pickling solution. The concentration of hydrogen peroxide is 30 wt%. Stop adding hydrogen peroxide when the solution pH reaches 1.5, and carry out pickling at a stirring speed of 120 - 200 r / min for 3 hours. When the solution pH reaches 3.5, separate and take out the pickled anode plate and the pickled solution for the next operation;

[0014] The main components of the anode mud are metal oxides (such as PbO, CoO, etc.), hydroxides or salts. During pickling, neutralization reactions (such as MeO + 2H⁺→Me²⁺+H2O) or dissolution reactions occur, consuming H⁺ and causing the acidity of the pickled anode solution to decrease.

[0015] S3, water washing, lead removal (although the process name is lead removal, in fact, a large amount of other heavy metal ions are also removed) and pressure filtration;

[0016] Wash the anode plate taken out after pickling for 5 - 15 minutes, and return 10% of the volume of the washing water to the pretreatment tank after water washing; transport the pickled solution to the lead - removal tank. Add 0.2 - 0.5 kg of barium carbonate per cubic meter of the pickled solution to the lead - removal tank, and react at a stirring speed of 100 - 150 r / min for 0.5 hours, and then age the reaction for 3 hours; send the mixture after the reaction in the lead - removal tank to a filter press for pressure filtration to obtain the solution after lead removal;

[0017] S4, microbial deep - soaking acid supplementation;

[0018] The post-desilvering solution is introduced into a deep immersion tank, and acidophilic sulfur-oxidizing bacteria solution is added to the deep immersion tank to obtain a deep immersion solution. The volume ratio of the post-desilvering solution to the acidophilic sulfur-oxidizing bacteria solution is 10 cubic meters of treatment solution corresponding to 1 cubic meter of bacteria solution, and the bacteria solution concentration is 0.5*10 9 ~2*10 9 CFU / mL. The deep immersion tank contains elemental sulfur powder with a mass-volume ratio of at least 1% g / mL of bacteria solution. Stir at a stirring speed of 200-300 r / min in an environment of 30 °C, and introduce air at a gas bubbling rate of 0.1-0.8 m 3 / h. The reaction time is 1-3 hours. After the reaction, the bacteria solution is recovered through a 0.01-0.1 μm filter membrane, and the remaining part of the filtrate is the new electrowinning anolyte ready for use;

[0019] In the above steps, acidophilic sulfur-oxidizing bacteria can generate highly oxidizing Fe³⁺ by oxidizing ferrous ions (Fe²⁺→Fe³⁺) in the anode slime, and indirectly oxidize refractory metal sulfides (such as CoS, NiS) as an "electron carrier", promoting the dissolution of valuable metals such as cobalt and nickel in ionic form (reaction formula: MeS + 2Fe³⁺→Me²⁺ + S 0 + 2Fe²⁺). At the same time, acidophilic sulfur-oxidizing bacteria produce sulfuric acid by oxidizing sulfur powder in an acidic environment to supplement the acidity of the electrowinning anolyte. In addition, this strain has tolerance to low-concentration metal ions and can use trace amounts of some metal ions as nutrients, thus ensuring stable microbial activity and maintaining the organic balance required for the electrowinning process.

[0020] It should be noted that deep immersion only treats the post-desilvering solution. At this time, the anode plate has been taken out and waits to enter the electrowinning system together with the newly generated electrowinning solution.

[0021] S5. Return the new electrowinning anolyte in step S4 and the anode plate after washing in step S3 to the electrowinning system for cobalt electrowinning. After the electrowinning is completed, an anode plate with anode slime and an electrowinning anolyte are obtained, and return to execute steps S1-S4 for circulation.

[0022] In traditional processes, some washing methods that directly use anolyte for washing without adding exogenous acid will gradually cause the acidity of the anolyte to decrease and cannot meet the acidity requirements of the anolyte during cobalt electrowinning and the acidity requirements during anode slime washing. Others directly add exogenous acids such as H2SO4 after the acidity drops. This will undoubtedly cause a waste of a large amount of exogenous acid, and this simple and crude way of adding acid can only temporarily dissolve part of the anode slime and cannot achieve the effect of effectively removing heavy metal ions in the circulating solution and maintaining the organic balance of acidity.

[0023] The microbial process in this application converts the energy of the exogenous substrate into acid output to ensure that the hydrogen ion concentration of the anolyte is within a stable range during the circulation process, 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 that may remain in the anode mud (such as surfactants and organic phosphonates used in the electrolytic process) can be decomposed into CO2 and water by the bacterial strain through the metabolic enzyme system. The extracellular polymers (EPS) produced by bacterial metabolism contain functional groups such as carboxyl and hydroxyl groups, which can adsorb heavy metal ions (such as Pb²⁺ and Zn²⁺) remaining in the solution. In this way, the microbial process combined with inorganic processes such as pickling and lead removal can effectively reduce the content of impurity metal ions in the circulating liquid. At the same time, the circulating liquid can still maintain a stable acidity after multiple cycles, achieving waste utilization ( Waste ① Spent anolyte Provides some of the acidity for pickling, and Waste ② Anode mud The effect of some cobalt and sulfur ions remaining in the circulating fluid after dissolution (as nutrients for microorganisms) further improves the purity of the final electrolytic cobalt product.

[0026] Furthermore, in steps S1 and S4, the particle size of the sulfur powder is no greater than 50 microns.

[0027] Furthermore, in step S2, the pickling solution also includes the pretreatment solution filtered and recovered in step S1, and the electrolytic anolyte and the pretreatment solution filtered and recovered in step S1 are mixed in a volume ratio of 3:1 to obtain a mixed solution, and hydrogen peroxide with a mass volume ratio of 1.5% g / mL is added to the mixed solution to obtain the pickling solution.

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

[0029] Furthermore, in step S1, new sulfur powder with a mass-to-volume ratio of 0.2% g / mL is added in each cycle; or 0.1 g / mL of sulfur powder is added once in step S1, and the same amount is added again after 50 cycles.

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

[0031] Furthermore, in the step S4, the acidophilic sulfur oxidizing bacteria in the deep immersion tank are immobilized on a polyurethane foam carrier, and the microbial loading rate thereof is not less than 50%.

[0032] Furthermore, in the step S1, the thermophilic sulfur-oxidizing bacteria in the pretreatment tank are supplemented with at least 1% volume of new bacterial liquid every 10 batches of cycles.

[0033] Furthermore, in the step S4, the acidophilic sulfur-oxidizing bacteria in the deep immersion tank are supplemented with at least 2% of the volume of new bacterial liquid every 10 batches of cycles.

[0034] Furthermore, in the step S4, 90% of the volume of the filtrate in the obtained new electrowinning anolyte is returned to the electrowinning system, and the remaining 10% of the volume of the filtrate is used as the deep soaking bottom liquid.

[0035] In the above optimization scheme, since the new electrolytic anolyte contains sulfur ions and Co 2+ Substances such as sulfur and sulfur dioxide can serve as nutrients for microorganisms. 10% of the new electrolytic anode liquid is kept in the deep immersion tank and waits for use in the next cycle, thereby further improving microbial activity and reducing substrate (sulfur powder) consumption.

[0036] 3. Beneficial effects

[0037] Compared with the prior art, the present invention has the following beneficial effects:

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

[0039] (2) The present invention realizes the recycling of washing liquid without the need for external acid supplementation. The only required additive, sulfur powder, costs about 0.5 to 1 yuan per cubic meter, which is significantly lower than the cost of external acid. In addition, under normal circumstances, an appropriate amount of sulfur powder can be added at one time to ensure dozens of cycles without the need for re-addition, thereby improving resource utilization and reducing production costs and environmental load.

[0040] (3) The two microorganisms, namely thermophilic sulfur-oxidizing bacteria and acidophilic sulfur-oxidizing bacteria, introduced in the present invention can be nourished by substrates + waste (part of the ions dissolved from the old anolyte + anode mud) during each cycle. Moreover, the present invention ingeniously designs the timing of the two microbial immersions. For example, there is almost no heavy metal toxicity in the pre-immersion solution during the first microbial pre-immersion, and there is also not much heavy metal toxicity during the second deep microbial immersion because the lead removal of the old anolyte has been completed. Thus, the biological activity can be maintained, and the loss amount is extremely low after multiple cycles. For instance, the thermophilic sulfur-oxidizing bacteria may lose about 1% every 10 batches of cycles. Even if a very small amount of the bacterial strain is lost, it can be selected whether to supplement according to the demand, achieving the effect of once and for all. An organic and green cyclic electrowinning cobalt process is constructed, which conforms to the low-carbon and high-efficiency concepts of modern metallurgy and has good environmental friendliness and sustainability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the surface of the anode plate after washing by the washing method of the embodiment of the present invention;

[0042] Figure 2 Schematic diagram of the surface of the anode plate before washing by the washing method of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following more detailed description of the embodiments of the present invention does not limit the scope of the claimed present invention, but is only for illustrative purposes and does not limit the description of the features and characteristics of the present invention, to present the best mode of implementing the present invention and to enable those skilled in the art to implement the present invention. However, it should be understood that various modifications and variations can be made without departing from the scope of the present invention defined by the appended claims. The detailed description should only be considered illustrative, not restrictive. If there are any such modifications and variations, they will all fall within the scope of the present invention described herein. In addition, the background art is intended to illustrate the research and development status and significance of the present technology and is not intended to limit the present invention or the application fields of the present application and the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs; the terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0045] The bacterial solutions of thermophilic sulfur-oxidizing bacteria (Acidithiobacillus caldus) and acidophilic sulfur-oxidizing bacteria (Acidithiobacillus ferrooxidans) in this application were obtained through legal and compliant public channels that are known and available for purchase by the public. They are known strains publicly sold by international depository centers or domestic agents, and their genetic material or physiological characteristics have not been modified. Therefore, it is not necessary to provide a deposit number. The details are as follows:

[0046] (1) Thermophilic sulfur-oxidizing bacteria: Purchase through the domestic agent "Biobowei Biological". Submit the inquiry and unit qualifications to the China Bio-Equipment Network (https: / / www.bio-equip.com) to purchase. The strain number is ATCC51757.

[0047] (2) Acidophilic sulfur oxidizing bacteria: purchased from the German Collection of Microorganisms (DSMZ). Orders can be placed online on the DSMZ official website. The strain number is DSM14882 (type strain, corresponding to ATCC23270).

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] Example 1

[0050] This embodiment provides a method for efficiently washing electrolytic cobalt anode slime and recycling the washing liquid. The anode plate is a titanium-coated lead dioxide anode plate (with anode slime attached to the surface), comprising the following steps:

[0051] S1, microbial pretreatment soaking;

[0052] Prepare a pretreatment tank containing hot water at a temperature of 70°C, add thermophilic sulfur oxidizing bacteria liquid into the pretreatment tank to obtain a pretreatment liquid, wherein the ratio of the hot water volume to the bacterial liquid volume is 10 cubic meters of hot water to 1 cubic meter of bacterial liquid, and the bacterial liquid concentration is 1*10 8 CFU / mL, the pretreatment tank contains at least 0.5% g / mL of elemental sulfur powder at a mass-to-volume ratio of the bacterial liquid (i.e., at least 0.5 g of elemental sulfur powder for every 100 mL of bacterial liquid, and the sulfur powder particle size is not greater than 50 μm). In this embodiment, 0.1 g / mL of sulfur powder is added at one time during the first cycle, so that 50 cycles can be repeated without adding it again. In other embodiments, 0.2% g / mL of sulfur powder can also be added in batches, which will not be repeated here. The anode plate with anode mud attached is placed in a pretreatment liquid at a temperature of 70°C for soaking and washing, with a volume-to-mass ratio of the pretreatment liquid to the anode plate of 5 L:1 kg. The reaction is carried out at a stirring speed of 150 r / min for 30 minutes to initially partially dissolve the oxides in the anode mud and make the anode mud fluffy. After the reaction is completed, the bacterial liquid is filtered through a 0.1 μm filter membrane to recover the bacterial liquid, and the anode plate is transferred to an acid washing tank.

[0053] S2, pickling process;

[0054] The pickling solution includes an electrolytic anolyte, hydrogen peroxide, and a pretreatment solution filtered and recovered in step S1. The electrolytic anolyte and the pretreatment solution filtered and recovered in step S1 are mixed in a volume ratio of 3:1 to obtain a mixed solution. To the mixed solution, hydrogen peroxide is added at a mass volume ratio of 1.5% g / mL (i.e., 1.5 g of hydrogen peroxide is contained in every 100 ml of the mixed solution) to obtain an acid pickling solution. The concentration of hydrogen peroxide is 30 wt%. When the pH of the solution reaches 1.5, the addition of hydrogen peroxide is stopped, and the pickling is performed at a stirring speed of 150 r / min for 3 hours. When the pH of the solution reaches 3.5, the pickled anode plate and the pickled liquid are separated and taken out to wait for the next operation.

[0055] S3, water washing, lead removal and filter pressing;

[0056] The anode plates removed after pickling are washed with water for 8 minutes, and 10% of the volume of the washing water is returned to the pretreatment tank after washing; the pickling liquid is transported to the lead removal tank, 0.4 kg of barium carbonate is added to the lead removal tank per cubic meter of the pickling liquid, and the reaction is carried out at a stirring speed of 100 r / min for 0.5 hours, followed by aging reaction for 3 hours; the mixture after the reaction in the lead removal tank is sent to a filter press for filtration to obtain the lead removal liquid.

[0057] S4, deep soaking of microorganisms to supplement acid;

[0058] The lead-removed liquid is connected to a deep soaking tank, and an acidophilic sulfur-oxidizing bacteria solution is added to the deep soaking tank to obtain a deep soaking liquid. The acidophilic sulfur-oxidizing bacteria in the deep soaking tank are immobilized on a polyurethane foam carrier, and the microbial load rate is not less than 50%. The ratio of the volume of the lead-removed liquid to the volume of the acidophilic sulfur-oxidizing bacteria solution is 10 cubic meters of treated liquid corresponding to 1 cubic meter of bacterial solution, and the bacterial solution concentration is 1*10 9 CFU / mL, the deep immersion tank contains at least 1% g / mL of elemental sulfur powder at a mass volume ratio of the bacterial liquid (that is, at least 1 gram of elemental sulfur powder for every 100 ml of bacterial liquid, and 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 during the first cycle, so that it can be circulated 50 times without adding again. In other embodiments, 0.5% g / mL of sulfur powder can also be added in batches, which will not be repeated here; the mixture is stirred at a stirring speed of 200 r / min at 30°C and 0.5 m3 per cubic meter of liquid. 3 Air was introduced at an aeration rate of / h (the dissolved oxygen concentration was maintained at 2-3 mg / L), and the reaction time was 2 hours. After the reaction, the bacterial solution was recovered through a 0.01 μm filter membrane, and the remaining filtrate was used as the new electrodeposition anolyte.

[0059] S5. Return the newly electrowon anolyte from step S4 and the anode plates after water washing in step S3 to the electrowinning system for cobalt electrowinning. After electrowinning, anode plates with anode slime and electrowon anolyte are obtained, and then return to execute steps S1 - S4 for cycling.

[0060] To verify the technical effects of this embodiment, the concentrations of hydrogen ions, lead ions, and cobalt ions in the newly electrowon anolyte were detected respectively. The hydrogen ion concentration was 1.56 M, the lead ion concentration was 0.6 ppm, and the cobalt ion concentration was 2.6 ppm.

[0061] Example 2

[0062] This embodiment provides a method for efficient washing of electrowon cobalt anode slime and recycling of washing solution. Its specific operation steps are basically the same as those of Example 1, and the main difference is that: in step S4, 90% by volume of the filtrate in the newly electrowon anolyte obtained is returned to the electrowinning system, and the other 10% by volume of the filtrate is used as the deep soaking bottom liquid. The deep soaking bottom liquid is mixed with the de - leaded solution and the acidophilic sulfur - oxidizing bacteria solution to obtain the deep soaking solution.

[0063] To verify the technical effects of this embodiment, the concentrations of hydrogen ions, lead ions, and cobalt ions in the newly electrowon anolyte were detected respectively. The hydrogen ion concentration was 1.55 M, the lead ion concentration was 0.59 ppm, and the cobalt ion concentration was 2.6 ppm.

[0064] Example 3

[0065] This embodiment provides a method for efficient washing of electrowon cobalt anode slime and recycling of washing solution. To verify its recycling performance, its specific operation steps are basically the same as those of Example 1, and the main difference is that: continue to repeat the cycle of washing + electrowinning 9 times (a total of 10 times including 1 time in Example 1).

[0066] To verify the technical effects of this embodiment, the concentrations of hydrogen ions, lead ions, and cobalt ions in the newly electrowon anolyte after each cycle were detected respectively and recorded in Table 1.

[0067] Example 4

[0068] This embodiment provides a method for efficient washing of electrowon cobalt anode slime and recycling of washing solution. To verify its recycling performance, its specific operation steps are basically the same as those of Example 2, and the main difference is that: continue to repeat the cycle of washing + electrowinning 9 times (a total of 10 times including 1 time in Example 2).

[0069] To verify the technical effects of this embodiment, the concentrations of hydrogen ions, lead ions, and cobalt ions in the newly electrowon anolyte after each cycle were detected respectively and recorded in Table 1.

[0070] Table 1. Comparison of ion concentrations in the newly electrowon solution after each cycle in Examples 3 and 4.

[0071]

[0072] Example 5

[0073] This example provides a method for efficiently washing cobalt electrowinning anode slime and recycling the washing solution. To further verify its recycling performance, the specific operation steps are basically the same as those in Example 2, with the main difference being that the cycle of washing + electrowinning is repeated 49 more times (a total of 50 times including the 1 time in Example 2).

[0074] To avoid data redundancy and verify the technical effect of this example, the hydrogen ion, lead ion, and cobalt ion concentrations of the new electrowinning anode solution after the last (i.e., the 50th) cycle are directly detected. The hydrogen ion concentration is 1.45 M, the lead ion concentration is 0.86 ppm, and the cobalt ion concentration is 3.1 ppm.

[0075] It can be seen that the washing method of the present invention can still ensure stable acidity and heavy metal ion concentrations after 50 cycles. Although there is a decrease in acidity and an increase in ion concentrations, this may be due to the loss of some strains during filtration, resulting in a decrease in overall activity. However, it still meets the requirements for cobalt electrowinning and anode slime washing. At this time, only sulfur powder needs to be replenished as a substrate, and whether to replenish new bacterial liquid can be considered according to user needs. Just replenish 1% volume of new bacterial liquid for thermophilic sulfur-oxidizing bacteria and 2% volume of new bacterial liquid for acidophilic sulfur-oxidizing bacteria every 10 batches of cycles to restore the original activity.

[0076] Comparative Example 1

[0077] This Comparative Example 1 provides a traditional method for washing cobalt electrowinning anode slime with external acid and recycling the washing solution. The specific operations include: soaking the titanium-coated lead dioxide anode plate (with anode slime on the surface) in hot water for 1 h; preparing an acid washing solution, which includes electrowinning anode solution + 2% dilute sulfuric acid (i.e., 20 kg of dilute sulfuric acid per cubic meter of anode solution, and the concentration of dilute sulfuric acid is 20 wt%). Immerse the anode plate after hot water soaking in the acid washing solution for acid washing. Stop adding dilute sulfuric acid when the pH of the washing solution is 1.3, and the acid washing time is 4 h. Transfer it to the lead removal tank when the pH of the washing solution is 3; wash the anode plate after acid washing with water for 10 min, and the anode slime on the surface of the anode plate has been cleaned; then remove lead from the acid washing solution. Add 0.5 kg of barium carbonate per cubic meter of washing solution to the lead removal tank, stir at a speed of 120 r / min, react for 0.5 h, and age for 3 h; filter the solution after lead removal, and return the filtrate to the electrowinning circulating solution for use.

[0078] To verify the technical effect of this Comparative Example 1, the hydrogen ion, lead ion, and cobalt ion concentrations of the solution after lead removal are detected respectively. The hydrogen ion concentration is 1.69 M, the lead ion concentration is 5.4 ppm, and the cobalt ion concentration is 8.0 ppm.

[0079] It can be seen that this simple method of removing lead after external acid washing not only wastes a large amount of external acid, but also cannot ensure the efficient removal of heavy metal ions. If no external acid is added, the acidity may drop significantly after multiple cycles, unable to meet the requirements of electrowinning cobalt and dissolving anode slime.

[0080] By comparing Examples 1 to 4 with Comparative Example 1, it can be found that the washing + electrowinning cycle method of the present invention can not only efficiently clean the anode slime on the surface of the anode plate (see Figure 1 and Figure 2 ), but also ensure that the hydrogen ion concentration of the new anode solution is maintained within the range of 1.4 - 1.6 M (i.e., 1.4 - 1.6 mol / L) without the need for external acid supplementation. Further, the effect after one cycle of Example 2 by using 10% of the new electrowinning solution as the deep immersion bottom liquid is not much different from that of Example 1. However, after 10 cycles, that is, Example 4, its hydrogen ion concentration shows a more stable effect compared to the 100% return of the electrowinning solution in Examples 1 and 3, and the lead ion concentration shows a slow decreasing trend. This indirectly reflects that diverting part of the bottom liquid for microbial deep immersion can enhance the activity of microorganisms, and can actively optimize the properties of the circulating liquid through acid production and lead removal functions. The change in cobalt ion concentration may not be significant because its stability mainly depends on the electrowinning process itself. Nevertheless, the present invention can significantly reduce the cobalt ion concentration.

[0081] In the foregoing, the present invention has been described in detail in connection with specific exemplary embodiments. However, it should be understood that various modifications and variations can be made without departing from the scope of the present invention as defined by the appended claims. The detailed description should be considered illustrative only and not restrictive. If there are any such modifications and variations, they will all fall within the scope of the present invention described herein. In addition, the background art is intended to illustrate the research and development status and significance of the present technology, and is not intended to limit the present invention or the application fields of the present application and the present invention.

[0082] More specifically, although the exemplary embodiments of the present invention have been described herein, the present invention is not limited to these embodiments, but includes any and all embodiments that those skilled in the art can recognize from the foregoing detailed description through modification, omission, such as combinations between various embodiments, adaptive changes, and / or substitutions. The limitations in the claims can be widely interpreted according to the language used in the claims, and are not limited to the examples described in the foregoing detailed description or during the implementation of the application. These examples should 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 set forth in the claims. Therefore, the scope of the present invention should be determined only by the appended claims and their legal equivalents, rather than by the description and examples given above.

[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 invention belongs. In case of conflict, the definitions in this specification shall control. When a flow rate, power, refractive index, time, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this shall be understood to specifically disclose all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the ranges are separately disclosed. For example, a range of 1 - 50 should be understood to include any number, combination of numbers, or sub - ranges selected from 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 fractional values between the above integers, e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Regarding sub - ranges, specifically consider "nested sub - ranges" extending from any endpoint within the range. For example, the nested sub - ranges of the exemplary 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 electrowinning cobalt anode slime and recycling of washing liquid, characterized in that, The steps include: S1, microbial pretreatment soaking; Prepare a pretreatment tank containing hot water at a temperature of 60 to 70 °C, add a bacterial solution of thermophilic sulfur-oxidizing bacteria to the pretreatment tank to obtain a pretreatment solution, where the volume ratio of hot water to the bacterial solution is 10 cubic meters of hot water corresponding to 1 cubic meter of the bacterial solution, and the concentration of the bacterial solution is 0.5*10 8 ~4*10 8 CFU / mL, and the mass-volume ratio of elemental sulfur powder with a content of at least 0.5% g / mL of the bacterial solution in the pretreatment tank; place the anode plate with anode mud attached into the pretreatment solution at a temperature of 70 °C for soaking and washing, the volume-mass ratio of the pretreatment solution to the anode plate is 5L:1kg, and react at a stirring speed of 150 to 300 r / min for 30 to 60 minutes to initially partially dissolve the oxides in the anode mud and fluff up the anode mud; after the reaction, filter and recover the bacterial solution through a 0.01 to 0.5 μm filter membrane, and transfer the anode plate to the pickling tank; S2, pickling process; The pickling solution includes an electrolytic anolyte and hydrogen peroxide. The pickling solution is obtained by adding hydrogen peroxide at a mass volume ratio of 1.5% g / mL to the electrolytic anolyte. The concentration of hydrogen peroxide is 30 wt%. When the pH of the solution reaches 1.5, the addition of hydrogen peroxide is stopped. The pickling is carried out at a stirring speed of 120-200 r / min for 3 hours. When the pH of the solution reaches 3.5, the pickled anode plate and the pickled liquid are separated and removed for the next step. S3, water washing, lead removal and filter pressing; The anode plates removed after pickling are washed with water for 5 to 15 minutes, and 10% of the washing water is returned to the pretreatment tank. The pickled liquid is transferred to a lead removal tank, 0.2 to 0.5 kg of barium carbonate is added to the lead removal tank per cubic meter of pickled liquid, and the mixture is stirred at a speed of 100 to 150 r / min for 0.5 hour, followed by aging for 3 hours. The mixture after the reaction in the lead removal tank is transferred to a filter press for filtration to obtain a lead-removed liquid. S4, deep soaking of microorganisms to supplement acid; The post-desilvering solution is introduced into a deep immersion tank, and an acidophilic thiobacillus solution is added to the deep immersion tank to obtain a deep immersion solution. The volume ratio of the post-desilvering solution to the acidophilic thiobacillus solution is 10 cubic meters of treatment solution corresponding to 1 cubic meter of bacterial solution, and the bacterial solution concentration is 0.5*10 9 ~2*10 9 CFU / mL. The deep immersion tank contains elemental sulfur powder with a mass-volume ratio of at least 1% g / mL of the bacterial solution. Stir at a stirring speed of 200-300 r / min in an environment of 30°C, and introduce air at a gas bubbling rate of 0.1-0.8 m 3 / h. The reaction time is 1-3 hours. After the reaction, the bacterial solution is recovered through a 0.01-0.1 μm filter membrane, and the remaining part of the filtrate is the new electrowinning anolyte ready for use; S5. Return the new electrolytic anolyte from step S4 and the anode plates washed with water from step S3 to the electrolytic system for cobalt electrolysis. After the electrolysis is completed, anode plates with anode mud and electrolytic anolyte are obtained, and the system returns to execute steps S1 to S4 for a cycle.

2. The method for efficient washing of electrowinning cobalt anode slime and recycling of washing liquid according to claim 1, characterized in that In steps S1 and S4, the particle size of the sulfur powder is no more than 50 microns.

3. A method for efficient washing of electrowinning cobalt anode slime and recycling of washing liquid according to claim 1, characterized in that In step S2, the pickling solution also includes the pretreatment solution filtered and recovered in step S1. The electrolytic anolyte and the pretreatment solution filtered and recovered in step S1 are mixed in a volume ratio of 3:1 to obtain a mixed solution, and hydrogen peroxide with a mass volume ratio of 1.5% g / mL is added to the mixed solution to obtain the pickling solution.

4. A method for efficient washing of electrowinning cobalt anode slime and recycling of washing liquid according to claim 1, characterized in that, 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.

5. The high-efficiency washing method for electrowinning cobalt anode slime and the recycling method for washing liquid according to claim 1, characterized in that In the step S1, new sulfur powder with a mass-to-volume ratio of 0.2% g / mL is added in each cycle; or 0.1 g / mL of sulfur powder is added once in the step S1, and after 50 cycles, the same amount is added again in one time.

6. The high-efficiency washing method for electrowinning cobalt anode slime and the recycling method for washing liquid according to claim 1, wherein In the step S4, new sulfur powder with a mass-to-volume ratio of 0.5% g / mL is added in each cycle; or 0.25 g / mL of sulfur powder is added in the step S4 at one time, and after 50 cycles, the same amount is added again at one time.

7. A method for efficient washing of electrowinning cobalt anode slime and recycling of washing liquid according to claim 1, characterized in that, In the step S4, the acidophilic sulfur oxidizing bacteria in the deep immersion tank are immobilized on a polyurethane foam carrier, and the microbial loading rate thereof is not less than 50%.

8. An efficient washing method for electrowinning cobalt anode slime and a method for recycling washing liquid according to claim 1, characterized in that, In the step S1, the thermophilic sulfur-oxidizing bacteria in the pretreatment tank are supplemented with at least 1% of the volume of new bacterial liquid every 10 batches of cycles.

9. The high-efficiency washing method for electrowinning cobalt anode slime and the recycling method for washing liquid according to claim 1, characterized in that, In the step S4, the acidophilic sulfur-oxidizing bacteria in the deep immersion tank are supplemented with at least 2% of the volume of new bacterial solution every 10 batches of cycles.

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

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