Process for preparing zinc powder in zinc-containing solid waste treatment solution through electrodeposition

Abstract

The invention relates to the technical field of zinc-containing solid waste treatment, in particular to a process for preparing zinc powder in a zinc-containing solid waste treatment solution through electrodeposition. The invention discloses a process for preparing zinc powder by electrodeposition in a zinc-containing solid waste treatment solution, which comprises the following steps: adding an impurity removal agent into the zinc-containing solid waste treatment solution, and carrying out solid-liquid separation after impurity removal to obtain an impurity-removed solution; performing extraction treatment on the impurity-removed liquid to obtain a loaded organic phase and raffinate, and performing washing and back extraction on the loaded organic phase to obtain back extraction liquid; and treating the strip liquor as electrolyte, and performing electrolytic deposition to obtain the zinc powder. According to the technology, the technical problems that a traditional zinc-containing solid waste treatment pyrogenic process is high in energy consumption, large in pollution and large in product impurity amount, and a wet process is long in flow, difficult to control and high in cost are solved.

Description

Technical Field

[0001] The invention relates to the technical field of zinc-containing solid waste treatment, and in particular to a process for preparing zinc powder by electrolytic deposition in a zinc-containing solid waste treatment solution. Background Art

[0002] Zinc-containing solid waste mainly refers to waste generated by industries such as metal smelting, zinc-manganese batteries, and steel smelting dust removal. These wastes contain heavy metals such as Zn, Pb, and Cd, with complex composition, large output, and difficult treatment. They are persistently toxic and highly mobile, not easy to degrade, and are extremely harmful to humans and the environment. The zinc-containing solid waste generated by the steel industry each year accounts for about 10% of steel production, which contains rich resources such as zinc and lead, but due to technical barriers, these resources are difficult to be comprehensively utilized.

[0003] At present, the resource utilization of zinc-containing solid waste is mainly divided into two methods: pyrometallurgy and hydrometallurgy. Pyrometallurgy is to mix zinc-containing solid waste with coal or coke powder and send it into a rotary kiln or rotary hearth furnace for reaction. Metals such as lead and zinc are volatilized into the gas phase while being reduced, and then oxidized into oxides, which are recovered after cooling. Although this method has a large processing capacity, it has high energy consumption and will produce secondary pollution. The actual production efficiency is low, the obtained products have many impurities, and the resource utilization rate is also low. In addition, serious nodules will occur in the furnace, which requires frequent shutdowns for repairs, high equipment maintenance costs, and poor economic benefits.

[0004] Wet treatment mainly includes two processes: alkaline leaching and acid leaching. These two processes use alkali or acid as the leachate, respectively, to leach the valuable metals in the zinc-containing solid waste into the solution, and then recycle them respectively. For example, patents CN116219499 A and CN 104988537 A both disclose a resource recovery process for zinc-containing solid waste. These two processes use ammonium chloride solution to leach zinc-containing solid waste. After leaching, impurities such as Fe, Cu, Pb, and Cd in the leachate are removed through multiple stages of impurity removal. The purified liquid is used as an electrolyte to enter the electrolytic deposition system to prepare zinc powder. Patent CN 114672665 A discloses a processing technology for preparing zinc ingots by electrowinning, which uses sulfuric acid and Helicobacter ferrooxidans to synergistically leach zinc ions from zinc-containing solid waste, then extracts and recovers the zinc ions enriched therein, and finally prepares zinc ingots by electrowinning.

[0005] The wet leaching process can efficiently recover valuable metals from zinc-containing solid waste, with high resource utilization rate, and the prepared products are of high purity and good activity. However, this method has a long process, complex process, many influencing factors, difficult process control, and relatively high production cost. Therefore, how to reduce production costs and simplify process flow while ensuring product quality and recovery efficiency has become a technical problem that needs to be solved in the current field of resource utilization of zinc-containing solid waste.

[0006] To this end, the present application provides a process for preparing zinc powder by electrolytic deposition in a zinc-containing solid waste treatment solution. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the present invention provides a process for preparing zinc powder by electrolysis in a zinc-containing solid waste treatment solution. During the preparation process, an impurity remover removes impurity ions through a replacement or precipitation reaction, an extractant complexes with zinc ions to achieve enrichment, and back extraction returns the zinc ions to the aqueous phase. During the electrolysis process, anodic oxidation and cathode reduction are performed to precipitate the zinc ions at the cathode, thereby solving the technical problems of high energy consumption, high pollution, many product impurities, and long wet process, difficult control, and high cost in traditional zinc-containing solid waste treatment pyrolysis.

[0008] The technical solution adopted by this application to solve its technical problem is: A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution comprises the following steps: Adding an impurity remover to the zinc-containing solid waste treatment solution, and performing solid-liquid separation after impurity removal to obtain an impurity-removed liquid; The impurity-removed liquid is subjected to extraction treatment to obtain a loaded organic phase and a raffinate, and the loaded organic phase is washed and stripped to obtain a stripping liquid; The stripping solution is treated and used as an electrolyte to perform electrolytic deposition to obtain zinc powder.

[0009] In some specific embodiments, the impurity remover is zinc powder, the amount of the impurity remover added is 10-20 g / L, and the impurity removal time is 0.5-1.5 h.

[0010] In some specific embodiments, in the extraction process, the extractant is a mixture of at least one of P204, P507, and TBP and sulfonated kerosene, and the mass content of P204, P507 or TBP in the extractant is 30-70%.

[0011] In some specific embodiments, during extraction, the O / A ratio is 3-7:1, the extraction temperature is 15-35° C., the extraction time is 5-15 min, the extraction method is cascade countercurrent extraction, and the extraction stages are 6-8.

[0012] In some specific embodiments, the loaded organic phase is washed with a detergent, and the detergent is any one of water, dilute sulfuric acid, and dilute hydrochloric acid; the volume ratio of the organic phase volume to the detergent during washing is 5-10:1, and the number of washing times is 1-3 times; the concentration of dilute sulfuric acid or dilute hydrochloric acid is 0.1-0.5 mol / L.

[0013] In some specific embodiments, the stripping solution is a sulfuric acid solution or a hydrochloric acid solution, and the concentration of the stripping solution is 1-3 mol / L; the O / A ratio of the stripping process is 2-6:1, the stripping time is 5-15 min, and the stripping level is 5-7.

[0014] In some specific embodiments, when treating the stripping solution, an additive is added and the pH is adjusted to 3-5; The additive is any one of bone glue, sodium dodecylbenzene sulfonate, ethanol, strontium carbonate and thiourea, and the dosage of the additive is 1-5%; the agent for adjusting pH is any one of zinc powder, zinc hydroxide and zinc oxide.

[0015] In some specific embodiments, during the electrolytic deposition process, the zinc ion concentration is maintained at 20-60 g / L, the anode plate is a lead-silver alloy plate, and the cathode plate is an aluminum plate; the current density during electrolysis is 500-700 A / m², the electrolysis temperature is 40-70°C, and the electrolysis time is 12-24 h.

[0016] In some specific embodiments, the zinc-containing solid waste treatment solution is any one of the treatment solutions of steel dust removal ash, zinc smelting sludge, zinc-containing waste, and zinc dust.

[0017] In some specific embodiments, the zinc powder obtained by the electrolytic deposition has a purity of 99.9% and a particle size of 1-6 microns.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The process described in the present application first adds zinc powder to the zinc-containing solid waste treatment solution to remove impurities and separate the solid and liquid, then uses at least one extractant of P204, P507, TBP mixed with sulfonated kerosene to extract the impurity-removed liquid, then uses a detergent to wash the loaded organic phase and then strip extract to obtain a stripping solution, and finally adds bone glue, sodium dodecylbenzene sulfonate and other additives to the stripping solution to adjust the pH to 3-5 as an electrolyte, and uses a lead-silver alloy plate anode and an aluminum plate cathode to electrolyze for 12-24 hours at a current density of 500-700A / m² and a temperature of 40-70°C to prepare zinc powder. The purity of the prepared zinc powder can reach 99.9%, the particle size is 1-6 microns and the activity is good. At the same time, the process flow is simple, easy to control, and does not produce secondary pollution. The impurity-removed solid can recover valuable metals, and the extractant can be recycled. It is suitable for large-scale industrial production and realizes the efficient resource utilization of zinc-containing solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0020] Figure 1 This is a flow chart of a process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution as described in the present application. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0022] As used herein, "and / or" includes the term of all combinations of any one or more associated listed items. The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It is further understood that "including", when used in this specification, specifies the stated features, integers, steps, operations, elements and / or compositions, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, compositions and / or combinations thereof.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It is further understood that terms, such as defined in commonly used dictionaries, are interpreted in accordance with their meanings in the context of the relevant art and are not idealized or overly formal meanings unless explicitly defined as such herein.

[0024] The exemplary invention described herein may appropriately lack any one or more element limitations that are not specifically disclosed herein. Therefore, the terms "comprise", "include", "contain", etc. should be understood broadly and non-restrictively. In addition, the terminology used herein is used as a description, not a limitation, and it is unintentional to use these terminology expressions that do not include any equivalent characteristics, but only describe some of their characteristics, but various modifications are possible within the scope of the present invention according to the rights. Therefore, although the present invention has been specifically disclosed by preferred embodiments and optional features, the modifications disclosed herein to embody the changes of the present invention may be recorded by those skilled in the art, and such modifications and changes will be considered to be within the scope of the present invention.

[0025] Explanation of terms: 1. P204: Its chemical name is di(2-ethylhexyl) phosphate, which is a commonly used extractant, mainly used to extract metal ions (such as zinc, copper, nickel, etc.) from aqueous solutions. It forms complexes with metal ions and transfers metal ions from the aqueous phase to the organic phase.

[0026] During the extraction process, P204 has a high selectivity for metal ions and can effectively separate zinc ions and other impurity ions.

[0027] 2. P507 (2-ethylhexylphosphonic acid-2-ethylhexyl ester): It is an acidic phosphorus extractant with excellent performance, commonly used for the separation and enrichment of metal ions in hydrometallurgy.

[0028] P507 has good extraction ability for metal ions such as zinc and copper, and has high selectivity and stability during the extraction process.

[0029] 3. TBP: Its chemical name is tributyl phosphate. It is a commonly used extractant, mainly used for extracting metal ions and organic matter.

[0030] TBP forms a stable complex with metal ions during the extraction process, transferring metal ions from the aqueous phase to the organic phase. It is often mixed with other extractants (such as P204, P507) to improve extraction efficiency and selectivity.

[0031] 4. Sulfonated kerosene: Sulfonated kerosene is a kerosene that has been sulfonated and is usually used as a diluent for extractants.

[0032] During the extraction process, sulfonated kerosene can adjust the density and viscosity of the extractant, allowing it to better contact and separate from the water phase. It can also improve the stability of the extractant and prevent the extractant from emulsifying or decomposing during use.

[0033] 5. O / A ratio: O / A ratio refers to the volume ratio or mass ratio of the organic phase (Organic Phase) to the aqueous phase (Aqueous Phase).

[0034] In the extraction process, the O / A ratio is an important parameter that directly affects the extraction efficiency and the recovery rate of metal ions. A suitable O / A ratio can ensure that the metal ions are fully contacted and transferred between the two phases, while reducing the amount and cost of the extractant.

[0035] 6. Anode plate: Anode plate is one of the electrodes used in the electrolytic cell for the electrolysis process.

[0036] During the electrolysis process, the anode plate is usually made of a material with good conductivity, such as lead-silver alloy. The function of the anode plate is to introduce current into the electrolyte through an electrochemical reaction, while an oxidation reaction occurs at the anode to generate oxygen or other oxidizing substances.

[0037] In the electrolytic deposition process of zinc-containing solid waste treatment, the main function of the anode plate is to conduct electricity and ensure the smooth progress of the electrolytic reaction.

[0038] 7. Cathode Plate: Cathode plate is one of the electrodes used in the electrolytic cell for the electrolysis process.

[0039] During the electrolysis process, the cathode plate is usually made of a material with good conductivity and corrosion resistance, such as aluminum plate. The function of the cathode plate is to introduce current into the electrolyte through an electrochemical reaction, while a reduction reaction occurs at the cathode, causing zinc ions to be deposited as metallic zinc on the surface of the cathode plate.

[0040] In the electrolytic deposition process of zinc-containing solid waste treatment, the choice of cathode plate has an important influence on the quality and purity of zinc powder. Aluminum plate is often used as cathode plate material due to its good conductivity and cost-effectiveness.

[0041] like Figure 1 As shown, a process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution comprises the following steps: S1. Adding an impurity remover to the zinc-containing solid waste treatment solution, performing solid-liquid separation after impurity removal, and obtaining an impurity-removed liquid; S2. The impurity-removed liquid is subjected to extraction treatment to obtain a loaded organic phase and a raffinate, and the loaded organic phase is washed and stripped to obtain a stripping solution; S3. The stripping solution is treated and used as an electrolyte to perform electrolytic deposition to obtain zinc powder.

[0042] Specifically, in step S1, the impurity remover is zinc powder, the amount of the impurity remover added is 10-20 g / L, and the impurity removal time is 0.5-1.5 h.

[0043] In step S1, zinc powder removes Cu in the solution through a replacement reaction. 2+ , Pb 2+ The resulting metal element precipitate can be removed by solid-liquid separation. The reaction is: Zn+Cu 2+ →Zn 2+ +Cu Zn+Pb 2+ →Zn 2+ +Pb

[0044] Therefore, step S1 is intended to remove some impurities in the solution, such as metal ions such as iron, lead, copper, and cadmium. If impurities are not removed or are insufficiently removed, the impurities may be extracted together with zinc ions in the subsequent extraction process, affecting the purity of the zinc powder. The accumulation of impurities in the electrolyte may interfere with the electrolytic process, resulting in problems such as reduced zinc powder quality and reduced current efficiency.

[0045] Specifically, in step S2, in the extraction process, the extractant is a mixture of at least one of P204, P507, and TBP and sulfonated kerosene, and the mass content of P204, P507 or TBP in the extractant is 30-70%. During the extraction, the O / A ratio is 3-7:1, the extraction temperature is 15-35°C, the extraction time is 5-15min, the extraction method is cascade countercurrent extraction, and the extraction stages are 6-8.

[0046] In the present application, an organic solvent is used to selectively dissolve out the target metal ions, such as zinc ions. The extraction process utilizes the difference in the distribution coefficient of metal ions between the aqueous phase (zinc-containing solid waste treatment solution) and the organic phase (extractant). When the two phases are in full contact, the zinc ions are transferred to the organic phase, while other impurity ions remain in the aqueous phase. The extractants used in this process are P204, P507 or a mixture of TBP and sulfonated kerosene, which have high selectivity for zinc. The extraction process is a cascade countercurrent operation, which can improve the extraction efficiency.

[0047] Specifically, in step S2, the loaded organic phase is washed with a detergent, wherein the detergent is any one of water, dilute sulfuric acid, and dilute hydrochloric acid; the volume ratio of the organic phase volume to the detergent during washing is 5-10:1, and the number of washing times is 1-3 times; the concentration of dilute sulfuric acid or dilute hydrochloric acid is 0.1-0.5 mol / L.

[0048] Washing is to further remove impurity ions that may be entrained in the loaded organic phase. Since some non-target components may be brought into the organic phase during the extraction process, water or dilute acid is needed as a detergent to clean the loaded organic phase to ensure that the impurities will not affect the subsequent stripping and electrolytic processes. Washing is usually carried out in multiple stages to ensure that impurities are completely removed.

[0049] Specifically, in step S2, the stripping solution is a sulfuric acid solution or a hydrochloric acid solution, and the concentration of the stripping solution is 1-3 mol / L; the O / A ratio of the stripping process is 2-6:1, the stripping time is 5-15 min, and the stripping level is 5-7.

[0050] Stripping refers to the process of transferring zinc ions that have been transferred to the organic phase back to the aqueous phase. This is done by adding an appropriate stripping solution (such as sulfuric acid or hydrochloric acid) to the organic phase and changing the environmental conditions (such as pH value) so that the zinc ions return to the aqueous phase. The aqueous phase after stripping is an electrolyte rich in zinc ions, which can be used for electrolytic production of zinc powder. Stripping also uses a multi-stage countercurrent method to maximize the recovery rate of zinc.

[0051] Therefore, through steps S1 and S2, high-purity zinc ions can be efficiently extracted from the complex zinc-containing solid waste treatment solution, preparing for the subsequent electrolytic zinc powder preparation. In addition, this method also has the advantage of not generating secondary pollution, which meets environmental protection requirements.

[0052] Specifically, in step S3, when the stripping solution is treated, an additive is added and the pH is adjusted to 3-5; the additive is any one of gelatin, sodium dodecylbenzene sulfonate, ethanol, strontium carbonate, and thiourea, and the amount of the additive is 1-5%; the agent for adjusting the pH is any one of zinc powder, zinc hydroxide, and zinc oxide.

[0053] In the present application, additives such as gelatin, sodium dodecylbenzene sulfonate, ethanol, strontium carbonate, thiourea, etc. can be used as crystal seeds or lattice distorters, which can adsorb on the cathode surface or change the local charge distribution, thereby affecting the deposition behavior of zinc ions on the cathode. For example, these substances may inhibit the excessive growth of zinc ions, making the deposited zinc crystals more delicate and smooth.

[0054] Moreover, an appropriate amount of additives can optimize the electrolysis process without affecting the stability of the electrolyte, while too much may cause unnecessary side reactions or affect the performance of the electrolyte.

[0055] When adjusting the pH value, adjust the pH of the electrolyte to between 3-5 by adding zinc powder, zinc hydroxide or zinc oxide. The appropriate pH range helps to maintain the optimal solubility of zinc ions, while avoiding the co-deposition of other impurity ions such as iron and lead, and ensuring the purity of the final product. Too high or too low pH may cause zinc ions to precipitate or co-precipitate with other impurities, reduce the purity of zinc powder, and may damage the equipment.

[0056] Specifically, in step S3, during the electrolytic deposition process, the zinc ion concentration is maintained at 20-60 g / L, the anode plate is a lead-silver alloy plate, and the cathode plate is an aluminum plate; the current density during electrolysis is 500-700 A / m², the electrolysis temperature is 40-70°C, and the electrolysis time is 12-24 h.

[0057] In this application, the temperature is controlled within the range of 40-70°C and the current density is 500-700A / m². Such parameter selection can ensure that zinc ions have enough power to migrate to the cathode and be reduced to metallic zinc there. A higher current density can obtain more zinc powder in a shorter time, but too high a current density may lead to dendrite formation; while the appropriate temperature helps to maintain the fluidity of the electrolyte and the efficiency of ion transmission.

[0058] The selection of anode material and cathode material uses lead-silver alloy plate as anode plate and aluminum plate as cathode plate. The anode plate mainly plays a conductive role in this process, while aluminum plate is an ideal cathode material due to its good conductivity and cost-effectiveness. When voltage is applied, zinc ions will accept electrons at the cathode to become metallic zinc and deposit.

[0059] Zinc ion concentration management maintains the zinc ion concentration between 20-60g / L, which ensures that there are sufficient zinc ions to participate in the reaction during the entire electrolysis process, while also preventing unnecessary side reactions or poor deposition morphology due to excessive concentration.

[0060] Specifically, the zinc-containing solid waste treatment solution is any one of the treatment solutions of steel dust removal ash, zinc smelting sludge, zinc-containing waste, and zinc dust.

[0061] Specifically, the zinc powder obtained by the electrolytic deposition has a purity of 99.9% and a particle size of 1-6 microns.

[0062] Embodiment 1: A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution, comprising the following steps: The composition of the zinc-containing solid waste treatment solution of a steel plant is shown in Table 1: Table 1 Element composition of zinc-containing solid waste treatment solution

[0063] Take the zinc-containing solid waste treatment solution shown in the table above, add zinc powder for impurity removal, the zinc powder addition amount is 10g / L, stir and remove impurities for 0.5h at room temperature, after impurity removal, perform solid-liquid separation to obtain impurity removal liquid and impurity removal solid, the impurity removal liquid enters the next step, the impurity removal solid is dissolved with sulfuric acid and the valuable metals therein are recovered step by step. The composition of the impurity removal liquid is shown in Table 2 below.

[0064] Table 2 Element composition of impurity removal liquid

[0065] The zinc ions in the impurity removal liquid were extracted using an extractant, the extractant used was composed of P204 and sulfonated kerosene, the mass fraction of P204 in the extractant was 30%, the O / A ratio used for extraction was 3:1, the extraction temperature was 15°C, the extraction time was 5 minutes, and the countercurrent extraction was 6 levels. The composition of the loaded organic phase after the extraction was completed is shown in Table 3 below.

[0066] Table 3 Element composition of the loaded organic phase

[0067] The loaded organic phase was washed with water, the volume ratio of the organic phase to the detergent was 5:1, and the washing was performed once. After the washing was completed, 1 mol / L sulfuric acid was used for stripping, and the O / A ratio was maintained at 2:1 during stripping, the stripping time was 5 min, and the stripping level was 5. After the stripping was completed, a stripping solution was obtained, and the composition of the stripping solution is shown in Table 4 below.

[0068] Table 4 Element composition in stripping solution

[0069] Add ethanol as an additive to the stripping solution, the amount of ethanol added is 1%, and then add zinc powder to adjust the pH of the system to 3. After the adjustment is completed, a zinc sulfate electrolyte is obtained. The composition of the electrolyte is shown in Table 5. The electrolyte is introduced into an electrolytic cell, with a lead-silver alloy as the anode plate and an aluminum plate as the cathode plate. The current density is 500A / m at 40°C. 2 Zinc powder was obtained by electrolysis for 12 h under the above conditions.

[0070] Table 5 Element composition of the electrolyte

[0071] Embodiment 2: A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution, comprising the following steps: The composition of the zinc-containing solid waste treatment solution of a steel plant is shown in Table 6: Table 6 Element composition of zinc-containing solid waste treatment solution

[0072] Take the zinc-containing solid waste treatment solution shown in the table above, add zinc powder for impurity removal, the zinc powder addition amount is 15g / L, stir and remove impurities for 1h at room temperature, after the impurity removal is completed, perform solid-liquid separation to obtain impurity removal liquid and impurity removal solid, the impurity removal liquid enters the next step, the impurity removal solid is dissolved with sulfuric acid and the valuable metals therein are recovered step by step. The composition of the impurity removal liquid is shown in Table 7 below.

[0073] Table 7 Element composition of impurity removal liquid

[0074] The zinc ions in the impurity removal liquid were extracted using an extractant, the extractant used was composed of P204 and sulfonated kerosene, the mass fraction of P204 in the extractant was 50%, the O / A ratio used for extraction was 5:1, the extraction temperature was 25°C, the extraction time was 10 minutes, and the countercurrent extraction was 7 levels. The composition of the loaded organic phase after the extraction was completed is shown in Table 8 below.

[0075] Table 8 Element composition of the loaded organic phase

[0076] The loaded organic phase was washed with water, the volume ratio of the organic phase to the detergent was 7:1, and the washing was performed twice. After the washing was completed, 2 mol / L sulfuric acid was used for stripping, and the O / A ratio was maintained at 3:1 during stripping, the stripping time was 10 min, and the stripping level was 6. After the stripping was completed, a stripping solution was obtained, and the composition of the stripping solution is shown in Table 9 below.

[0077] Table 9 Element composition in stripping solution

[0078] Add ethanol as an additive to the stripping solution, the amount of ethanol added is 3%, and then add zinc powder to adjust the system pH to 4. After the adjustment is completed, a zinc sulfate electrolyte is obtained. The composition of the electrolyte is shown in Table 10. The electrolyte is introduced into an electrolytic cell, with a lead-silver alloy as the anode plate and an aluminum plate as the cathode plate. The current density is 600A / m at 60°C. 2 Zinc powder was obtained by electrolysis for 18 h under the above conditions.

[0079] Table 10 Element composition of electrolyte

[0080] Embodiment 3: A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution, comprising the following steps: The composition of the zinc-containing solid waste treatment solution of a steel plant is shown in Table 11: Table 11 Element composition of zinc-containing solid waste treatment solution

[0081] Take the zinc-containing solid waste treatment solution shown in the table above, add zinc powder for impurity removal, the zinc powder addition amount is 20g / L, stir and remove impurities at room temperature for 1.5h, after the impurity removal is completed, perform solid-liquid separation to obtain impurity removal liquid and impurity removal solid, the impurity removal liquid enters the next step, the impurity removal solid is dissolved with sulfuric acid and the valuable metals therein are recovered step by step. The composition of the impurity removal liquid is shown in Table 12 below.

[0082] Table 12 Element composition of impurity removal liquid

[0083] The zinc ions in the impurity removal liquid were extracted using an extractant, the extractant used was composed of P204 and sulfonated kerosene, the mass fraction of P204 in the extractant was 70%, the O / A ratio used for extraction was 7:1, the extraction temperature was 35°C, the extraction time was 15min, and the countercurrent extraction was 8 levels. After the extraction was completed, the composition of the loaded organic phase was shown in Table 13 below.

[0084] Table 13 Element composition of the loaded organic phase

[0085] The loaded organic phase was washed with water, the volume ratio of the organic phase to the detergent was 10:1, and the washing was performed 3 times. After the washing was completed, 3 mol / L sulfuric acid was used for back extraction, and the O / A ratio was maintained at 5:1 during back extraction. The back extraction time was 15 min, and the back extraction level was 7. After the back extraction was completed, a back extraction solution was obtained, and the composition of the back extraction solution is shown in Table 14 below.

[0086] Table 14 Element composition in stripping solution

[0087] Add ethanol as an additive to the stripping solution, the amount of ethanol added is 5%, and then add zinc powder to adjust the system pH to 5. After the adjustment is completed, a zinc sulfate electrolyte is obtained. The composition of the electrolyte is shown in Table 15. The electrolyte is introduced into an electrolytic cell, with a lead-silver alloy as the anode plate and an aluminum plate as the cathode plate. The electrolyte is heated at 70°C and a current density of 700A / m 2 Zinc powder was obtained by electrolysis for 24 hours under the above conditions.

[0088] Table 15 Element composition of electrolyte

[0089] Comparative Example 1 A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution comprises the following steps: No additives were added to the stripping solution, and the other conditions were the same as those in Example 1.

[0090] Comparative Example 2 A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution comprises the following steps: Additives were added and the pH was adjusted to 2. The other conditions were the same as those in Example 1.

[0091] Comparative Example 3 A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution comprises the following steps: Additives were added and the pH was adjusted to 6. The other conditions were the same as those in Example 1.

[0092] In the present application, the content of zinc powder components is detected by atomic absorption spectroscopy; the particle size of zinc powder is detected by laser diffraction particle size analyzer; the zinc powder prepared in Examples 1-3 and Comparative Examples 1-3 is subjected to element content detection and particle size detection, and the results are summarized in Table 16.

[0093] Table 16

[0094] As can be seen from Table 16, the zinc powder prepared in Examples 1-3 has extremely high purity (over 99.9%) and very fine particle size (between 1.5 and 5.6 microns). Such high purity and micronization characteristics make the zinc powder suitable for application scenarios requiring pure and fine materials, such as conductive materials in the electronics industry, catalysts in the chemical industry, etc.

[0095] The zinc powders prepared in Comparative Examples 1-3 have relatively low purities, reaching 95.42%, 89.23%, and 91.12% respectively, and the particle sizes are relatively large, ranging from 25 microns to 42 microns. Such zinc powders may contain more impurities, affecting their application effects, especially when high-purity materials are required.

[0096] Cause Analysis: Comparative Example 1: No additives were added, which may affect the deposition behavior of zinc ions on the cathode and fail to effectively control the growth of zinc crystals, resulting in larger zinc powder particles. At the same time, due to the lack of lattice distortion effect provided by the additives, the purity of the zinc powder is also reduced.

[0097] Comparative Example 2: The pH was adjusted to 2. Too low a pH may promote the co-precipitation of other metal ions (such as iron, lead, etc.), reducing the purity of the zinc powder. In addition, an overly acidic environment may also be unfavorable for the stable existence of zinc ions, thereby affecting the quality of the zinc powder.

[0098] Comparative Example 3: The pH value was adjusted to 6. A higher pH value may also cause some impurity ions to precipitate together, reducing the purity of the zinc powder. Moreover, if the pH value is too high, the optimal dissolution state of zinc ions may be changed, affecting their normal deposition and causing the zinc powder particle size to increase.

[0099] In summary, Examples 1-3 use appropriate impurity removers to remove impurities, selectively extract zinc ions, reduce impurities by washing, recover zinc ions by stripping, and add appropriate additives and adjust pH value during electrolytic deposition. These steps ensure high enrichment of zinc ions and form a uniform and fine zinc crystal structure during the electrolysis process, thereby obtaining high-purity and micronized zinc powder. However, Comparative Examples 1-3 lack certain key steps or improper parameter settings, resulting in zinc powder quality and performance that are not as expected.

[0100] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A process for preparing zinc powder by electrowinning in a zinc-containing solid waste treatment solution, characterized in that: The following steps are involved: Adding an impurity remover to the zinc-containing solid waste treatment solution, and performing solid-liquid separation after impurity removal to obtain an impurity-removed liquid; The impurity-removed liquid is subjected to extraction treatment to obtain a loaded organic phase and a raffinate, and the loaded organic phase is washed and stripped to obtain a stripping liquid; The stripping solution is treated and used as an electrolyte to perform electrolytic deposition to obtain zinc powder; The impurity remover is zinc powder, the amount of the impurity remover added is 10-20 g / L, and the impurity removal time is 0.5-1.5 h.

2. The process according to claim 1, characterized in that In the extraction treatment, the extractant is a mixture of at least one of P204, P507, and TBP and sulfonated kerosene, and the mass content of P204, P507 or TBP in the extractant is 30-70%.

3. The process according to claim 2, characterized in that During extraction, the O / A ratio is 3-7:1, the extraction temperature is 15-35°C, the extraction time is 5-15min, the extraction method is cascade countercurrent extraction, and the extraction stages are 6-8.

4. The process according to claim 1, characterized in that The loaded organic phase is washed with a detergent, which is any one of water, dilute sulfuric acid, and dilute hydrochloric acid; the volume ratio of the organic phase to the detergent during washing is 5-10:1, and the number of washings is 1-3 times; the concentration of the dilute sulfuric acid or dilute hydrochloric acid is 0.1-0.5 mol / L.

5. The process according to claim 1, characterized in that The stripping solution is a sulfuric acid solution or a hydrochloric acid solution, and the concentration of the stripping solution is 1-3 mol / L; the O / A ratio of the stripping process is 2-6:1, the stripping time is 5-15 minutes, and the stripping level is 5-7 levels.

6. The process according to claim 1, characterized in that When treating the stripping solution, an additive is added and the pH is adjusted to 3-5; The additive is any one of bone glue, sodium dodecylbenzene sulfonate, ethanol, strontium carbonate and thiourea, and the dosage of the additive is 1-5%; the agent for adjusting pH is any one of zinc powder, zinc hydroxide and zinc oxide.

7. The process according to claim 1, characterized in that During the electrolytic deposition process, the zinc ion concentration is maintained at 20-60g / L, the anode plate is a lead-silver alloy plate, and the cathode plate is an aluminum plate; the current density during electrolysis is 500-700A / m², the electrolysis temperature is 40-70℃, and the electrolysis time is 12-24h.

8. The process according to claim 1, characterized in that The zinc-containing solid waste treatment solution is any one of the treatment solutions for steel dust removal ash, zinc smelting sludge, zinc-containing waste, and zinc dust.

9. The process according to claim 1, characterized in that The zinc powder obtained by the electrolytic deposition has a purity of 99.9% and a particle size of 1-6 microns.

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