Method for wet preparation of 5n and above high purity zinc

Abstract

A wet process for preparing high-purity zinc of 5N and above involves using a mixture of neutral zinc leaching solution and zinc back-extraction solution + cathode electrodeposition waste solution as the anolyte and catholyte, respectively. A nested tank consisting of an outer and an inner tank is used, with electrode plates of different polarities and corresponding electrodeposition solutions placed in the outer and inner tanks for electrodeposition. The anode tank yields anode electrodeposition waste solution, while the cathode tank yields high-purity zinc with a zinc content ≥99.999% and cathode electrodeposition waste solution. The anode electrodeposition waste solution is purified, filtered, and zinc is extracted to obtain purification residue, raffinate, and a zinc-loaded organic phase. The raffinate is neutrally leached to obtain zinc-containing solid materials, yielding a neutral zinc leaching solution sent to the anode tank. A portion of the cathode electrodeposition waste solution is used for back-extraction of the zinc-loaded organic phase to obtain a zinc back-extraction solution. The impurity ions in the zinc back-extraction solution are all <0.05 ppm. This solution is mixed with the remaining cathode electrodeposition waste solution and sent to the cathode tank. This invention combines the preparation of 5N and above high-purity zinc with the purification and impurity removal of wet zinc smelting, achieving multiple benefits in one step. It features a short process, simple equipment, low energy consumption, minimal environmental pollution, and good economic benefits.

Description

Technical Field

[0001] This invention relates to a method for preparing high-purity zinc of 5N and above using a wet process, belonging to the technical fields of high-purity zinc preparation and wet zinc smelting purification. Background Technology

[0002] High-purity metals have become strategic resource materials with strong demand in high-end manufacturing. 5N and above high-purity zinc is mainly used in batteries, semiconductor dopants, electronic devices, reference electrodes, biomedicine, alloys, and precision castings in aerospace, automotive, and nuclear industries, as well as in various high-purity zinc salts, high-purity zinc organic compounds, and chemical reducing agents.

[0003] Traditional zinc sulfate electrowinning methods cannot produce high-purity zinc due to the high impurity content of the electrolyte and its continuous accumulation. High-purity zinc of 5N and above is produced using crude zinc, #1 or #0 zinc as raw materials, employing pyrometallurgical refining processes such as multiple distillations, multiple vacuum distillations, or multiple zone melting. Distillation methods are lengthy, involve numerous and complex equipment, and are energy-intensive; vacuum distillation equipment cannot be scaled up, processing only small quantities of samples at a time, resulting in intermittent production and low productivity, making large-scale production difficult; zone melting requires expensive cooling at the low melting point of zinc to obtain short melting zones, and this method also demands high raw material purity, with time-consuming and energy-intensive purification processes. Therefore, the preparation of high-purity zinc using wet processes has gradually become a research hotspot.

[0004] Chinese patent application number 99115463.0 discloses a high-purity zinc and its preparation method. It uses various zinc minerals and industrial by-products containing zinc, which exist in the form of soluble zinc such as ZnO, Zn(OH)2, and ZnCO3, as raw materials. After leaching with an ammonium-ammonia-water solution system and purification with zinc powder, the zinc is electrolyzed to obtain high-purity zinc with Zn>99.998%. Chinese Patent Application No. 202310376082.9 discloses a method for preparing high-purity zinc. First, metallic zinc, ammonium fluoride, and ammonium chloride are mixed with an oxidant to undergo a first oxidation reaction, yielding a mixed solution of zinc fluoride and ammonium chloride. This solution is then purified with zinc powder, filtered, and a reducing purified solution is obtained. Chlorine gas is introduced into the reducing purified solution to undergo a second oxidation reaction, yielding a crystallizing liquid. This liquid is then cooled and crystallized, resulting in a mixed slurry of zinc fluoride and ammonium chloride. Solid-liquid separation yields mixed crystals of zinc fluoride and ammonium chloride. These crystals are mixed with water and ammonium salt or ammonia to obtain an electrolyte, which is then electrowinning to obtain high-purity zinc with a purity of 99.999%~99.999999%. Chinese Patent Application No. 202310376060.2 discloses a method for preparing high-purity zinc from zinc slag. First, zinc slag is dissolved in an ammonium chloride solution, then purified with metallic zinc powder. The Zn content in the crystallizing solution is adjusted... 2+ The concentration and temperature of Zn in the mother liquor 2+By adjusting the concentration and temperature of the Zn(NH3)2Cl2 slurry, high-purity Zn(NH3)2Cl2 crystals were prepared. The Zn(NH3)2Cl2 crystals were mixed with water, ammonium salt or ammonia to obtain an electrolyte, and then electrowinning was performed to obtain high-purity zinc with a purity of 99.999%~99.999999%.

[0005] In summary, the pyrometallurgical refining process for producing high-purity zinc is lengthy, involves complex equipment, is small-scale, energy-intensive, and costly. The aforementioned existing patented wet methods for producing high-purity zinc are all ammonia-ammonia-aqueous solution systems. Currently, there are no reports of industrial-scale production of high-purity zinc using this process, primarily due to difficulties in operation control, severe cathode dendrite formation, and unstable product quality. Production practice shows that ammonia-based electrowinning generally only yields #2 zinc (Zn > 99.95%). Furthermore, the high volatility of ammonia causes severe environmental pollution at the production site. In addition, both methods are singular in function, producing only zinc. Summary of the Invention

[0006] To address the problems existing in the preparation of high-purity zinc using pyrometallurgical refining and ammonia electrowinning processes, this invention provides a wet method for preparing 5N and higher-purity zinc, which features a short production process, simple equipment, low energy consumption, environmental friendliness, easy operation, stable product quality, and low production cost. The inventors conducted extensive and in-depth research and, through creative effort, completed this invention.

[0007] The technical solution adopted in this invention is as follows:

[0008] A method for wet preparation of high-purity zinc of 5N and above includes the following steps:

[0009] Step 1, Electrowinning: Using neutral zinc leaching solution as the anolyte and a mixture of zinc back-extraction solution and cathodic electrodeposition waste solution as the catholyte, a nested tank consisting of an outer tank and an inner tank is used. Electrode plates of different polarities and their corresponding electrodeposition solutions are placed in the outer tank and the inner tank, respectively. Electrode plates of different polarities are connected to the corresponding electrodes of the DC power supply for electrodewinning. The tank containing the anolyte and the anolyte is called the anolyte tank, which yields the anolyte electrodeposition waste solution. The tank containing the cathode plate and the catholyte is called the cathode tank, which yields high-purity zinc with a zinc content of ≥99.999% and the cathodic electrodeposition waste solution.

[0010] Step 2, Electrowinning waste liquid treatment: The anodic electrowinning waste liquid obtained in Step 1 is sent to purification and filtration, and then zinc is extracted to obtain purification residue, raffinate and zinc-loaded organic phase; part of the cathodic electrowinning waste liquid obtained in Step 1 is used for back-extraction of the zinc-loaded organic phase to obtain zinc back-extraction solution and empty organic phase; the zinc back-extraction solution and the remaining cathodic electrowinning waste liquid are returned to Step 1.

[0011] Step 3, Raffinate and Empty Organic Phase Treatment: The raffinate obtained in Step 2 is used for neutral leaching of zinc-containing solid materials followed by liquid-solid separation. The resulting zinc neutral leachate is returned to Step 1. The empty organic phase obtained in Step 2 is recycled in Step 2 for zinc extraction.

[0012] Furthermore, the zinc neutral leaching solution in steps 1 and 3 contains 20-160 g / L zinc, 8-40 g / L manganese, 20-150 mg / L iron, and small amounts of copper, cadmium, nickel, cobalt, arsenic, antimony, fluorine, and chloride ions, with a pH of 4.0-5.0.

[0013] Furthermore, the zinc back-extraction solution in steps 1 and 2 contains 40-160 g / L zinc, 15-110 g / L H2SO4, and trace amounts of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony, and iron ions at levels <0.05 ppm.

[0014] Furthermore, in step 1, the outer tank is a single integral hollow rectangular tank, the inner tank has grid windows on the front and back and anion exchange membranes installed, and a diaphragm bag is provided inside or outside the inner tank.

[0015] Furthermore, in step 1, the electrode plates of different polarities are either anode plates or cathode plates, with the anode plate being a lead-based alloy anode and the cathode plate being an aluminum plate.

[0016] Furthermore, the current density during electrowinning in step 1 is 300~600 A / m. 2 The electrodeposition temperature is 30~50℃, the electrodeposition time is 24~48 h, the electrolyte circulation rate is 5~70 mL / min, the zinc acid mass concentration ratio of the cathode electrodeposition waste liquid is 2~4, and any one or more of bone glue, gelatin and aloe vera are added to the cathode liquid to improve the crystallization state of the cathode surface, with an addition amount of 0.04~0.5 kg / t·Zn.

[0017] Furthermore, in step 2, the purification of the anodic electrodeposition waste liquid involves removing copper, cadmium, nickel, cobalt, and iron. This is achieved by first adding zinc powder and antimony salt to remove copper, cadmium, nickel, and cobalt. The purification control conditions are: zinc powder addition of 2-4 g / L, antimony addition of 3-5 mg / L, purification temperature of 70-75℃, and purification time of 1-2 hours. After purification, zinc-containing solid materials are added to the filtrate for neutralization, hydrolysis, precipitation, and iron removal. The final pH is controlled to be 5.2-5.6.

[0018] Further, in step 2, zinc extraction uses P204 diluted with No. 260 solvent oil to a volume percentage concentration of 20%~40% as the extractant, with a water-to-oil ratio of 0.2~5:1 and an extraction stage of 2~6 stages; the zinc-loaded organic reverse extraction has a water-to-oil ratio of 1:3~10 and a reverse extraction stage of 1~4 stages.

[0019] Further, the neutral leaching conditions described in step 3 are: leaching temperature of 60-75℃, liquid-to-solid ratio of raffinate and zinc-containing solid material of 4-20:1 mL / g, pH of leaching endpoint controlled at 4.0-5.0, and leaching time of 1-5 h.

[0020] Furthermore, the zinc-containing solid materials in step 3 include zinc roasted sand, zinc oxide ore, secondary zinc oxide dust, slag, and zinc ash.

[0021] The principle of the method of this invention is as follows:

[0022] 1. During zinc electrowinning, the lead on the lead-based alloy anode undergoes the following oxidation reaction:

[0023]

[0024]

[0025]

[0026]

[0027] Oxidative corrosion of lead-based alloy anodes shortens anode plate life and increases the content of lead ions and their compounds in the electrolyte, resulting in cathode zinc only reaching the 0# zinc standard. This is one of the most important reasons why conventional zinc electrowinning cannot produce zinc of 99.999% (5N) and above. This invention, by employing a nested tank consisting of an outer and inner tank, with electrode plates of different polarities and corresponding electrowinning solutions placed in the outer and inner tanks respectively, effectively prevents the diffusion of lead ions and their compounds dissolved from the lead-based anode to the cathode. This solves the problems of lead deposition at the cathode and excessive lead content in the cathode product zinc, achieving the production of high-purity zinc.

[0028] 2. During zinc electrowinning, water, manganese, and iron undergo the following oxidation reaction in the anode tank:

[0029] ① Oxidation reaction of water:

[0030] ② Oxidation reaction of manganese:

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] In hydrometallurgical zinc refining, manganese ore powder, iron oxide, or some sulfide ores are typically added during leaching, resulting in a manganese-containing electrolyte. During zinc electrowinning, low-valence manganese ions are oxidized to high-valence manganese at the anode. Some of the low-valence manganese is oxidized to manganese dioxide, some of which adheres to the anode plate to protect it, and some forms anode slime, which is then returned to the leaching process. High-valence manganese ions are also reduced to low-valence manganese at the cathode. By controlling the amount of manganese ore powder added during leaching and the zinc electrowinning conditions, the manganese ion content in the zinc electrolyte can be maintained at 3-5 g / L, which is beneficial for zinc production.

[0038] Currently, due to the presence of manganese minerals in some zinc raw materials, the manganese balance in hydrometallurgical zinc refining systems cannot be maintained using traditional zinc electrowinning and leaching systems. This leads to a continuous accumulation of manganese in the hydrometallurgical zinc refining system. Excessive manganese in the zinc electrolyte significantly increases energy consumption and reduces current efficiency. Therefore, traditional hydrometallurgical zinc refining necessitates the use of reagent oxidation to remove manganese through an open-circuit portion of the zinc electrolyte. This method generally introduces impurity ions that are seriously harmful to zinc production, and the reagents are expensive, consumed in large quantities, and have high production costs. This invention prevents the reduction of high-valence manganese at the cathode, achieving efficient removal of manganese at the anode, and avoiding the problems associated with traditional open-circuit partial electrolytic waste liquid and reagent-based manganese removal.

[0039] ③ Oxidation reaction of iron:

[0040] In traditional zinc electrowinning, iron ions are continuously oxidized and reduced between the anode and cathode, increasing energy consumption, causing zinc back dissolution at the cathode, and reducing current efficiency. Zinc electrolytes generally require an iron ion content of <20 mg / L. When the iron ion content exceeds 20 mg / L, it is necessary to add oxidants such as hydrogen peroxide or manganese ore powder to oxidize the ferrous ions, followed by neutralization with a neutralizing agent. This method suffers from low ferrous ion oxidation efficiency and high production costs. This invention prevents the movement of iron ions between the anode and cathode, directly electro-oxidizing ferrous ions to ferric iron in the anode tank, thus avoiding the problems associated with adding reagents to oxidize ferrous ions.

[0041] 3. This invention prevents lead from precipitating in the cathode product zinc and the movement of manganese and iron ions between the anode and cathode, as well as the reduction of high-valence manganese and iron ions at the cathode. Simultaneously, the cathode bath uses a mixture of zinc back-extraction solution and cathode electrodeposition waste solution as the cathode electrolyte. Because impurity ions do not accumulate in this solution, with a content <0.05 ppm, far lower than the impurity ion content in conventional zinc electrolytes, this invention achieves low-energy, high-efficiency, and environmentally friendly production of 5N and above high-purity zinc (Zn). 2+ The reduction reaction is:

[0042]

[0043] 4. The reaction for purifying anolyte wastewater to remove copper, cadmium, nickel, cobalt, and iron is as follows:

[0044] ① Zinc powder is added to purify the anodic electrodeposition waste solution, removing metals such as Cu, Cd, Ni, and Co with a standard electrode potential greater than Zn. The reaction is as follows:

[0045] (Me = Cu, Cd, Ni, Co)

[0046] ②The neutralization, hydrolysis, and precipitation reaction of iron is as follows:

[0047]

[0048] 5. The extraction reaction of zinc with organic zinc-supported zinc is as follows:

[0049]

[0050] The forward reaction is the zinc extraction reaction, and the reverse reaction is the zinc back extraction reaction.

[0051] 6. The reaction for neutral leaching of zinc-containing solid materials is as follows:

[0052] The main phases in zinc roasted sand, zinc oxide ore, secondary zinc oxide dust, slag, and zinc ash are zinc oxide and other metal oxides. The neutral leaching of the raffinate mainly involves the following reactions:

[0053] (Me=Zn, Cd, Cu, Pb, Co, Ca, Mg, Fe)

[0054] The method of the present invention has at least the following advantages:

[0055] (1) Compared with the pyrometallurgical method for producing high-purity zinc, the method of the present invention has a shorter process, simpler equipment, lower energy consumption, and lower production cost; compared with the ammonium-ammonia-water system electrowinning zinc process, the method of the present invention is green and environmentally friendly, has simple process operation, and stable product quality.

[0056] (2) The method of the present invention uses a double tank, wherein the inner tank blocks the diffusion of manganese ions and iron ions from the anode tank into the cathode tank. Low-valent manganese and ferrous ions are eventually oxidized into manganese dioxide and ferric ions respectively in the anode tank, which avoids the consumption of chemical reagents for removing manganese and ferrous ions and the introduction of impurity ions in the wet zinc smelting system, and the production cost is low.

[0057] (3) The method of the present invention is based on the fact that the content of impurity ions in the zinc back-extraction solution is much lower than that in the new solution of traditional wet zinc smelting and the electrowinning process does not accumulate. In addition, the inner tank blocks the diffusion of lead ions, manganese ions and iron ions from the anode tank into the cathode tank, thereby avoiding the precipitation of lead, manganese and iron at the cathode, which leads to the impurity ion content of the cathode product exceeding the standard, thus realizing the preparation of high-purity zinc of 5N and above.

[0058] (4) The method of the present invention combines the preparation of high-purity zinc with the wet zinc refining and impurity removal in an organic synergy, achieving multiple benefits in one step. The process is short, the production cost is low, and the economic benefits are good. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the sleeve used in the method of the present invention. The electrode plates and electrolyte placed in the inner and outer sleeves can be changed according to the actual situation.

[0060] Figure 2 This is a schematic diagram of the inner groove structure;

[0061] Figure 3 This is a process flow diagram of the present invention, which can be based on... Figure 1 The electrode plates and electrolyte placed in the inner and outer tanks are adjusted accordingly. Detailed Implementation

[0062] The invention will be further described below with reference to the accompanying drawings and embodiments.

[0063] like Figure 1 As shown, a set of two tanks is first set up, consisting of an outer tank 1 and an inner tank 2. Electrode plates of different polarities and corresponding electrowinning solutions are placed in the outer and inner tanks, respectively. The tank containing the anode plate and anolyte is the anode tank, and the tank containing the cathode plate and catholyte is the cathode tank. The outer tank is a single, integral, rectangular cavity tank, and the inner tank is a set of movable tanks spaced apart within the outer tank. The movable tanks can be suspended from the outer tank. Various methods can be used to suspend the movable tanks. For example, hanging ears can be provided on both sides of the top of the movable tank, and the hanging ears can be hung on the front and rear tank walls of the outer tank by using hooks 9 to lift and lower the movable tank. The suspension method of the movable tanks can be implemented by those skilled in the art using existing technology, and will not be elaborated further here. A diaphragm bag 8 is provided inside or outside the movable tank to prevent anode mud from adhering to the ion exchange membrane 7. An electrowinning waste liquid discharge port 5 is opened on the end wall of the outer tank. Figure 2As shown, the inner tank has grid windows 6 cut out on the front and back, and anion exchange membranes 7 are installed on the grid windows. An electrowinning solution inlet 10 is provided at the top of the inner tank, and an electrowinning waste solution outlet 11 is provided on the side wall. The electrowinning waste solution outlet 11 discharges the electrowinning waste solution M through an external pipe. During electrowinning, the electrowinning solutions A and B are different. For example, if A is the cathodic solution, then B is the anodic solution. The resulting electrowinning waste solutions E and M are also different. If M matches A, it is the cathodic electrowinning waste solution; if E matches B, it is the anodic electrowinning waste solution, and vice versa. If A is the anodic solution, then B is the cathodic solution; if M matches A, it is the anodic electrowinning waste solution; if E matches B, it is the cathodic electrowinning waste solution. An electrowinning solution distribution hole 12 is provided at the bottom of the inner tank to evenly distribute the electrowinning solution and reduce concentration polarization. An electrode plate 4 of one polarity and its corresponding electrowinning solution A are placed in each inner tank, and an electrode plate 3 of the other polarity and its corresponding electrowinning solution B are placed in the outer tank. The cathode and anode are connected to the negative and positive terminals of a DC power supply, respectively, and the power is turned on for electrowinning. The anode is a lead-based alloy anode, and the cathode is an aluminum plate. The anode electrowinning waste liquid generated during the electrowinning process is sent for purification → filtration → zinc extraction to obtain purification residue, raffinate, and zinc-loaded organic phase; part of the cathode electrowinning waste liquid is used for back-extraction of the zinc-loaded organic phase to obtain zinc back-extraction solution and empty organic phase, and the remaining cathode electrowinning waste liquid and zinc back-extraction solution are returned to electrowinning; the raffinate is used for neutral leaching of zinc-containing solid materials, and the zinc neutral leaching solution obtained after liquid-solid separation is returned to electrowinning, while the empty organic phase is circulated in the extraction system for zinc extraction.

[0064] Example 1

[0065] like Figure 3 As shown, a neutral zinc leaching solution containing 8 g / L manganese, 160 g / L zinc, 60 mg / L iron, and trace amounts of copper, cadmium, nickel, cobalt, arsenic, antimony, fluorine, and chlorine ions, with a pH of 4.6, and a lead-based alloy anode are added to the outer tank, which is the anode tank. A mixture of zinc back-extraction solution containing 160 g / L zinc, 15 g / L H2SO4, and trace metal ions of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony, and iron (<0.05 ppm level) and cathode electrowinning waste solution, along with an aluminum plate, is added to the inner tank of the outer diaphragm bag, which is the cathode tank. The lead-based alloy anode and the aluminum plate cathode are connected to the positive and negative terminals of a DC power supply, respectively. Electrowinning is performed by turning on the power supply and controlling the electrowinning current density at 300 A / m. 2The electrowinning temperature was 30℃, the electrowinning time was 48 h, the zinc acid-to-cathode concentration ratio in the cathode electrowinning waste solution was 2, the electrolyte circulation rate was 5 mL / min, the amount of aloe vera extract added to the cathode solution was 0.1 kg / t·Zn, and the zinc content of the cathode product produced by electrowinning was ≥99.999%. During the electrowinning process, a mixture of zinc back-extraction solution and cathode electrowinning waste solution was continuously added to the cathode tank through the electrowinning solution inlet 10, while a portion of the cathode electrowinning waste solution was discharged through the electrowinning waste solution outlet 11; zinc neutral leaching solution was continuously added to the anode tank, while a portion of the anode electrowinning waste solution was discharged through the electrowinning waste solution outlet 5. The anodic electrodeposition waste liquid was purified to remove copper, cadmium, nickel, and cobalt at a temperature of 75℃ for 1 hour with zinc powder added at 2 g / L and antimony added at 5 mg / L. After filtration, a purified residue containing manganese dioxide and copper, cadmium, nickel, and cobalt was obtained. The filtrate was neutralized and hydrolyzed to remove iron at the final pH of 5.4. Then, it was diluted with P2O4 with No. 260 solvent oil to a volume percentage concentration of 40% and subjected to 6-stage zinc extraction at a water-oil ratio of 0.2:1 to obtain a zinc-loaded organic phase. The raffinate was used for neutral leaching of zinc calcined sand under the following conditions: 75℃, liquid-solid ratio of 4:1, leaching time of 1 hour, and final pH of 4.8. After neutral leaching, the liquid and solid were separated, and the separated zinc neutral leaching solution was sent to the anode tank. A portion of the cathode electrodeposition waste liquid was used for back-extraction of the zinc-loaded organic phase under the following conditions: water-oil ratio of 1:3 and 4 back-extraction stages to obtain a zinc back-extraction solution. The zinc back-extraction solution and the remaining cathode electrodeposition waste liquid were mixed and sent to the cathode tank. The zinc back-extraction solution obtained after the anolyte is electrowinning, purification, extraction and back-extraction has a content of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony and iron ions <0.05 ppm.

[0066] Example 2

[0067] like Figure 3 As shown, a neutral zinc leaching solution containing 40 g / L manganese, 120 g / L zinc, 150 mg / L iron, and trace amounts of copper, cadmium, nickel, cobalt, arsenic, antimony, fluorine, and chlorine ions, with a pH of 5.0, and a lead-based alloy anode are added to an inner tank with a built-in diaphragm bag. This inner tank is the anode tank. A mixture of zinc back-extraction solution and cathode waste solution containing 130 g / L zinc, 110 g / L H₂SO₄, and trace metal ions (<0.05 ppm) of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony, and iron, along with an aluminum plate, is added to an outer tank, which is the cathode tank. The lead-based alloy anode and the aluminum plate cathode are connected to the positive and negative terminals of a DC power supply, respectively. Electrowinning is performed with the power supply turned on, and the electrowinning current density is controlled at 450 A / m². 2The electrowinning temperature was 50℃, the electrowinning time was 36 h, the zinc acid-to-acid mass concentration ratio of the cathode electrowinning waste solution was 4, the electrolyte circulation rate was 40 mL / min, the amount of bone glue added to the cathode solution was 0.5 kg / t·Zn, and the zinc content of the cathode product produced by electrowinning was ≥99.999%. During the electrowinning process, zinc neutral leaching solution was continuously added to the anode tank through the electrowinning solution inlet 10, while a portion of the anode electrowinning waste solution was discharged through the electrowinning waste solution outlet 11; a mixture of zinc back-extraction solution and cathode electrowinning waste solution was continuously added to the cathode tank, while a portion of the cathode electrowinning waste solution was discharged through the electrowinning waste solution outlet 5. The anodic electrodeposition waste liquid was purified to remove copper, cadmium, nickel, and cobalt at a temperature of 70℃ for 2 hours with zinc powder (4 g / L) and antimony (3 mg / L). After filtration, a purified residue containing manganese dioxide and copper, cadmium, nickel, and cobalt was obtained. The filtrate was neutralized and hydrolyzed at a final pH of 5.6 to remove iron. Then, it was diluted with P2O4 (30% by volume) using No. 260 solvent oil and subjected to four-stage zinc extraction at a water-to-oil ratio of 0.9:1 to obtain a zinc-loaded organic phase. The raffinate was used for neutral leaching of secondary zinc oxide dust under the following conditions: 60℃, liquid-to-solid ratio of 10:1, leaching time of 2 hours, and final pH of 4. After neutral leaching, the liquid and solid were separated, and the separated zinc neutral leaching solution was sent to the anode tank. A portion of the cathode electrodeposition waste liquid was used for back-extraction of the zinc-loaded organic phase under the following conditions: water-to-oil ratio of 1:6 and three back-extraction stages to obtain a zinc back-extraction solution. The zinc back-extraction solution and the remaining cathode electrodeposition waste liquid were mixed and sent to the cathode tank. The zinc back-extraction solution obtained after the anolyte is electrowinning, purification, extraction and back-extraction has a content of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony and iron ions <0.05 ppm.

[0068] Example 3

[0069] like Figure 3 As shown, a neutral zinc leaching solution containing 13 g / L manganese, 20 g / L zinc, 20 mg / L iron, and trace amounts of copper, cadmium, nickel, cobalt, arsenic, antimony, fluorine, and chlorine ions, with a pH of 4.0, and a lead-based alloy anode are added to the outer tank, which is the anode tank. A mixture of zinc back-extraction solution containing 40 g / L zinc, 70 g / L H2SO4, and trace metal ions of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony, and iron (<0.05 ppm level) and cathode electrowinning waste solution, along with an aluminum plate, is added to the inner tank of the outer diaphragm bag, which is the cathode tank. The lead-based alloy anode and the aluminum plate cathode are connected to the positive and negative terminals of a DC power supply, respectively. Electrowinning is performed by turning on the power supply and controlling the electrowinning current density at 600 A / m. 2The electrowinning temperature was 39℃, the electrowinning time was 24 h, the acid-zinc mass concentration ratio of the cathode electrowinning waste solution was 3.3, the electrolyte circulation rate was 70 mL / min, and the amount of gelatin and aloe vera added to the cathode solution was 0.04 kg / t·Zn. The zinc content of the cathode product produced by electrowinning was ≥99.999%. During the electrowinning process, a mixture of zinc back-extraction solution and cathode electrowinning waste solution was continuously added to the cathode tank through the electrowinning solution inlet 10, while a portion of the cathode electrowinning waste solution was discharged through the electrowinning waste solution outlet 11. Zinc neutral leaching solution was continuously added to the anode tank, while a portion of the anode electrowinning waste solution was discharged through the electrowinning waste solution outlet 5. The anodic electrodeposition waste liquid was purified to remove copper, cadmium, nickel, and cobalt at a temperature of 72℃ for 1.5 h with zinc powder (3 g / L) and antimony (4 mg / L). After filtration, a purified residue containing manganese dioxide and copper, cadmium, nickel, and cobalt was obtained. The filtrate was neutralized and hydrolyzed to remove iron at a final pH of 5.2. Then, it was diluted with P2O4 (20% by volume) using No. 260 solvent oil and subjected to two-stage zinc extraction at a water-to-oil ratio of 5:1 to obtain a zinc-loaded organic phase. The raffinate was used for neutral leaching of oxidizing ores under the following conditions: 70℃, liquid-to-solid ratio of 20:1, leaching time of 5 h, and final pH of 5. After neutral leaching, the liquid and solids were separated, and the separated zinc neutral leaching solution was sent to the anode tank. A portion of the cathode electrodeposition waste liquid was used for back-extraction of the zinc-loaded organic phase under the following conditions: water-to-oil ratio of 1:10 and one back-extraction stage to obtain a zinc back-extraction solution. The zinc back-extraction solution and the remaining cathode electrodeposition waste liquid were mixed and sent to the cathode tank. The zinc back-extraction solution obtained after the anolyte is electrowinning, purification, extraction and back-extraction has a content of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony and iron ions <0.05 ppm.

[0070] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for wet preparation of high-purity zinc of 5N and above, characterized in that, Includes the following steps: Step 1, Electrowinning: Using neutral zinc leaching solution as the anolyte and a mixture of zinc back-extraction solution and cathodic electrodeposition waste solution as the catholyte, a nested tank consisting of an outer tank and an inner tank is used. The inner tank has grid windows on the front and back and is equipped with anion exchange membrane. A diaphragm bag is placed inside or outside the inner tank. Electrode plates of different polarities and their corresponding electrodeposition solutions are placed in the outer tank and the inner tank, respectively. Electrode plates of different polarities are connected to the corresponding electrodes of the DC power supply for electrodewinning. The tank containing the anolyte and the anolyte is the anolyte tank, which yields anolyte electrodeposition waste solution. The tank containing the cathode plate and the catholyte is the cathode tank, which yields high-purity zinc with a zinc content of ≥99.999% and cathodic electrodeposition waste solution. Step 2, Treatment of Electrowinning Waste Liquid: The anodic electrowinning waste liquid obtained in Step 1 is sent to a purified filter, and then zinc is extracted to obtain purification residue, raffinate, and zinc-loaded organic phase; a portion of the cathodic electrowinning waste liquid obtained in Step 1 is used for back-extraction of the zinc-loaded organic phase to obtain zinc back-extraction solution and empty organic phase; the zinc back-extraction solution and the remaining cathodic electrowinning waste liquid are returned to Step 1; the purification of the anodic electrowinning waste liquid is to remove copper, cadmium, nickel, cobalt, and iron. First, zinc powder and antimony salt are added to remove copper, cadmium, nickel, and cobalt. Then, zinc-containing solid materials are added to the purified filtrate for neutralization, hydrolysis, precipitation, and iron removal. Step 3, Raffinate and Empty Organic Phase Treatment: The raffinate obtained in Step 2 is used for neutral leaching of zinc-containing solid materials followed by liquid-solid separation. The resulting zinc neutral leachate is returned to Step 1. The empty organic phase obtained in Step 2 is recycled in Step 2 for zinc extraction. The zinc neutral leaching solution in steps 1 and 3 contains 20-160 g / L zinc, 8-40 g / L manganese, 20-150 mg / L iron, and small amounts of copper, cadmium, nickel, cobalt, arsenic, antimony, fluorine, and chloride ions, with a pH of 4.0-5.

0. The zinc back-extraction solution in steps 1 and 2 contains 40-160 g / L zinc, 15-110 g / L H2SO4, and trace amounts of copper, cadmium, nickel, cobalt, manganese, arsenic, antimony, and iron ions at levels <0.05 ppm.

2. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, In step 1, the outer groove is a single integral hollow rectangular groove.

3. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, In step 1, the electrode plates of different polarities are either anode plates or cathode plates. The anode plate is a lead-based alloy anode, and the cathode plate is an aluminum plate.

4. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, The current density during electrowinning in step 1 is 300~600 A / m. 2 The electrodeposition temperature is 30~50 ℃, the electrodeposition time is 24~48 h, the electrolyte circulation rate is 5~70 mL / min, the zinc acid mass concentration ratio of the cathode electrodeposition waste liquid is 2~4, and any one or more of bone glue, gelatin and aloe vera extract are added to the cathode liquid to improve the crystallization state of the cathode surface, with an addition amount of 0.04~0.5 kg / t·Zn.

5. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, In step 2, zinc powder and antimony salt are added first to remove copper, cadmium, nickel and cobalt. The purification control conditions are: zinc powder addition amount 2~4 g / L, antimony 3~5 mg / L, purification temperature 70~75℃, purification time 1~2h. After purification, zinc-containing solid material is added to the filtrate for neutralization and hydrolysis. The control endpoint pH is 5.2~5.

6.

6. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, In step 2, zinc extraction uses P204 diluted with No. 260 solvent oil to a volume percentage concentration of 20%~40% as the extractant, with a water-to-oil ratio of 0.2~5:1 and 2~6 extraction stages; the zinc-loaded organic reverse extraction has a water-to-oil ratio of 1:3~10 and 1~4 reverse extraction stages.

7. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, The neutral leaching conditions described in step 3 are: leaching temperature of 60-75℃, liquid-to-solid ratio of raffinate and zinc-containing solid material of 4-20:1 mL / g, pH of leaching endpoint controlled at 4.0-5.0, and leaching time of 1-5 h.

8. The method for wet preparation of high-purity zinc of 5N and above according to claim 1, characterized in that, The zinc-containing solid materials in step 3 are zinc roasted sand, zinc oxide ore, secondary zinc oxide dust, slag, and zinc ash.

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