CN113564366A - Method for recovering valuable metals from electroplating sludge - Google Patents

Abstract

The invention discloses a method for recovering valuable metals from electroplating sludge, which adopts two-stage acid leaching to separate iron from other metals, avoids the influence of iron ions in the recovery process of other metals and ensures that the obtained additional products of other metals have higher quality. The method has the advantages of simple process, low treatment cost, complete circulation of water in the treatment process and no wastewater generation; realizes the high-efficiency separation and recovery of valuable metals in the electroplating sludge, forms different metal additional products, and has good environmental benefit and economic benefit.

Description

Method for recovering valuable metals from electroplating sludge

Technical Field

The invention belongs to the technical field of solid waste recycling, and particularly relates to a method for recovering valuable metals from electroplating sludge.

Background

The electroplating sludge contains a large amount of recyclable valuable metal resources, and the recycling value is huge. If the treatment is not carried out, the resource waste is caused. The existing valuable metal recovery method mainly comprises a pyrogenic process and a wet process. The pyrogenic process is used for sintering the electroplating sludge, but the product is mainly heavy metal alloy, so that single metal is not easy to recover. And because the water content of the electroplating sludge is large and the heat value is low, the energy consumption is large in the sintering process, the cost is high, the pollution is large in the sintering process, and the requirement on flue gas emission is high. The wet method mainly comprises an acid leaching method, an ammonia leaching method and a microorganism leaching method. Among them, the microbial leaching method is not industrially used because of its slow reaction rate and low efficiency. The ammonia leaching method has extremely strict requirements on production environment because ammonia gas is easy to volatilize in the production process, thus easily causing production accidents and causing harm to the bodies of production operators. Therefore, in the actual production process, the electroplating sludge is mainly treated by adopting a hydrometallurgy technology, and valuable metal ions in the electroplating sludge are separated and recovered. The prior art mainly has the following problems:

1. because the components of the electroplating sludge are complex, the acid leaching is not thorough, and the heavy metal ions remained in the acid leaching slag are more than the requirements on the heavy metal ions in the identification standard of hazardous wastes, so that the acid leaching slag needs to be treated according to the hazardous wastes, and the cost is increased suddenly.

2. In the process of recovering valuable metal ions in the pickle liquor, because of the existence of a large amount of organic matters, different metals are difficult to separate, and the recovery utilization rate of single metal is low.

3. Hydrometallurgical processes are often costly and limited by economic benefits.

CN102719657A discloses a method for recycling heavy metals in electroplating sludge, which comprises screening and domesticating to obtain Thiobacillus ferrooxidans and Thiobacillus thiooxidans capable of resisting high-concentration heavy metals, respectively stirring and mixing the Thiobacillus ferrooxidans and the Thiobacillus thiooxidans with electroplating sludge under certain conditions, respectively performing bioleaching to obtain a copper-containing leachate or a nickel-containing leachate, removing impurities from the copper-containing leachate, performing electrodeposition to obtain copper, removing impurities from the nickel-containing leachate, performing electrodeposition to obtain nickel, and recovering the nickel. However, this method has problems of small throughput, high processing cost, complicated operation, low purity of the recovered product, and the like.

CN103966446A discloses a method for separating and recovering copper, iron and nickel from electroplating sludge, which mainly comprises the following steps: the first step is as follows: dissolving the electroplating sludge, and removing ferric ions in a ferric hydroxide precipitation form by adjusting pH; the second step is that: forming copper and nickel precipitates by adjusting pH, filtering and washing, adding glycerol to form a crimson copper glycerol solution, realizing the separation of copper and nickel, and separating out copper hydroxide precipitates from the separated crimson solution by adjusting pH; the third step: and washing the nickel hydroxide precipitate obtained in the second step, dissolving the nickel hydroxide precipitate with sulfuric acid to obtain a nickel sulfate solution, and evaporating the nickel sulfate solution to dryness to obtain the nickel bisulfate. The method fully utilizes the difference of chemical properties of copper, nickel and iron, realizes the problem that the copper, the iron and the nickel in the electroplating sludge are difficult to recover when coexisting, and respectively obtains corresponding recovered products; however, the reaction rate of glycerol introduced by the method is extremely low in a dilute solution, and the glycerol may be blackened when being contacted with oxides, so that the treatment difficulty of subsequent filtrate is increased.

CN109280777A discloses a method for selectively recovering heavy metals in electroplating sludge by a chlorination roasting method, the method comprises the steps of mixing the electroplating sludge with a chlorinating agent, roasting at 159-400 ℃, collecting volatilized chromium chloride through tail gas, absorbing the chromium chloride with water to obtain a chromium chloride solution, dissolving the residual solid materials with water, and carrying out solid-liquid separation to obtain a metal chloride mixed solution and solid sludge. The method takes hydrochloric acid as a chlorinating agent to treat the electroplating sludge, the recovery rate of chromium in the electroplating sludge can reach more than 85%, the recovery rate of nickel and copper can reach more than 90%, but the method does not realize separate separation and recovery of different metal ions.

Therefore, it is highly desirable to develop a method for recovering valuable metals from electroplating sludge, which can realize the efficient separation and resource utilization of different metal ions in the electroplating sludge, and does not generate wastewater and cause secondary pollution in the treatment process.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a method for recovering valuable metals from electroplating sludge, which adopts two-stage acid leaching to separate heavy metal ions of copper, iron, nickel, zinc and chromium from waste residues in the electroplating sludge, and then sequentially adds an alkali solution, a vulcanizing agent, an inorganic solution containing phosphate radicals and a nickel and zinc extracting agent to separate and recover various heavy metal ions. The method has the advantages of low treatment cost, simple process flow, no waste water generation in the treatment process and no secondary pollution.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for recovering valuable metals from electroplating sludge, which comprises the following steps:

(1) mixing electroplating sludge and water to prepare electroplating sludge slurry, adding a first acid solution, performing primary acid leaching under the condition that the pH value is 3-4, and performing solid-liquid separation to obtain a first acid leaching solution and a first acid leaching residue;

(2) mixing the first acid leaching residue and the second acid solution in the step (1), performing secondary acid leaching under the condition that the pH value is 1-2, and performing solid-liquid separation to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid immersion liquid in the step (2) with a first alkali solution, and performing solid-liquid separation to obtain first separation slag and first separation liquid;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with a vulcanizing agent to perform copper precipitation reaction, and performing solid-liquid separation to obtain a second separated solution and copper sulfide-containing slag;

(5) and (5) mixing the second separation liquid obtained in the step (4) with an inorganic solution containing phosphate radicals to perform chromium precipitation reaction, and performing solid-liquid separation to obtain a third separation liquid and chromium phosphate-containing slag.

The method carries out two-stage acid leaching treatment on the electroplating sludge, wherein the pH value is controlled to be 3-4 in the first-stage acid leaching process, most of other valuable metals except iron are leached, and the pH value is controlled to be 1-2 in the second-stage acid leaching process, so that iron and other metals which are not easy to leach in the first-stage acid leaching process are leached. And the two-stage acid leaching treatment is adopted, so that iron and other metals are separated, the influence of iron ions on the other metals in the recovery process of the other metals is avoided, and the low iron impurity content, the high quality and the higher value of the additional products are ensured when the additional products are formed by the other metals. Meanwhile, the addition amount of corresponding agents can be saved in the metal separation process, and the cost is reduced. According to the method, the copper ions in the first mixed solution are separated by the vulcanizing agent, and compared with the copper separation by an extraction method, no organic matter is introduced, so that the subsequent difficulty in separating chromium, nickel and zinc is avoided. According to the method, the inorganic solution containing phosphate radicals is adopted for carrying out chromium precipitation reaction, and chromium in the electroplating sludge is separated and recovered.

Preferably, the pH in step (1) is 3-4, and may be 3, 3.2, 3.5, 3.7, 3.9 or 4, for example.

Preferably, the pH value in the step (2) is 1-2, such as 1, 1.2, 1.4, 1.5, 1.6, 1.8, 1.9 or 2.

The solid-liquid separation is not limited in the present invention, and any method known to those skilled in the art that can be used for solid-liquid separation, such as filtration, sedimentation, centrifugation, or the like, can be used.

Preferably, hydrogen peroxide is added to the primary acid leaching in step (1).

The addition of hydrogen peroxide in the primary acid leaching of the invention leads Fe in the electroplating sludge²⁺Oxidation to Fe³⁺Meanwhile, organic matters in the sludge can be decomposed, and the influence of the organic matters on the subsequent metal separation process is reduced. The first acid leaching slag mainly comprises ferric hydroxide and a small amount of undissolved copper, nickel, zinc and chromium.

Preferably, the water content of the electroplating sludge in the step (1) is 60-75%, for example, 60%, 61%, 65%, 68%, 70%, 73% or 75%.

The electroplating sludge is fresh electroplating sludge with the water content of 60-75%, water is added to prepare electroplating sludge slurry, and the solid-liquid ratio of the electroplating sludge to the water solution in the pulping process is 1: 1-1.5: 1.

Preferably, in the process of preparing the electroplating sludge slurry, the solid-to-liquid ratio of the electroplating sludge to water is 1: 1-1.5: 1, and may be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, for example.

Preferably, the iron content of the electroplating sludge is 1% to 5% by mass, and may be, for example, 1%, 1.5%, 2%, 3%, 4%, or 5%.

Preferably, the copper content in the electroplating sludge is 1% to 10% by mass, and may be, for example, 1%, 2%, 3%, 5%, 8%, or 10%.

Preferably, the chromium content of the electroplating sludge is 0.1-5% by mass, for example, 0.1%, 0.5%, 1%, 3%, 4% or 5%.

Preferably, the zinc content in the electroplating sludge is 0.5-10% by mass, for example, 0.5%, 1%, 2%, 5%, 8% or 10%.

Preferably, the mass content of nickel in the electroplating sludge is 1% to 35%, and may be, for example, 1%, 5%, 10%, 15%, 20%, 30%, or 35%.

Preferably, the first acid solution includes any one of a sulfuric acid solution, a nitric acid solution, or a hydrochloric acid solution.

Preferably, the concentration of the first acid solution is 1-5 mol/L, for example, 1mol/L, 1.5mol/L, 2mol/L, 3mol/L, 4mol/L or 5 mol/L.

Preferably, the time of the primary acid leaching is 30-60 min, for example, 30min, 35min, 40min, 45min, 50min, 55min or 60 min.

The second acid solution in the step (2) comprises any one of a sulfuric acid solution, a nitric acid solution or a hydrochloric acid solution.

Preferably, the concentration of the second acid solution is 1-5 mol/L, for example, 1mol/L, 1.5mol/L, 2mol/L, 3mol/L, 4mol/L or 5 mol/L.

Preferably, the time of the secondary acid leaching is 30-60 min, for example, 30min, 35min, 40min, 45min, 50min, 55min or 60 min.

The second acid leaching residue in the step (2) is washed by adopting an aqueous solution, the washing is stopped when the electric conductivity of the washing water is kept stable, and the washing water can be returned to the step (1) to be used as water for preparing the electroplating sludge slurry by mixing the electroplating sludge and the water. And (3) carrying out heavy metal ion determination on the washed waste residues by adopting the standard of 'hazardous waste identification standard leaching toxicity identification' (GB5085.3-2007), wherein the content of each metal ion is lower than the hazardous waste identification standard, and carrying out outsourcing treatment on the washed waste residues.

Preferably, the first alkali solution in step (3) comprises any one of or a combination of at least two of a sodium hydroxide solution, a sodium carbonate solution or a sodium bicarbonate solution, wherein typical but non-limiting combinations include a combination of a sodium hydroxide solution and a sodium carbonate solution, a combination of a sodium carbonate solution and a sodium bicarbonate solution or a combination of a sodium hydroxide solution, a sodium carbonate solution and a sodium bicarbonate solution.

In the step (3), only a small amount of copper, nickel, chromium and zinc exist in the second acid immersion liquid, so that the influence on the iron ion precipitation effect is greatly weakened, the first alkali solution reacts with iron ions as accurately as possible, the consumption of the first alkali solution is greatly reduced, and the treatment cost is further reduced. The obtained first separation slag contains rich iron element and can be sold as a commodity.

Preferably, the pH of the mixing is 3 to 3.5, which may be 3, 3.1, 3.2, 3.3, 3.4 or 3.5, for example.

Preferably, the vulcanizing agent of step (4) comprises sodium sulfide or sulfur.

Preferably, the mass concentration of the vulcanizing agent is 10% to 20%, and may be, for example, 10%, 12%, 15%, 17%, 19%, or 20%.

Preferably, the addition amount of the vulcanizing agent is such that the molar ratio of sulfur ions in the vulcanizing agent to copper ions in the first mixed solution is (1.5-2): 1, and may be, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2: 1.

The copper sulfide-containing slag obtained in the step (4) can be sold as a commodity.

Preferably, the phosphate group-containing inorganic solution of step (5) includes any one of phosphoric acid, sodium phosphate, sodium dihydrogen phosphate, or disodium hydrogen phosphate.

Preferably, the phosphate-containing inorganic solution has a mass concentration of 20% to 30%, and may be, for example, 20%, 22%, 25%, 28%, or 30%.

The amount of the inorganic solution containing phosphoric acid added is preferably such that the molar ratio of the phosphate to the chromium ions in the second separation liquid is (1.5 to 2):1, and may be, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2: 1.

The chromium phosphate-containing slag obtained in the step (5) of the invention can be sold as a commodity.

Preferably, step (5) further comprises mixing the third separated liquid with a nickel extractant to perform nickel extraction, thereby obtaining a nickel-containing extract and a first raffinate.

Preferably, the nickel-containing extract and the first sulfuric acid solution are mixed and stripped to produce a nickel extractant and a nickel-containing solution.

The nickel extracting agent can be returned to be mixed with the third separation liquid, and the nickel can be extracted in a recycling way.

Preferably, the nickel-containing solution is electrolyzed to obtain a nickel product.

The nickel product comprises a nickel ingot, the purity of the nickel ingot is 99.92% -99.98%, and the nickel ingot can be sold as a commodity.

Preferably, the nickel extractant in the step (5) comprises a mixed solution of di- (2-ethylhexyl) phosphoric acid and kerosene.

Preferably, the volume ratio of the di- (2-ethylhexyl) phosphoric acid to the kerosene is (0.3-0.5: 1), and for example, may be 0.3:1, 0.35:1, 0.4:1, 0.45:1 or 0.5: 1.

Preferably, the pH of the nickel extraction is 4-6, for example, 4, 4.2, 4.4, 4.5, 5, 5.3, 5.5, 5.8 or 6.

Preferably, the volume ratio of the third separation liquid to the nickel extractant is 1 (1-2), and may be, for example, 1:1, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:1.9, or 1: 2.

Preferably, the concentration of the first sulfuric acid solution is 10-12 mol/L, for example, 10mol/L, 10.3mol/L, 10.5mol/L, 10.8mol/L, 11mol/L, 11.5mol/L or 12 mol/L.

Preferably, the volume ratio of the nickel-containing extraction liquid to the first sulfuric acid solution is (20-25): 1, and may be, for example, 20:1, 21:1, 22:1, 23:1, 24:1 or 25: 1.

Preferably, step (5) further comprises mixing the first raffinate and the zinc extractant to perform zinc extraction, thereby obtaining a zinc-containing extract and a second raffinate.

The second raffinate can be returned to the step (1) to be used as water for preparing the electroplating sludge slurry by mixing the electroplating sludge and the water, and the method for recovering the valuable metals from the electroplating sludge has the advantages of complete circulation of the water, no waste water and no secondary pollution.

Preferably, the zinc-containing extract and the second sulfuric acid solution are mixed and back-extracted to obtain the zinc extractant and the zinc-containing solution.

The zinc extractant can be returned to be mixed with the first raffinate, and the extracted zinc can be recycled.

Preferably, the zinc-containing solution is electrolyzed to obtain a zinc product.

The zinc product comprises zinc ingots, the purity of the zinc ingots is 99.15-99.85%, and the zinc ingots can be sold as commodities.

Preferably, the zinc extracting agent in the step (5) is a mixed solution of di- (2-ethylhexyl) phosphoric acid and kerosene.

Preferably, the volume ratio of the di- (2-ethylhexyl) phosphoric acid to the kerosene is (0.3-0.5: 1), and for example, may be 0.3:1, 0.35:1, 0.4:1, 0.45:1 or 0.5: 1.

Preferably, the pH of the zinc extraction is 2-3, for example, 2, 2.1, 2.2, 2.3, 2.5, 2.7, 2.9 or 3.

Preferably, the volume ratio of the first raffinate to the zinc extractant is 1 (1-2), and may be, for example, 1:1, 1:1.3, 1:1.5, 1:1.6, 1:1.8, 1:1.9, or 1: 2.

Preferably, the concentration of the second sulfuric acid solution is 4-6 mol/L, for example, 4mol/L, 4.1mol/L, 4.5mol/L, 4.8mol/L, 5mol/L, 5.5mol/L or 6 mol/L.

Preferably, the volume ratio of the zinc-containing extract to the second sulfuric acid solution is (3-6: 1), and may be, for example, 3:1, 3.2:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, or 6: 1.

In the invention, the third separation liquid is preferably extracted to separate nickel and then zinc. Because the pH of the extracted nickel is 4-6, the pH of the extracted zinc is 2-3. And the pH of the first raffinate is reduced during the extraction of nickel. Therefore, the dosage of the first sulfuric acid solution added in the process of extracting the zinc can be saved due to the adjustment of the pH value. Secondly, if zinc is extracted firstly, a small part of nickel is also extracted when the pH value is 2-3, so that the zinc and the nickel are not separated thoroughly.

The recitation of numerical ranges herein includes not only the above-recited values, but also any values between any of the above-recited numerical ranges not recited, and for brevity and clarity, is not intended to be exhaustive of the specific values encompassed within the range.

As a preferred technical scheme of the method, the method comprises the following steps:

(1) mixing electroplating sludge with the water content of 60-75% with water to prepare electroplating sludge slurry, wherein the solid-liquid ratio of the electroplating sludge to the water is 1: 1-1.5: 1, adding a first acid solution with the concentration of 1-5 mol/L, performing primary acid leaching for 30-60 min under the condition that the pH value is 3-4, and performing solid-liquid separation to obtain a first acid leaching solution and a first acid leaching residue;

(2) mixing the first acid leaching residue obtained in the step (1) with a second acid solution with the concentration of 1-5 mol/L, performing secondary acid leaching for 30-60 min under the condition that the pH value is 1-2, and performing solid-liquid separation to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid immersion liquid obtained in the step (2) with a first alkali solution, reacting under the condition that the pH value is 3-3.5, and performing solid-liquid separation to obtain first separation slag and first separation liquid;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with a vulcanizing agent with the mass concentration of 10-20% according to the molar ratio (1.5-2) of sulfur ions in the vulcanizing agent to copper ions in the first mixed solution to carry out copper precipitation reaction, and carrying out solid-liquid separation to obtain a second separated liquid and copper sulfide-containing slag;

(5) according to the mol ratio (1.5-2) of phosphate radicals in the inorganic solution containing phosphate radicals to chromium ions in the second separation liquid, 1, mixing the second separation liquid obtained in the step (4) with the inorganic solution containing phosphate radicals with the mass concentration of 20-30%, carrying out chromium precipitation reaction, and carrying out solid-liquid separation to obtain a third separation liquid and chromium phosphate-containing slag;

mixing the third separation liquid and a nickel extracting agent according to a volume ratio of 1 (1-2), and performing nickel extraction under the condition that the pH value is 4-6 to obtain a nickel-containing extraction liquid and a first raffinate; mixing the nickel-containing extraction liquid and a first sulfuric acid solution with the concentration of 10-12 mol/L according to the volume ratio of (20-25) to 1, and performing back extraction to obtain a nickel extraction agent and a nickel-containing solution; electrolyzing the nickel-containing solution to obtain a nickel product;

mixing the first raffinate and a zinc extracting agent according to a volume ratio of 1 (1-2), and performing zinc extraction under the condition that the pH value is 2-3 to obtain a zinc-containing extract and a second raffinate; mixing the zinc-containing extraction liquid and a second sulfuric acid solution with the concentration of 4-6 mol/L according to the volume ratio of (3-6) to 1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; and electrolyzing the zinc-containing solution to obtain a zinc product.

Compared with the prior art, the invention has the beneficial effects that:

(1) the method for recovering valuable metals from electroplating sludge provided by the invention has the advantages that water is completely circulated in the treatment process, no wastewater is generated, and no secondary pollution is generated;

(2) the method for recovering valuable metals from electroplating sludge provided by the invention recovers the main valuable metals in the electroplating sludge, and respectively forms different metal additional products, namely copper sulfide, chromium phosphate, nickel ingots and zinc ingots, so that the resource waste is avoided, and the sales income of byproducts is increased;

(3) the method for recovering valuable metals from electroplating sludge provided by the invention has good separation effect on iron, copper, chromium, nickel and zinc in the electroplating sludge, and high metal recovery rate, wherein the recovery rate of zinc can reach more than 95.67%, the recovery rate of nickel can reach more than 96.32%, the recovery rate of copper can reach more than 95.74%, the recovery rate of chromium can reach more than 85.44%, and the recovery rate of iron can reach more than 84.19%.

Drawings

FIG. 1 is a process flow chart of the method for recovering valuable metals from electroplating sludge provided by the invention.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The invention provides a process flow chart of a method for recovering valuable metals from electroplating sludge, which is shown in figure 1, wherein the solid line in the process flow chart represents the flow of each substance in the electroplating sludge treatment process, and the dotted line in the process flow chart represents the recycling of each substance, and the method comprises the following steps:

(1) mixing electroplating sludge with the water content of 60-75% with water to prepare electroplating sludge slurry, wherein the solid-liquid ratio of the electroplating sludge to the water is 1: 1-1.5: 1, adding a first acid solution with the concentration of 1-5 mol/L, adjusting the pH value to 3-4, performing primary acid leaching for 30-60 min, and performing solid-liquid separation to obtain a first acid leaching solution and first acid leaching residue; the mass content of iron, copper, chromium, zinc and nickel in the electroplating sludge is 1-5%, 1-10%, 0.1-5%, 0.5-10% and 1-35%;

(2) mixing the first acid leaching residue obtained in the step (1) with a second acid solution with the concentration of 1-5 mol/L, performing secondary acid leaching for 30-60 min under the condition that the pH value is 1-2, and performing solid-liquid separation to obtain a second acid leaching solution and a second acid leaching residue; washing the second acid leaching residue by using an aqueous solution, returning washing water to the step (1) to be used as water for preparing electroplating sludge slurry by mixing electroplating sludge and water, and carrying out external treatment on the washed waste residue;

(3) mixing the second acid immersion liquid obtained in the step (2) with a first alkali solution, reacting under the condition that the pH value is 3-3.5, and performing solid-liquid separation to obtain first separation slag and first separation liquid; the first separated slag is sold as a commodity;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with a vulcanizing agent with the mass concentration of 10-20% according to the molar ratio of sulfur ions in the vulcanizing agent to copper ions in the first mixed solution of (1.5-2): 1, and carrying out copper precipitation reaction to obtain a second separated liquid and copper sulfide-containing slag through solid-liquid separation; the copper sulfide-containing slag is sold as a commodity;

(5) mixing the second separation solution obtained in the step (4) with inorganic solution containing phosphate radicals with the mass concentration of 20-30% according to the molar ratio of the phosphate radicals in the inorganic solution containing phosphate radicals to the chromium ions in the second separation solution of (1.5-2) to 1, and carrying out chromium precipitation reaction to obtain a third separation solution and chromium phosphate-containing slag through solid-liquid separation; the chromium phosphate-containing slag is sold as a commodity;

mixing the third separation liquid and a nickel extracting agent according to a volume ratio of 1 (1-2), and performing nickel extraction under the condition that the pH value is 4-6 to obtain a nickel-containing extraction liquid and a first raffinate; mixing the nickel-containing extraction liquid and a first sulfuric acid solution with the concentration of 10-12 mol/L according to the volume ratio of (20-25) to 1, and performing back extraction to obtain a nickel extraction agent and a nickel-containing solution; electrolyzing the nickel-containing solution to obtain a nickel product;

mixing the first raffinate and a zinc extracting agent according to a volume ratio of 1 (1-2), and performing zinc extraction under the condition that the pH value is 2-3 to obtain a zinc-containing extract and a second raffinate; mixing the zinc-containing extraction liquid and a second sulfuric acid solution with the concentration of 4-6 mol/L according to the volume ratio of (3-6) to 1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; and electrolyzing the zinc-containing solution to obtain a zinc product.

Example 1

The embodiment provides a method for recovering valuable metals from electroplating sludge, which comprises the following steps:

(1) 300g of electroplating sludge (with the water content of about 70%) is soaked in 250mL of aqueous solution according to the solid-to-liquid ratio of 1.2:1 to prepare electroplating sludge slurry. Mixing electroplating sludge slurry and 3mol/L sulfuric acid solution, adjusting the pH value to 3.5, adding 25% hydrogen peroxide solution by mass concentration, carrying out primary acid leaching for 50min, and filtering to obtain first acid leaching solution and first acid leaching residue, wherein the solid-to-liquid ratio of the electroplating sludge slurry to the hydrogen peroxide solution is 15: 1; the electroplating sludge contains valuable metal components and mass contents of Fe3.64%, Cu5.55%, Cr3.80%, Zn5.23% and Ni2.85% respectively;

(2) mixing the first acid leaching residue in the step (1) with a sulfuric acid solution with the concentration of 3mol/L under the condition that the pH value is 1.5, carrying out secondary acid leaching for 40min, and filtering to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid leaching solution in the step (2) with a sodium hydroxide solution with the mass concentration of 25% under the condition of pH of 3.2, and filtering to obtain a first separation residue and a first separation solution; the first separated slag is sold as a commodity; washing the second acid leaching residue by tap water, returning washing water to the step (1) as water for soaking electroplating sludge, and carrying out external treatment on the washed waste residue;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with 15% sodium sulfide by mass concentration according to the molar ratio of sulfide ions to copper ions of 1.7:1 to perform copper precipitation reaction, and filtering to obtain a second separated solution and copper sulfide-containing slag; the copper sulfide-containing slag is sold as a commodity;

(5) mixing the second separation liquid obtained in the step (4) with 25% of sodium dihydrogen phosphate according to the molar ratio of sodium dihydrogen phosphate to chromium ions of 1.7:1 to perform chromium precipitation reaction, and filtering to obtain a third separation liquid and chromium phosphate-containing slag; the chromium phosphate-containing slag is sold as a commodity;

controlling the pH value to be 5, and mixing the third separated liquid and the nickel extracting agent according to the volume ratio of 1:1.5 to obtain nickel-containing extract liquid and first raffinate; mixing the nickel-containing extract and a first sulfuric acid solution with the concentration of 11mol/L according to the volume ratio of 22:1, and performing back extraction to obtain a nickel extractant and a nickel-containing solution; the nickel extractant returns to be mixed with the third separation liquid for circular extraction; electrolyzing the nickel-containing solution to obtain a nickel ingot; the nickel ingots are sold as commodities; the nickel extracting agent is formed by mixing di- (2-ethyl hexyl) phosphoric acid and kerosene according to the volume ratio of 0.4: 1;

controlling the pH value to be 2.5, and mixing the first raffinate and the zinc extractant according to the volume ratio of 1:1.5 to obtain a zinc-containing extract and a second raffinate; mixing the zinc-containing extract liquid and a second sulfuric acid solution with the concentration of 5mol/L according to the volume ratio of 4.5:1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; the zinc extractant returns to be mixed with the first raffinate for circular extraction; electrolyzing the zinc-containing solution to obtain a zinc ingot; the zinc extracting agent is formed by mixing di- (2-ethylhexyl) phosphoric acid and kerosene according to the volume ratio of 0.4: 1; the zinc ingot is sold as a commodity.

The metal components in the solid sample obtained after the treatment were analyzed, and the results are shown in table 1.

TABLE 1

Name of solid	Quality of	Zn(％)	Ni(％)	Cu(％)	Cr(％)	Fe(％)
							Second acid leaching residue	83.1g	0.015	0.011	0.114	0.055	0.185
Copper sulfide-containing slag	7.92g	0.15	0.05	61.69	/	4.32
							First separated slag	19.6g	0.14	0.06	0.06	2.31	16.74
Chromium phosphate-containing slag	9.7g	0.03	/	0.05	34.67	0.31
							Zinc ingot	4.6g	99.84	/	0.11	/	0.02
Nickel ingot	2.4g	0.04	99.92	/	/	/

In table 1, "/" indicates that the metal component was not detected, and the percentages of the respective metals are mass percentages.

The sum of the mass percentages of Zn, Ni, Cu, Cr, and Fe in the various solids in Table 1 is not 100% because impurities are also present in the solids.

The data in table 1 are expanded to 1t of electroplating sludge, and the data in table 2 are obtained through material balance calculation.

TABLE 2

	Zn	Ni	Cu	Cr	Fe
						Electroplating sludge (g)	15737.07	8575.65	16699.95	11434.20	10952.76
Second acid leaching residue (g)	42.20	32.22	316.90	135.34	442.19
						Copper sulphide containing slag (g)	40.22	13.96	16343.71	0.00	984.12
First separated slag (g)	92.90	41.45	39.34	1340.67	9437.32
						Chromium slag containing phosphoric acid (g)	9.85	17.10	0.00	9958.19	86.49
Zinc ingot (g)	15548.65	17.84	0.00	0.00	2.65
						Nickel ingot (g)	3.25	8453.08	0.00	0.00	0.00
Recovery rate	98.80％	98.57％	97.87％	87.09％	86.16％

According to the standard of hazardous waste identification standard leaching toxicity identification (GB5085.3-2007), after the electroplating sludge is comprehensively treated by the process flow, the content of metal elements in the waste residues obtained by washing the second acid leaching residues with the aqueous solution is shown in Table 3, and the metal element components in the waste residues are lower than the hazardous waste identification standard.

TABLE 3

Example 2

The embodiment provides a method for recovering valuable metals from electroplating sludge, which comprises the following steps:

(1) 300g of electroplating sludge (with the water content of about 70%) is soaked in 200mL of aqueous solution according to the solid-to-liquid ratio of 1.5:1 to prepare electroplating sludge slurry. Mixing electroplating sludge slurry and a nitric acid solution with the concentration of 5mol/L, adjusting the pH to 3, adding a hydrogen peroxide solution with the mass concentration of 30%, wherein the solid-to-liquid ratio of the electroplating sludge slurry to the hydrogen peroxide solution is 10:1, performing primary acid leaching for 30min, and filtering to obtain a first acid leaching solution and a first acid leaching residue; the electroplating sludge contains valuable metal components and mass contents of Fe3.64%, Cu5.55%, Cr3.80%, Zn5.23% and Ni2.85% respectively;

(2) mixing the first acid leaching residue in the step (1) with a nitric acid solution with the concentration of 5mol/L under the condition that the pH value is 1, carrying out secondary acid leaching for 60min, and filtering to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid leaching solution in the step (2) with a sodium carbonate solution with the mass concentration of 30% under the condition of pH of 3.5, and filtering to obtain a first separation residue and a first separation liquid; the first separated slag is sold as a commodity; washing the second acid leaching residue by tap water, returning washing water to the step (1) as water for soaking electroplating sludge, and carrying out external treatment on the washed waste residue;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with 20% sulfur by mass according to the molar ratio of the sulfur ions to the copper ions of 2:1 to perform copper precipitation reaction, and filtering to obtain a second separated solution and copper sulfide-containing slag; the copper sulfide-containing slag is sold as a commodity;

(5) mixing the second separation liquid obtained in the step (4) with sodium phosphate with the mass concentration of 30% according to the molar ratio of the sodium phosphate to the chromium ions of 2:1 to perform chromium precipitation reaction, and filtering to obtain a third separation liquid and chromium phosphate-containing slag; the chromium phosphate-containing slag is sold as a commodity;

controlling the pH value to be 6, and mixing the third separated liquid and the nickel extracting agent according to the volume ratio of 1:2 to obtain nickel-containing extract liquid and first raffinate; mixing nickel-containing extract liquid and a first sulfuric acid solution with the concentration of 12mol/L according to the volume ratio of 20:1, and performing back extraction to obtain a nickel extractant and a nickel-containing solution; the nickel extractant returns to be mixed with the third separation liquid for circular extraction; electrolyzing the nickel-containing solution to obtain a nickel ingot; the nickel ingots are sold as commodities; the nickel extracting agent is formed by mixing di- (2-ethyl hexyl) phosphoric acid and kerosene according to the volume ratio of 0.5: 1;

controlling the pH value to be 3, and mixing the first raffinate and the zinc extractant according to the volume ratio of 1:2 to obtain a zinc-containing extract and a second raffinate; mixing zinc-containing extract liquid and a second sulfuric acid solution with the concentration of 6mol/L according to the volume ratio of 3:1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; the zinc extractant returns to be mixed with the first raffinate for circular extraction; electrolyzing the zinc-containing solution to obtain a zinc ingot; the zinc extracting agent is formed by mixing di- (2-ethylhexyl) phosphoric acid and kerosene according to the volume ratio of 0.5: 1; the zinc ingot is sold as a commodity.

Example 3

The embodiment provides a method for recovering valuable metals from electroplating sludge, which comprises the following steps:

(1) 300g of mixed electroplating sludge (the water content is about 70 percent) is soaked in 300 mL of aqueous solution according to the solid-to-liquid ratio of 1:1 to prepare electroplating sludge slurry. Adding 1mol/L hydrochloric acid solution, adjusting the pH value to 4, adding 20% hydrogen peroxide solution by mass concentration, carrying out primary acid leaching for 60min when the solid-to-liquid ratio of the electroplating sludge and the hydrogen peroxide solution is 20:1, and filtering to obtain first acid leaching solution and first acid leaching residue; the electroplating sludge contains valuable metal components and mass contents of Fe3.64%, Cu5.55%, Cr3.80%, Zn5.23% and Ni2.85% respectively;

(2) mixing the first acid leaching residue in the step (1) with hydrochloric acid solution with the concentration of 1mol/L under the condition that the pH value is 2, carrying out secondary acid leaching for 30min, and filtering to obtain a second acid leaching solution and a second acid leaching residue;

(3) reacting and mixing the second acid leaching solution in the step (2) with a sodium bicarbonate solution with the mass concentration of 20% under the condition of pH being 3, and filtering to obtain a first separation residue and a first separation solution; the first separated slag is sold as a commodity; washing the second acid leaching residue by tap water, returning washing water to the step (1) as water for soaking electroplating sludge, and carrying out external treatment on the washed waste residue;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with 10% sodium sulfide according to the molar ratio of sulfide ions to copper ions of 1.5:1 to perform copper precipitation reaction, and filtering to obtain a second separated solution and copper sulfide-containing slag; the copper sulfide-containing slag is sold as a commodity;

(5) mixing the second separation liquid obtained in the step (4) with a disodium hydrogen phosphate solution with the mass concentration of 20% according to the molar ratio of disodium hydrogen phosphate to chromium ions of 1.5:1 to perform chromium precipitation reaction, and filtering to obtain a third separation liquid and chromium phosphate-containing slag; the chromium phosphate-containing slag is sold as a commodity;

controlling the pH value to be 4, and mixing the third separation liquid and the nickel extracting agent according to the volume ratio of 1:1 to obtain a nickel-containing extraction liquid and a first raffinate; mixing nickel-containing extract liquid and first sulfuric acid solution with the concentration of 10mol/L according to the volume ratio of 25:1, and performing back extraction to obtain a nickel extractant and a nickel-containing solution; the nickel extractant returns to be mixed with the third separation liquid for circular extraction; electrolyzing the nickel-containing solution to obtain a nickel ingot; the nickel ingots are sold as commodities; the nickel extracting agent is formed by mixing di- (2-ethyl hexyl) phosphoric acid and kerosene according to the volume ratio of 0.3: 1;

mixing the first raffinate and the zinc extractant at a pH value of 2 according to a volume ratio of 1:1 to obtain a zinc-containing extract and a second raffinate; mixing zinc-containing extract liquid and a second sulfuric acid solution with the concentration of 4mol/L according to the volume ratio of 6:1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; the zinc extractant returns to be mixed with the first raffinate for circular extraction; electrolyzing the zinc-containing solution to obtain a zinc ingot; the zinc extracting agent is formed by mixing di- (2-ethylhexyl) phosphoric acid and kerosene according to the volume ratio of 0.3: 1; the zinc ingot is sold as a commodity.

Comparative example 1

The comparative example provides a method for recovering valuable metals from electroplating sludge, the method is the same as the example 1 except that the two-stage acid leaching of the step (1) and the step (2) is replaced by the one-stage acid leaching, and the specific one-stage acid leaching comprises the following steps:

300g of electroplating sludge (with the water content of about 70%) is soaked in 250mL of aqueous solution according to the solid-to-liquid ratio of 1.2:1 to prepare electroplating sludge slurry. Mixing electroplating sludge slurry and 3mol/L sulfuric acid solution, adjusting pH to 1.5, performing acid leaching for 40min, and filtering to obtain acid leaching solution and acid leaching residue; the electroplating sludge contains valuable metal components and mass contents of Fe3.64%, Cu5.55%, Cr3.80%, Zn5.23% and Ni2.85%, respectively.

The method for recovering valuable metals from electroplating sludge provided by the comparative example only carries out acid leaching treatment under the condition that the pH is 1.5, and the iron ions in the electroplating sludge are Fe³⁺The iron ions enter the first pickle liquor in a form of the (I) and have great influence on other metals in the recovery process of other metals, the recovery rate is greatly reduced, and the content of iron impurities is high when other metals form additional products.

Comparative example 2

This comparative example provides a method for recovering valuable metals from electroplating sludge, which is the same as example 1 except that the pH in step (1) is 5.

Comparative example 3

This comparative example provides a method for recovering valuable metals from electroplating sludge, which is the same as example 1 except that the pH in step (2) is 0.5.

The contents of the metal components before and after the treatment of the electroplating sludge in examples 1 to 3 and comparative examples 1 to 3 were measured, and the recovery rate of each metal was calculated from the ratio of the difference between the components before and after the treatment of the electroplating sludge and the contents of the components in the electroplating sludge before the treatment, and the results are shown in table 4.

TABLE 4

From table 4, the following points can be seen:

(1) it can be seen from the comprehensive examples 1 to 3 that the method for recovering valuable metals from electroplating sludge provided by the invention has a good separation effect on iron, copper, chromium, zinc and nickel in the electroplating sludge, and is high in metal recovery rate, wherein the recovery rate of zinc can reach more than 95.67%, the recovery rate of nickel can reach more than 96.32%, the recovery rate of copper can reach more than 95.74%, the recovery rate of chromium can reach more than 85.44%, and the recovery rate of iron can reach more than 84.19%;

(2) by combining example 1 with comparative example 1, it can be seen that the recovery rate of zinc in example 1 is 98.80%, the recovery rate of nickel is 98.57%, the recovery rate of copper is 97.87%, the recovery rate of chromium is 87.09%, and the recovery rate of iron is 86.16% compared with the primary acid leaching in comparative example 1 when two-stage acid leaching is adopted in example 1; whereas the recovery rate of each metal was reduced in comparative example 1, in which the recovery rate of zinc was 90.21%, the recovery rate of nickel was 90.10%, the recovery rate of copper was 86.35%, the recovery rate of chromium was 73.54%, and the recovery rate of iron was 82.23%; therefore, the method adopts two-stage acid leaching, so that the recovery rate of each metal in the electroplating sludge can be greatly improved;

(3) as can be seen by combining example 1 and comparative example 2, the pH in step (1) of example 1 was 3.5, and the recovery rate of zinc was 98.80%, the recovery rate of nickel was 98.57%, the recovery rate of copper was 97.87%, the recovery rate of chromium was 87.09%, and the recovery rate of iron was 86.16% in example 1, compared to the pH of 5 in step (1) of comparative example 2; the recovery rate of each metal in comparative example 2 was greatly reduced, wherein the recovery rate of zinc was 85.26%, the recovery rate of nickel was 88.31%, the recovery rate of copper was 73.45%, the recovery rate of chromium was 63.11%, and the recovery rate of iron was 60.68%; therefore, the pH value is controlled to be 3-4 in the step (1), most of other valuable metals except iron are leached, a foundation is laid for efficient separation and recovery of each subsequent metal, and the recovery rate of each metal in the electroplating sludge is obviously improved;

(4) it can be seen from the combination of example 1 and comparative example 3 that the pH in step (2) of example 1 was 1.5, and the metal recovery rates in example 1 and comparative example 3 were not significantly different from those in step (2) of comparative example 3, but the consumption of sulfuric acid was increased due to the excessively low pH in step (2) of comparative example 3, which in turn led to an increase in the consumption of sodium hydroxide solution in step (3), resulting in an increase in the treatment cost of electroplating sludge.

In conclusion, the method for recovering valuable metals from electroplating sludge provided by the invention has the advantages that the main valuable metals in the electroplating sludge are efficiently separated and recovered, the process flow is simple, the treatment cost is low, the recovered metals form different metal additional products, the resource waste is avoided, and the sales income of byproducts is increased.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims (10)

1. A method for recovering valuable metals from electroplating sludge is characterized by comprising the following steps:

(1) mixing electroplating sludge and water to prepare electroplating sludge slurry, adding a first acid solution, performing primary acid leaching under the condition that the pH value is 3-4, and performing solid-liquid separation to obtain a first acid leaching solution and a first acid leaching residue;

(2) mixing the first acid leaching residue and the second acid solution in the step (1), performing secondary acid leaching under the condition that the pH value is 1-2, and performing solid-liquid separation to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid immersion liquid in the step (2) with a first alkali solution, and performing solid-liquid separation to obtain first separation slag and first separation liquid;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with a vulcanizing agent to perform copper precipitation reaction, and performing solid-liquid separation to obtain a second separated solution and copper sulfide-containing slag;

(5) and (5) mixing the second separation liquid obtained in the step (4) with an inorganic solution containing phosphate radicals to perform chromium precipitation reaction, and performing solid-liquid separation to obtain a third separation liquid and chromium phosphate-containing slag.

2. The method according to claim 1, wherein the water content of the electroplating sludge in the step (1) is 60-75%;

preferably, in the process of preparing the electroplating sludge slurry, the solid-to-liquid ratio of the electroplating sludge to water is 1: 1-1.5: 1;

preferably, the first acid solution comprises any one of a sulfuric acid solution, a nitric acid solution or a hydrochloric acid solution;

preferably, the concentration of the first acid solution is 1-5 mol/L;

preferably, the time of the primary acid leaching is 30-60 min.

3. The method of claim 1 or 2, wherein the second acid solution of step (2) comprises any one of a sulfuric acid solution, a nitric acid solution, or a hydrochloric acid solution;

preferably, the concentration of the second acid solution is 1-5 mol/L;

preferably, the time of the secondary acid leaching is 30-60 min.

4. The method according to any one of claims 1 to 3, wherein the first alkali solution in step (3) comprises any one of or a combination of at least two of a sodium hydroxide solution, a sodium carbonate solution or a sodium bicarbonate solution;

preferably, the pH of the mixture is 3-3.5.

5. The method according to any one of claims 1 to 4, wherein the vulcanizing agent of step (4) comprises sodium sulfide or sulfur;

preferably, the mass concentration of the vulcanizing agent is 10-20%;

preferably, the addition amount of the vulcanizing agent is that the molar ratio of sulfur ions in the vulcanizing agent to copper ions in the first mixed solution is (1.5-2): 1;

preferably, the inorganic solution containing phosphate groups of step (5) includes any one of phosphoric acid, sodium phosphate, sodium dihydrogen phosphate, or disodium hydrogen phosphate;

preferably, the mass concentration of the inorganic solution containing phosphate radicals is 20-30%;

preferably, the addition amount of the inorganic solution containing phosphate radicals is such that the molar ratio of the phosphate radicals to the chromium ions in the second separation liquid is (1.5-2): 1.

6. The method according to any one of claims 1 to 5, wherein the step (5) further comprises mixing the third separated liquid with a nickel extractant to perform nickel extraction, so as to obtain a nickel-containing extract and a first raffinate;

preferably, the nickel-containing extraction liquid and the first sulfuric acid solution are mixed and back-extracted to obtain a nickel extraction agent and a nickel-containing solution;

preferably, the nickel-containing solution is electrolyzed to obtain a nickel product.

7. The method of claim 6, wherein the nickel extractant of step (5) comprises a mixture of di- (2-ethylhexyl) phosphoric acid and kerosene;

preferably, the volume ratio of the di- (2-ethylhexyl) phosphoric acid to the kerosene is (0.3-0.5): 1;

preferably, the pH value of the nickel extraction is 4-6;

preferably, the volume ratio of the third separation liquid to the nickel extracting agent is 1 (1-2);

preferably, the concentration of the first sulfuric acid solution is 10-12 mol/L;

preferably, the volume ratio of the nickel-containing extraction liquid to the first sulfuric acid solution is (20-25): 1.

8. The method of claim 6, wherein step (5) further comprises mixing the first raffinate with a zinc extractant to perform zinc extraction to obtain a zinc-containing extract and a second raffinate;

preferably, the zinc-containing extract and the second sulfuric acid solution are mixed and back-extracted to obtain a zinc extractant and a zinc-containing solution;

preferably, the zinc-containing solution is electrolyzed to obtain a zinc product.

9. The method of claim 8, wherein the zinc extractant of step (5) comprises a mixture of di- (2-ethylhexyl) phosphoric acid and kerosene;

preferably, the volume ratio of the di- (2-ethylhexyl) phosphoric acid to the kerosene is (0.3-0.5): 1;

preferably, the pH of the zinc extraction is 2-3;

preferably, the volume ratio of the first raffinate to the zinc extractant is 1 (1-2);

preferably, the concentration of the second sulfuric acid solution is 4-6 mol/L;

preferably, the volume ratio of the zinc-containing extract to the second sulfuric acid solution is (3-6): 1.

10. A method according to any one of claims 1 to 9, characterized in that the method comprises the steps of:

(1) mixing electroplating sludge with the water content of 60-75% with water to prepare electroplating sludge slurry, wherein the solid-to-liquid ratio of the electroplating sludge to the water is 1: 1-1.5: 1, adding a first acid solution with the concentration of 1-5 mol/L, performing primary acid leaching for 30-60 min under the condition that the pH value is 3-4, and performing solid-liquid separation to obtain a first acid leaching solution and a first acid leaching residue;

(2) mixing the first acid leaching residue obtained in the step (1) with a second acid solution with the concentration of 1-5 mol/L, performing secondary acid leaching for 30-60 min under the condition that the pH value is 1-2, and performing solid-liquid separation to obtain a second acid leaching solution and a second acid leaching residue;

(3) mixing the second acid immersion liquid obtained in the step (2) with a first alkali solution, reacting under the condition that the pH value is 3-3.5, and performing solid-liquid separation to obtain first separation slag and first separation liquid;

(4) mixing the first pickle liquor obtained in the step (1) with the first separated liquor obtained in the step (3) to obtain a first mixed liquor; mixing the first mixed solution with a vulcanizing agent with the mass concentration of 10-20% according to the molar ratio (1.5-2) of sulfur ions in the vulcanizing agent to copper ions in the first mixed solution to carry out copper precipitation reaction, and carrying out solid-liquid separation to obtain a second separated liquid and copper sulfide-containing slag;

(5) according to the mol ratio (1.5-2) of phosphate radicals in the inorganic solution containing phosphate radicals to chromium ions in the second separation liquid, 1, mixing the second separation liquid obtained in the step (4) with the inorganic solution containing phosphate radicals with the mass concentration of 20-30%, carrying out chromium precipitation reaction, and carrying out solid-liquid separation to obtain a third separation liquid and chromium phosphate-containing slag;

mixing the third separation liquid and a nickel extracting agent according to a volume ratio of 1 (1-2), and performing nickel extraction under the condition that the pH value is 4-6 to obtain a nickel-containing extraction liquid and a first raffinate; mixing the nickel-containing extraction liquid and a first sulfuric acid solution with the concentration of 10-12 mol/L according to the volume ratio of (20-25) to 1, and performing back extraction to obtain a nickel extraction agent and a nickel-containing solution; electrolyzing the nickel-containing solution to obtain a nickel product;

mixing the first raffinate and a zinc extracting agent according to a volume ratio of 1 (1-2), and performing zinc extraction under the condition that the pH value is 2-3 to obtain a zinc-containing extract and a second raffinate; mixing the zinc-containing extraction liquid and a second sulfuric acid solution with the concentration of 4-6 mol/L according to the volume ratio of (3-6) to 1, and performing back extraction to obtain a zinc extractant and a zinc-containing solution; and electrolyzing the zinc-containing solution to obtain a zinc product.

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