Production process for recovering nonferrous metals from ferronickel slag

Abstract

The invention discloses a production process for recovering nonferrous metals from ferronickel slag, and belongs to the technical field of comprehensive utilization of ferronickel slag. Comprising the following steps that S1, before smelting, blast furnace ferronickel slag, electric furnace ferronickel slag and blast furnace ferronickel slag are mixed and crushed, and ferronickel slag powder is obtained; s2, mixing the ferronickel slag powder with ammonium sulfate to obtain a roasted product, and soaking the roasted product in water to obtain magnesium-removed ferronickel slag powder; s3, the magnesium-removed ferronickel slag powder is subjected to reduction smelting, a calcium agent and an alkaline substance are added in the smelting process, and magnesium-removed reduction smelting ferronickel slag is obtained; s5, the magnesium-removed and aluminum-removed reduction smelting ferronickel slag is leached through sulfuric acid, and a sulfuric acid leaching solution is obtained; and S7, the mother liquor is placed in an electrolytic bath to be electrolyzed, and the heavy metal ions in the electrolytic bath are reduced into metal elementary substances on a cathode according to the deposition sequence by adjusting the potential. According to the method, metal in the ferronickel slag can be efficiently separated, the purity of the recycled metal is improved, and the performance of the prepared nonferrous metal material is good.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of nickel-ferronickel slag, and in particular to a production process for recovering nonferrous metals from nickel-ferronickel slag. Background Art

[0002] Ferronickel slag is produced during the smelting of nickel-iron alloys. It is a spherical granular industrial waste slag formed by water quenching of a melt with oxides such as Fe2O3, SiO2 and MgO as the main components. It is usually dark green. Every ton of nickel produced will produce 6 to 16 tons of waste slag. Ferronickel slag has become the fourth largest smelting industrial waste slag in my country after iron slag, steel slag and red mud.

[0003] The composition of nickel-iron slag varies due to the different ore sources, properties and smelting processes. Blast furnace nickel-iron slag belongs to the SiO2-Al2O3-CaO system, with a CaO content of 20% to 30%. It has the characteristics of high calcium content and low iron content. The mineral content phases include dicalcium silicate, tricalcium silicate, magnesium carbonate, calcium carbonate, forsterite and magnesium spinel, etc., and have certain potential activity; electric furnace nickel-iron slag belongs to the SiO2-MgO-Fe2O3 system, with a high MgO content (≥20%), a low CaO content (≤10%), and its Fe2O3 content is significantly higher than that of blast furnace nickel-iron slag. It has the characteristics of high magnesium and iron content and low calcium content. The mineral phase is mainly magnesium (iron) olivine, which has the characteristics of low potential activity, poor grindability and high utilization cost. AOD slag is mainly composed of metal oxides, including magnesium oxide (MgO), which may exist in the slag in the form of periclase (crystalline form of MgO). Magnesium in slag usually exists in stable chemical forms such as periclase (MgO) and helps to form stable crystalline phases such as struvite (MgNH4PO4·6H2O) and spinel (MgO·Al2O3), thereby enhancing the binding of heavy metals. Therefore, high magnesium content in slag helps to stabilize and fix heavy metals, reduce their leaching and environmental risks. The increase in magnesium (Mg) content in molten steel has a significant effect on the morphology of spinel inclusions. When spinel inclusions change from spherical to angular, their specific surface area may increase. Angular morphology usually has more edges and corners, which can provide more adsorption sites, thereby potentially enhancing the adsorption capacity of spinel for heavy metals. Ferronickel slag contains non-ferrous metals such as cobalt, magnesium, aluminum, nickel, cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), etc. Among them, cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) belong to the heavy metal category. It also contains non-ferrous metals such as iron, while nickel, cobalt, copper and iron belong to valuable metals. Nickel is an important industrial metal and is widely used in stainless steel, alloy steel, nickel-based alloy, electroplating and batteries. Nickel is an important industrial metal and is widely used in stainless steel, alloy steel, nickel-based alloy, electroplating and batteries. The recovery of nickel can not only reduce the mining of new nickel mines, but also reduce environmental pollution. Copper is a conductive material widely used in wires and cables, electrical equipment and industrial machinery and equipment. The recovery of copper can effectively reduce the dependence on new copper mines, while reducing energy consumption and environmental pollution. Iron is one of the most abundant metal elements on earth and is the main raw material for steel production. The recovery of iron from ferronickel slag can be used as a supplementary raw material for the steel industry and reduce the demand for iron ore. Nickel recycling can not only reduce the mining of new nickel ore, but also reduce environmental pollution.Nonferrous metals usually have good electrical and thermal conductivity. The presence of heavy metal impurities may interfere with these properties because different metals have different electronic structures and free electron densities, which affects the overall electrical and thermal conductivity of the material. Heavy metal impurities may change the lattice structure, causing lattice distortion, which affects the mechanical properties of the material. Nickel-iron slag contains a variety of metals. In order to reduce the impact of heavy metal impurities on the performance of nonferrous metal materials, it is necessary to improve the purity of nonferrous metals recovered from nickel-iron slag. Sulfuric acid leaching is a commonly used wet smelting process, but sulfuric acid leaching does not completely dissolve nickel-iron slag, but selectively dissolves the valuable metals therein. The slag after sulfuric acid leaching still contains unleached metals and other mineral components. These unleached metals may be wrapped in silicate mineral structures, making it difficult to react with sulfuric acid during the leaching process. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a production process for recovering non-ferrous metals from ferronickel slag. The production process for recovering non-ferrous metals from ferronickel slag has a high recovery rate, can efficiently separate the metals in the ferronickel slag, and improve the purity of the recovered metals. The non-ferrous metal materials used for preparation have good performance, and the leaching property of heavy metal ions in the ferronickel slag in sulfuric acid is increased, thereby improving the resource utilization of heavy metals.

[0005] The purpose of the present invention is achieved by the following technical solutions: The production process for recovering nonferrous metals from ferronickel slag comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing the nickel-iron slag powder and ammonium sulfate, and calcining the mixture at 300-400° C. to obtain a calcined product, and infiltrating the calcined product in water to obtain a demagnesized nickel-iron slag powder; S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent and alkaline substances during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduction smelting nickel-iron slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5, leaching the de-magnesiumized and de-aluminized ferronickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, adding benzenetricarboxylic acid to the sulfuric acid leaching solution, and filtering and separating a precipitate; S6, extracting the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to extract cobalt ions and nickel ions, thereby obtaining a tributyl phosphate extract and a mother liquor; S7. placing the mother liquor in an electrolytic cell for electrolysis, and adjusting the potential so that the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition.

[0006] Furthermore, the alkaline substance is one of sodium peroxide, sodium carbonate and sodium tetraborate.

[0007] Furthermore, the calcium agent is one of limestone and quicklime.

[0008] Furthermore, in step S6, after obtaining the tributyl phosphate extract, the pH of the tributyl phosphate extract is adjusted to alkaline, and the cobalt ions will form a water-insoluble cobalt hydroxide precipitate, while by adding sodium carbonate, the nickel ions can form a nickel carbonate precipitate with lower solubility.

[0009] Furthermore, in the step S2, the mass ratio of the nickel-iron slag powder to the ammonium sulfate is 1:3.5, and the roasting time is 120 min.

[0010] Furthermore, in step S5, after obtaining the sulfuric acid leaching solution, a nanofiltration membrane with suitable pore size and charge characteristics is used to selectively separate the metal ions in the sulfuric acid leaching solution according to the size and charge properties of the metal ions.

[0011] Furthermore, the nanofiltration membrane is selected from DURACID membrane or MNF-Acid membrane.

[0012] Furthermore, in the step S7, during the electrolysis process, the current used for electrodeposition is in the form of a pulse flow.

[0013] Furthermore, in step S2, after the roasting treatment, ammonia and sulfur dioxide will also be produced. Ammonia and sulfur dioxide can be selectively separated by water or lime slurry. After separation, sulfur dioxide can be used as a raw material for producing sulfuric acid, and the produced sulfuric acid can be used in step S5.

[0014] Furthermore, ammonia and sulfur dioxide can react to generate ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The production process for recovering nonferrous metals from ferronickel slag provided by the present invention comprises mixing blast furnace ferronickel slag, electric furnace ferronickel slag and blast furnace ferronickel slag, and the dilution effect of calcium: when the blast furnace ferronickel slag has a high calcium content, the calcium content in the mixture can be increased, which will increase the possibility of magnesium and calcium elements forming calcium silicate minerals, thereby reducing the formation of forsterite. The ferronickel slag powder is mixed with ammonium sulfate, and roasted at 300-400°C to obtain a roasted product, and the roasted product is placed in water for infiltration to obtain a demagnesiumized ferronickel slag powder, which reduces the magnesium content in the reduction smelting process and reduces the formation of MgO·Al2O3 (magnesium aluminum spinel). Alkaline substances are added during the smelting process, which can react with aluminum oxide to form sodium metaaluminate, further reducing the formation of MgO·Al2O3 (magnesium aluminum spinel), so that heavy metal ions do not combine with MgO·Al2O3 (magnesium aluminum spinel). Sodium aluminate remains in the de-magnesiumizing reduction smelting nickel-iron slag, and the de-magnesiumizing reduction smelting nickel-iron slag is immersed in water, and the sodium aluminate is dissolved in water, and the de-magnesiumizing reduction smelting nickel-iron slag is obtained by filtration. In this process, aluminum salts can be recovered, and the de-magnesiumizing reduction smelting nickel-iron slag is obtained by rapid cooling, which will also affect the formation of MgO·Al2O3.

[0016] The de-magnesiumized and de-aluminized reduction smelting nickel-iron slag is leached with sulfuric acid to obtain a sulfuric acid leaching solution, which has a high content of heavy metal ions. Benzenetricarboxylic acid is added to the sulfuric acid leaching solution, and the precipitate is separated by filtering. The carboxyl group of benzenetricarboxylic acid (BTC) is chemically combined with copper ions and zinc ions to precipitate the copper ions and zinc ions in the fly ash. The metal ions are directly precipitated from the acidic solution without alkaline neutralization to form a stable compound of copper ions and zinc ions, and the copper ions and zinc ions can be recovered; the sulfuric acid leaching solution treated in step S5 is extracted with tributyl phosphate to extract cobalt ions and nickel ions, and a tributyl phosphate extract and a mother liquor are obtained, and the cobalt ions and nickel ions can be recovered; S7, the mother liquor is placed in an electrolytic cell for electrolysis, and the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition by adjusting the potential, and the heavy metal ions can be recovered in sequence. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with specific embodiments. It should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0018] Example 1 The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, nickel-iron slag powder and ammonium sulfate are mixed, the mass ratio of nickel-iron slag powder and ammonium sulfate is 1:3.5, and roasting treatment is carried out at 300 ° C to obtain a roasted product, the roasting time is 120min, and the roasted product is placed in water and infiltrated to obtain magnesium-removed nickel-iron slag powder; after the roasting treatment, ammonia and sulfur dioxide are also produced, ammonia and sulfur dioxide can be selectively separated by water or lime slurry, and after separation, sulfur dioxide can be used as a raw material for producing sulfuric acid, and the produced sulfuric acid can be used in step S5.

[0019] S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent limestone and alkaline substance sodium peroxide during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduced nickel-iron smelting slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5, leaching the de-magnesiumized and de-aluminized ferronickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, adding benzenetricarboxylic acid to the sulfuric acid leaching solution, and filtering and separating the precipitate; S6, extracting the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to extract cobalt ions and nickel ions, obtaining a tributyl phosphate extract and a mother liquor, and after obtaining the tributyl phosphate extract, adjusting the pH of the tributyl phosphate extract to alkaline, the cobalt ions will form a water-insoluble cobalt hydroxide precipitate, and by adding sodium carbonate, the nickel ions can form a nickel carbonate precipitate with low solubility; S7. Place the mother liquor in an electrolytic cell for electrolysis. By adjusting the potential, the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition. During the electrolysis process, the current used for electrodeposition is in the form of pulse flow. Pulse electrodeposition (Pulse) adjusts the metal ion concentration at the electrode-solution interface by turning the current on and off, which can effectively eliminate concentration polarization and increase the metal nucleation rate, thereby forming a large number of smaller nuclei and improving the quality of the deposited layer.

[0020] Furthermore, the alkaline substance is one of sodium peroxide, sodium carbonate and sodium tetraborate.

[0021] Furthermore, the calcium agent is one of limestone and quicklime.

[0022] Non-heavy metal ions usually refer to those metal ions that are not easy to undergo redox reactions in chemical reactions. The characteristics of these ions are that they are usually in a stable oxidation state, unlike some heavy metal ions that have multiple oxidation states, and are easily reduced to metal elements in the order of deposition on the cathode. Therefore, heavy metals can be recovered in sequence and heavy metal ions can be separated from the mother liquor.

[0023] Multi-step electrolysis: The electrolysis process is divided into multiple steps, each of which is used to deposit specific metal ions. This allows the gradual removal of different metals and improves the overall separation efficiency.

[0024] The potential in the electrolytic cell can be controlled to promote the reduction and deposition of specific metal ions. For example, the potential can be adjusted to preferentially deposit metals with lower reduction potentials, while other metal ions remain in solution, and then other metals can be deposited by adjusting the potential. This method can achieve selective deposition and recovery of metals.

[0025] In this embodiment, Before roasting, the nickel-iron slag was irregular in shape and uneven in particle size distribution. As the roasting time increased, the surface of the nickel-iron slag gradually became loose under the action of (NH4)2SO4, and the particle size gradually became smaller. The main reason is that there is a highly active SO4 in (NH4)2SO4. 2− , for MgSiO3Mg in slag 1.8 Fe 0.2 (SiO4) can play an effective decomposition role, destroying its stable silicate structure and generating soluble MgSO4 into the solution.

[0026] Calcium treatment agent: Calcium is an effective additive that can react with magnesium and aluminum in the slag to form liquid composite inclusions, thereby reducing the formation of spinel inclusions.

[0027] P507 (tributyl phosphate) is a commonly used acidic phosphorus extractant, which plays an important role in metal extraction, especially in the extraction and separation of rare earth elements and non-ferrous metals. In addition to forming a stable complex with aluminum (Al³⁺), P507 can also form complexes with a variety of metal ions, including but not limited to nickel (Ni), cobalt (Co), copper (Cu), zinc (Zn) and rare earth metal ions. Step S5, add benzene tricarboxylic acid to the sulfuric acid leaching solution, filter and separate the precipitate, copper ions and zinc ions have been separated, and cobalt ions and nickel ions are extracted in this step.

[0028] Example 2 The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing nickel-iron slag powder and ammonium sulfate in a mass ratio of 1:3.5, calcining the mixture at 360°C to obtain a calcined product for 120 min, and soaking the calcined product in water to obtain magnesium-free nickel-iron slag powder; ammonia and sulfur dioxide can react to generate ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.

[0029] S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent quicklime and alkaline substance sodium carbonate during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduced nickel-iron smelting slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5, leaching the de-magnesiumized and de-aluminized ferronickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, adding benzenetricarboxylic acid to the sulfuric acid leaching solution, and filtering and separating the precipitate; S6, extracting the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to extract cobalt ions and nickel ions, obtaining a tributyl phosphate extract and a mother liquor, and after obtaining the tributyl phosphate extract, adjusting the pH of the tributyl phosphate extract to alkaline, the cobalt ions will form a water-insoluble cobalt hydroxide precipitate, and by adding sodium carbonate, the nickel ions can form a nickel carbonate precipitate with low solubility; S7. Place the mother liquor in an electrolytic cell for electrolysis. By adjusting the potential, the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition. During the electrolysis process, the current used for electrodeposition is in the form of pulse flow. Pulse electrodeposition (Pulse) adjusts the metal ion concentration at the electrode-solution interface by turning the current on and off, which can effectively eliminate concentration polarization and increase the metal nucleation rate, thereby forming a large number of smaller nuclei and improving the quality of the deposited layer.

[0030] Example 3 The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing nickel-iron slag powder and ammonium sulfate, the mass ratio of nickel-iron slag powder to ammonium sulfate is 1:3.5, and calcining at 400° C. to obtain a calcined product, the calcination time is 120 min, and the calcined product is infiltrated in water to obtain magnesium-removed nickel-iron slag powder; S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent quicklime and limestone, and alkaline substance sodium tetraborate during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduction smelting nickel-iron slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5, leaching the de-magnesiumized and de-aluminized ferronickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, adding benzenetricarboxylic acid to the sulfuric acid leaching solution, and filtering and separating the precipitate; S6, extracting the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to extract cobalt ions and nickel ions, obtaining a tributyl phosphate extract and a mother liquor, and after obtaining the tributyl phosphate extract, adjusting the pH of the tributyl phosphate extract to alkaline, the cobalt ions will form a water-insoluble cobalt hydroxide precipitate, and by adding sodium carbonate, the nickel ions can form a nickel carbonate precipitate with low solubility; S7. Place the mother liquor in an electrolytic cell for electrolysis. By adjusting the potential, the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition. During the electrolysis process, the current used for electrodeposition is in the form of pulse flow. Pulse electrodeposition (Pulse) adjusts the metal ion concentration at the electrode-solution interface by turning the current on and off, which can effectively eliminate concentration polarization and increase the metal nucleation rate, thereby forming a large number of smaller nuclei and improving the quality of the deposited layer.

[0031] Example 4 The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing nickel-iron slag powder and ammonium sulfate, the mass ratio of nickel-iron slag powder to ammonium sulfate is 1:3.5, and calcining at 300° C. to obtain a calcined product, the calcination time is 120 min, and the calcined product is placed in water for infiltration to obtain magnesium-free nickel-iron slag powder; S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent limestone and alkaline substance sodium peroxide during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduced nickel-iron smelting slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5. Using sulfuric acid to leach the de-magnesiumized and de-aluminized ferronickel slag for reduction smelting to obtain a sulfuric acid leaching solution. Using a nanofiltration membrane DURACID membrane with suitable pore size and charge characteristics, the metal ions in the sulfuric acid leaching solution can be selectively separated according to the size and charge properties of the metal ions.

[0032] The MNF-Acid membrane has the thinnest selective layer, the strongest hydrophilicity, and the highest permeability. Both DURACID and MNF-Acid membranes have the characteristics of small pore size and narrow pore size distribution, which can ensure the precise separation of heavy metals and are suitable for application scenarios with high separation accuracy requirements.

[0033] Example 5 The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing nickel-iron slag powder and ammonium sulfate, the mass ratio of nickel-iron slag powder to ammonium sulfate is 1:3.5, and calcining at 300° C. to obtain a calcined product, the calcination time is 120 min, and the calcined product is placed in water for infiltration to obtain magnesium-free nickel-iron slag powder; S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent limestone and alkaline substance sodium peroxide during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduced nickel-iron smelting slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5. Using sulfuric acid to leach the de-magnesiumized and de-aluminized ferronickel slag for reduction smelting to obtain a sulfuric acid leaching solution. Using a nanofiltration membrane MNF-Acid membrane with suitable pore size and charge characteristics, the metal ions in the sulfuric acid leaching solution can be selectively separated according to the size and charge properties of the metal ions.

[0034] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A production process for recovering nonferrous metals from ferronickel slag, characterized in that: The following steps are involved: S1, before smelting, blast furnace nickel ferro slag, electric furnace nickel ferro slag, and blast furnace nickel ferro slag are mixed and crushed, and vertically milled to obtain nickel ferro slag powder; S2, mixing the nickel-iron slag powder and ammonium sulfate, and calcining the mixture at 300-400° C. to obtain a calcined product, and infiltrating the calcined product in water to obtain a demagnesized nickel-iron slag powder; S3, reducing and smelting the demagnesized nickel-iron slag powder, heating it to above 1500° C., using carbon powder as a reducing agent, reducing the iron oxide in the demagnesized nickel-iron slag powder to metallic iron during the smelting process, adding calcium agent and alkaline substances during the smelting process, and rapidly cooling the metallic iron after it is discharged from the smelting furnace to obtain demagnesized reduction smelting nickel-iron slag; S4, placing the de-magnesiumized reduction smelting ferronickel slag in water for infiltration, and filtering to obtain the de-magnesiumized dealuminated reduction smelting ferronickel slag; S5, leaching the de-magnesiumized and de-aluminized ferronickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, adding benzenetricarboxylic acid to the sulfuric acid leaching solution, and filtering and separating a precipitate; S6, extracting the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to extract cobalt ions and nickel ions, thereby obtaining a tributyl phosphate extract and a mother liquor; S7. placing the mother liquor in an electrolytic cell for electrolysis, and adjusting the potential so that the heavy metal ions in the electrolytic cell are reduced to metal elements on the cathode in the order of deposition.

2. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: The alkaline substance is one of sodium peroxide, sodium carbonate and sodium tetraborate.

3. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: The calcium agent is one of limestone and quicklime.

4. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: In step S6, after obtaining the tributyl phosphate extract, the pH of the tributyl phosphate extract is adjusted to alkaline, and the cobalt ions will form a water-insoluble cobalt hydroxide precipitate, while the nickel ions can form a nickel carbonate precipitate with low solubility by adding sodium carbonate.

5. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: In the step S2, the mass ratio of the nickel-iron slag powder to the ammonium sulfate is 1:3.5, and the roasting time is 120 minutes.

6. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: In the step S5, after obtaining the sulfuric acid leaching solution, a nanofiltration membrane with suitable pore size and charge characteristics is used to selectively separate the metal ions in the sulfuric acid leaching solution according to the size and charge properties of the metal ions.

7. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 6, characterized in that: The nanofiltration membrane is selected from DURACID membrane or MNF-Acid membrane.

8. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: In the step S7, during the electrolysis process, the current used for electrodeposition is in the form of a pulse flow.

9. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 1, characterized in that: In step S2, after the roasting treatment, ammonia and sulfur dioxide will also be produced. Ammonia and sulfur dioxide can be selectively separated by water or lime slurry. After separation, sulfur dioxide can be used as a raw material for producing sulfuric acid, and the produced sulfuric acid can be used in step S5.

10. The production process for recovering nonferrous metals from ferronickel slag as claimed in claim 9, characterized in that: Ammonia and sulfur dioxide can react to generate ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.