Production process for recovering non-ferrous metals from nickel iron slag

Abstract

The invention discloses a production process for recovering non-ferrous metals from nickel-iron slag, belonging to the technical field of comprehensive utilization of nickel-iron slag. The process includes the following steps: S1. Before smelting, blast furnace nickel-iron slag and electric furnace nickel-iron slag are mixed and crushed to obtain nickel-iron slag powder; S2. The nickel-iron slag powder and ammonium sulfate are mixed to obtain a calcined product, and the calcined product is soaked in water to obtain de-magnesium nickel-iron slag powder; S3. The de-magnesium nickel-iron slag powder is subjected to reduction smelting, and calcium agents and alkaline substances are added during the smelting process to obtain de-magnesium reduced smelting nickel-iron slag; S5. The de-magnesium and de-aluminum reduced smelting nickel-iron slag is leached with sulfuric acid to obtain a sulfuric acid leaching solution; S7. The mother liquor is placed in an electrolytic cell for electrolysis. By adjusting the potential, heavy metal ions in the electrolytic cell are reduced to metal simple substances on the cathode according to the deposition sequence. The invention can efficiently separate metals in nickel-iron slag, improve the purity of the recovered metals, and the non-ferrous metal materials prepared therefrom have good performance.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of nickel-iron slag, and specifically relates to a production process for recovering non-ferrous metals from nickel-iron slag. Background Art

[0002] Nickel-iron slag is a spherical granular industrial waste residue formed by quenching with water a melt mainly composed of oxides such as Fe2O3, SiO2, and MgO generated during the smelting of nickel-iron alloy, and usually appears dark green. 6 - 16 t of waste residue is generated for every 1 t of nickel produced. Nickel-iron slag has become the fourth largest smelting industrial waste residue in China after iron slag, steel slag, and red mud.

[0003] The composition of nickel-iron slag varies due to differences in ore sources, properties, and smelting processes. Blast furnace nickel-iron slag belongs to the SiO2-Al2O3-CaO system, with a CaO content of 20% - 30%. It is characterized by a high calcium content and a low iron content. The mineral phases include dicalcium silicate, tricalcium silicate, magnesium carbonate, calcium carbonate, forsterite, and magnesia spinel, etc., and has certain potential activity. Electric furnace nickel-iron slag belongs to the SiO2-MgO-Fe2O3 system, with a relatively high MgO content (≥20%) and a low CaO content (≤10%). Moreover, its Fe2O3 content is significantly higher than that of blast furnace nickel-iron slag. It is characterized by high magnesium and iron contents and a low calcium content. The main mineral phase is magnesium (iron) olivine, with 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 form of periclase (the crystal form of MgO) in the slag. Magnesium in the slag usually exists in stable chemical forms such as periclase (MgO), etc., and helps to form stable crystalline phases such as struvite (MgNH4PO4·6H2O) and spinel (MgO·Al2O3), thereby enhancing the binding of heavy metals. Therefore, the high content of magnesium in the slag helps to stabilize and immobilize heavy metals, reducing their leachability and environmental risks. The increase in the content of magnesium (Mg) in the molten steel has a significant impact on the morphology of spinel inclusions. When the spinel inclusions change from spherical to angular, their specific surface area may increase. The angular morphology usually has more edges and corners, where more adsorption sites can be provided, thus possibly enhancing the adsorption capacity of spinel for heavy metals. Nickel-iron slag contains non-ferrous metals such as cobalt, magnesium, aluminum, nickel, cobalt (Co), chromium (Cr), copper (Cu), as well as lead (Pb), zinc (Zn), etc. Among them, cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) belong to heavy metals, and it also contains non-ferrous metals such as iron. Among them, nickel, cobalt, copper, and iron are valuable metals. Nickel is an important industrial metal, widely used in fields such as stainless steel, alloy steel, nickel-based alloys, electroplating, and batteries; Nickel is an important industrial metal, widely used in fields such as stainless steel, alloy steel, nickel-based alloys, electroplating, and batteries. The recovery of nickel can not only reduce the exploitation of new nickel mines but also reduce environmental pollution; Copper is a conductive material widely used in wire and cable, electrical equipment, and industrial mechanical 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 the earth and is the main raw material for steel production. Recovering iron from nickel-iron slag can be used as a supplementary raw material for the steel industry, reducing the demand for iron ore. The recovery of nickel can not only reduce the exploitation of new nickel mines but also reduce environmental pollution.Non-ferrous metals usually have good electrical and thermal conductivity. The presence of heavy metal impurities may interfere with these properties because the electronic structures and free electron densities of different metals are different, thus affecting the overall electrical and thermal conductivity of the material. Heavy metal impurities may change the lattice structure, resulting in lattice distortion, thereby affecting the mechanical properties of the material. Nickel iron slag contains various metals. In order to reduce the influence of heavy metal impurities on the properties of non-ferrous metal materials, it is necessary to improve the purity of non-ferrous metals recovered from nickel iron slag. The sulfuric acid leaching method is a commonly used hydrometallurgical process. However, sulfuric acid leaching does not completely dissolve nickel iron slag, but selectively dissolves the valuable metals in it. The slag after sulfuric acid leaching still contains un-leached metals and other mineral components. These un-leached metals may be wrapped in the silicate mineral structure and are thus difficult to react with sulfuric acid during the leaching process. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a production process for recovering non-ferrous metals from nickel iron slag. The production process for recovering non-ferrous metals from nickel iron slag has a high recovery rate, can efficiently separate the metals in nickel iron slag, improve the purity of the metals after recovery, has good properties for the non-ferrous metal materials prepared, and increases the leachability of heavy metal ions in nickel iron slag in sulfuric acid, improving the resource utilization of heavy metals.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] A production process for recovering non-ferrous metals from nickel iron slag, comprising the following steps:

[0007] S1. Before smelting, mix blast furnace nickel iron slag and electric furnace nickel iron slag, crush and vertically mill them to obtain nickel iron slag powder;

[0008] S2. Mix the nickel iron slag powder with ammonium sulfate, conduct roasting treatment at 300 - 400 °C to obtain a roasted product, and soak the roasted product in water to obtain de-magnesium nickel iron slag powder;

[0009] S3. Conduct reduction smelting on the de-magnesium nickel iron slag powder, heat it to above 1500 °C, use carbon powder as a reducing agent to reduce the iron oxide in the de-magnesium nickel iron slag powder to metallic iron during the smelting process, add calcium agents and alkaline substances during the smelting process, and quickly cool it after the metallic iron is discharged from the smelting furnace to obtain de-magnesium reduced smelting nickel iron slag;

[0010] S4. Soak the de-magnesium reduced smelting nickel iron slag in water and filter to obtain de-magnesium and de-aluminum reduced smelting nickel iron slag;

[0011] S5. Leach the de-magnesium and de-aluminum reduced smelting nickel iron slag with sulfuric acid to obtain a sulfuric acid leaching solution, add benzene tricarboxylic acid to the sulfuric acid leaching solution, and filter to separate out the precipitate;

[0012] 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;

[0013] 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.

[0014] Furthermore, the alkaline substance is one of sodium peroxide, sodium carbonate and sodium tetraborate.

[0015] Furthermore, the calcium agent is one of limestone and quicklime.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Furthermore, the nanofiltration membrane is selected from DURACID membrane or MNF-Acid membrane.

[0020] Furthermore, in the step S7, during the electrolysis process, the current used for electrodeposition is in the form of a pulse flow.

[0021] 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.

[0022] Furthermore, ammonia and sulfur dioxide can react to generate ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The production process for recovering nonferrous metals from ferronickel slag provided by the present invention comprises mixing blast furnace ferronickel slag and electric 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 placed in water for infiltration, 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.

[0025] 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

[0026] 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.

[0027] Example 1

[0028] The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps:

[0029] S1, before smelting, blast furnace ferronickel slag and electric furnace ferronickel slag are mixed and crushed, and vertically ground to obtain ferronickel slag powder;

[0030] 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.

[0031] 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;

[0032] S4, soaking the de-magnesiumized ferronickel slag in water, and filtering to obtain the de-magnesiumized ferronickel slag;

[0033] 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;

[0034] 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;

[0035] 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.

[0036] Furthermore, the alkaline substance is one of sodium peroxide, sodium carbonate and sodium tetraborate.

[0037] Furthermore, the calcium agent is one of limestone and quicklime.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] In this embodiment,

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Example 2

[0046] The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps:

[0047] S1. Before smelting, mix blast furnace nickel slag and electric furnace nickel slag, crush and vertically mill them to obtain nickel slag powder;

[0048] S2. Mix the nickel slag powder with ammonium sulfate at a mass ratio of 1:3.5, conduct roasting treatment at 360 °C to obtain a roasted product, with a roasting time of 120 min. Immerse the roasted product in water to obtain magnesium-removed nickel slag powder. Ammonia and sulfur dioxide can react to form ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.

[0049] S3. Conduct reduction smelting on the magnesium-removed nickel slag powder, heat it to above 1500 °C, use carbon powder as a reducing agent to reduce iron oxide in the magnesium-removed nickel slag powder to metallic iron during smelting. Add calcium agent quicklime and alkaline substance sodium carbonate during the smelting process. After the metallic iron is discharged from the smelting furnace, quickly cool it to obtain magnesium-removed reduced smelting nickel slag;

[0050] S4. Immerse the magnesium-removed reduced smelting nickel slag in water and filter to obtain magnesium-removed and aluminum-removed reduced smelting nickel slag;

[0051] S5. Leach the magnesium-removed and aluminum-removed reduced smelting nickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, add benzene tricarboxylic acid to the sulfuric acid leaching solution, and filter to separate the precipitate;

[0052] S6. Extract the cobalt ions and nickel ions from the sulfuric acid leaching solution treated in step S5 with tributyl phosphate to obtain a tributyl phosphate extraction solution and a mother liquor. After obtaining the tributyl phosphate extraction solution, adjust the pH of the tributyl phosphate extraction solution to alkaline, cobalt ions will form cobalt hydroxide precipitate insoluble in water, and by adding sodium carbonate, nickel ions can form nickel carbonate precipitate with relatively low solubility;

[0053] S7. Place the mother liquor in an electrolytic cell for electrolysis. By adjusting the potential, heavy metal ions in the electrolytic cell are reduced to metallic elements in the deposition order on the cathode. During electrolysis, the current form used for electrodeposition is pulsed current. Pulse electrodeposition (Pulse) adjusts the metal ion concentration at the electrode-solution interface by turning the current on and off, can effectively eliminate concentration polarization, improve the metal nucleation rate, thus forming a large number of nuclei with relatively small sizes and improving the quality of the deposited layer.

[0054] Example 3

[0055] The production process for recovering non-ferrous metals from nickel slag provided in this example includes the following steps:

[0056] S1. Before smelting, mix blast furnace nickel slag and electric furnace nickel slag, crush and vertically mill them to obtain nickel slag powder;

[0057] 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;

[0058] 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;

[0059] S4, soaking the de-magnesiumized ferronickel slag in water, and filtering to obtain the de-magnesiumized ferronickel slag;

[0060] 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;

[0061] 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;

[0062] 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.

[0063] Example 4

[0064] The production process for recovering nonferrous metals from ferronickel slag provided in this embodiment comprises the following steps:

[0065] S1, before smelting, blast furnace ferronickel slag and electric furnace ferronickel slag are mixed and crushed, and vertically ground to obtain ferronickel slag powder;

[0066] 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;

[0067] S3. Carry out reduction smelting on the magnesium-depleted nickel-iron slag powder, heat it to above 1500 °C, use carbon powder as a reducing agent, reduce the iron oxide in the magnesium-depleted nickel-iron slag powder to metallic iron during the smelting process, add calcium agent limestone and alkaline substance sodium peroxide during the smelting process. After the metallic iron is discharged from the smelting furnace, it is rapidly cooled to obtain magnesium-depleted reduced smelting nickel-iron slag;

[0068] S4. Immerse the magnesium-depleted reduced smelting nickel-iron slag in water and filter to obtain magnesium-depleted and aluminum-depleted reduced smelting nickel-iron slag;

[0069] S5. Leach the magnesium-depleted and aluminum-depleted reduced smelting nickel-iron slag with sulfuric acid to obtain a sulfuric acid leaching solution. Use a nanofiltration membrane DURACID membrane with appropriate pore size and charge characteristics to achieve selective separation of metal ions in the sulfuric acid leaching solution according to the size and charge properties of metal ions.

[0070] The selective layer of the MNF-Acid membrane is the thinnest, has strong hydrophilicity, and has the highest permeability. Both the 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.

[0071] Example 5

[0072] The production process for recovering non-ferrous metals from nickel-iron slag provided in this example includes the following steps:

[0073] S1. Before smelting, mix blast furnace nickel-iron slag, electric furnace nickel-iron slag, and blast furnace nickel-iron slag, carry out crushing and vertical grinding to obtain nickel-iron slag powder;

[0074] S2. Mix the nickel-iron slag powder and ammonium sulfate, the mass ratio of the nickel-iron slag powder to ammonium sulfate is 1:3.5, carry out roasting treatment at 300 °C to obtain a roasted product, the roasting time is 120 min, immerse the roasted product in water to obtain magnesium-depleted nickel-iron slag powder;

[0075] S3. Carry out reduction smelting on the magnesium-depleted nickel-iron slag powder, heat it to above 1500 °C, use carbon powder as a reducing agent, reduce the iron oxide in the magnesium-depleted nickel-iron slag powder to metallic iron during the smelting process, add calcium agent limestone and alkaline substance sodium peroxide during the smelting process. After the metallic iron is discharged from the smelting furnace, it is rapidly cooled to obtain magnesium-depleted reduced smelting nickel-iron slag;

[0076] S4. Immerse the magnesium-depleted reduced smelting nickel-iron slag in water and filter to obtain magnesium-depleted and aluminum-depleted reduced smelting nickel-iron slag;

[0077] S5. Leach the magnesium-depleted and aluminum-depleted reduced smelting nickel-iron slag with sulfuric acid to obtain a sulfuric acid leaching solution. Use a nanofiltration membrane MNF-Acid membrane with appropriate pore size and charge characteristics to achieve selective separation of metal ions in the sulfuric acid leaching solution according to the size and charge properties of metal ions.

[0078] The above embodiments are only the preferred embodiments of the present invention, and the scope of protection of the present invention cannot be limited thereby. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A production process for recovering non-ferrous metals from nickel-iron slag, characterized in that, It includes the following steps: S1. Before smelting, mix blast furnace nickel slag and electric furnace nickel slag, crush and vertically grind them to obtain nickel slag powder; S2. Mix the nickel slag powder with ammonium sulfate, conduct roasting treatment at 300 - 400 °C to obtain a roasted product, soak the roasted product in water to obtain magnesium - removed nickel slag powder; S3. Conduct reduction smelting on the magnesium - removed nickel slag powder, heat it to above 1500 °C, use carbon powder as a reducing agent to reduce iron oxide in the magnesium - removed nickel slag powder to metallic iron during the smelting process, add calcium agent and alkaline substance during the smelting process, and after the metallic iron is discharged from the smelting furnace, quickly cool it to obtain magnesium - removed reduced smelting nickel slag; S4. Soak the magnesium - removed reduced smelting nickel slag in water and filter to obtain magnesium - removed and aluminum - removed reduced smelting nickel slag; S5. Leach the magnesium - removed and aluminum - removed reduced smelting nickel slag with sulfuric acid to obtain a sulfuric acid leaching solution, add benzene - tricarboxylic acid to the sulfuric acid leaching solution, and filter to separate out the precipitate; S6. Extract the cobalt ions and nickel ions from the sulfuric acid leaching solution processed in step S5 with tributyl phosphate to obtain a tributyl phosphate extraction solution and a mother liquor; S7. Place the mother liquor in an electrolytic cell for electrolysis. By adjusting the potential, heavy metal ions in the electrolytic cell are reduced to metal elements in accordance with the deposition sequence on the cathode; The alkaline substance is one of sodium peroxide, sodium carbonate, and sodium tetraborate.

2. The production process for recovering non-ferrous metals from nickel-iron slag according to claim 1, characterized in that, The calcium agent is one of limestone and quicklime.

3. The production process for recovering non-ferrous metals from nickel-iron slag as claimed in claim 1, characterized in that, In step S6, after obtaining the tributyl phosphate extraction solution, adjust the pH of the tributyl phosphate extraction solution to alkaline, cobalt ions will form cobalt hydroxide precipitate insoluble in water, and by adding sodium carbonate, nickel ions will form nickel carbonate precipitate.

4. The production process for recovering non-ferrous metals from nickel iron slag as described in claim 1, characterized in that, In step S2, the mass ratio of the nickel slag powder to the ammonium sulfate is 1:3.5, and the roasting time is 120 min.

5. The production process for recovering non-ferrous metals from nickel-iron slag as claimed in claim 1, characterized in that, In step S5, after obtaining the sulfuric acid leaching solution, use a nanofiltration membrane with a suitable pore size and charge characteristics to selectively separate metal ions in the sulfuric acid leaching solution according to the size and charge properties of metal ions.

6. The production process for recovering non-ferrous metals from nickel-iron slag as described in claim 5, characterized in that, The nanofiltration membrane selects DURACID membrane or MNF - Acid membrane.

7. The production process for recovering non-ferrous metals from nickel iron slag as described in claim 1, characterized in that, In step S7, during the electrolysis process, the current form used for electrodeposition is pulsed current.

8. The production process for recovering non-ferrous metals from nickel-iron slag according to claim 1, characterized in that, In step S2, after the roasting treatment, ammonia and sulfur dioxide are also generated. Ammonia and sulfur dioxide are selectively separated by water or lime slurry. After separation, sulfur dioxide is used as a raw material for producing sulfuric acid, and the produced sulfuric acid is used in step S5.

9. The production process for recovering non-ferrous metals from nickel iron slag as described in claim 8, characterized in that, Ammonia and sulfur dioxide react to form ammonium sulfite, which is further oxidized to ammonium sulfate and then used in step S2.