Recovery treatment process of nickel smelting slag

Abstract

The invention belongs to the technical field of metallurgical slag resource utilization, and particularly relates to a nickel smelting slag recycling process. Comprising the following steps: mixing and drying stainless steel pickling sludge, Bayer process red mud and coke powder to prepare iron-containing coke powder; setting a slag pot position and a spray gun position; when the molten nickel smelting slag falls down, iron-containing coke powder is sprayed out at a constant speed through argon by using a spray gun, the molten nickel smelting slag is blown away, and then a reduction reaction is carried out; a fluxing agent is added into the reduced molten nickel smelting slag, then vacuumizing is conducted, magnesium is reduced and evaporated, magnesium steam is collected and cooled, and elementary substance magnesium and magnesium-removed molten nickel smelting slag are obtained; coke powder and metal carbide powder are added into the magnesium-removed molten nickel smelting slag, cooling is conducted after reaction, reaction materials are taken to be crushed, ground and magnetically separated, Fe-Ni-Cr enriched alloy is obtained and used for a steel plant, remaining materials are used as aggregate in a cement plant, the production process is simple, the recovery process is short, energy consumption of equipment can be greatly reduced, and the metal recovery rate is increased.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical slag resource utilization technology, specifically relating to a recycling and treatment process for nickel smelting slag. Background Technology

[0002] In modern industry, nickel, as an important strategic metal, is widely used in alloy manufacturing, battery materials, and superalloys. However, the large amount of waste slag generated during its smelting process often contains unreacted metals, compounds, and other recyclable resources, resulting not only in resource waste but also causing serious environmental pollution if the waste slag is not properly treated. Therefore, developing a resource utilization technology for nickel-containing smelting slag that can effectively recover valuable metals while reducing environmental pollution has significant economic value.

[0003] Currently, the main technical routes for treating nickel-containing smelting slag include hydrometallurgy, pyrometallurgy, and bio-smelting. Hydrometallurgy is an emerging process in the nickel-cobalt smelting industry, mainly consisting of three steps: leaching, extraction, and electrolysis. It has low energy consumption and low pollution, but the process is complex and costly. Bio-smelting mainly utilizes microorganisms to dissolve nickel and cobalt in nickel-cobalt ore into a solution, and then separates the nickel and cobalt from the solution through chemical methods. It is green and environmentally friendly with low energy consumption, but it also suffers from complex processes and high costs. Pyrometallurgy is a traditional process in the nickel smelting industry, mainly consisting of three steps: roasting, reduction, and refining. Its process is mature and reliable, but due to the need for continuous high-temperature roasting of the nickel smelting slag and the inability of the reducing agent to fully penetrate into the roasted liquid smelting slag upon addition, resulting in uneven dispersion and slow reduction efficiency, it further prolongs the high-temperature roasting time. Therefore, pyrometallurgy suffers from high energy consumption. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention presents a recycling process for nickel smelting slag. This recycling process improves upon pyrometallurgical methods by modifying the reducing agent and mixing process, and is conducted entirely in a vacuum furnace. The production process is simple, the recycling flow is short, and it can significantly reduce equipment energy consumption. Furthermore, by controlling the reduction conditions and adding metal carbides, nickel and chromium are enriched in iron, thereby improving the metal recovery rate.

[0005] A process for recycling nickel smelting slag includes the following steps: S1: Mix stainless steel pickling sludge, Bayer red mud and coke powder in a mass ratio of 1:(1-1.5):(10-15), then dry at 80-100℃ until the moisture content is 8-10%, crush and grind into powder to obtain iron-containing coke powder, and add it into the spray gun. S2: Collect the freshly molten nickel smelting slag and load it into a slag pot. The molten nickel smelting slag occupies 2 / 3 of the volume of the slag pot. Suspend and fix the slag pot containing the molten nickel smelting slag in the upper part of the vacuum special atmosphere furnace. Set the nozzle of the spray gun in step S1 in the lower part of the vacuum special atmosphere furnace. The bottom of the slag pot is equipped with a door. When the external air pressure of the slag pot decreases to 15000Pa, the door will automatically open downward under the action of the air pressure difference. S3: The furnace body of the sealed vacuum special atmosphere furnace is evacuated at a uniform speed to 16000-16500Pa. The furnace is preheated to 600-800℃ at a heating rate of 10-15℃ / min, and then the vacuum is continued to 10000-12000Pa. When the opening at the bottom of the slag pot is opened, the molten nickel smelting slag flows out from the slag pot. At this time, the spray gun is turned on, and iron-containing coke powder is sprayed out at a uniform speed through argon gas. The flow rate is set to 3-5m / s. The argon gas carries the iron-containing coke powder and blows the molten nickel smelting slag into small droplets, which then flow into the furnace bottom along the furnace wall. When all the molten nickel smelting slag has flowed into the furnace bottom, the furnace temperature is raised to 1500-1550℃ and held for 20-25 minutes to obtain reduced molten nickel smelting slag. S4: Add flux accounting for 2-5% of the mass of the reduced molten nickel smelting slag into the furnace, keep the temperature inside the vacuum special atmosphere furnace constant, continue to evacuate the vacuum inside the furnace to 750-1000Pa, heat for 5-10 minutes, then introduce argon gas to discharge the magnesium vapor generated in the furnace through the exhaust system, and then collect and cool it through the collection device to obtain elemental magnesium. Demagnesized molten nickel smelting slag is generated in the furnace. S5: Cool the vacuum special atmosphere furnace to 1300-1350℃, then add 4.5-5% coke powder and 0.1-0.5% (Cr,Fe)7C3 metal carbide powder (by mass of the demagnesified molten nickel slag) into the furnace. After holding the reaction at this temperature for 1-1.5 hours, cool the furnace to room temperature. Remove the material from the furnace, crush and grind it, and then perform magnetic separation to obtain Fe-Ni-Cr enriched alloy, which can be used directly in steel plants. The remaining material after magnetic separation can be used as aggregate in cement plants.

[0006] Furthermore, in step S1, the main chemical components of the stainless steel pickling sludge have a mass fraction of 30-32.5% O, 30-31.4% Ca, 20-23% Fe, 3-3.51% Cr, 3.21-3.34% F, 1.94-2.18% Si, 0.83-1.01% Mn and 0.62-0.81% Ni, and the main chemical components of the Bayer process red mud have a mass fraction of 20-23% SiO2, 2-8% CaO, 10-20% Al2O3, 40-60% Fe2O3, 2-10% Na2O and 1-3% TiO2.

[0007] Furthermore, the molten nickel slag in step S2 is electric furnace nickel-iron slag, which belongs to the SiO2-MgO-Fe2O3 ternary slag system.

[0008] Furthermore, in step S2, when the external air pressure of the slag pot decreases, the opening automatically opens under the action of pressure. Specifically, the opening automatically opens when the external air pressure decreases to less than 15000Pa.

[0009] Furthermore, in step S2, the slag pot containing molten nickel smelting slag is suspended and fixed above the inside of the vacuum special atmosphere furnace by a silicon carbide support. The furnace wall of the vacuum special atmosphere furnace is also provided with a vacuum cover and a splash guard from the inside to the outside. The splash guard has an insertion port, and the vacuum cover has a vacuum port. The spray gun extends into the furnace through the insertion port and the vacuum port, and the nozzle of the spray gun is located 20-30cm below the opening of the slag pot, and the parallel distance from the center of the opening of the slag pot is 35-50cm.

[0010] Furthermore, in step S3, the total amount of iron-containing coke powder injected is 1.2-1.3 times the sum of the molar masses of iron, silicon, and aluminum in the molten nickel smelting slag.

[0011] Furthermore, the flux in step S4 is CaF2.

[0012] Furthermore, the magnetic separation intensity in step S5 is 100-150 MT. Beneficial effects

[0013] 1. This invention utilizes a spray gun to spray argon-loaded iron-containing coke powder onto falling molten nickel smelting slag within a high-temperature vacuum special atmosphere furnace. Under the action of the airflow, the molten nickel smelting slag is dispersed into small molten droplets, which then flow down the furnace wall to the furnace bottom. During this process, the iron-containing coke powder fully contacts and combines with the large number of molten droplets formed. When the molten droplets re-aggregate into molten nickel smelting slag at the furnace bottom, the molten droplets carry the iron-containing coke powder and are evenly dispersed into the molten nickel smelting slag. This significantly increases the carbon reduction area, greatly shortens the time for carbon reduction of metal oxides, reduces the heating time of the vacuum special atmosphere furnace, and thus significantly reduces the energy consumption of the equipment.

[0014] 2. This invention mixes and dries stainless steel pickling sludge, Bayer red mud and coke powder to obtain an iron-containing coke powder reducing agent. When the iron-containing coke powder reducing agent is mixed into molten nickel smelting slag, it can quickly initiate the reduction reaction of SiO2, Fe2O3 and carbon, which have a high content in the molten nickel smelting slag, thereby further shortening the reduction reaction time and reducing equipment energy consumption.

[0015] 3. In the process of adding iron-containing coke powder for reduction, this invention first controls the reduction reaction conditions to 10000-12000 Pa and 1500-1550 °C, and adds iron-containing coke powder at a ratio of 1.2-1.3 times the sum of the molar masses of iron, silicon, and aluminum. This allows the Fe oxides and SiO2 in the molten nickel smelting slag to be reduced first, generating an iron-silicon alloy phase. Then, the reduction reaction conditions are controlled at 750-1000 Pa, with the temperature remaining constant, thereby triggering the reduction reaction of magnesium oxides and aluminum oxides. Under the reduction action of residual carbon and the iron-silicon alloy phase, elemental magnesium and elemental aluminum are generated. At high temperature, elemental magnesium vaporizes into magnesium vapor, and then Ar gas is introduced to exhaust the magnesium vapor for collection and cooling, achieving the purpose of magnesium recovery. At the same time, the magnesium-aluminum spinel phase in the molten nickel smelting slag is destroyed, preventing its adsorption of heavy metal ions during subsequent cooling, thereby better generating Fe-Ni-Cr alloy and improving the metal recovery rate.

[0016] 4. This invention involves adding coke powder and metal carbide (Cr,Fe)7C3 to the demagnesified molten nickel slag in an Ar atmosphere. The coke powder further reduces iron, nickel, and chromium oxides, while the metal carbide (Cr,Fe)7C3 promotes the migration and enrichment of the generated nickel and chromium elements into the Fe element. This results in the formation of a high-purity Fe-Ni-Cr enriched gold during subsequent cooling, which can be separated from other materials by magnetic separation, significantly improving the metal recovery rate.

[0017] 5. The valuable metal recycling process of the present invention effectively utilizes the temperature of the nickel slag when it comes out of the furnace. The entire recycling process is carried out in a vacuum furnace from beginning to end. It only requires adjusting the parameters in the vacuum furnace and adding materials at specific times, and finally cooling and magnetic separation. The recycling process is simple to operate, has a short process, and low energy consumption, making it very suitable for industrial production. Attached Figure Description

[0018] Figure 1 This is a flow chart of the nickel smelting slag recycling process used in an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0020] A recycling process for nickel smelting slag, such as Figure 1 As shown, it includes the following steps: S1: Mix stainless steel pickling sludge, Bayer red mud and coke powder in a mass ratio of 1:1:10, then dry at 80°C until the moisture content is 8%, crush and grind into powder to obtain iron-containing coke powder, and add it into the spray gun. S2: Collect the freshly molten nickel slag and load it into a slag pot. The molten nickel slag is electric furnace nickel-iron slag, belonging to the SiO2-MgO-Fe2O3 ternary slag system. The molten nickel slag occupies 2 / 3 of the slag pot volume. The slag pot containing the molten nickel slag is suspended and fixed above the inside of the vacuum special atmosphere furnace by a silicon carbide support. The vacuum special atmosphere furnace wall is provided with a vacuum cover and a splash guard from the inside to the outside. The nozzle of the spray gun in step S1 is set inside the vacuum special atmosphere furnace at the bottom. The nozzle of the spray gun is located 20cm below the opening of the slag pot and 35cm away from the center of the opening of the slag pot. The bottom of the slag pot is provided with a door. When the external air pressure of the slag pot decreases to below 15000Pa, the door will automatically open downward under the action of the air pressure difference. S3: The furnace body of the sealed vacuum special atmosphere furnace is evacuated to 16000Pa at a uniform speed. The furnace is preheated to 600°C at a heating rate of 10°C / min, and then evacuated to 10000Pa. When the opening at the bottom of the slag pot is opened, the molten nickel smelting slag flows out of the slag pot. At this time, the spray gun is turned on, and iron-containing coke powder is sprayed out at a uniform speed through argon gas. The flow rate is set to 3m / s. The total amount of iron-containing coke powder injected is 1.2 times the sum of the molar masses of iron, silicon and aluminum elements in the molten nickel smelting slag. The argon gas carries the iron-containing coke powder and blows the molten nickel smelting slag into small droplets, which then flow into the furnace bottom along the furnace wall. When all the molten nickel smelting slag has flowed into the furnace bottom, the furnace temperature is raised to 1500°C and held for 20 minutes to obtain reduced molten nickel smelting slag. S4: Add CaF2 accounting for 2% of the mass of the reduced molten nickel smelting slag into the furnace, keep the temperature inside the vacuum special atmosphere furnace constant, continue to evacuate the vacuum inside the furnace to 750Pa, heat for 5 minutes, then introduce argon gas to discharge the magnesium vapor generated in the furnace through the exhaust system, and then collect and cool it through the collection device to obtain elemental magnesium. Demagnesated molten nickel smelting slag is generated in the furnace. S5: Cool the vacuum special atmosphere furnace to 1300℃, then add 4.5% coke powder and 0.1% (Cr,Fe)7C3 metal carbide powder (by mass of the demagnesified molten nickel slag) to the furnace. After holding the reaction at this temperature for 1 hour, cool the furnace to room temperature. Remove the material from the furnace, crush and grind it, and then perform magnetic separation at a magnetic separation intensity of 100MT to obtain Fe-Ni-Cr enriched alloy, which can be directly used in steel plants. The remaining material after magnetic separation can be used as aggregate in cement plants. Example

[0021] A recycling process for nickel smelting slag, such as Figure 1 As shown, it includes the following steps: S1: Stainless steel pickling sludge, Bayer red mud and coke powder are mixed evenly in a mass ratio of 1:1.5:15, then dried at 80°C until the moisture content is 8%, crushed and ground into powder to obtain iron-containing coke powder. S2: Collect the freshly molten nickel slag and load it into a slag pot. The molten nickel slag is electric furnace nickel-iron slag, belonging to the SiO2-MgO-Fe2O3 ternary slag system. The molten nickel slag occupies 2 / 3 of the slag pot volume. The slag pot containing the molten nickel slag is suspended and fixed above the inside of the vacuum special atmosphere furnace by a silicon carbide support. The vacuum special atmosphere furnace wall is provided with a vacuum cover and a splash guard from the inside to the outside. The nozzle of the spray gun in step S1 is set inside the vacuum special atmosphere furnace at the bottom. The nozzle of the spray gun is located 20cm below the opening of the slag pot and 35cm away from the center of the opening of the slag pot. The bottom of the slag pot is provided with a door. When the external air pressure of the slag pot decreases to below 15000Pa, the door will automatically open downward under the action of the air pressure difference. S3: The furnace body of the sealed vacuum special atmosphere furnace is evacuated to 16000Pa at a uniform speed. The furnace is preheated to 600°C at a heating rate of 10°C / min, and then evacuated to 10000Pa. When the opening at the bottom of the slag pot is opened, the molten nickel smelting slag flows out of the slag pot. At this time, the spray gun is turned on, and iron-containing coke powder is sprayed out at a uniform speed through argon gas. The flow rate is set to 3m / s. The total amount of iron-containing coke powder injected is 1.3 times the sum of the molar masses of iron, silicon and aluminum elements in the molten nickel smelting slag. The argon gas carries the iron-containing coke powder and blows the molten nickel smelting slag into small droplets, which then flow into the furnace bottom along the furnace wall. When all the molten nickel smelting slag has flowed into the furnace bottom, the furnace temperature is raised to 1500°C and held for 20 minutes to obtain reduced molten nickel smelting slag. S4: Add CaF2 accounting for 5% of the mass of the reduced molten nickel smelting slag into the furnace, keep the temperature inside the vacuum special atmosphere furnace constant, continue to evacuate the vacuum inside the furnace to 750Pa, heat for 5 minutes, and then introduce argon gas to discharge the magnesium vapor generated in the furnace through the exhaust system, and then collect and cool it through the collection device to obtain elemental magnesium. Demagnesated molten nickel smelting slag is generated in the furnace. S5: Cool the vacuum special atmosphere furnace to 1300℃, then add 5% coke powder and 0.5% (Cr,Fe)7C3 metal carbide powder (by mass of the demagnesified molten nickel slag) to the furnace. After holding the reaction at this temperature for 1 hour, cool the furnace to room temperature. Remove the material from the furnace and crush and grind it. Then, perform magnetic separation at a magnetic separation intensity of 100MT to obtain Fe-Ni-Cr enriched alloy, which can be directly used in steel plants. The remaining material after magnetic separation can be used as aggregate in cement plants. Example

[0022] A recycling process for nickel smelting slag, such as Figure 1 As shown, it includes the following steps: S1: Stainless steel pickling sludge, Bayer red mud and coke powder are mixed evenly in a mass ratio of 1:1:10, then dried at 100°C until the moisture content is 10%, crushed and ground into powder to obtain iron-containing coke powder. S2: Collect the freshly molten nickel slag and load it into a slag pot. The molten nickel slag is electric furnace nickel-iron slag, belonging to the SiO2-MgO-Fe2O3 ternary slag system. The molten nickel slag occupies 2 / 3 of the slag pot volume. The slag pot containing the molten nickel slag is suspended and fixed above the inside of the vacuum special atmosphere furnace by a silicon carbide support. The vacuum special atmosphere furnace wall is provided with a vacuum cover and a splash guard from the inside to the outside. The nozzle of the spray gun in step S1 is set inside the vacuum special atmosphere furnace at the bottom. The nozzle of the spray gun is located 30cm below the opening of the slag pot and 50cm away from the center of the opening of the slag pot. The bottom of the slag pot is provided with a door. When the external air pressure of the slag pot decreases to below 15000Pa, the door will automatically open downward under the action of the air pressure difference. S3: The furnace body of the sealed vacuum special atmosphere furnace is evacuated to 16500Pa at a uniform speed. The furnace is preheated to 800°C at a heating rate of 15°C / min, and then evacuated to 12000Pa. When the opening at the bottom of the slag pot is opened, the molten nickel smelting slag flows out of the slag pot. At this time, the spray gun is turned on, and iron-containing coke powder is sprayed out at a uniform speed through argon gas. The flow rate is set to 5m / s. The total amount of iron-containing coke powder injected is 1.2 times the sum of the molar masses of iron, silicon and aluminum elements in the molten nickel smelting slag. The argon gas carries the iron-containing coke powder and blows the molten nickel smelting slag into small droplets, which then flow into the furnace bottom along the furnace wall. When all the molten nickel smelting slag has flowed into the furnace bottom, the furnace temperature is raised to 1550°C and held for 20 minutes to obtain reduced molten nickel smelting slag. S4: Add CaF2 accounting for 2% of the mass of the reduced molten nickel smelting slag into the furnace, keep the temperature inside the vacuum special atmosphere furnace constant, continue to evacuate the vacuum inside the furnace to 1000Pa, heat for 10 minutes, then introduce argon gas to discharge the magnesium vapor generated in the furnace through the exhaust system, and then collect and cool it through the collection device to obtain elemental magnesium. Demagnesized molten nickel smelting slag is generated in the furnace. S5: Cool the vacuum special atmosphere furnace to 1350℃, then add 4.5% coke powder and 0.1% (Cr,Fe)7C3 metal carbide powder (by mass of the demagnesified molten nickel slag) to the furnace. After holding the reaction at this temperature for 1.5 hours, cool the furnace to room temperature. Remove the material from the furnace, crush and grind it, and then perform magnetic separation at a magnetic separation intensity of 100MT to obtain Fe-Ni-Cr enriched alloy, which can be directly used in steel plants. The remaining material after magnetic separation can be used as aggregate in cement plants.

[0023] Comparative Example 1 A recycling process for nickel smelting slag differs from Example 1 in that, in Comparative Example 1, the freshly removed molten nickel smelting slag is directly loaded into a vacuum special atmosphere furnace in step S2, and in step S3, after the furnace is evacuated to a vacuum of 10000 Pa, the spray gun is directly turned on, and iron-containing coke powder is uniformly sprayed into the molten nickel smelting slag using argon gas. After the iron-containing coke powder is sprayed out, the temperature is raised to 1500°C and held for 20 minutes to obtain reduced molten nickel smelting slag. The remaining steps are the same as in Example 1.

[0024] Comparative Example 2 A recycling process for nickel smelting slag differs from Example 1 in that, in Comparative Example 2, iron-containing coke powder was not prepared, and the iron-containing coke powder in step S3 was replaced with coke powder of equal mass. The remaining steps are the same as in Example 1.

[0025] Comparative Example 3 A recycling process for nickel smelting slag differs from Example 1 in that (Cr,Fe)7C3 metal carbide powder was not added in step S5 in Comparative Example 3, while the remaining steps were the same as in Example 1.

[0026] Experiment 1: Molten nickel slag (from the same batch and of equal mass) fresh from Examples 1-3, Comparative Example 1, and Comparative Example 2 were cooled into solid slag samples. The same amount of iron-containing coke powder as in Examples 1-3 and Comparative Example 1 was added to the solid slag samples from Examples 1-3 and Comparative Example 1, respectively. The same amount of coke powder as in Comparative Example 2 was added to the solid slag sample from Comparative Example 2. Test samples I for each group were obtained. The mass of test sample I for each group was measured and recorded as m1. 0.1g of the test sample was taken from each group. Sample I was placed in a 250 mL tetrafluoroethylene beaker. A small amount of deionized water was added first until the sample no longer stuck to the inner wall of the beaker. Then, while stirring, 15 mL of concentrated hydrochloric acid, 5 mL of concentrated nitric acid, 10 mL of hydrofluoric acid, and 10 mL of concentrated sulfuric acid were added sequentially. The beaker was then heated continuously until the liquid in the beaker boiled dry and all white fumes were emitted. Heating was stopped, and the beaker was cooled to room temperature and rinsed with water. Then, 5 mL of concentrated hydrochloric acid was added, and the solution was heated to near boiling. After cooling to room temperature, the solution was transferred to a 100 mL volumetric flask and diluted to volume. The total iron content (w1) of 0.1 g of sample I was measured according to the national standard GB / T63705-2007, "Determination of Total Iron Content in Iron Ore - Titanium Trichloride Reduction Method". The same batch and mass of molten nickel smelting slag as those in the above experiments were used to prepare reduced molten nickel smelting slag through the implementation methods of Examples 1-3, Comparative Examples 1 and 2. The slag was cooled to solidify to obtain test samples II for each group. The mass of test sample II for each group was measured and recorded as m2. 0.1g of test sample II for each group was taken and its metallic iron content w2 was measured according to the national standard GB / T6730.6-2016 Determination of metallic iron content in iron ore by titration with titanium trichloride-sodium acetate. The total iron mass of test sample I for each group was calculated as w1×m1, and the metallic iron content of test sample II for each group was calculated as w2×m2. The Fe metallization rate for each group was calculated as (w2×m2) / (w1×m1)×100%. In the same time period, the higher the Fe metallization rate, the higher the reduction efficiency. Three parallel experiments were conducted, and the data were recorded and compiled into a table, as shown in Table 1.

[0027] Table 1: Fe metallization rate of molten nickel smelting slag and iron-containing coke powder

[0028] As can be seen from the data in Table 1, under the same reduction time, the Fe metallization rate of Examples 1-3 is significantly higher than that of Comparative Examples 1-2. This proves that by spraying argon-loaded iron-containing coke powder onto falling molten nickel smelting slag through a spray gun, the time for C to reduce metal oxides can be significantly shortened, the heating time of the vacuum special atmosphere furnace can be reduced, and thus the energy consumption of the equipment can be reduced. At the same time, it also proves that by preparing an iron-containing coke powder reducing agent by combining stainless steel pickling sludge, Bayer red mud and coke powder, the efficiency of the carbon reducing agent in the reduction reaction can be improved.

[0029] Experiment 2: Seven portions of freshly molten nickel smelting slag (from the same batch and of the same mass) were taken. One portion was cooled into a solid state and mixed with iron-containing coke powder as in Example 1 to obtain slag material. The mass of this material was measured and recorded as m. 渣 The remaining six samples were divided into two groups of three, and Fe-Ni-Cr enriched gold alloys were prepared using the steps in Example 1 and Comparative Example 3, respectively. The mass of each sample was recorded as m. 合金 The content of each metal element in the slag was measured and recorded as W. 渣Fe W 渣Ni and W 渣Cr The contents of each metal element in the Fe-Ni-Cr enriched alloys of Example 1 and Comparative Example 3 were measured and denoted as W. 合金Fe W 合金Ni and W 合金Cr Calculate the Fe recovery rate = (m 合金 ×W 合金Fe ) / (m 渣 ×W 渣Fe) × 100%, Ni recovery rate = (m 合金 ×W 合金Ni ) / (m 渣 ×W 渣Ni ) × 100%, Cr recovery rate = (m 合金 ×W 合金Cr ) / (m 渣 ×W 渣Cr () × 100%, and the recorded data is shown in Table 2.

[0030] Table 2: Recovery rates of various metal elements in molten nickel smelting slag and iron-containing coke powder

[0031] As can be seen from the data in Table 2, the metal recovery rates of Fe, Ni, and Cr in Example 1 are all higher than those in Comparative Example 3. When (Cr,Fe)7C3 metal carbide powder is not added, the Fe recovery rate decreases from about 91% to 88%, which is not much different. However, the Ni recovery rate decreases from about 90% to about 72.5%, and the Cr recovery rate decreases from about 82% to about 49%. This proves that the main function of (Cr,Fe)7C3 metal carbide powder is to enrich Ni and Cr into Fe, thereby generating Fe-Ni-Cr alloy, which can be magnetically separated and improve the recovery rate of Ni and Cr.

[0032] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A process for recycling and treating nickel smelting slag, characterized in that, Includes the following steps: S1: Mix stainless steel pickling sludge, Bayer red mud and coke powder in a mass ratio of 1:(1-1.5):(10-15), then dry at 80-100℃ until the moisture content is 8-10%, crush and grind into powder to obtain iron-containing coke powder, and add it into the spray gun. S2: Collect the freshly molten nickel smelting slag and load it into a slag pot. The molten nickel smelting slag occupies 2 / 3 of the volume of the slag pot. Suspend and fix the slag pot containing the molten nickel smelting slag in the upper part of the vacuum special atmosphere furnace. Set the nozzle of the spray gun in step S1 in the lower part of the vacuum special atmosphere furnace. The bottom of the slag pot is equipped with a door. When the external air pressure of the slag pot decreases to 15000Pa, the door will automatically open downward under the action of the air pressure difference. S3: The furnace body of the sealed vacuum special atmosphere furnace is evacuated at a uniform speed to 16000-16500Pa. The furnace is preheated to 600-800℃ at a heating rate of 10-15℃ / min, and then the vacuum is continued to 10000-12000Pa. When the opening at the bottom of the slag pot is opened, the molten nickel smelting slag flows out from the slag pot. At this time, the spray gun is turned on, and iron-containing coke powder is sprayed out at a uniform speed through argon gas. The flow rate is set to 3-5m / s. The argon gas carries the iron-containing coke powder and blows the molten nickel smelting slag into small droplets, which then flow into the furnace bottom along the furnace wall. When all the molten nickel smelting slag has flowed into the furnace bottom, the furnace temperature is raised to 1500-1550℃ and held for 20-25 minutes to obtain reduced molten nickel smelting slag. S4: Add flux accounting for 2-5% of the mass of the reduced molten nickel smelting slag into the furnace, keep the temperature inside the vacuum special atmosphere furnace constant, continue to evacuate the vacuum inside the furnace to 750-1000Pa, heat for 5-10 minutes, then introduce argon gas to discharge the magnesium vapor generated in the furnace through the exhaust system, and then collect and cool it through the collection device to obtain elemental magnesium. Demagnesized molten nickel smelting slag is generated in the furnace. S5: Cool the vacuum special atmosphere furnace to 1300-1350℃, then add 4.5-5% coke powder and 0.1-0.5% (Cr,Fe)7C3 metal carbide powder (by mass of the demagnesified molten nickel slag) into the furnace. After holding the reaction at this temperature for 1-1.5 hours, cool the furnace to room temperature. Remove the material from the furnace, crush and grind it, and then perform magnetic separation to obtain Fe-Ni-Cr enriched alloy, which can be used directly in steel plants. The remaining material after magnetic separation can be used as aggregate in cement plants.

2. The nickel smelting slag recycling process according to claim 1, characterized in that, In step S1, the main chemical components of the stainless steel pickling sludge have a mass fraction of 30-32.5% O, 30-31.4% Ca, 20-23% Fe, 3-3.51% Cr, 3.21-3.34% F, 1.94-2.18% Si, 0.83-1.01% Mn and 0.62-0.81% Ni. The main chemical components of the Bayer process red mud have a mass fraction of 20-23% SiO2, 2-8% CaO, 10-20% Al2O3, 40-60% Fe2O3, 2-10% Na2O and 1-3% TiO2.

3. The recycling and treatment process for nickel smelting slag according to claim 1, characterized in that, The molten nickel slag in step S2 is electric furnace nickel-iron slag, which belongs to the SiO2-MgO-Fe2O3 ternary slag system.

4. The process for recycling and treating nickel smelting slag according to claim 1, characterized in that, In step S2, the slag pot containing molten nickel smelting slag is suspended and fixed above the inside of the vacuum special atmosphere furnace by a silicon carbide support. The furnace wall of the vacuum special atmosphere furnace is also provided with a vacuum cover and a splash guard from the inside to the outside. The splash guard has an insertion port and the vacuum cover has a vacuum port. The spray gun extends into the furnace through the insertion port and the vacuum port, and the nozzle of the spray gun is located 20-30cm below the opening of the slag pot, and the parallel distance from the center of the opening of the slag pot is 35-50cm.

5. The process for recycling and treating nickel smelting slag according to claim 1, characterized in that, In step S3, the total amount of iron-containing coke powder injected is 1.2-1.3 times the sum of the molar masses of iron, silicon and aluminum in the molten nickel smelting slag.

6. The process for recycling and treating nickel smelting slag according to claim 1, characterized in that, The flux in step S4 is CaF2.

7. The process for recycling and treating nickel smelting slag according to claim 1, characterized in that, The magnetic separation intensity in step S5 is 100-150 MT.

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