A method for recovering valuable metals from converter steel slag

Abstract

The application provides a method for recovering valuable metals based on converter steel slag, comprising the following steps: S1, designing the mixing ratio of two kinds of waste slag according to the components of the converter steel slag and tungsten-molybdenum acid slag, so that the liquid phase temperature of the mixed material is between 1100-1300 DEG C; S2, after determining the mixing ratio of the converter steel slag and the tungsten-molybdenum acid slag, determining the adding amount of the silicon reducing agent according to the total amount of oxygen elements in the highest oxides of the valuable metals in the mixed material of the converter steel slag and the tungsten-molybdenum acid slag; S3, uniformly mixing the converter steel slag, the tungsten-molybdenum acid slag and the silicon reducing agent according to the determined adding ratio to obtain mixed material I; S4, placing the mixed material I into a crucible and heating in an inert atmosphere to make the sample melt completely, then performing constant temperature treatment to obtain a stable melt, and after the smelting is finished, separating the metal from the slag phase after cooling to room temperature. Through the cooperative smelting of the converter steel slag and the tungsten-molybdenum acid slag, the valuable metals in the converter steel slag and the tungsten-molybdenum acid slag can be effectively recovered, and the method has remarkable environmental and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valuable metal recovery, in particular to a method for recovering valuable metals based on converter steel slag. BACKGROUND

[0002] Converter steel slag and tungsten-molybdenum acid slag are two important industrial solid wastes generated in the smelting process of iron and steel and non-ferrous metals. At present, China's iron and steel industry produces about 420 million tons of smelting slag per year, and the non-ferrous metal industry produces 128 million tons of waste slag per year. However, the resource utilization rate of solid waste in these two industries is generally low, and the resource utilization rate of converter steel slag is less than 30%, and low-grade tungsten-molybdenum acid slag is largely stored in enterprises, resulting in a large waste of metal resources. Therefore, efficient recovery of valuable metal resources from metallurgical solid waste is a key problem that needs to be solved for the sustainable development of the metallurgical industry.

[0003] At present, the steel industry mainly uses physical methods and fire smelting methods to recover valuable metals from converter steel slag. Although the traditional physical method does not pollute the environment during the recovery process, the valuable metal recovery efficiency is low. Fire smelting mainly uses carbon as a reducing agent and needs to add additional additives, which will produce a large amount of carbon emissions. Tungsten-molybdenum acid slag is a secondary waste slag after wet treatment in the non-ferrous metal industry, and its composition is complex and the grade of valuable metals is low. However, its fire smelting recovery process usually needs to add a large amount of additives, increasing the recovery cost. Therefore, a new technical method is urgently needed to effectively recover valuable metals from converter steel slag and tungsten-molybdenum acid slag, and to realize efficient utilization of resources and environmental protection. SUMMARY

[0004] In view of the above problems, the purpose of the present application is to provide a method for recovering valuable metals based on converter steel slag, which can effectively recover valuable metals from converter steel slag and tungsten-molybdenum acid slag through synergistic smelting, while reducing environmental pollution and processing cost, and has significant environmental and economic benefits.

[0005] To achieve the above purpose, the present application is realized by the following technical scheme:

[0006] A method for recovering valuable metals based on converter steel slag, comprising the following steps:

[0007] S1: According to the composition of converter steel slag and tungsten-molybdenum acid slag, the mixing ratio of the two kinds of waste slag is designed, so that the liquidus temperature of the mixed material is between 1100-1300℃;

[0008] S2: After determining the mixing ratio of converter steel slag and tungsten-molybdenum acid slag, the amount of silicon reducing agent is determined according to the total amount of oxygen elements in the highest oxides of valuable metals in the mixed material of converter steel slag and tungsten-molybdenum acid slag;

[0009] S3: Based on the determined addition ratio of converter steel slag, tungsten molybdenum acid slag, and silicon reducing agent, the three are mixed evenly to obtain mixture I;

[0010] S4: Place the mixture I into a crucible and heat it in an inert atmosphere until the sample is completely melted. Then, perform a constant temperature treatment to obtain a stable melt. After the melting is completed and cooled to room temperature, separate the metal from the slag phase.

[0011] Furthermore, the main components of the converter steel slag include SiO2, CaO, FeO / Fe2O3, Al2O3, MnO2, and P2O5; the main components of the tungsten-molybdenum acid slag include WO3, MoS2, CoO, Ta2O5, Nb2O5, NiO, CuO, SiO2, and Na2O.

[0012] Furthermore, S1 specifically includes the following steps:

[0013] The mass fraction of each oxide in converter steel slag and tungstic molybdate slag was determined by X-ray fluorescence spectroscopy.

[0014] Based on the mass fractions of CaO, SiO2, Na2O, and Al2O3 in the mixture formed by converter steel slag and tungsten molybdenum acid slag, the corresponding component points are found in the CaO-Na2O-SiO2-Al2O3 multi-component phase diagram, and the temperature of the liquid phase region where it is located is determined, that is, the temperature at which the mixed raw materials are completely melted to form a liquid phase.

[0015] Adjust the mass ratio of converter steel slag to tungsten molybdenum acid slag to keep the liquid phase temperature of the mixture between 1100-1300℃.

[0016] Furthermore, the valuable metals in the mixture of converter slag and tungsten-molybdenum acid slag described in S2 include W, Mo, Co, Ta, Nb, Ni, Cu, and Fe.

[0017] Furthermore, the molar ratio of the total amount of elemental silicon in the silicon reducing agent in S2 to the total amount of oxygen in the highest oxide of the valuable metal is 1:2.

[0018] Furthermore, the silicon reducing agent is selected from any one or more combinations of high-purity silicon powder, industrial silicon blocks, and photovoltaic silicon cutting powder.

[0019] Furthermore, in S4, mixture I is heated to 1400-1500℃ in an inert atmosphere, causing the sample to melt completely.

[0020] Furthermore, after the sample in S4 is completely melted, it is kept at a constant temperature for 2 hours to obtain a stable melt.

[0021] Furthermore, the crucible is selected from ceramic crucibles such as corundum and magnesium oxide ceramics.

[0022] Furthermore, the inert atmosphere in S4 is argon.

[0023] The beneficial effects of this invention are as follows:

[0024] 1) This invention utilizes the CaO, SiO2, MgO, and other components in steel slag to reduce the use of other fluxing agents through component regulation. Furthermore, it leverages the components in the steel slag to capture low-grade strategic metals in tungsten-molybdenum acid slag, thereby achieving efficient recovery of all elements. This method reduces the use of fluxing agents and additives in pyrometallurgical processes, thus mitigating environmental pollution, particularly carbon emissions. By co-processing two types of solid waste from the metallurgical industry, this method simplifies the solid waste recycling process, is easy to operate, and is suitable for large-scale industrial application. This invention provides a new technological path for sustainable development in the metallurgical industry, significantly improving the resource utilization rate of converter steel slag and tungsten-molybdenum acid slag, and has significant environmental and economic benefits.

[0025] 2) Both converter steel slag and tungsten-molybdenum acid slag have high melting points, and direct smelting of both requires high temperatures and consumes a lot of energy, which is difficult to achieve in actual production processes. This invention utilizes the synergistic smelting of converter steel slag and tungsten-molybdenum acid slag to fully utilize the useful components in both waste slags, achieve efficient recovery of valuable metals, reduce the use of external fluxing agents, and improve the resource utilization rate of converter steel slag and tungsten-molybdenum acid slag.

[0026] 3) After reduction, elements such as Fe, Mn, and P in the steel slag form larger Fe-Mn-P alloy particles. These alloy particles can undergo alloying reactions with rare and valuable metals (W, Mo, Co, Ta, Nb, Ni, Cu, Fe) in the tungsten-molybdenum slag, thereby capturing these rare and valuable metals and promoting enrichment. In addition, the oxides of steel slag, such as CaO and SiO2, together with SiO2 and Na2O in the tungsten-molybdenum slag, can jointly regulate the melting temperature of the slag phase. By combining with the tungsten-molybdenum slag, a silicate slag phase CaO-Na2O-SiO2-Al2O3 with a lower melting temperature can be obtained, providing a liquid phase with better fluidity for the mass transfer process of the alloy phase and synergistically promoting the enrichment effect of the alloy.

[0027] 4) This invention utilizes silicon as a reducing agent to achieve efficient reduction of valuable metal oxides in converter steel slag and tungsten-molybdenum acid slag, thereby reducing carbon emissions.

[0028] 5) This invention utilizes the compositional characteristics of converter steel slag and tungsten-molybdenum acid slag for compositional control, eliminating the need for complex pretreatment steps and specialized equipment, simplifying the recycling process and facilitating large-scale industrial applications. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 Figure 1 shows the liquid phase temperature and the recovery rate of valuable metals of the mixed raw material of converter steel slag and tungsten molybdenum acid slag in each embodiment; wherein, Figure (a) shows the liquid phase temperature of the mixed raw material of converter steel slag and tungsten molybdenum acid slag in each embodiment, and Figure (b) shows the recovery rate of valuable metals in each embodiment.

[0031] Figure 2 This is an EPMA elemental distribution analysis diagram of the slag-gold interface in the smelting sample of Example 4.

[0032] Figure 3 This is a photograph of the smelting sample from Example 4.

[0033] Figure 4 This is an elemental distribution analysis diagram of the EPMA alloy sample from Example 4. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but 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.

[0035] This embodiment provides a method for recovering valuable metals from converter steel slag, including:

[0036] S1. Raw material proportioning design: Based on the composition of converter steel slag and tungsten-molybdenum acid slag, the mixing ratio of the two waste slags is designed to keep the liquid phase temperature of the mixture between 1100-1300℃. This includes the following steps:

[0037] The mass fraction of each oxide in converter steel slag and tungsten-molybdenum acid slag was determined by X-ray fluorescence spectroscopy (XRF). Based on the mass fractions of CaO, SiO2, Na2O, and Al2O3 in the mixture formed by converter steel slag and tungsten-molybdenum acid slag, the corresponding component points were found in the CaO-Na2O-SiO2-Al2O3 multi-component phase diagram, and the temperature of the liquid phase region where they are located (i.e., the liquid phase temperature of the mixed raw materials) was determined. The mass ratio of converter steel slag to tungsten-molybdenum acid slag was adjusted to keep the liquid phase temperature of the mixture between 1100-1300℃.

[0038] Specifically, in this embodiment, the main components of the converter steel slag are: SiO2 (10-20%), CaO (30-40%), FeO / Fe2O3 (30-40%), Al2O3 (<5%), MgO (2-10%), MnO2 (1-8%), P2O5 (<5%), etc.

[0039] The main components of tungsten molybdenum acid slag are: MoS2 (3-8%), WO3 (0-6%), CoO (2-10%), Ta2O5 (0-3%), Nb2O5 (0-3%), NiO (0-5%), CuO (0-10%), SiO2 (10-30%), Na2O (0-10%), etc.

[0040] The liquid phase temperatures of converter steel slag and tungsten-molybdenum acid slag with different ratios are as follows:

[0041] 100g of converter steel slag: CaO: 35-40g, SiO2: 10-15g, Al2O3: 0-5g, corresponding to a liquidus temperature of 2200-2300℃.

[0042] 100g of tungsten-molybdenum acid slag: SiO2: 30-35%, Al2O3: 0-5g, Na2O: 10-15g, corresponding to a liquidus temperature of 1650-1700℃.

[0043] 100g converter steel slag + 100g tungsten-molybdenum acid slag: CaO: 40-45g, SiO2: 70-75g, Na2O: 10-15g, Al2O3: 0-5g, corresponding liquid phase temperature is 1270-1300℃.

[0044] 50g converter steel slag + 100g tungsten-molybdenum acid slag: CaO: 20-25g, SiO2: 55-60g, Na2O: 15-20g, Al2O3: 0-5g, corresponding liquid phase temperature is 1200-1230℃.

[0045] 50g converter steel slag + 150g tungsten-molybdenum acid slag: CaO: 20-25g, SiO2: 85-95g, Na2O: 20-25g, Al2O3: 5-10g, corresponding liquid phase temperature is 1150-1180℃.

[0046] 50g converter steel slag + 200g tungsten-molybdenum acid slag: CaO: 20-25g, SiO2: 100-105g, Na2O: 30-35g, Al2O3: 5-10g, corresponding liquid phase temperature is 1100-1130℃.

[0047] The data above shows that smelting tungsten-molybdenum acid slag or converter steel slag alone requires heating to above 1650℃ and 2200℃ respectively for complete melting, which increases energy consumption in actual smelting and makes it difficult to achieve. Combining the two components can significantly reduce the melting temperature. Furthermore, it can be observed that as the mass of the tungsten-molybdenum acid slag increases, the liquidus temperature of the mixed raw materials gradually decreases.

[0048] The main reaction equation involved in this invention is: Fe₂O₃ + Si = Fe + SiO₂. Raising the reaction temperature to above 1400℃ transforms the reaction from a solid-solid reaction to a solid-liquid reaction, significantly increasing the reaction rate. If the oxides CaO, SiO₂, Al₂O₃, and Na₂O can form a low-melting-point silicate phase (CaO-SiO₂-Al₂O₃-Na₂O) below 1400℃, more liquid phase can be provided for the reduction reaction, which is beneficial for reactant and heat transfer during the reaction process, thus increasing the reaction rate.

[0049] This invention adjusts the liquid phase temperature of the mixture (converter slag + tungsten-molybdenum acid slag) to between 1100-1300℃, enabling the mixture to form a suitable liquid phase, which helps improve the rate of the silicothermic reduction reaction and the uniformity of mixing. When the liquid phase temperature of the mixture is too high, it increases energy consumption costs and accelerates the wear and tear on equipment and refractory materials (the highest experimental temperature for commonly used alumina materials is 1700℃, and magnesium oxide crucibles are prone to cracking at 1700℃), increasing maintenance and replacement costs. Therefore, this invention preferably adjusts the liquid phase temperature of the mixture (converter slag + tungsten-molybdenum acid slag) to between 1100-1300℃.

[0050] S2: After determining the mixing ratio of converter steel slag and tungsten-molybdenum acid slag, determine the amount of silicon reducing agent to be added based on the total amount of oxygen in the highest oxide of valuable metals in the converter steel slag and tungsten-molybdenum acid slag mixture. Valuable metals (including W, Mo, Co, Ta, Nb, Ni, Cu, and Fe) in the converter steel slag and tungsten-molybdenum acid slag mixture mainly exist in oxide form. In calculating the silicon reducing agent addition ratio, this step assumes that all valuable metals exist in their highest-valence oxide form (i.e., WO3, MoO3, Co2O3, Ta2O5, Nb2O5, NiO, CuO, Fe2O3). The total oxygen content in the highest-valence oxides of the valuable metals is calculated using the silicothermic reaction equation: MeOx + x / 2Si = Me + x / 2SiO2 (where MeOx = WO3, MoO3, Co2O3, Ta2O5, Nb2O5, NiO, CuO, Fe2O3). The required theoretical maximum silicon addition amount is then calculated. The molar ratio of the total elemental silicon in the silicon reducing agent to the total oxygen content in the highest-valence oxides of the valuable metals is 1:2. High-purity silicon powder, industrial silicon blocks, photovoltaic silicon cutting powder, etc., can be used as the silicon reducing agent.

[0051] S3: Based on the determined addition ratio of converter steel slag, tungsten molybdenum acid slag, and silicon reducing agent, the three are mixed evenly to ensure uniform distribution of the mixture, thus obtaining mixture I;

[0052] S4: Place the mixture I into a crucible (a ceramic crucible such as corundum or magnesium oxide) and heat it to 1400-1500℃ in an inert atmosphere to completely melt the sample. During heating, the heating temperature is generally 100-200℃ higher than the complete melting temperature of the mixture (i.e., the liquid phase temperature of the mixture) to improve the reaction efficiency and the final recovery rate of valuable metals.

[0053] After the sample is completely melted, it is held at that temperature for 2 hours to obtain a stable melt. At this time, the alloy of the reduced valuable metal is deposited at the bottom of the melt. After melting is completed and cooled to room temperature, the metal and slag phases are separated to obtain a metallic phase containing valuable metal and a harmless slag phase. The mixture can be melted using heating equipment such as a tube furnace or induction melting furnace.

[0054] Example 1

[0055] The method for recovering valuable metals from converter steel slag in this embodiment includes the following steps:

[0056] 1) Mix 50g of converter steel slag (SiO2 content: 10-20%, CaO content: 30-40%, FeO / Fe2O3 content: 30-40%, Al2O3 content: <5%, MgO content: 2-10%, MnO2 content: 1-8%, P2O5 content: <5%), 50g of tungstic soda slag (MoS2 content: 3-8%, WO3 content: 0-6%, CoO content: 2-10%, Ta2O5 content: 0-3%, Nb2O5 content: 0-3%, NiO content: 0-5%, CuO content: 0-10%, SiO2 content: 10-30%, Na2O content: 0-10%) with 10g of silicon powder evenly to ensure uniform distribution of the mixture, thus obtaining mixture I;

[0057] 2) Place the mixture I into a crucible (a ceramic crucible such as corundum or magnesium oxide), introduce argon gas into the tube furnace and adjust the temperature control program to raise the temperature to 1500℃ so that the sample is completely melted.

[0058] 3) After the sample is completely melted, it is kept at the temperature for 2 hours to obtain a stable melt. At this time, the alloy of the reduced valuable metals is deposited at the bottom of the melt. After the melting is completed and cooled to room temperature, the metal and slag phases are separated to obtain a metallic phase containing valuable metals such as Fe, Mn, W, Mo, Ni, Co, and Cu, and a harmless slag phase.

[0059] Example 2

[0060] The method for recovering valuable metals based on converter steel slag provided in this embodiment is basically the same as that in embodiment 1. The only difference is that in this embodiment, 50g of converter steel slag, 100g of tungsten molybdenum acid slag and 15g of silicon powder are uniformly mixed to obtain mixture I.

[0061] Example 3

[0062] The method for recovering valuable metals based on converter steel slag provided in this embodiment is basically the same as that in embodiment 1. The only difference is that in this embodiment, 50g of converter steel slag, 150g of tungsten molybdenum acid slag and 20g of silicon powder are uniformly mixed to obtain mixture I.

[0063] Example 4

[0064] The method for recovering valuable metals based on converter steel slag provided in this embodiment is basically the same as that in embodiment 1. The only difference is that in this embodiment, 50g of converter steel slag, 200g of tungsten molybdenum acid slag and 25g of silicon powder are uniformly mixed to obtain mixture I.

[0065] Effect test

[0066] like Figure 1 As shown in (a), the addition of tungsten-molybdenum acid slag can lower the melting temperature of converter steel slag, and the melting temperature gradually decreases with increasing tungsten-molybdenum acid slag addition. The final alloy sample's valuable metal recovery rate is as follows: Figure 1 As shown in (b), with the increase of the proportion of tungsten-molybdenum acid slag added, the recovery rate of valuable metals such as Fe, W, Mo and Cu in the alloy gradually increases. The main reasons are as follows:

[0067] 1) As the amount of tungsten-molybdenum acid slag added increases, the overall melting temperature of the mixed raw materials gradually decreases. At 1500℃, the more tungsten-molybdenum acid slag added, the earlier the reaction system melts, the higher the melt fluidity, and the better the recovery of valuable metals. 2) Fe and Mn elements in steel slag can capture W, Mo, Cu, and other elements in the tungsten-molybdenum acid slag. With increasing tungsten-molybdenum acid slag addition, more W, Mo, and Cu elements are present in the system, thus ultimately undergoing alloying reactions with Fe and Mn and being captured, leading to an increased recovery rate.

[0068] In this invention, steel slag has an alloy-capturing effect: Fe has excellent binding affinity with valuable metals such as W, Mo, Ta, Nb, Co, and Ni. After being reduced, Fe in the steel slag can act as an alloy-capturing agent, combining with other valuable metals and undergoing alloying, thereby increasing the enrichment rate of various valuable metals during the smelting process. (See attached diagram) Figure 2As shown, elemental analysis of the sample obtained in Example 4 revealed that the main components of the alloy droplets were Fe, Cu, and Mo. This confirms that during the smelting process, Fe underwent an alloying reaction with Mo and Cu, forming Fe-Cu-Mo alloy droplets. During the smelting process, these small alloy droplets migrate from the slag phase to the alloy phase, forming alloy ingots upon cooling (as shown in the attached figure). Figure 3 As shown in the figure, this enables the recycling of valuable metals.

[0069] See attached document Figure 4 As shown, elemental analysis of the alloy obtained in Example 4 revealed that the main phase composition of the alloy ingot consisted of valuable metals Fe, Cu, Mo, and P, confirming that the method of the present invention can achieve simultaneous enrichment and recovery of multiple valuable metals.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering valuable metals from converter steel slag, characterized in that, Includes the following steps: S1: Design the mixing ratio of the two waste slags based on the composition of converter steel slag and tungsten molybdenum acid slag, so that the complete melting liquid phase temperature of the mixture is between 1100-1300℃. S2: After determining the mixing ratio of converter steel slag and tungsten molybdenum acid slag, determine the amount of silicon reducing agent to be added based on the total amount of oxygen in the highest oxide of valuable metal in the mixture of converter steel slag and tungsten molybdenum acid slag. S3: Based on the determined addition ratio of converter steel slag, tungsten molybdenum acid slag, and silicon reducing agent, the three are mixed evenly to obtain mixture I; S4: Place the mixture I into a crucible and heat it in an inert atmosphere until the sample is completely melted. Then, perform a constant temperature treatment to obtain a stable melt. After the melting is completed and cooled to room temperature, separate the metal from the slag phase. The main components of the converter steel slag include SiO2, CaO, FeO / Fe2O3, Al2O3, MnO2, and P2O5; the main components of the tungsten-molybdenum acid slag include WO3, MoS2, CoO, Ta2O5, Nb2O5, NiO, CuO, SiO2, and Na2O; S1 specifically includes the following steps: The mass fraction of each oxide in converter steel slag and tungstic molybdate slag was determined by X-ray fluorescence spectroscopy. Based on the mass fractions of CaO, SiO2, Na2O and Al2O3 in the mixture formed by converter steel slag and tungsten molybdenum acid slag, the corresponding component points are found in the CaO-Na2O-SiO2-Al2O3 multi-component phase diagram, and the temperature of the liquid phase region where it is located is determined, that is, the temperature at which the mixture completely melts to form a liquid phase. Adjust the mass ratio of converter steel slag to tungsten molybdenum acid slag to keep the temperature of the fully molten liquid phase of the mixture between 1100-1300℃.

2. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, Valuable metals in the mixture of converter slag and tungsten-molybdenum acid slag described in S2 include W, Mo, Co, Ta, Nb, Ni, Cu, and Fe.

3. The method for recovering valuable metals from converter steel slag according to claim 2, characterized in that, The molar ratio of the total amount of elemental silicon in the silicon reducing agent in S2 to the total amount of oxygen in the highest oxide of the valuable metal is 1:

2.

4. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, The silicon reducing agent is selected from any one or more combinations of high-purity silicon powder, industrial silicon blocks, and photovoltaic silicon cutting powder.

5. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, In S4, mixture I is heated to 1400-1500℃ in an inert atmosphere until the sample is completely melted.

6. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, After the sample in S4 is completely melted, it is kept at a constant temperature for 2 hours to obtain a stable melt.

7. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, The crucible is made of corundum or magnesium oxide ceramic.

8. The method for recovering valuable metals from converter steel slag according to claim 1, characterized in that, The inert atmosphere in S4 is argon.

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