Method for recovering and utilizing all components of noble metal by plasma synergistic smelting

Abstract

This application provides a method for enhanced precious metal recovery and full-component utilization through plasma synergistic melting, relating to the field of solid waste recycling. The method involves first mixing solid waste and a reducing agent to obtain a first mixture; then, under a working atmosphere, plasma melting of the first mixture yields high-temperature liquid slag, a liquid matte phase, and a liquid alloy phase; the liquid matte phase and the liquid alloy phase are respectively subjected to hydrometallurgical recovery of precious metals; the high-temperature liquid slag is water-quenched to obtain glass frit; the glass frit is ground and dried to obtain treated glass frit; the treated glass frit and a binder solution are second-mixed to obtain a second mixture; the second mixture is then molded and heat-treated to obtain microcrystalline glass; the solid waste includes waste automotive catalysts, flue gas desulfurization gypsum slag and cyanide tailings, and / or sulfuric acid slag. This method utilizes plasma melting technology to synergistically process multiple complex secondary resources, achieving efficient enrichment of precious metals and high-value conversion of all material components.

Description

Technical Field

[0001] This application relates to the field of solid waste recycling, and in particular to a method for enhancing the recovery and full utilization of precious metals through plasma co-melting. Background Technology

[0002] Waste automotive catalysts are important secondary resources of platinum group metals (PGMs) such as platinum, palladium, and rhodium, and their recycling has enormous economic and strategic value. Cyanide leaching is a common process for gold extraction, but it produces cyanide tailings containing residual gold (Au), silver (Ag), and various metals such as iron and copper. This tailings not only occupy land but also pose serious environmental risks. Meanwhile, the production of flue gas desulfurization (FGD) gypsum slag (mainly composed of calcium sulfate) from industries such as coal-fired power plants is enormous, and its treatment and utilization also present an environmental challenge.

[0003] Sulfuric acid slag primarily originates from the solid residue formed during the roasting of sulfide minerals to produce sulfuric acid. This type of slag typically contains high concentrations of iron oxides and is enriched with precious metals such as gold and silver, as well as valuable metal components like copper, zinc, and lead. Due to the limitations of traditional processing techniques, large quantities of sulfuric acid slag are stockpiled for extended periods, not only consuming land resources but also posing a potential risk of heavy metal leaching and environmental pollution. In the current context of green metallurgy and circular economy development, the dual attributes of sulfuric acid slag as a carrier of iron resources and a medium for enriching precious metals are receiving increasing attention.

[0004] Existing precious metal recovery technologies are mainly divided into pyrometallurgical and hydrometallurgical processes. Pyrometallurgical processes, such as plasma smelting, utilize high temperatures to enrich precious metals into metal or matte phase collectors, offering advantages such as fast processing speed and strong adaptability to raw materials. However, traditional pyrometallurgical processes typically require the addition of large amounts of collectors and slag-forming agents (such as lime and quartz), increasing costs and energy consumption. Furthermore, the resulting slag is usually treated as a low-value product or waste, failing to achieve high-value utilization of all components. Hydrometallurgical processes are complex, often using strong acids and alkalis, easily generating secondary pollution, and are ineffective in processing complex, multi-component raw materials.

[0005] Furthermore, the four different types of solid waste mentioned above are currently treated or disposed of using independent and unrelated process routes. For example, spent catalysts are sent to specialized precious metal recycling plants, cyanide tailings undergo harmless treatment or inefficient gold extraction, and desulfurization gypsum is mainly used to produce building materials or is landfilled. This decentralized treatment model results in a long overall process chain, large equipment investment, high energy consumption, and low resource utilization.

[0006] Therefore, there is an urgent need to develop a new integrated technology that can co-process multiple solid wastes, reduce external material consumption through internal material recycling, and simultaneously achieve efficient recovery of precious metals and complete resource utilization of residual components. Summary of the Invention

[0007] The purpose of this application is to provide a method for enhancing the recovery and full utilization of precious metals through plasma co-melting, in order to solve the above-mentioned problems.

[0008] To achieve the above objectives, this application provides a method for enhancing the recovery and full utilization of precious metals through plasma-assisted smelting, comprising:

[0009] The solid waste and the reducing agent are mixed in the first step to obtain a first mixture;

[0010] Under the working atmosphere, the first mixture is subjected to plasma melting to obtain high-temperature liquid slag, liquid matte phase and liquid alloy phase;

[0011] The liquid matte phase and the liquid alloy phase are respectively subjected to hydrometallurgical recovery of precious metals;

[0012] The high-temperature liquid slag is water-quenched to obtain glass material;

[0013] The glass material is ground and dried to obtain the treated glass material;

[0014] The treated glass frit and binder solution are mixed a second time to obtain a second mixture;

[0015] The second mixture is molded and heat-treated to obtain microcrystalline glass;

[0016] The solid waste includes waste automotive catalysts, flue gas desulfurization gypsum residue and cyanide tailings and / or sulfuric acid slag.

[0017] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0018] A. The composition of the waste automotive catalyst, based on a total mass of 100%, includes:

[0019] Al2O3 35%-98%, SiO2 0%-40%, MgO 0%-15%, Fe2O3 0%-10%, CaO 0%-3%, with the balance being other catalytic additives and precious metals;

[0020] The precious metal content in the waste automotive catalyst is 1000-5000 g / t;

[0021] B. The components of the flue gas desulfurization gypsum residue include CaSO4;

[0022] C. The composition of the cyanide tailings, based on a total mass of 100%, includes:

[0023] Fe2O3 15%-50%, SiO2 20%-50%, Al2O3 1%-10%, CaO 2-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals;

[0024] The mass content of precious metals in the cyanide tailings is 10-250 g / t;

[0025] D. The composition of the sulfuric acid slag, based on a total mass of 100%, includes:

[0026] Fe2O3 30-90%, SiO2 5-20%, Al2O3 0.5-10%, CaO 0.5-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals;

[0027] The mass content of precious metals in the sulfuric acid slag is 5-300 g / t;

[0028] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0029] A. In the first mixture, the mass ratio of CaO to SiO2 is 0.3-0.4:1, the mass ratio of MgO to SiO2 is 0.2-0.3:1, and the mass ratio of Al2O3 to SiO2 is 0.18-0.3:1;

[0030] B. The iron content in the first mixture is 10%-25% of the total mass, and the molar amount of iron is 1-2.5 times the molar amount of sulfur.

[0031] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0032] A. The water content of the first mixture is <3%;

[0033] B. The particle size of the first mixture is 20-200 mesh;

[0034] C. The reducing agent includes coke.

[0035] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0036] A. The working atmosphere includes inert gases and / or reducing gases;

[0037] B. The plasma melting temperature is 1550-1800℃, and the time is 0.5-3h.

[0038] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0039] A. When the working atmosphere includes argon and hydrogen, the molar amount of the reducing agent is 0.1-0.6 times the molar amount of iron.

[0040] When the working atmosphere includes an inert gas, the molar amount of the reducing agent is 1.5-3 times the molar amount of the iron element;

[0041] B. When the working atmosphere includes argon and hydrogen, the total volume of the working atmosphere, calculated as 100%, includes:

[0042] 60%-90%Ar, 10%-40%H2;

[0043] C. The total flow rate of the working gas introduced into the working atmosphere is 2-30 m³ / h. 3 / h.

[0044] Optionally, a formulation agent may also be added during the preparation of the first mixture;

[0045] The formulation agent includes one or more of calcium oxide compounds, silicon oxide compounds, iron oxide compounds, and magnesium oxide compounds.

[0046] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0047] A. The proportion of -200 mesh particles in the treated glass feed is 60%-85%;

[0048] B. The moisture content of the treated glass frit is <3%;

[0049] C. The flexural strength of the microcrystalline glass is ≥50MPa, and the Vickers hardness is ≥19Gpa.

[0050] Optionally, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0051] A. The mass of the binder in the binder solution is 8%-12% of the mass of the treated glass frit;

[0052] B. The adhesive in the adhesive solution includes polyethylene glycol and polyvinyl alcohol;

[0053] The mass ratio of the polyethylene glycol to the polyvinyl alcohol is 2-5:2;

[0054] C. The mass concentration of the adhesive solution is 5%-8%.

[0055] Optionally, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially;

[0056] The heating rate of the first heat treatment is 3-5℃ / min, the final temperature is 750-850℃, and the holding time is 2-4h;

[0057] The heating rate of the second heat treatment is 2-3℃ / min, the final temperature is 900-1050℃, and the holding time is 3-6h;

[0058] The cooling rate of the heat treatment is 5-10℃ / min.

[0059] Compared with the prior art, the beneficial effects of this application include:

[0060] The method for enhancing precious metal recovery and full-component utilization through plasma synergistic melting provided in this application utilizes plasma melting technology to synergistically process multiple complex secondary resources. By generating composite alloy trapping agents and slag-forming agents in situ, it achieves efficient enrichment of precious metals and high-value conversion of all material components. This method eliminates the disposal problems of multiple solid wastes at the source, avoids secondary pollution that may be generated during decentralized treatment, and reduces the amount of chemical reagents added during the melting process. Therefore, it greatly reduces fixed asset investment and processing costs. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0062] Figure 1 This is a schematic diagram of the process flow for the plasma-assisted melting method for enhancing the recovery and utilization of precious metals and all components, as provided in Example 1. Detailed Implementation

[0063] Currently, the treatment of four types of solid waste—waste automotive catalysts, flue gas desulfurization gypsum slag, cyanide tailings, and / or sulfuric acid incineration slag—is completely fragmented. This model leads to huge redundant investments and low resource utilization efficiency. Furthermore, most metallurgical processes follow a linear economic model, i.e., "resource-product-waste," and even recycling processes often generate new, difficult-to-treat waste residues or wastewater. To address the problems arising from this model, this application proposes the following solution.

[0064] First, the solution provided in this application will be explained in more detail as follows:

[0065] This application provides a method for enhancing the recovery and full utilization of precious metals through plasma-assisted melting, including:

[0066] The solid waste and the reducing agent are mixed in the first step to obtain a first mixture;

[0067] Under the working atmosphere, the first mixture is subjected to plasma melting to obtain high-temperature liquid slag, liquid matte phase and liquid alloy phase;

[0068] The liquid matte phase and the liquid alloy phase are respectively subjected to hydrometallurgical recovery of precious metals;

[0069] The high-temperature liquid slag is water-quenched to obtain glass material;

[0070] It should be noted that water quenching inhibits the uncontrolled natural crystallization of high-temperature liquid slag during the cooling process, thereby obtaining an amorphous glass with uniform chemical composition, i.e., glass material;

[0071] The glass material is ground and dried to obtain the treated glass material;

[0072] The treated glass frit and binder solution are mixed a second time to obtain a second mixture;

[0073] The second mixture is molded and heat-treated to obtain microcrystalline glass;

[0074] In some embodiments, a blank of the desired shape is pressed into a blank by means of molding or the like. The desired shape is not limited and can be any desired shape.

[0075] The solid waste includes waste automotive catalysts, flue gas desulfurization gypsum residue and cyanide tailings and / or sulfuric acid slag.

[0076] Traditional pyrometallurgical precious metal recovery typically uses a single metal as the collector, most commonly iron, copper, or lead. These single-metal collectors have varying affinities for different precious metals, and at high temperatures, the partition coefficient of precious metals between the collector and the slag is limited, resulting in the loss of some precious metals in the slag. This application recognizes that these four types of waste have natural complementarity in their main chemical components: waste automotive catalysts are rich in Al2O3 and SiO2 (slag skeleton), cyanide tailings / sulfuric acid slag are rich in Fe2O3 (collector precursor), and gypsum is rich in CaSO4 (slag-forming agent precursor). Furthermore, non-major components in the waste play a crucial synergistic role in the high-temperature plasma smelting process: cyanide tailings / sulfuric acid slag are typically rich in metal oxides or residues such as Cu, Zn, and Pb. Under strong reducing conditions, these metallic elements react with FeO (derived from the reduction of Fe2O3) to form multi-component matte phases such as Cu-Fe-S, Zn-Fe-S, and Pb-Fe-S, as well as intermetallic compounds such as Cu-Pt and Pd-Cu. Among these, the partition coefficient of copper-based matte relative to palladium is 2-3 times higher than that of pure iron matte, and the trapping ability of lead-based alloys relative to platinum is better than that of single iron trapping agents. This multi-component complex system composed of the "intrinsic" components of solid waste generates ideal phase separation (liquid slag, liquid matte, and liquid alloy) in the molten pool through in-situ chemical reactions, achieving differentiated and efficient enrichment of different precious metals.

[0077] The core mechanism of plasma smelting technology lies in its unique ultra-high temperature gradient field and active plasma environment, which provide ideal metallurgical reaction conditions for complex solid waste systems. The extreme conditions of ultra-high temperature in the plasma arc region instantly break the kinetic limitations in conventional pyrometallurgy, enabling the rapid dissociation of refractory platinum group metal oxides (such as PtO2 and RhO3) and complex aluminosilicate supports. At the same time, the high-energy electrons and ions in the plasma exert a strong physicochemical activation effect on the surface of solid waste particles, significantly reducing the activation energy of noble metal reduction. More importantly, the strong electric and magnetic field effects formed in the plasma environment cause violent electromagnetic stirring inside the molten pool, accelerating the mass transfer process of multi-metal capture alloys such as Fe-Cu-Zn-Pb in the melt. This allows complex intermetallic compounds (such as Pt3Fe, PdCu, and RhZn) that are difficult to achieve at conventional smelting temperatures to form rapidly and reach thermodynamic equilibrium. Ultimately, driven by the density difference, the high-density precious metal enriched aluminate phase and matte phase settle to the bottom of the furnace, while the low-density aluminosilicate slag floats to the top, achieving clear separation of the three phases and efficient enrichment and recovery of precious metals.

[0078] Therefore, this application solves the environmental problems of four different solid wastes through process synergy, in-situ synthesis, and full-component utilization of waste, and completely transforms them into valuable commodities, maximizing resource utilization efficiency and economic benefits. The specific analysis is as follows:

[0079] On the one hand, under a reducing smelting atmosphere, iron, copper, and other metal oxides in cyanide tailings / sulfuric acid slag are reduced to metals and fused with other metal elements (such as lead and zinc) to form a multi-element alloy scavenger phase in situ. This multi-element alloy scavenger phase has similar physicochemical properties to precious metals and can efficiently capture platinum group metals such as platinum, palladium, and rhodium (PGMs) from waste automotive catalysts and gold from cyanide tailings / sulfuric acid slag. On the other hand, the decomposition of desulfurized gypsum under a reducing atmosphere and high temperature involves the following two core reactions at temperatures above 1100°C, with carbon acting as a reducing agent:

[0080] CaSO4 + 2C → CaS + 2CO2;

[0081] 3CaSO4+ CaS → 4CaO + 4SO2;

[0082] The generated CaO is a strongly basic oxide. As a network modifier, it disrupts the three-dimensional network structure of [SiO4] tetrahedra and [AlO4] tetrahedra, significantly reducing the melting point and viscosity of the aluminosilicate system. This facilitates the rapid transformation of the originally refractory SiO2-Al2O3 system into a highly fluid CaO-MgO-Al2O3-SiO2 quaternary silicate melt. Under strong reducing conditions, sulfur dioxide gas reacts with metallic iron in the molten pool to generate ferrous sulfide (FeS), as shown in the following reaction:

[0083] 3Fe + SO2 → FeS + 2FeO;

[0084] The generated FeS reacts with a small amount of Cu that is not captured by the alloy phase to form iron-copper matte (FeS-Cu2S). This matte phase is insoluble in both the metal and slag phases. Because its density is between that of the metal and the slag, it forms an independent liquid phase layer. Among them, matte is an excellent scavenger of chalcophiles. The cyanide tailings contain a certain amount of silver (Ag), and silver has a strong affinity for chalcophiles. Therefore, this in-situ formed iron-copper matte is mainly used for the selective enrichment of silver. This is equivalent to opening up a highly efficient "second trapping channel" for specific elements such as silver outside of the main trapping process. This not only improves the silver recovery rate but also simplifies the subsequent precious metal separation and purification, allowing for the separation of the Ag-rich matte phase from the PGMs (platinum group metals)-rich alloy phase. Compared to traditional iron or copper traps, the in-situ formed composite alloy + matte phase trap can achieve a higher and more comprehensive precious metal recovery rate, especially for raw materials with complex compositions (containing Pt, Pd, Rh, Au, and Ag), where its advantages are more obvious.

[0085] In addition, this application utilizes a core process (plasma melting) to convert and redistribute matter and energy. The core chemical reagents required for the process are generated in situ from waste automotive catalysts, flue gas desulfurization gypsum slag and cyanide tailings and / or sulfuric acid slag during the process. This not only saves costs but also closes the material flow, reducing dependence on external primary resources. There is no waste at the output of the process. The main product is an alloy phase enriched with precious metals, and the secondary product is a matte phase enriched with silver. Both are high-value intermediate products. The slag, which accounts for the largest mass fraction, is a high-quality raw material for producing high-value-added microcrystalline glass ceramics because its composition is precisely designed into an ideal CMAS system in the process.

[0086] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0087] A. The composition of the waste automotive catalyst, based on a total mass of 100%, includes:

[0088] Al2O3 35%-98%, SiO2 0%-40%, MgO 0%-15%, Fe2O3 0%-10%, CaO 0%-3%, with the balance being other catalytic additives and precious metals;

[0089] Optionally, the composition of the waste automotive catalyst, based on a total mass of 100%, includes: Al2O3, which can be any value between 35%, 40%, 50%, 60%, 70%, 80%, 90%, 98%, or 35%-98%; SiO2, which can be any value between 0%, 10%, 20%, 30%, 40%, or 0%-40%; MgO, which can be any value between 0%, 5%, 10%, 15%, or 0%-15%; Fe2O3, which can be any value between 0%, 5%, 10%, or 0%-10%; and CaO, which can be any value between 0%, 1%, 2%, 3%, or 0%-3%.

[0090] The precious metal content in the waste automotive catalyst is 1000-5000 g / t;

[0091] Optionally, the mass content of precious metals in waste automotive catalysts can be any value between 1000 g / t, 2000 g / t, 3000 g / t, 4000 g / t, 5000 g / t, or 1000-5000 g / t.

[0092] In some embodiments, the mass content of Pt in the precious metals of waste automotive catalysts is 150-400 g / t, the mass content of Pd is 800-1500 g / t, and the mass content of Rh is 100-300 g / t.

[0093] Optionally, the mass content of Pt can be any value between 150 g / t, 200 g / t, 300 g / t, 400 g / t or 150-400 g / t; the mass content of Pd can be any value between 800 g / t, 900 g / t, 1000 g / t, 1100 g / t, 1200 g / t, 1300 g / t, 1400 g / t, 1500 g / t or 800-1500 g / t; and the mass content of Rh can be any value between 100 g / t, 200 g / t, 300 g / t or 100-300 g / t.

[0094] B. The components of the flue gas desulfurization gypsum residue include CaSO4;

[0095] C. The composition of the cyanide tailings, based on a total mass of 100%, includes:

[0096] Fe2O3 15%-50%, SiO2 20%-50%, Al2O3 1%-10%, CaO 2-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals;

[0097] Optionally, the composition of the cyanide tailings, based on 100% of the total mass, includes: Fe2O3, which can be any value between 15%, 20%, 30%, 40%, 50%, or 15%-50%; SiO2, which can be any value between 20%, 30%, 40%, 50%, or 20%-50%; Al2O3, which can be any value between 1%, 5%, 10%, or 1%-10%; CaO, which can be any value between 2%, 5%, 10%, or 2%-10%; Cu, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%; Pb, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%; and Zn, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%.

[0098] The mass content of precious metals in the cyanide tailings is 10-250 g / t;

[0099] Optionally, the mass content of precious metals in the cyanide tailings can be any value between 10 g / t, 50 g / t, 100 g / t, 150 g / t, 200 g / t, 250 g / t or 10-250 g / t.

[0100] In some embodiments, the mass content of Au in the precious metals of cyanide tailings is 0.5-50 g / t, and the mass content of Ag is 10-200 g / t;

[0101] The mass content of Au in the precious metals of cyanide tailings can be 0.5 g / t, 1 g / t, 5 g / t, 10 g / t, 20 g / t, 30 g / t, 40 g / t, 50 g / t or any value between 0.5 and 50 g / t, and the mass content of Ag can be 10 g / t, 50 g / t, 100 g / t, 200 g / t or any value between 10 and 200 g / t.

[0102] D. The composition of the sulfuric acid slag, based on a total mass of 100%, includes:

[0103] Fe2O3 30-90%, SiO2 5-20%, Al2O3 0.5-10%, CaO 0.5-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals;

[0104] Optionally, the composition of the sulfuric acid slag, based on a total mass of 100%, includes: Fe2O3, which can be any value between 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 30-90%; SiO2, which can be any value between 5%, 10%, 15%, 20%, or 5-20%; Al2O3, which can be any value between 0.5%, 1%, 5%, 10%, or 0.5%-10%; CaO, which can be any value between 0.5%, 1%, 2%, 5%, 10%, or 0.5%-10%; Cu, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%; Pb, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%; and Zn, which can be any value between 0%, 1%, 2%, 3%, 4%, 5%, or 0-5%.

[0105] The mass content of precious metals in the sulfuric acid slag is 5-300 g / t;

[0106] Optionally, the mass content of precious metals in sulfuric acid slag can be any value between 5 g / t, 10 g / t, 50 g / t, 100 g / t, 200 g / t, 300 g / t, or 5-300 g / t.

[0107] In some embodiments, the mass content of Au in the sulfuric acid slag is 0.5-50 g / t, and the mass content of Ag is 10-250 g / t.

[0108] Optionally, the mass content of Au in the sulfuric acid slag can be 0.5 g / t, 1 g / t, 5 g / t, 10 g / t, 20 g / t, 30 g / t, 40 g / t, 50 g / t or any value between 0.5 and 50 g / t, and the mass content of Ag can be 10 g / t, 50 g / t, 100 g / t, 150 g / t, 200 g / t, 250 g / t or any value between 10 and 250 g / t;

[0109] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0110] A. In the first mixture, the mass ratio of CaO to SiO2 is 0.3-0.4:1, the mass ratio of MgO to SiO2 is 0.2-0.3:1, and the mass ratio of Al2O3 to SiO2 is 0.18-0.3:1;

[0111] Optionally, the mass ratio of CaO to SiO2 in the first mixture can be any value between 0.3:1, 0.35:1, 0.4:1, or 0.3-0.4:1; the mass ratio of MgO to SiO2 can be any value between 0.2:1, 0.25:1, 0.3:1, or 0.2-0.3:1; and the mass ratio of Al2O3 to SiO2 can be any value between 0.18:1, 0.2:1, 0.3:1, or 0.18-0.3:1.

[0112] It is important to note that the reasons for and beneficial effects of the above-mentioned mass ratio limits are as follows: Controlling the CaO / SiO2 mass ratio within the range of 0.3-0.4 ensures that the silicate melt has suitable basicity and fluidity, effectively promoting the rapid separation of the noble metal phase and the slag phase, and providing an ideal CaO-SiO2 basic network structure for subsequent slag preparation of glass-ceramics; controlling the MgO / SiO2 mass ratio within the range of 0.2-0.3 not only stabilizes the high-temperature melt structure and prevents excessive erosion of the furnace lining, but more importantly, the magnesium-containing silicate phase formed at this ratio contributes to the glass-ceramic process. During the preparation process, it can act as a nucleating agent to promote uniform crystal precipitation, thereby improving the mechanical strength and chemical stability of the glass. When the mass ratio of Al2O3 / SiO2 is controlled within the range of 0.18-0.3, the reasonable adjustment of melt viscosity during the melting process and the performance optimization of the glass-ceramic product are taken into account. At this ratio, Al2O3 can ensure that the melt maintains good fluidity at 1550-1800℃, and can also form a rigid aluminum-oxygen tetrahedral network structure in the glass-ceramic, which significantly improves the strength performance of the final product and achieves dual optimization of metallurgical separation efficiency and resource-based product quality.

[0113] B. The iron content in the first mixture is 10%-25% of the total mass, and the molar amount of iron is 1-2.5 times the molar amount of sulfur.

[0114] Optionally, the mass of iron in the first mixture can be any value between 10%, 15%, 20%, 25% or 10%-25% of the total mass, and the molar amount of iron can be any value between 1, 1.5, 2, 2.5 or 1-2.5 times the molar amount of sulfur.

[0115] It is important to note that the limits of 10%-25% iron content and 1-2.5 Fe / S molar ratio are based on a comprehensive consideration of the precious metal capture mechanism and phase equilibrium optimization: when the iron content is below 10%, the amount of FeS-based matte and alloy phases formed is insufficient, failing to provide a sufficient capture carrier for precious metals, resulting in the loss of precious metals in the slag phase; while an iron content exceeding 25% will cause the system to generate an excessive amount of metallic iron phase, not only consuming additional reducing agents and increasing costs, but also diluting the concentration of precious metals in the alloy phase, reducing the efficiency of subsequent wet recovery; the control of the Fe / S molar ratio is even more critical, with the aim of constructing a two-phase capture system in which metallic iron and matte phases coexist, fully leveraging the synergistic advantages of the two phases: when the Fe / S molar ratio is controlled within this range, sulfur in the system preferentially reacts with some iron. A FeS-based matte phase should be generated, while the remaining excess iron exists in a metallic state and forms a multi-element alloy phase with heterogeneous metals such as Cu, Zn, and Pb. This dual-phase coexistence structure has significant trapping advantages—the matte phase (FeS-CuS-ZnS) exhibits strong chemical affinity and good miscibility with palladium and platinum, while the metal alloy phase (Fe-Cu-Pb) effectively collects noble metals through the formation of intermetallic compounds. Compared to a simple matte phase system, this matte-alloy phase dual trapping mechanism not only expands the trapping range of noble metals but also regulates the distribution of noble metals in different chemical states through the dynamic equilibrium between the two phases, preventing some noble metals from escaping into the slag phase due to chemical morphology limitations. This achieves full-spectrum trapping of noble metals in various valence and compound states, significantly improving the overall recovery rate. In some embodiments, the method for enhancing noble metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0116] A. The water content of the first mixture is <3%;

[0117] Optionally, the water content of the first mixture can be any value of 0.1%, 1%, 2%, 2.9%, or <3%;

[0118] In some embodiments, the first mixture is dried at 90-200°C to reduce its moisture content to <3%;

[0119] B. The particle size of the first mixture is 20-200 mesh;

[0120] Optionally, the particle size of the first mixture can be any value between 20 mesh, 50 mesh, 100 mesh, 150 mesh, 200 mesh, or 20 mesh and 200 mesh.

[0121] In some embodiments, the first mixture is ground to a particle size between 20 mesh and 200 mesh;

[0122] C. The reducing agent includes coke.

[0123] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma-assisted melting satisfies at least one of the following conditions:

[0124] A. The working atmosphere includes inert gases and / or reducing gases;

[0125] B. The plasma melting temperature is 1550-1800℃, and the time is 0.5-3h.

[0126] Optionally, the plasma melting temperature can be any value between 1550℃, 1600℃, 1700℃, 1800℃ or 1550-1800℃, and the time can be any value between 0.5h, 1h, 2h, 3h or 0.5-3h.

[0127] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0128] A. When the working atmosphere includes argon and hydrogen, the molar amount of the reducing agent is 0.1-0.6 times the molar amount of iron.

[0129] Optionally, when the working atmosphere includes argon and hydrogen, the molar amount of the reducing agent can be any value between 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.1-0.6 times the molar amount of iron.

[0130] It should be further explained that coke reacts with silicon oxide at high temperatures (>1500℃) to generate elemental silicon, which then forms a ferrosilicon alloy with the iron phase. Its insoluble properties severely restrict the recovery rate of precious metals. However, when the working gas of the plasma melting furnace used in this application is a reducing gas, the amount of coke can be reduced, which greatly reduces the thermodynamic tendency of ferrosilicon alloy formation.

[0131] When the working atmosphere includes an inert gas, the molar amount of the reducing agent is 1.5-3 times the molar amount of the iron element;

[0132] Optionally, when the working atmosphere includes an inert gas, the molar amount of the reducing agent can be any value between 1.5, 2, 2.5, 3, or 1.5-3 times the molar amount of iron.

[0133] B. When the working atmosphere includes argon and hydrogen, the total volume of the working atmosphere, calculated as 100%, includes:

[0134] 60%-90%Ar, 10%-40%H2;

[0135] Optionally, when the working atmosphere includes argon and hydrogen, the total volume of the working atmosphere is 100%, and Ar can be any value between 60%, 70%, 80%, 90% or 60%-90%, and H2 can be any value between 10%, 20%, 30%, 40% or 10%-40%.

[0136] C. The total flow rate of the working gas introduced into the working atmosphere is 2-30 m³ / h. 3 / h.

[0137] Optionally, the total flow rate of the working gas introduced into the working atmosphere can be 2 m³ / s. 3 / h、5m 3 / h, 10 m 3 / h、20 m 3 / h、30 m 3 / h or 2-30m 3 Any value between / h.

[0138] In some embodiments, a formulation agent is also added when the first mixture is prepared;

[0139] The formulation agent includes one or more of calcium oxide compounds, silicon oxide compounds, iron oxide compounds, and magnesium oxide compounds.

[0140] It is important to note that the addition of additives is for the precise control of the chemical composition and physical properties of the melt, ensuring that key mass ratios such as CaO / SiO2, MgO / SiO2, and Al2O3 / SiO2 reach the set range. This satisfies the requirement for ideal phase separation during the smelting process and provides the optimal compositional basis for the subsequent preparation of high-quality microcrystalline glass from the slag. By selectively adding specific oxide additives, not only can deviations and inhomogeneities in the original solid waste composition be compensated for, but also full-process quality control can be achieved from the efficient capture of precious metals to the high-value utilization of slag, ensuring that the microcrystalline glass products possess excellent mechanical strength, chemical stability, and thermal stability.

[0141] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0142] A. The proportion of -200 mesh particles in the treated glass feed is 60%-85%;

[0143] Optionally, the proportion of -200 mesh particles in the processed glass frit can be any value between 60%, 70%, 80%, 85%, or 60%-85%.

[0144] B. The moisture content of the treated glass frit is <3%;

[0145] Optionally, the moisture content of the processed glass frit can be any value of 0.1%, 1%, 2%, 2.9%, or <3%;

[0146] C. The flexural strength of the microcrystalline glass is ≥50MPa, and the Vickers hardness is ≥19Gpa.

[0147] Optionally, the flexural strength of the microcrystalline glass can be any value of 50 MPa, 51 MPa, 52 MPa, 53 MPa, 54 MPa, 55 MPa, 56 MPa, 57 MPa, 58 MPa, 59 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa or ≥50 MPa, and the Vickers hardness can be any value of 19 GPa, 20 GPa, 22 GPa, 24 GPa, 26 GPa, 28 GPa, 30 GPa, 35 GPa, 40 GPa or ≥19 GPa.

[0148] In some embodiments, the method for enhancing precious metal recovery and full component utilization through plasma co-melting satisfies at least one of the following conditions:

[0149] A. The mass of the binder in the binder solution is 8%-12% of the mass of the treated glass frit;

[0150] Optionally, the mass of binder in the binder solution can be any value between 8%, 9%, 10%, 11%, 12% or 8%-12% of the mass of the treated glass frit;

[0151] B. The adhesive in the adhesive solution includes polyethylene glycol and polyvinyl alcohol;

[0152] It should be noted that when preparing the binder solution, polyethylene glycol and polyvinyl alcohol should be added at 60-80℃ and stirred thoroughly until completely dissolved. This binder solution can provide good plasticity and bonding strength during compression molding and completely decomposes during subsequent sintering without affecting the performance of the product.

[0153] The mass ratio of the polyethylene glycol to the polyvinyl alcohol is 2-5:2;

[0154] Optionally, the mass ratio of polyethylene glycol to polyvinyl alcohol can be any value between 2:2, 3:2, 4:2, 5:2 or 2-5:2;

[0155] C. The mass concentration of the adhesive solution is 5%-8%.

[0156] Optionally, the mass concentration of the adhesive solution can be any value between 5%, 6%, 7%, 8%, or 5%-8%.

[0157] In some embodiments, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially;

[0158] The heating rate of the first heat treatment is 3-5℃ / min, the final temperature is 750-850℃, and the holding time is 2-4h;

[0159] Optionally, the heating rate of the first heat treatment can be any value between 3℃ / min, 4℃ / min, 5℃ / min or 3-5℃ / min, the final temperature can be any value between 750℃, 800℃, 850℃ or 750-850℃, and the holding time can be any value between 2h, 3h, 4h or 2-4h.

[0160] It is important to note that during the first heat treatment process, it is crucial to ensure the formation of a large number of tiny, uniformly distributed crystal nuclei. The temperature range of 750-850℃ is the optimal temperature range for crystal nuclei formation rate.

[0161] The heating rate of the second heat treatment is 2-3℃ / min, the final temperature is 900-1050℃, and the holding time is 3-6h;

[0162] Optionally, the heating rate of the second heat treatment can be any value between 2℃ / min, 2.5℃ / min, 3℃ / min or 2-3℃ / min, the final temperature can be any value between 900℃, 950℃, 1000℃, 1050℃ or 900-1050℃, and the holding time can be any value between 3h, 4h, 5h, 6h or 3-6h.

[0163] It should be noted that after the nucleation of the first heat treatment is completed, the temperature is raised to 900-1050℃ at a heating rate of 2-3℃ / min. The temperature is then maintained at this temperature for 3-6 hours to allow the previously formed crystal nuclei to grow fully and form a fine and intertwined grain structure. This temperature range is the optimal temperature range for crystal growth rate.

[0164] The cooling rate of the heat treatment is 5-10℃ / min.

[0165] Optionally, the cooling rate of the heat treatment can be any value between 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, or 5-10℃ / min.

[0166] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0167] Example 1

[0168] This embodiment provides a method for enhancing the recovery and full utilization of precious metals through plasma-assisted smelting. The process of this method is as follows: Figure 1 As shown, the specific steps are as follows:

[0169] S1: Take 100g of waste automotive catalyst (platinum group metal waste), whose main chemical composition (mass percentage) is: Al2O3 35.96%, SiO2 32.97%, MgO 9.06%, Fe2O3 6.22%, CaO 0.42%, with the remainder being other catalyst additives and precious metals; the total precious metal content (PGMs) is 1636.8 g / t, of which Pt 237.11 g / t, Pd 1238.43 g / t, and Rh 161.26 g / t;

[0170] Take 200g of cyanide tailings (containing gold and silver residue). Its main chemical composition (mass percentage) is: Fe2O3 40.77%, SiO2 34.75%, Al2O3 5.2%, CaO 5.8%, Cu 4.33%, Pb 4.86%, Zn 3.42%, with the balance being other metal oxides, sulfides, and precious metals; the total precious metal content is 61.8 g / t, of which Au 10.8 g / t and Ag 51 g / t.

[0171] Take 140g of desulfurized gypsum residue, whose main component is CaSO4, with a CaO content of 39.12% and a S content of 22.3%;

[0172] Take 25g of industrial-grade magnesium oxide and 80g of industrial-grade silicon oxide as supplementary slag-type conditioning agents, and take 25g of coke as a reducing agent. The molar amount of the reducing agent is 1.9 times the molar amount of iron.

[0173] The above materials are dried, ground, and thoroughly mixed to obtain a mixed furnace charge with a moisture content of <3% and a particle size between 20 mesh and 200 mesh. The mass ratio of CaO to SiO2 in the mixed furnace charge is 0.37:1, the mass ratio of MgO to SiO2 is 0.24:1, and the mass ratio of Al2O3 to SiO2 is 0.25:1. The mass of iron accounts for 10.78% of the total mass, and the molar amount of iron is 1.11 times the molar amount of sulfur.

[0174] S2: Add the above mixed furnace charge to a 15kW DC non-transfer arc plasma melting furnace, using nitrogen as the plasma working gas at a flow rate of 4m³ / h. 3 / h, to maintain the stability of the electric arc, after adding the furnace charge, first purge the residual oxygen with pure nitrogen gas, and stop the gas supply when the nitrogen content in the tail gas is greater than 99%, start the plasma arc, heat and melt the furnace charge, control the overall temperature of the molten pool at 1600±50℃, and the melting time is 1.5h.

[0175] S3: During smelting, Fe2O3, CuO, etc. in the furnace charge are reduced to metallic Fe and Cu, which together with Pb, Zn, etc., form Fe-Cu based alloy droplets, which settle and accumulate at the bottom of the furnace, while simultaneously capturing PGMs and Au; CaSO4 decomposes to generate CaO and SO2, with CaO entering the slag, and SO2 reacting with some Fe to generate FeS matte phase, enriching Ag; the slag phase is mainly composed of CaO, Al2O3, SiO2, and MgO, which floats to the top after clarification; the flue gas generated during the smelting process is collected, treated, and then discharged into the atmosphere;

[0176] After smelting, 61.86g of the alloy phase enriched with precious metals, 42.53g of the matte phase rich in silver, and approximately 353.68g of liquid slag (slag phase) were released sequentially. The analysis results of each phase are shown in Tables 1 and 2. The analysis showed that the recovery rates of precious metals based on the slag phase were all high: platinum (Pt) 98.21%, rhodium (Rh) 96.49%, palladium (Pd) 99.77%, gold (Au) 96.73%, and silver (Ag) 95.84%.

[0177] Table 1. Mass content of precious metals in each phase of the smelting process (g / t)

[0178]

[0179] Table 2. Distribution rate of precious metals in each phase of smelting (%)

[0180]

[0181] Note: The formulas for calculating the distribution rate of precious metals in each phase of smelting are as follows: Alloy phase precious metal distribution rate % = (mass of alloy phase × mass fraction of precious metals in alloy phase) / (mass of raw material × mass fraction of precious metals in raw material) × 100%; Matte phase precious metal distribution rate % = (mass of mate phase × mass fraction of precious metals in mate phase) / (mass of raw material × mass fraction of precious metals in raw material) × 100%; Slag phase precious metal distribution rate % = (mass of slag phase × mass fraction of precious metals in slag phase) / (mass of raw material × mass fraction of precious metals in raw material) × 100%. Note that due to errors in the mass fraction of precious metals during the testing process, the final distribution rate of precious metals in each phase of smelting will also have some error. Therefore, an error of less than 2% in the distribution rate of precious metals in each phase of smelting is normal.

[0182] S4: The silver-rich matte phase, which is an alloy phase enriched with precious metals, is subjected to water quenching and hydrometallurgical recovery of precious metals.

[0183] The discharged molten slag was directly poured into water for water quenching to obtain glassy granules. These granules were then crushed to a density of -200 mesh (73%) and dried until their weight no longer changed (moisture content <3%). The glass powder was mixed with a composite binder solution of polyethylene glycol and polyvinyl alcohol (mass ratio 3:2) (binder concentration 6.5%, binder mass 10% of glass powder mass). The mixture was then molded. The blank was placed in a muffle furnace and heated at 5℃ / min for 2 hours for nucleation. The temperature was then increased to 1000℃ at 3℃ / min and held for 4 hours for crystallization. Finally, the temperature was reduced to room temperature at 5℃ / min to complete the preparation of the microcrystalline glass. A total of 344.13g of microcrystalline glass ceramic was obtained, with a flexural strength of 58.95MPa and a Vickers hardness of 19.62GPa.

[0184] Example 2

[0185] This embodiment provides a method for enhancing the recovery and utilization of precious metals and all components through plasma co-melting. The difference from Embodiment 1 is that sulfuric acid slag is used instead of cyanide tailings as the source of precious metals (Au, Ag) and iron.

[0186] The specific steps are as follows:

[0187] S1: Take 100g of waste automotive catalyst, whose main chemical components (mass percentage) are: Al2O3 35.96%, SiO2 32.97%, MgO 9.06%, Fe2O3 6.22%, CaO 0.42%, with the remainder being other catalytic additives and precious metals; the total precious metal content (PGMs) is 1636.8 g / t, of which Pt 237.11 g / t, Pd 1238.43 g / t, and Rh 161.26 g / t;

[0188] Take 200g of sulfuric acid slag, whose main chemical composition (mass percentage) is: Fe2O3 81.92%, SiO2 6.15%, Al2O3 1.23%, CaO 0.92%, Cu 0.96%, Pb 0.12%, Zn 1.13%, with the balance being other metal oxides, sulfides, and precious metals; the total precious metal content is 77 g / t, of which Au 10.2 g / t and Ag 66.8 g / t;

[0189] Take 120g of desulfurized gypsum residue, whose main component is CaSO4, with a CaO content of 39.12% and a S content of 22.3%;

[0190] Take 20g of industrial-grade magnesium oxide and 100g of industrial-grade silicon oxide as supplementary slag-type conditioning agents, and take 42g of coke as a reducing agent. The molar amount of the reducing agent is 1.64 times the molar amount of iron.

[0191] The above materials are thoroughly mixed, dried, and ground to obtain a mixed furnace charge with a moisture content of <3% and a particle size between 20 mesh and 200 mesh. The mass ratio of CaO to SiO2 in the mixed furnace charge is 0.34:1, the mass ratio of MgO to SiO2 is 0.21:1, and the mass ratio of Al2O3 to SiO2 is 0.26:1. The mass of iron accounts for 20.45% of the total mass, and the molar amount of iron is 2.38 times the molar amount of sulfur.

[0192] S2: Add the above mixed furnace charge to a 15kW DC non-transfer arc plasma melting furnace, using nitrogen as the plasma working gas at a flow rate of 4m³ / h. 3 / h, to maintain the stability of the electric arc, after adding the furnace charge, first purge the residual oxygen with pure nitrogen gas, and stop the gas supply when the nitrogen content in the tail gas is greater than 99%, start the plasma arc, heat and melt the furnace charge, control the overall temperature of the molten pool at 1600±50℃, and the melting time is 1.5h.

[0193] S3: During smelting, Fe2O3, CuO, etc. in the furnace charge are reduced to metallic Fe and Cu, which together with Pb, Zn, etc., form Fe-Cu-based alloy droplets, which settle and accumulate at the bottom of the furnace, while capturing PGMs and Au; CaSO4 decomposes to generate CaO and SO2. CaO enters the slag, and SO2 reacts with some Fe to generate FeS matte phase, enriching Ag; the slag phase is mainly composed of CaO, Al2O3, SiO2, and MgO, which floats to the upper layer after clarification;

[0194] After smelting, 88.95g of the alloy phase enriched with precious metals, 60.25g of the matte phase rich in silver, and approximately 273.85g of liquid slag (slag phase) were released sequentially. The analysis results of each phase are shown in Tables 3 and 4. The analysis showed that the recovery rates of precious metals based on the slag phase were all high: platinum (Pt) 99.19%, rhodium (Rh) 97.11%, palladium (Pd) 99.05%, gold (Au) 98.39%, and silver (Ag) 98.16%.

[0195] Table 3. Mass content of precious metals in each phase of smelting (g / t)

[0196]

[0197] Table 4. Distribution rate of precious metals in each phase of smelting (%)

[0198]

[0199] Note: The distribution rate of precious metals in each phase of the smelting process was calculated using the same method as in Example 1;

[0200] S4: The discharged liquid slag is directly poured into water for water quenching to obtain glassy granules. The glass powder is crushed to -200 mesh (73%) and dried until its weight no longer changes (moisture content <3%). The glass powder is mixed with a composite binder solution of polyethylene glycol and polyvinyl alcohol (mass ratio 3:2) (binder concentration 6.5%, binder mass is 10% of glass powder mass) and molded. The blank is placed in a muffle furnace, heated at 5℃ / min, and held at 800℃ for 2h for nucleation treatment. Then, the temperature is increased to 1000℃ at 3℃ / min and held for 4h for crystallization treatment. Finally, the temperature is cooled to room temperature at 5℃ / min to complete the preparation of microcrystalline glass. 266.45g of microcrystalline glass ceramic is obtained, with a flexural strength of 57.2MPa and a Vickers hardness of 19.3GPa.

[0201] Example 3

[0202] This embodiment provides a method for enhancing the recovery and full utilization of precious metals through plasma co-melting. The difference from Embodiment 1 is that a combination of reducing gas and inert gas is used as the working gas, while the amount of coke added is reduced.

[0203] The specific steps are as follows:

[0204] S1: Take 100g of waste automotive catalyst, whose main chemical components (mass percentage) are: Al2O3 35.96%, SiO2 32.97%, MgO 9.06%, Fe2O3 6.22%, CaO 0.42%, with the remainder being other catalytic additives and precious metals; the total precious metal content (PGMs) is 1636.8 g / t, of which Pt 237.11 g / t, Pd 1238.43 g / t, and Rh 161.26 g / t;

[0205] Take 200g of cyanide tailings. Its main chemical composition (mass percentage) is: Fe2O3 40.77%, SiO2 34.75%, Al2O3 5.2%, CaO 5.8%, Cu 4.33%, Pb 4.86%, Zn 3.42%, with the balance being other metal oxides, sulfides, and precious metals; the total precious metal content is 61.8 g / t, of which Au 10.8 g / t and Ag 51 g / t.

[0206] Take 140g of desulfurized gypsum residue, whose main component is CaSO4, with a CaO content of 39.12% and a S content of 22.3%;

[0207] Take 25g of industrial-grade magnesium oxide and 80g of industrial-grade silicon oxide as supplementary slag-type conditioning agents, and take 5g of coke as a reducing agent. The molar amount of the reducing agent is 0.38 times the molar amount of iron.

[0208] The above materials are thoroughly mixed, dried, and ground to obtain a mixed furnace charge with a moisture content of <3% and a particle size between 20 mesh and 200 mesh. The mass ratio of CaO to SiO2 in the mixed furnace charge is 0.37:1, the mass ratio of MgO to SiO2 is 0.24:1, and the mass ratio of Al2O3 to SiO2 is 0.25:1. The mass of iron accounts for 11.17% of the total mass, and the molar amount of iron is 1.11 times the molar amount of sulfur.

[0209] S2: Add the above mixed charge to a 15kW DC non-transfer arc plasma melting furnace, using hydrogen and argon as the plasma working gases, wherein the hydrogen gas integral rate is 15%, the argon gas integral rate is 85%, and the flow rate is 4m³ / h. 3 / h, to maintain arc stability, after adding furnace charge, first purge residual oxygen with pure nitrogen gas, and stop purging when the nitrogen content in the tail gas is greater than 99%, start the plasma arc, first pre-melt in pure argon atmosphere, and after a uniform molten pool is formed, adjust the working gas to 85%Ar+15%H2, start the reduction reaction, control the overall temperature of the molten pool at 1600±50℃, and the melting time is 1.5h;

[0210] S3: During smelting, Fe2O3, CuO, etc. in the furnace charge are reduced to metallic Fe and Cu, which together with Pb, Zn, etc., form Fe-Cu-based alloy droplets, which settle and accumulate at the bottom of the furnace, while capturing PGMs and Au; CaSO4 decomposes to generate CaO and SO2. CaO enters the slag, and SO2 reacts with some Fe to generate FeS matte phase, enriching Ag; the slag phase is mainly composed of CaO, Al2O3, SiO2, and MgO, which floats to the upper layer after clarification;

[0211] After smelting, 63.76g of the alloy phase enriched with precious metals, 42.29g of the matte phase rich in silver, and approximately 346.88g of liquid slag (slag phase) were released sequentially. The analysis results of each phase are shown in Tables 5 and 6. The analysis showed that the recovery rates of precious metals based on the slag phase were all high: platinum (Pt) 98.98%, rhodium (Rh) 97.20%, palladium (Pd) 99.75%, gold (Au) 97.59%, and silver (Ag) 96.67%.

[0212] Table 5. Mass content of precious metals in each phase of smelting (g / t)

[0213]

[0214] Table 6. Distribution rate of precious metals in each phase of smelting (%)

[0215]

[0216] Note: The distribution rate of precious metals in each phase of the smelting process was calculated using the same method as in Example 1;

[0217] S4: The discharged liquid slag is directly poured into water for water quenching to obtain glassy granules. The glass powder is crushed to -200 mesh (73% of the total particle size) and dried until its weight no longer changes (moisture content <3%). The glass powder is mixed with a composite binder solution of polyethylene glycol and polyvinyl alcohol (mass ratio 3:2) (binder concentration 6.5%, binder mass is 10% of glass powder mass) and molded. The blank is placed in a muffle furnace, heated at 5℃ / min, and held at 800℃ for 2h for nucleation treatment. Then, the temperature is increased to 1000℃ at 3℃ / min and held for 4h for crystallization treatment. Finally, the temperature is reduced to room temperature at 5℃ / min to complete the preparation of microcrystalline glass. 336.82g of microcrystalline glass ceramic is obtained, with a flexural strength of 56.54MPa and a Vickers hardness of 19.71GPa.

[0218] Comparative Example 1

[0219] The difference from Example 1 is that the amount of cyanide tailings added during the batching process in this comparative example was reduced, resulting in the iron content in the mixed furnace charge being less than 10%, and the final precious metal recovery rate being relatively low.

[0220] The specific steps are as follows:

[0221] S1: Take 100g of waste automotive catalyst, whose main chemical components (mass percentage) are: Al2O3 35.96%, SiO2 32.97%, MgO 9.06%, Fe2O3 6.22%, CaO 0.42%, with the remainder being other catalytic additives and precious metals; the total precious metal content (PGMs) is 1636.8 g / t, of which Pt 237.11 g / t, Pd 1238.43 g / t, and Rh 161.26 g / t;

[0222] 100g of cyanide tailings (containing gold and silver residue) was taken. Its main chemical components (mass percentage) were: Fe₂O₃ 40.77%, SiO₂ 34.75%, Al₂O₃ 5.2%, CaO 5.8%, Cu 4.33%, Pb 4.86%, Zn 3.42%, with the remainder being other metal oxides, sulfides, and precious metals. The total precious metal content was 61.8 g / t, including Au 10.8 g / t and Ag 51 g / t.

[0223] Take 140g of desulfurized gypsum residue, whose main component is CaSO4, with a CaO content of 39.12% and a S content of 22.3%;

[0224] Take 25g of industrial-grade magnesium oxide and 80g of industrial-grade silicon dioxide as supplementary slag-forming agents, and take 15g of coke as a reducing agent. Both the slag-forming agents and the reducing agents are additives.

[0225] The above materials are dried, ground, and thoroughly mixed to obtain a mixed furnace charge with a moisture content of <3% and a particle size between 20 mesh and 200 mesh. The mass ratio of CaO to SiO2 in the mixed furnace charge is 0.41:1, the mass ratio of MgO to SiO2 is 0.27:1, and the mass ratio of Al2O3 to SiO2 is 0.28:1. The mass of iron accounts for 7.15% of the total mass, and the molar amount of iron is 0.6 times the molar amount of sulfur.

[0226] S2: Add the above mixed furnace charge to a 15kW DC non-transfer arc plasma melting furnace, using nitrogen as the plasma working gas at a flow rate of 4m³ / h. 3 / h, to maintain the stability of the electric arc, after adding the furnace charge, first purge the residual oxygen with pure nitrogen gas, and stop the gas supply when the nitrogen content in the tail gas is greater than 99%, start the plasma arc, heat and melt the furnace charge, control the overall temperature of the molten pool at 1600±50℃, and the melting time is 1.5h.

[0227] S3: During smelting, Fe2O3, CuO, etc. in the furnace charge are reduced to metallic Fe and Cu, which together with Pb, Zn, etc., form Fe-Cu-based alloy droplets, which settle and accumulate at the bottom of the furnace, while capturing PGMs and Au; CaSO4 decomposes to generate CaO and SO2. CaO enters the slag, and SO2 reacts with some Fe to generate FeS matte phase, enriching Ag; the slag phase is mainly composed of CaO, Al2O3, SiO2, and MgO, which floats to the upper layer after clarification;

[0228] After smelting, 32.27g of the alloy phase enriched with precious metals, 23.31g of the matte phase rich in silver, and approximately 300.69g of liquid slag (slag phase) were released sequentially. The analysis results of each phase are shown in Tables 7 and 8. The analysis showed that the recovery rates of precious metals based on the slag phase were all high: platinum (Pt) 82.75%, rhodium (Rh) 79.68%, palladium (Pd) 80.36%, gold (Au) 80.51%, and silver (Ag) 62.86%.

[0229] Table 7. Mass content of precious metals in each phase of smelting (g / t)

[0230]

[0231] Table 8. Distribution rate of precious metals in each phase of smelting (%)

[0232]

[0233] Note: The distribution rate of precious metals in each phase of the smelting process was calculated using the same method as in Example 1;

[0234] S4: The discharged liquid slag is directly poured into water for water quenching to obtain glassy granules. The glass powder is crushed to -200 mesh (73%) and dried until its weight no longer changes (moisture content <3%). The glass powder is mixed with a composite binder solution of polyethylene glycol and polyvinyl alcohol (mass ratio 3:2) (binder solution mass concentration 6.5%, binder mass is 10% of glass powder mass) and molded. The blank is placed in a muffle furnace, heated at 5℃ / min, and held at 800℃ for 2h for nucleation treatment. Then, the temperature is raised to 1000℃ at 3℃ / min and held for 4h for crystallization treatment. Finally, the temperature is cooled to room temperature at 5℃ / min to complete the preparation of microcrystalline glass. 292.57g of microcrystalline glass ceramic is obtained, with a flexural strength of 55.2MPa and a Vickers hardness of 19.86GPa.

[0235] Comparative Example 2

[0236] The difference from Example 1 is that the amount of waste automotive catalyst added during the preparation of this comparative example increased the mass fraction of aluminum phase in the raw materials, resulting in an Al2O3 / SiO2 ratio of 0.38 in the raw materials. The final flexural strength of the resulting microcrystalline glass was difficult to meet the requirements. In this comparative example, due to the excessive alumina content, its Vickers hardness was improved.

[0237] The specific steps are as follows:

[0238] S1: Take 200g of waste automotive catalyst, whose main chemical components (mass percentage) are: Al2O3 35.96%, SiO2 32.97%, MgO 9.06%, Fe2O3 6.22%, CaO 0.42%, with the remainder being other catalytic additives and precious metals; the total precious metal content (PGMs) is 1636.8 g / t, of which Pt 237.11 g / t, Pd 1238.43 g / t, and Rh 161.26 g / t;

[0239] Take 200g of cyanide tailings. Its main chemical composition (mass percentage) is: Fe2O3 40.77%, SiO2 34.75%, Al2O3 5.2%, CaO 5.8%, Cu 4.33%, Pb 4.86%, Zn 3.42%, with the balance being other metal oxides, sulfides, and precious metals; the total precious metal content is 61.8 g / t, of which Au 10.8 g / t and Ag 51 g / t.

[0240] Take 140g of desulfurized gypsum residue, whose main component is CaSO4, with a CaO content of 39.12% and a S content of 22.3%;

[0241] Take 25g of industrial-grade magnesium oxide and 80g of industrial-grade silicon oxide as supplementary slag-type conditioning agents, and take 15g of coke as a reducing agent. The molar amount of the reducing agent is 1.06 times the molar amount of iron.

[0242] The above materials are thoroughly mixed, dried, and ground to obtain a mixed furnace charge with a moisture content of <3% and a particle size between 20 mesh and 200 mesh. The mass ratio of CaO to SiO2 in the mixed furnace charge is 0.31:1, the mass ratio of MgO to SiO2 is 0.25:1, and the mass ratio of Al2O3 to SiO2 is 0.38:1. The mass of iron accounts for 9.97% of the total mass, and the molar amount of iron is 1.18 times the molar amount of sulfur.

[0243] S2: Add the above mixed furnace charge to a 15kW DC non-transfer arc plasma melting furnace, using nitrogen as the plasma working gas at a flow rate of 4m³ / h. 3 / h, to maintain the stability of the electric arc, after adding the furnace charge, first purge the residual oxygen with pure nitrogen gas, and stop the gas supply when the nitrogen content in the tail gas is greater than 99%, start the plasma arc, heat and melt the furnace charge, control the overall temperature of the molten pool at 1600±50℃, and the melting time is 1.5h.

[0244] S3: During smelting, Fe2O3, CuO, etc. in the furnace charge are reduced to metallic Fe and Cu, which together with Pb, Zn, etc., form Fe-Cu-based alloy droplets, which settle and accumulate at the bottom of the furnace, while capturing PGMs and Au; CaSO4 decomposes to generate CaO and SO2. CaO enters the slag, and SO2 reacts with some Fe to generate FeS matte phase, enriching Ag; the slag phase is mainly composed of CaO, Al2O3, SiO2, and MgO, which floats to the upper layer after clarification;

[0245] After smelting, 64.55g of precious metal-enriched alloy phase, 46.61g of silver-enriched matte phase, and approximately 435.23g of liquid slag (slag phase) were released sequentially. The analysis results of each phase are shown in Tables 9 and 10. The analysis showed that the recovery rates of precious metals based on the slag phase were all high: platinum (Pt) 85.87%, rhodium (Rh) 78.27%, palladium (Pd) 82.62%, gold (Au) 84.89%, and silver (Ag) 74.95%.

[0246] Table 9. Mass content of precious metals in each phase of the smelting process (g / t)

[0247]

[0248] Table 10. Distribution rate of precious metals in each phase of smelting (%)

[0249]

[0250] Note: The distribution rate of precious metals in each phase of the smelting process was calculated using the same method as in Example 1;

[0251] S4: The discharged liquid slag is directly poured into water for water quenching to obtain glassy granules. The glass powder is crushed to -200 mesh (73%) and dried until its weight no longer changes (moisture content <3%). The glass powder is mixed with a composite binder solution of polyethylene glycol and polyvinyl alcohol (mass ratio 3:2) (binder concentration 6.5%, binder mass is 10% of glass powder mass) and molded. The blank is placed in a muffle furnace, heated at 5℃ / min, and held at 800℃ for 2h for nucleation treatment. Then, the temperature is increased to 1000℃ at 3℃ / min and held for 4h for crystallization treatment. Finally, the temperature is reduced to room temperature at 5℃ / min to complete the preparation of microcrystalline glass. 423.48g of microcrystalline glass ceramic is obtained, with a flexural strength of 46.3MPa and a Vickers hardness of 20.85GPa.

[0252] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0253] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for enhancing the recovery and full utilization of precious metals through plasma-assisted smelting, characterized in that, include: The solid waste and the reducing agent are mixed in the first step to obtain a first mixture; Under the working atmosphere, the first mixture is subjected to plasma melting to obtain high-temperature liquid slag, liquid matte phase and liquid alloy phase; The liquid matte phase and the liquid alloy phase are respectively subjected to hydrometallurgical recovery of precious metals; The high-temperature liquid slag is water-quenched to obtain glass material; The glass material is ground and dried to obtain the treated glass material; The treated glass frit and binder solution are mixed a second time to obtain a second mixture; The second mixture is molded and heat-treated to obtain microcrystalline glass; The solid waste includes waste automotive catalysts, flue gas desulfurization gypsum residue and cyanide tailings and / or sulfuric acid slag. The composition of the waste automotive catalyst, based on a total mass of 100%, includes: Al2O3 35%-98%, SiO2 0%-40%, MgO 0%-15%, Fe2O3 0%-10%, CaO 0%-3%, with the balance being other catalytic additives and precious metals; The precious metal content in the waste automotive catalyst is 1000-5000 g / t; The components of the flue gas desulfurization gypsum residue include CaSO4; The composition of the cyanide tailings, based on a total mass of 100%, includes: Fe2O3 15%-50%, SiO2 20%-50%, Al2O3 1%-10%, CaO 2-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals; The mass content of precious metals in the cyanide tailings is 10-250 g / t; The composition of the sulfuric acid slag, based on a total mass of 100%, includes: Fe2O3 30-90%, SiO2 5-20%, Al2O3 0.5-10%, CaO 0.5-10%, Cu 0-5%, Pb 0-5%, Zn 0-5%, with the balance being other metal oxides, sulfides, and precious metals; The mass content of precious metals in the sulfuric acid slag is 5-300 g / t; In the first mixture, the mass ratio of CaO to SiO2 is 0.3-0.4:1, the mass ratio of MgO to SiO2 is 0.2-0.3:1, and the mass ratio of Al2O3 to SiO2 is 0.18-0.3:

1. The iron content in the first mixture is 10%-25% of the total mass, and the molar amount of iron is 1-2.5 times the molar amount of sulfur.

2. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 1, characterized in that, At least one of the following conditions must be met: A. The water content of the first mixture is <3%; B. The particle size of the first mixture is 20-200 mesh; C. The reducing agent includes coke.

3. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 1, characterized in that, At least one of the following conditions must be met: A. The working atmosphere includes inert gases and / or reducing gases; B. The plasma melting temperature is 1550-1800℃, and the time is 0.5-3h.

4. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 3, characterized in that, At least one of the following conditions must be met: A. When the working atmosphere includes argon and hydrogen, the molar amount of the reducing agent is 0.1-0.6 times the molar amount of iron. When the working atmosphere includes an inert gas, the molar amount of the reducing agent is 1.5-3 times the molar amount of the iron element; B. When the working atmosphere includes argon and hydrogen, the total volume of the working atmosphere, calculated as 100%, includes: 60%-90%Ar, 10%-40%H2; C. The total flow rate of the working gas introduced into the working atmosphere is 2-30 m³ / h. 3 / h.

5. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 1, characterized in that, A conditioning agent is also added during the preparation of the first mixture; The formulation agent includes one or more of calcium oxide compounds, silicon oxide compounds, iron oxide compounds, and magnesium oxide compounds.

6. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 1, characterized in that, At least one of the following conditions must be met: A. The proportion of -200 mesh particles in the treated glass feed is 60%-85%; B. The moisture content of the treated glass frit is <3%; C. The flexural strength of the microcrystalline glass is ≥50MPa, and the Vickers hardness is ≥19Gpa.

7. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to claim 1, characterized in that, At least one of the following conditions must be met: A. The mass of the binder in the binder solution is 8%-12% of the mass of the treated glass frit; B. The adhesive in the adhesive solution includes polyethylene glycol and polyvinyl alcohol; The mass ratio of the polyethylene glycol to the polyvinyl alcohol is 2-5:2; C. The mass concentration of the adhesive solution is 5%-8%.

8. The method for enhanced precious metal recovery and full component utilization through plasma-assisted smelting according to any one of claims 1-7, characterized in that, The heat treatment includes a first heat treatment and a second heat treatment performed sequentially. The heating rate of the first heat treatment is 3-5℃ / min, the final temperature is 750-850℃, and the holding time is 2-4h; The heating rate of the second heat treatment is 2-3℃ / min, the final temperature is 900-1050℃, and the holding time is 3-6h; The cooling rate of the heat treatment is 5-10℃ / min.

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