Method for cooperatively smelting and enriching platinum group metals by using multi-source nickel-containing solid waste plasma

Abstract

This application provides a method for the plasma-assisted matte formation and enrichment of platinum group metals from multi-source nickel-containing solid waste, relating to the field of comprehensive treatment of multi-source solid waste. The method includes: mixing a first raw material and a second raw material to obtain a mixture; granulating the mixture to obtain granulated material; and plasma melting the granulated material under a reducing atmosphere to obtain an upper slag layer and a lower layer of nickel-matte enriched with platinum group metals; at least one of the first and second raw materials contains a platinum group metal. Utilizing the complementary acid-base components of the main components of the first and second raw materials, under the high energy density, high temperature, and low viscosity molten pool conditions provided by the plasma arc, multi-source solid waste melting and matte formation can be achieved without the addition of a large amount of flux; nickel-matte has a strong capturing ability relative to platinum group metals, and combined with the strong convection and arc jet stirring of the plasma molten pool, platinum group metals are efficiently migrated and enriched into the nickel-matte phase, with an enrichment factor of not less than 50 times.

Description

Technical Field

[0001] This application relates to the field of comprehensive treatment of multi-source solid waste, and in particular to a method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste. Background Technology

[0002] With the continuous expansion of the automotive, petrochemical, and electroplating industries, a large amount of solid waste, such as waste petrochemical catalysts, waste automotive catalysts, electroplating sludge, and nickel-containing smelting slag, is constantly being generated. These solid wastes generally contain basic valuable metals such as nickel, cobalt, molybdenum, and copper, as well as rare and dispersed platinum group metals such as platinum, palladium, and rhodium, possessing high recycling value. However, due to differences in upstream production processes and usage environments, these solid wastes have complex compositions and diverse metal occurrence forms, and coexist with large amounts of acidic, high-melting-point components such as Al2O3 and SiO2, resulting in technical bottlenecks such as high difficulty in traditional resource recovery, high energy consumption, and low precious metal recovery efficiency.

[0003] Currently, industrial processing methods mainly include hydrometallurgical processes, conventional pyrometallurgical smelting, and flotation pre-enrichment. While hydrometallurgical processes offer high metal recovery rates, when processing high-alumina silicon waste catalysts, a large amount of Al2O3 dissolves during acid leaching, leading to a decrease in Al content in the leachate. 3+ Excessive concentration leads to co-precipitation with platinum group metals, making separation difficult. Furthermore, the impurity removal process for high-alumina leaching solutions is complex, generating large amounts of aluminum salt wastewater containing heavy metals, resulting in high treatment costs and making it unsuitable for large-scale solid waste treatment. While traditional electric arc furnaces or reverberatory furnaces offer advantages such as short process flow and strong adaptability, when treating high-alumina silicon waste catalysts, the liquidus temperature of the Al2O3-SiO2 slag system exceeds 1550℃, requiring the furnace temperature to be raised to above 1700℃ to obtain fluid slag, resulting in high energy consumption per unit. Simultaneously, the high viscosity of the slag phase makes it difficult for fine matte droplets to settle, leading to a high platinum group metal slag loss rate. The flotation pre-enrichment process has strict requirements on the occurrence form of platinum group metals in the waste catalyst. When platinum group metals are embedded in the Al2O3 support as highly dispersed nano-sized particles, the flotation recovery rate is low, and the flotation tailings still contain a large amount of platinum group metals, resulting in severe resource loss.

[0004] Furthermore, existing technologies generally adopt a model of treating individual solid wastes independently, failing to explore the complementary potential between different components of solid wastes. For example, when treating high-alumina and high-silicon waste catalysts alone, large quantities of limestone and dolomite need to be purchased as fluxes to lower the melting point, resulting in high energy consumption and large slag volume. On the other hand, when treating sludge or slag containing heavy metals alone, large amounts of sulfiding agents and reducing agents are required. This dual waste of materials and energy caused by individual treatment greatly limits the economic benefits and widespread application of solid waste resource utilization technologies.

[0005] On the other hand, the metallurgical industry is facing the constraints of the "dual-carbon strategy," and enterprises urgently need new metallurgical technologies that can efficiently recover precious metals while reducing energy consumption. Traditional pyrometallurgical equipment cannot simultaneously meet the requirements of high temperature, low oxygen potential, rapid reaction, and enhanced metal capture. Against this backdrop, plasma metallurgy technology, with its ultra-high energy density, controllable atmosphere, and rapid heating characteristics, provides a new approach to solving the difficulties in melting high-melting-point materials, enhancing the in-situ sulfidation matte-making process, and reducing precious metal loss. However, existing plasma metallurgical research is still mainly focused on single mineral or single solid waste treatment areas, with limited systematic research and application of co-melting systems for complex solid wastes of multiple types. Furthermore, existing plasma metallurgical research has not effectively solved the problems of high viscosity in high-alumina silicon slag systems, which makes it difficult for fine matte droplets to settle and the high loss of platinum group metals.

[0006] Therefore, there is an urgent need to provide a multi-source solid waste integrated smelting technology system based on plasma heat source to solve the above problems. Summary of the Invention

[0007] Because the high-alumina silicon waste catalyst (first raw material) has a high melting point and high viscosity when treated by pyrometallurgy alone, the recovery rate of platinum group metals is low; and when nickel-containing solid waste (second raw material) is treated alone, a large amount of flux and sulfiding agent are required, resulting in large consumption of auxiliary materials and large slag volume; at the same time, the existing plasma metallurgy technology has not yet established a synergistic batching and matte enrichment system for complex solid waste from multiple sources.

[0008] To address the aforementioned problems, this application provides a method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste.

[0009] To achieve the above objectives, this application provides a method for enriching platinum group metals through multi-source nickel-containing solid waste plasma-assisted matte formation, comprising: The first raw material and the second raw material are mixed to obtain a mixture; The mixture is granulated to obtain the granulated material; Under a reducing atmosphere, the granulated material is subjected to plasma melting to obtain an upper slag and a lower nickel matte mixture enriched with platinum group metals. The first raw material includes solid waste containing acidic high-melting-point oxides such as Al2O3 and / or SiO2; The second raw material includes waste containing Ni, Fe and alkaline oxides; At least one of the first raw material and the second raw material contains a platinum group metal.

[0010] Optionally, the first raw material includes at least one of waste automotive exhaust purification catalyst, waste petrochemical catalyst, waste industrial adsorbent, and waste molecular sieve. And / or, the second raw material includes at least one of nickel-containing electroplating sludge, nickel-containing smelting slag, and nickel-containing waste hydrogenation catalyst.

[0011] Optionally, the first raw material, by mass, includes: 30%-90% Al2O3, 0.1%-40% SiO2, 0.1%-8% S, Fe<5%; the total mass content of platinum group metals Pt, Pd and Rh is 200-3000 g / t; And / or, the second raw material comprises, by mass, 10%-45% Fe, 2%-15% S, 30%-75% total of basic oxides CaO, MgO and FeO, and 5%-30% total of Cu, Co and Mo.

[0012] Optionally, the alkalinity of the mixture is R, where R = W(CaO + MgO + FeO) / W(SiO2 + Al2O3), and R ranges from 0.4 to 1.0. The molar ratio of sulfur in the mixture to the target total metals Ni, Cu, Co and Mo is 0.5-1.0:1.

[0013] Optionally, the oxygen partial pressure in the plasma melting is 10. -8 -10 -10 atm; And / or, the temperature of the plasma melting pool is 1300-1600℃, and the time is 0.5-3.0h; And / or, the morphology of the granulated material includes at least one of powder, spheres and lumps; The particle size of the granulated powder is 100-200 mesh. And / or, the moisture content of the granulated material is <1%.

[0014] Optionally, the upper slag, by weight (100%), comprises: 25%-40% FeO, 30%-45% SiO2, 5%-20% CaO, 5%-25%Al2O3, 2%-10% MgO; And / or, the Fe content in the nickel-matte mixture is 20%-50% by mass.

[0015] Optionally, auxiliary additives may be added during the mixing process; The auxiliary additives include at least one of the following: matte-forming promoter, nickel matte seed crystal, oxygen potential buffer, laterite nickel ore, and nickel sulfide concentrate; And / or, a reducing agent is also added during the plasma melting process.

[0016] Optionally, the matte-forming accelerator includes pyrite powder and / or sulfur powder; And / or, the nickel matte seed crystals include nickel matte powder and / or nickel sulfide powder; And / or, the oxygen potential buffer comprises magnetite powder and / or iron oxide powder; And / or, the reducing agent includes at least one of anthracite, semi-coke, graphite, petroleum coke, and biochar; And / or, the first and second raw materials contain organic carbon.

[0017] Optionally, the mass of the matte-forming accelerator accounts for 1%-15% of the mass of the mixture; And / or, the mass of the nickel matte seed crystal accounts for 1%-20% of the mass of the mixture; And / or, the oxygen potential buffer accounts for 1%-15% of the mass of the mixture; And / or, the mass of the reducing agent is 0.5%-10% of the mass of the granulated material.

[0018] Optionally, the upper molten slag is water-quenched to obtain the water-quenched material; The water-quenched material is used in the preparation of at least one of building materials, roadbed materials, and cement materials.

[0019] Compared with existing single solid waste treatment technologies, the beneficial effects of this application include: By using alkaline oxides from the second raw material to replace industrial limestone and dolomite flux, the slag shape is self-regulated through the complementarity of acid and alkali components, significantly reducing the amount of external flux required. The acid-alkali complementarity lowers the liquidus temperature of the mixture, and combined with the high energy density of plasma, good molten pool fluidity can be obtained at a lower superheat. The energy consumption per unit processing volume is lower than that of traditional high-temperature electric arc furnaces for processing high-alumina silicon materials. The synergistic effect of strong plasma convection and optimized slag shape results in a lower platinum group metal slag loss rate than traditional pyrometallurgical processes, and a higher overall recovery rate than typical levels for hydrometallurgical processes for processing high-alumina silicon materials. The main components of the water-quenched slag are FeO-SiO2-CaO-Al2O3-MgO, with low heavy metal content, meeting the resource utilization requirements of building materials and roadbed materials, and realizing the full resource utilization of solid waste. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the process for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste, as provided in Example 4. Detailed Implementation

[0022] First, the solution provided in this application will be explained in more detail as follows: This application provides a method for enriching platinum group metals through multi-source nickel-containing solid waste plasma-assisted matte production, comprising: The first raw material and the second raw material are mixed to obtain a mixture; The mixture is granulated to obtain the granulated material; Under a reducing atmosphere, the granulated material is subjected to plasma melting to obtain an upper slag and a lower nickel matte mixture enriched with platinum group metals. It should be noted that, thermodynamically, the slag phase (FeO-CaO-SiO2-Al2O3-MgO oxide ionic melt) and the nickel matte phase (NiS-FeS sulfide melt) are thermodynamically immiscible under operating temperature and oxygen partial pressure conditions due to the fundamentally different chemical bond properties, forming a stable two-liquid-phase system. This is the thermodynamic premise for stratification. From a physicochemical perspective, the typical nickel matte phase density is 4.5-5.5 g / cm³. 3 The density of the phase was significantly higher than that of the slag phase (2.6-3.2 g / cm³). 3 The density difference provides the driving force for gravity stratification; the high interfacial tension between the two phases prevents interpenetration and promotes the aggregation and growth of dispersed matte droplets at the interface. By controlling the slag basicity R (0.4-1.0), the viscosity of the molten slag is maintained at a low level, which further reduces the matte droplet settling resistance. At the kinetic level, the forced convection generated by the plasma arc jet accelerates the collision and coalescence of matte droplets; the bubble stirring effect generated by the rising CO bubbles enhances the renewal and mass transfer of the slag-matte interface; and the high-temperature field maintains the viscosity of the molten slag at a low viscosity state that is conducive to the settling of matte droplets. The synergistic effect of these three factors causes the nickel matte droplets dispersed in the molten pool to continuously coalesce and settle during the smelting process, eventually converging at the bottom of the molten pool to form a continuous nickel matte phase, thus achieving slag-matte stratification. The first raw material includes solid waste containing acidic high-melting-point oxides such as Al2O3 and / or SiO2; The second raw material includes waste containing Ni, Fe and alkaline oxides; At least one of the first raw material and the second raw material contains a platinum group metal.

[0023] It is worth noting that the multi-source solid waste integrated smelting technology system based on plasma heat source proposed in this application achieves efficient enrichment and recovery of precious and valuable metals through complementary component design, efficient sulfidation matte formation reaction, and synergistic control of slag-matte separation. This application is proposed against this industry backdrop, addressing the problems existing in current solid waste metallurgical treatment technologies by constructing a coupled system of "plasma enhancement—component complementarity—nickel matte capture," providing a novel technical path for the resource utilization of industrial solid waste and the efficient recovery of platinum group metals.

[0024] This application aims to address the technical problems in existing solid waste pyrometallurgical treatment technologies, such as the high viscosity of high-alumina silicon slag leading to difficulties in precious metal settling, high consumption of external flux, and low resource utilization rate in single solid waste treatment. This application provides a method for the plasma-assisted matte enrichment of platinum group metals from multi-source solid waste. By constructing a coupled system of "plasma enhancement—component complementarity—in-situ matte formation," and utilizing the complementary chemical compositions of the first raw material (acidic, high melting point) and the second raw material (alkaline, sulfur / iron / nickel-containing), a low-melting-point pentagonal slag system and a highly efficient nickel sulfide matte capture system are constructed under high plasma energy density and a reducing atmosphere.

[0025] In some embodiments, the first raw material includes at least one of waste automotive exhaust purification catalyst, waste petrochemical catalyst, waste industrial adsorbent, and waste molecular sieve. And / or, the second raw material includes at least one of nickel-containing electroplating sludge, nickel-containing smelting slag, and nickel-containing waste hydrogenation catalyst.

[0026] It is worth noting that this application, through multi-source synergy and waste-to-waste treatment, breaks through the limitations of traditional single solid waste treatment relying on external auxiliary materials, and constructs a "bidirectional acid-base complementarity" and "sulfur / carbon balance" mechanism. Slag-type complementarity: utilizing the abundant CaO, MgO, and FeO in the second raw material (sludge / slag) as inexpensive fluxes, directly neutralizes the acidic SiO2 and Al2O3 framework in the first raw material (catalyst), reducing the addition of industrial pure CaO / MgO flux; furthermore, it utilizes the organic components inherent in the raw materials as reducing agents and sulfates / sulfides as sulfur sources, achieving "endogenous" supply of reducing agents and sulfiding agents. Compared to traditional processes, the consumption of external fluxes and chemical reagents is reduced by more than 20%. Finally, through the precise ratio of the first and second raw materials, the initial melting temperature and liquidus temperature of the mixture are significantly reduced. Furthermore, with the high energy density of plasma, good rheological properties can be obtained without heating the entire molten pool to extremely high superheats, thereby shortening the melting time and reducing the power consumption per ton of processing capacity.

[0027] It should also be noted that the first raw material has a high Al2O3 content (30%-90%), which forms a high-viscosity aluminosilicate melt when smelted alone, with a liquidus temperature exceeding 1550℃; the second raw material contains 30%-75% total alkaline oxides such as CaO, MgO, and FeO. When the two are mixed, the alkaline oxides effectively depolymerize the aluminosilicate network, forming a low-melting-point pentagonal slag system with iron olivine (FeSiO3) and calcium aluminum feldspar (Ca2Al2SiO7) as the main mineral phases under the high-temperature field of plasma arc (1300-1600℃). The liquidus temperature is 250-350℃ lower than that of the first raw material alone, the slag viscosity is reduced, and the slag-matte separation kinetics are significantly improved.

[0028] The second raw material, Fe2O3 / Fe3O4, together with the CO / CO2 atmosphere in the system, forms a Fe2O3-FeO-CO-CO2 oxygen potential buffer system, which stabilizes the oxygen partial pressure in the molten pool at 10 at 1300-1600℃. -8 -10 -10 atm. This oxygen potential window has dual selectivity: on the one hand, it is higher than the partial pressure of oxygen decomposition of Ni, Co, and Mo sulfides (approximately 10 atm). -11 (atm), ensuring that Ni and Co exist stably in the matte phase in the form of sulfides; on the other hand, it is lower than the critical oxygen partial pressure (approximately 10 atm) at which FeO is largely reduced to metallic Fe. -7 (atm) suppresses excessive reduction alloying of iron, achieving selective allocation of "iron slag retention and nickel-cobalt matte".

[0029] The trapping of nickel matte relative to platinum group metals stems from a synergistic enhancement of thermodynamics and kinetics: thermodynamically, the partition coefficients of Pd, Pt, and Rh in NiS-FeS melts are all higher than 10. 4 10 3 and 10 2 It is far superior to silicate slag phase; kinetically, the forced convection (melt pool velocity 0.5-2 m / s) and bubble disturbance generated by plasma arc jet cause the slag-matte interface to be continuously renewed, and the mass transfer coefficient is improved compared with traditional static smelting. This allows the platinum group metals, which were originally dispersed in the skeleton of the waste catalyst support (Al2O3, SiO2), to migrate rapidly to the nickel matte phase after the support melts, and finally achieve an enrichment factor of not less than 50 times.

[0030] This application also enhances separation and improves recovery rate. The high-temperature field provided by plasma, combined with the optimized slag type (FeO-CaO-SiO2-Al2O3-MgO), significantly reduces slag viscosity, promotes the collision, aggregation and sedimentation of fine matte droplets, and significantly improves the recovery rate of platinum group metals.

[0031] In some embodiments, the first raw material comprises, by mass, 30%-90% Al2O3, 0.1%-40% SiO2, 0.1%-8% S, and Fe<5%; the total mass content of platinum group metals Pt, Pd, and Rh is 200-3000 g / t. Optionally, the raw materials of the first raw material, by mass, can be any value between 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 30-90% for Al2O3, 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, or 0.1-40% for SiO2, 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, or 0.1-40% for S, 0.1%, 1%, 2%, 4%, 6%, 8%, or 0.1%-8% for Fe, 0.1%, 1%, 2%, 3%, 4%, 4.99%, or less than 5% for Fe, and the total mass content of platinum group metals Pt, Pd, and Rh can be any value between 200 g / t, 500 g / t, 1000 g / t, 2000 g / t, 3000 g / t, or 200-3000 g / t for Pt, Pd, and Rh. And / or, the second raw material comprises, by mass, 10%-45% Fe, 2%-15% S, 30%-75% of the total mass content of basic oxides CaO, MgO and FeO, and 5%-30% of the total mass content of Cu, Co and Mo.

[0032] Optionally, the second raw material, by mass, can have Fe as any value between 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 10-45%, S as any value between 2%, 5%, 10%, 15% or 2-15%, the total mass content of alkaline oxides CaO, MgO and FeO as any value between 30%, 40%, 50%, 60%, 70%, 75% or 30-75%, and the total mass content of Cu, Co and Mo as any value between 5%, 10%, 15%, 20%, 25%, 30% or 5-30%.

[0033] In some embodiments, the alkalinity of the mixture is R, where R = W(CaO + MgO + FeO) / W(SiO2 + Al2O3), and R ranges from 0.4 to 1.0. Optionally, R can be any value between 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or 0.4-1; It is important to note the following: Lower limit control (R≥0.4): When R is below 0.4, the aluminosilicate network formed by SiO2 and Al2O3 in the slag exhibits excessive polymerization, leading to a sharp increase in slag viscosity. This makes it difficult for fine nickel matte droplets to penetrate the slag layer and settle, resulting in a significant increase in physical entrainment losses and a decrease in platinum group metal recovery. Upper limit control (R≤1.0): When R is above 1.0, excessive CaO and MgO may cause the precipitation of high-melting-point solid phases (such as magnesium aluminum spinel MgAl2O4), which in turn raises the liquidus temperature, worsens fluidity, and significantly exacerbates the corrosive effect of high-basicity slag on refractory materials. Optimal range: Within the range of 0.4-1.3, basic oxides (CaO, MgO, FeO) effectively disrupt the silicon-oxygen / aluminum-oxygen structure in high-melting-point materials, playing a "depolymerization" role and forming a low-melting-point, low-viscosity continuous liquid phase, providing optimal kinetic conditions for slag-matte separation. The basicity R of the mixture is set based on the slag structure theory and the phase diagram of the multi-component slag system. The degree of slag polymerization is usually characterized by the ratio of non-bridging oxygen to tetrahedral coordinated cations (NBO / T). The lower limit of R (≥0.4) is determined by the relationship between the slag NBO / T value and viscosity: when R<0.4, NBO / T<0.57, the aluminosilicate network polymerization is too high, the slag viscosity rises sharply, and according to Stokes' law, the matte droplet settling velocity is inversely proportional to viscosity. The physical entrainment loss of slag relative to matte droplets increases significantly, and the recovery rate of platinum group metals decreases. At the same time, Al2O3 exists in the form of tetracoordinate network formation when the basicity is insufficient, which further aggravates the slag polymerization. The upper limit of R value (≤1.0) is determined by the phase diagram of the CaO-MgO-Al2O3-SiO2-FeO slag system: when R>1.0, the system enters the primary crystallization region of high-melting-point mineral phases such as magnesium aluminum spinel (MgAl2O4, melting point 2135℃) and dicalcium silicate (Ca2SiO4, melting point 2130℃), the liquidus temperature rises in the opposite direction, and the fluidity deteriorates; at the same time, the activity of FeO decreases under high alkalinity conditions, and according to the thermodynamic equilibrium of the Fe-O system, the tendency of iron to be excessively reduced to metallic iron is enhanced, which affects the purity of the nickel matte phase; The molar ratio of sulfur in the mixture to the target total metals Ni, Cu, Co and Mo is 0.5-1.0:1.

[0034] Optionally, the molar ratio of sulfur in the mixture to the total target captured metals Ni, Cu, Co and Mo can be any value between 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1 or 0.5:1.

[0035] It is important to note that the sulfur metal molar ratio (S / M) is set based on the stoichiometric and thermodynamic relationships of the target metal sulfidation reaction. The lower limit of S / M (≥0.5) is determined by the minimum stoichiometric requirement for the complete formation of Cu2S (S / Cu = 0.5∶1), while also considering the consumption of effective sulfur by the formation of the FeS matrix phase and high-temperature sulfur volatilization, ensuring that Ni, Co, Cu, and Mo are fully sulfided into the nickel matte phase, providing sufficient capture carriers for platinum group metals. The upper limit of S / M (≤1.0) is determined by the thermodynamic constraints of the Fe-S system: based on the standard Gibbs free energy of FeS and NiS, excess sulfur preferentially reacts with iron, leading to an increase in the Fe / Ni ratio in the nickel matte phase and a decrease in matte grade; at the same time, excess free sulfur increases the partial pressure of sulfur vapor in the system, increasing SO2 emissions and exacerbating the flue gas treatment load. The synergistic control of slag basicity (R) and sulfur metal molar ratio (S / M) is crucial: the R value determines the slag viscosity and matte droplet settling kinetics, while the S / M value determines the amount and composition of the nickel-matte phase. These two factors are interconnected through the following mechanisms: First, the R value affects the activity of FeO in the slag, thus influencing the oxygen-sulfur potential balance of the Fe-S system and indirectly affecting the utilization rate of available sulfur in the matte-forming reaction. Second, the S / M value affects the volume fraction of the nickel-matte phase. A larger matte phase volume results in a larger slag-matte interface area and a stronger mass transfer driving force for platinum group metals, but also places higher demands on the slag viscosity (R needs to be within a reasonable range to ensure matte droplet settling). Therefore, satisfying only a single parameter constraint cannot guarantee efficient enrichment of platinum group metals; synergistic operation within the parameter window of R = 0.4-1.0 and S / M = 0.5-1.0:1 is necessary.

[0036] In some embodiments, the oxygen partial pressure of the plasma melting is 10. -8 -10 -10 atm; Optionally, the oxygen partial pressure in plasma melting can be 10. -8 10 -9 10 -10 Or 10 -8 -10 -10 Any value between atm; It should be noted that by controlling the oxygen partial pressure (10 -8 -10 -10 (atm), to suppress over-alloying of iron, reduce reducing agent consumption while ensuring matte grade, and maintain the oxygen partial pressure of the system at 10. -8 ~10 -10 atm: When the oxygen partial pressure is controlled at 10 -8 -10 -10 Within the atm range, oxidation can be prevented (<10). -8 atm): If the oxygen partial pressure is too high, valuable metals such as Ni and Co are easily oxidized and enter the slag phase, resulting in resource loss; inhibiting iron over-reduction (>10)-10 (atm): If the oxygen partial pressure is too low, a large amount of FeO in the slag will be reduced to metallic Fe and enter the matte phase. This not only leads to the ineffective consumption of reducing agent and sulfur source, but also generates low-grade nickel-iron alloy instead of the expected nickel matte, affecting subsequent separation and extraction. This window can achieve selective enrichment of "iron into slag, nickel / platinum group metals into matte"; And / or, the temperature of the plasma melting pool is 1300-1600℃, and the time is 0.5-3.0h; Optionally, the molten pool temperature of plasma melting can be any value between 1300℃, 1400℃, 1500℃, 1600℃ or 1300-1600℃, and the time can be any value between 0.5h, 1h, 2h, 3h or 0.5-3h. In some embodiments, a plasma melting furnace is used for plasma melting. The plasma melting furnace includes a transferred arc plasma furnace or a non-transferred arc plasma furnace, and the working gas is selected from argon, nitrogen, or a mixture thereof.

[0037] And / or, the morphology of the granulated material includes at least one of powder, spheres and lumps; The particle size of the granulated powder is 100-200 mesh. Optionally, the particle size of the granulated powder can be 100 mesh, 150 mesh, 200 mesh or any value between 100 and 200 mesh; The particle size of the spherical and blocky granulated materials is independently 10-30 mm; Optionally, the particle size of the spherical and block granulated materials can be independently 10 mm, 20 mm, 30 mm or any value between 10 and 30 mm; And / or, the moisture content of the granulated material is <1%.

[0038] Optionally, the moisture content of the granulated material can be any value of 0.01%, 0.1%, 0.9%, or less than 1%.

[0039] In some embodiments, the upper slag layer, by mass, comprises, on a 100% basis: 25%-40% FeO, 30%-45% SiO2, 5%-20% CaO, 5%-25%Al2O3, 2%-10% MgO; Optionally, the mass of the upper slag is 100%, and FeO can be any value between 25%, 30%, 35%, 40% or 25-40%, SiO2 can be any value between 30%, 35%, 40%, 45% or 30-45%, CaO can be any value between 5%, 10%, 15%, 20% or 5-20%, Al2O3 can be any value between 5%, 10%, 15%, 20%, 25% or 5-25%, and MgO can be any value between 2%, 4%, 6%, 8%, 10% or 2-10%. And / or, the Fe content in the nickel-matte mixture is 20%-50% by mass; Optionally, the Fe mass content in the nickel matte mixture can be any value between 20%, 30%, 40%, 50%, or 20-50%. And / or, the enrichment factor of platinum group metals in the nickel matte mixture is greater than or equal to 50 times the grade of platinum group metals in the mixture.

[0040] Optionally, compared to the mixture, the enrichment factor of platinum group metals in the nickel matte mixture can be any value of 50, 60, 70, 80, 90, 100 or greater than or equal to 50.

[0041] In some embodiments, auxiliary additives are also added during mixing; It should be noted that, based on the first and second raw materials, by adjusting the ratio of the first and second raw materials and optionally adding auxiliary additives, the slag basicity and sulfur-to-metal ratio of the mixture are made to meet the preset threshold. The mixture is then dried or granulated for pretreatment to obtain the material to be fed into the furnace. The auxiliary additives are used to adjust the slag basicity, adjust the sulfur-to-metal ratio, reduce the liquidus temperature of the molten slag, promote sulfidation and matte formation, promote matte droplet settling, or inhibit excessive reduction and alloying of iron. The auxiliary additives include at least one of the following: matte-forming promoter, nickel matte seed crystal, oxygen potential buffer, laterite nickel ore, and nickel sulfide concentrate; And / or, a reducing agent is also added during the plasma melting process.

[0042] In some embodiments, the matte-forming accelerator comprises pyrite powder and / or sulfur powder; And / or, the nickel matte seed crystals include nickel matte powder and / or nickel sulfide powder; And / or, the oxygen potential buffer comprises magnetite powder and / or iron oxide powder; And / or, the reducing agent includes at least one of anthracite, coke, graphite, petroleum coke, and biochar; And / or, the first and second raw materials contain organic carbon.

[0043] The selection of reducing agents should meet the following principles: First, the fixed carbon content should be high, and the reducing capacity should be sufficient to maintain the oxygen partial pressure in the molten pool at 10. -8 -10 -10 According to the oxygen potential diagram, the equilibrium oxygen partial pressure corresponding to the CO / CO2 atmosphere at 1300-1600℃ should fall within the above range. Secondly, the sulfur content should be low (preferably S<0.5%) to avoid introducing additional sulfur to interfere with the precise control of the S / M molar ratio of the mixture. Thirdly, the organic carbon (carbon deposits) inherent in the raw materials should be used as an endogenous reducing agent, with external reducing agents added as supplementary adjustments to reduce the consumption of auxiliary materials and reflect the resource utilization principle of multi-source solid waste co-processing.

[0044] It is important to note that by utilizing the organic components and carbon inherent in the raw materials, or by adding external reducing agents, nickel, cobalt, and some iron are reduced and sulfided to form a single nickel matte phase that traps platinum group metals and inhibits the formation of independent metal alloy phases; at the same time, the remaining Fe, Si, Al, Ca, and Mg are oxidized to form slag phases.

[0045] In some embodiments, the mass of the matte-forming accelerator accounts for 1%-15% of the mass of the mixture; Optionally, the mass of the matte-forming accelerator can be any value between 1%, 5%, 10%, 15% or 1-15% of the mass of the mixture; And / or, the mass of the nickel matte seed crystal accounts for 1%-20% of the mass of the mixture; Optionally, the mass of the nickel matte seed crystal can be any value between 1%, 5%, 10%, 15%, 20% or 1-20% of the mass of the mixture; And / or, the oxygen potential buffer accounts for 1%-15% of the mass of the mixture; Optionally, the mass of the oxygen potential buffer can be any value between 1%, 5%, 10%, 15% or 1-15% of the mass of the mixture; And / or, the mass of the reducing agent is 0.5%-10% of the mass of the granulated material.

[0046] Optionally, the mass of the reducing agent is any value between 0.5%, 1%, 5%, 10% or 0.5%-10% of the mass of the granulated material.

[0047] In some embodiments, when the organic carbon (carbon deposits) content of the first and second raw materials meets the reduction requirements, the amount of added reducing agent is taken as the lower limit (0.5%-3%); when the organic carbon content of the raw materials is insufficient, the amount of added reducing agent is taken as the upper limit (3%-10%). The specific amount is determined based on the carbon-oxygen molar ratio in the mixture. By adjusting the amount of reducing agent, the system spontaneously forms an oxygen potential buffer, stabilizing the oxygen partial pressure within the preset range.

[0048] In some embodiments, the upper molten slag is water-quenched to obtain water-quenched material; The water-quenched material is used in the preparation of at least one of building materials, roadbed materials, and cement materials.

[0049] 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.

[0050] Example 1 This embodiment provides a method for enriching platinum group metals by synergistic plasma-based matte formation from multi-source nickel-containing solid waste. The specific preparation steps are as follows: S1: Based on the principle of acid-base complementarity and sulfur metal balance of raw material components, the target slag basicity R=W(CaO+MgO+FeO) / W(SiO2+Al2O3) is set to 0.8, and the molar ratio S / M of the target sulfur metals (Ni, Cu, Co and Mo) is about 0.8. The specific ingredient ratio is as follows: Raw material A: 1000 g of waste automotive exhaust purification catalyst, mainly composed of SiO2 37.20%, Al2O3 38.09%, MgO 10.28%, containing Pt 13.70 g / t, Pd 131.79 g / t, and Rh 10.00 g / t; Raw material B: 500 g of waste hydrogenation catalyst, containing Al2O3 33.65%, Ni 3.44%, Mo 3.99%, C 23.76%, and S 7.12%; Raw material B: 1300 g of nickel-cobalt sulfide slag, containing Fe2O3 52.38%, Ni 2.66%, and Co 1.42%. Calculations show that the total amount of acidic oxides SiO2 + Al2O3 in the above raw materials is approximately 921.2 g, and the total amount of basic oxides CaO + MgO + FeO, of which FeO is calculated from the reduction of Fe2O3, is approximately 774.6 g. The slag basicity R≈0.84, and the estimated FeO mass percentage in the slag is approximately 35%, meeting the conditions for forming a low-melting-point fir olivine-based slag. Simultaneously, the total effective sulfur (S) in the mixture is approximately 35.6 g (approximately 1.11 mol), and the total amount of the main trapped metals (Ni+Co+Mo) is approximately 90.3 g (approximately 1.55 mol), resulting in a calculated sulfur-to-metal ratio S / M≈0.72. This ratio falls within the preset threshold of 0.5~1.0:1, prioritizing the sulfidation of Ni, Co, and Mo, while forcing excess Fe to oxidize and enter the slag phase. S2: Mix the above raw materials evenly and form pellets with a particle size of 10-20 mm (moisture content <1%). Continuously feed these pellets into a 1200 kVA DC arc plasma furnace. Use nitrogen as the plasma working gas, with a flow rate controlled at 15.0 L / h. Utilize the carbon inherent in raw material B to maintain a reducing atmosphere at high temperature, controlling the oxygen partial pressure to approximately 10. -9 Atm, the molten pool temperature is controlled at 1450℃ for 2 hours; S3: After smelting, approximately 1800 g of upper slag and approximately 182 g of lower nickel matte are obtained. The upper slag is water-quenched to obtain water-quenched material, which is then used for the resource utilization of building materials and / or roadbed materials.

[0051] Analysis of the main components showed that the upper slag contained 0.12 wt% Ni, 0.10 wt% Co, 35.42% FeO, 37.78% SiO2, 11.51% CaO, 16.21% Al2O3, and 4.23% MgO, with platinum group metals content <0.1 g / t. Iron in the slag mainly existed in the form of stable silicates. The lower nickel matte mainly consisted of Ni≈32%, Fe≈32%, and S≈15%, and was enriched with the vast majority of precious metals. Specifically, the Pt grade was approximately 73 g / t, the Pd grade approximately 702.2 g / t, and the Rh grade approximately 53.40 g / t. The calculated Ni recovery rate was 95.82%, the Co recovery rate was 95.2%, and the overall recovery rate of platinum group metals (Pt+Pd+Rh) was greater than 97%, with an enrichment factor exceeding 80 times.

[0052] Example 2 This embodiment provides a method for enriching platinum group metals by plasma-assisted matte production from multi-source nickel-containing solid waste. The difference from Embodiment 1 is that the raw material composition and ratio in step S1 are different, specifically: The first raw material A, consisting of 800g of waste petrochemical catalyst (high Al2O3 type), mainly comprises SiO2 5.20%, Al2O3 75.12%, Ni 3.50%, and Mo 4.02%; the second raw material B, consisting of 200g of waste automotive catalyst, contains Pt 13.70g / t, Pd 131.79g / t, and Rh 10.00g / t; and the third raw material, consisting of nickel-containing electroplating sludge, contains Ni 4.50%, Fe 20.07%, S 5.52%, and the total amount of alkaline oxides (CaO+MgO+FeO) is approximately 52%. The alkalinity R = 612 / 720 = 0.84, which is within the range of 0.4~1.0. The sulfur metal ratio S / M≈1.19, so the proportion of sludge needs to be reduced or adjusted by auxiliary additives. Adjustment plan: Add 800 g of laterite nickel ore (main components Ni 2.51%, Fe 15.02%, MgO 20.15%, SiO2 45.30%). The final alkalinity R = 0.81 and S / M = 0.99 meet the requirements.

[0053] Example 3 This embodiment provides a method for enriching platinum group metals by plasma co-processing of multi-source nickel-containing solid waste, which differs from Embodiment 2 in that the plasma melting parameters in step S2 are different, specifically: The oxygen partial pressure in plasma melting is 10. -8 Atm, the molten pool temperature of plasma melting is 1500℃, and the time is 3.0h.

[0054] Example 4 This embodiment provides a method for enriching platinum group metals by plasma co-processing of multi-source nickel-containing solid waste. The difference from Embodiment 2 is that a reducing agent (petroleum coke) is added during plasma smelting, at a rate of 2.5% of the mixture mass, to stabilize the oxygen partial pressure at 10. -9.5 atm.

[0055] The flowchart of the method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste is shown below. Figure 1 As shown.

[0056] Comparative Example 1 The difference from Example 1 is that no second raw material is added. Calculations show that the total amount of acidic oxides SiO2 + Al2O3 in the mixture of this comparative example is approximately 921.2 g, the total amount of basic oxides MgO is approximately 102.8 g, the slag basicity R≈0.11, and the total amount of available sulfur S in the mixture is approximately 35.6 g (approximately 1.11 mol), while the total amount of the main trapped metals (Ni + Co + Mo) is approximately 37.15 g (approximately 0.501 mol). The calculated sulfur-to-metal ratio S / M≈2.21.

[0057] Comparative Example 2 The difference from Example 2 is that no auxiliary additives are added.

[0058] Comparative Example 3 The difference from Example 1 is that the oxygen partial pressure in plasma melting is 10. -7 The plasma melting pool temperature was 1200℃ and the melting time was 4.0h.

[0059] The final Pt, Pd, and Rh grades, as well as the overall recovery rates of Ni, Co, and platinum group metals (Pt+Pd+Rh) in the above embodiments and comparative examples are shown in Table 1.

[0060] Table 1 Metal Grade and Recovery Rate

[0061] analyze: As shown in the above tests, by leveraging the complementary properties of the alkaline components in the second raw material and the acidic framework components in the first raw material, this invention controls the slag alkalinity R within the range of 0.4 to 1.0. Compared to the low recovery rate of 65.52% caused by low alkalinity (R ≈ 0.11), the optimized slag type in this invention combines low liquidus temperature (reduction of 250~350℃) with excellent settling kinetics, supporting a stable platinum group metal recovery rate of over 97%. When the raw material composition is unbalanced, as in Example 2, the S / M ratio is adjusted from 1.19 to 0.99 using laterite nickel ore, solving the bottleneck of insufficient enrichment factor in Comparative Example 2; the measured enrichment factor of 80~118 times proves that maintaining the S / M ratio at 0.5~1.0 can effectively block iron impurities from entering the matte phase, significantly improving the matte phase grade. Combined with 10 -8 -10 -10 The oxygen-controlled environment of the ATM and the stirring effect of the plasma arc enable the selective enrichment of target elements. This process breaks through the limitations of single solid waste disposal and achieves efficient resource enrichment of nickel, molybdenum, and platinum group metals from multi-source nickel-based solid waste under the premise of low cost and low energy consumption.

[0062] 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.

[0063] 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 enriching platinum group metals through plasma-assisted matte formation from multi-source nickel-containing solid waste, characterized in that, include: The first raw material and the second raw material are mixed to obtain a mixture; The mixture is granulated to obtain the granulated material; Under a reducing atmosphere, the granulated material is subjected to plasma melting to obtain an upper slag and a lower nickel matte mixture enriched with platinum group metals. The first raw material includes solid waste containing acidic high-melting-point oxides containing Al2O3 and / or SiO2; The second raw material includes waste containing Ni, Fe and alkaline oxides; At least one of the first raw material and the second raw material contains a platinum group metal.

2. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 1, characterized in that, The first raw material includes at least one of waste automotive exhaust purification catalyst, waste petrochemical catalyst, waste industrial adsorbent, and waste molecular sieve; And / or, the second raw material includes at least one of nickel-containing electroplating sludge, nickel-containing smelting slag, and nickel-containing waste hydrogenation catalyst.

3. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 2, characterized in that, The first raw material, by mass, comprises: 30%-90% Al2O3, 0.1%-40% SiO2, 0.1%-8% S, Fe<5%; the total mass content of platinum group metals Pt, Pd and Rh is 200-3000 g / t; And / or, the second raw material comprises, by mass, 10%-45% Fe, 2%-15% S, 30%-75% of the total mass content of basic oxides CaO, MgO and FeO, and 5%-30% of the total mass content of Cu, Co and Mo.

4. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 1, characterized in that, The alkalinity of the mixture is R, where R = W(CaO + MgO + FeO) / W(SiO2 + Al2O3), and R ranges from 0.4 to 1.

0. The molar ratio of sulfur in the mixture to the target total metals Ni, Cu, Co and Mo is 0.5-1.0:

1.

5. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 1, characterized in that, The oxygen partial pressure of the plasma melting is 10. -8 -10 -10 atm; And / or, the temperature of the plasma melting pool is 1300-1600℃, and the time is 0.5-3.0h; And / or, the morphology of the granulated material includes at least one of powder, spheres and lumps; The particle size of the granulated powder is 100-200 mesh. And / or, the moisture content of the granulated material is <1%.

6. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 1, characterized in that, The upper slag layer, by mass of 100%, includes: 25%-40% FeO, 30%-45% SiO2, 5%-20% CaO, 5%-25%Al2O3, 2%-10% MgO; And / or, the Fe content in the nickel-matte mixture is 20%-50% by mass.

7. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 1, characterized in that, Additional additives are also added during the mixing process; The auxiliary additives include at least one of the following: matte-forming promoter, nickel matte seed crystal, oxygen potential buffer, laterite nickel ore, and nickel sulfide concentrate; And / or, a reducing agent is also added during the plasma melting process.

8. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 7, characterized in that, The matte-forming accelerator includes pyrite powder and / or sulfur powder; And / or, the nickel matte seed crystals include nickel matte powder and / or nickel sulfide powder; And / or, the oxygen potential buffer comprises magnetite powder and / or iron oxide powder; And / or, the reducing agent includes at least one of anthracite, coke, graphite, petroleum coke, and biochar; And / or, the first and second raw materials contain organic carbon.

9. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to claim 7, characterized in that, The mass of the matte-forming accelerator accounts for 1%-15% of the mass of the mixture; And / or, the mass of the nickel matte seed crystal accounts for 1%-20% of the mass of the mixture; And / or, the oxygen potential buffer accounts for 1%-15% of the mass of the mixture; And / or, the mass of the reducing agent is 0.5%-10% of the mass of the granulated material.

10. The method for enriching platinum group metals by plasma-assisted matte formation from multi-source nickel-containing solid waste according to any one of claims 1-9, characterized in that, The upper molten slag is water-quenched to obtain the water-quenched material. The water-quenched material is used in the preparation of at least one of building materials, roadbed materials, and cement materials.

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