Method for recovering valuable metals in tungsten smelting slag

Abstract

The invention relates to the field of metallurgical solid waste resource utilization, and particularly provides a method for recycling valuable metals in tungsten smelting slag. The method comprises the following steps: (1) mixing tungsten smelting slag containing W, Ni, Co and optional Cu, molybdenum smelting slag containing Mo and Cu, a carbonaceous reducing agent and pyrite to obtain a mixture; and (2) the mixture is subjected to reduction vulcanization smelting, a smelting product comprising an alloy phase, a sulfonium phase and a slag phase is obtained, W, Mo, Co and Ni are enriched in the alloy phase, and Cu is enriched in the sulfonium phase. According to the method, the smelting temperature can be reduced, valuable metal can be efficiently recycled, additional fluxing agents do not need to be added, the distribution state of the metal can be optimized, and then the recycling cost is reduced.

Description

Technical Field

[0001] This application relates to the field of metallurgical solid waste resource utilization, specifically, it provides a method for recovering valuable metals from tungsten smelting slag. Background Technology

[0002] Tungsten smelting slag is the main solid residue generated during the hydrometallurgical process of tungsten. One of its main sources is the leaching residue produced after tungsten waste is extracted using a combined pyrometallurgical and hydrometallurgical process. This leaching residue contains various valuable metals such as cobalt (Co), nickel (Ni), and tungsten (W), making it a secondary resource with high recycling value. However, the complex phase composition after combined processing also increases the technical difficulty of efficient separation and recovery.

[0003] Currently, the main method for recovering valuable metals from tungsten smelting slag in industry is reduction smelting: by adding reducing agents and a large amount of fluxing agents (such as SiO2, Na2CO3, CaF2, etc.), the metal oxides are reduced and enriched in the resulting alloy phase at high temperatures. However, this method still faces the following problems when processing tungsten smelting slag: First, to achieve slag-metal separation, especially for complex tungsten smelting slags with high calcium and high silicon content, the smelting temperature is extremely high, resulting in huge energy consumption; second, to neutralize the large amount of alkaline oxides (such as CaO) in the slag and improve slag fluidity, a large amount of fluxing agents are required, which undoubtedly increases the processing cost. Another method involves co-processing tungsten-molybdenum acid slag and converter steel slag, and using a silicon reducing agent for molten reduction to obtain a product dominated by the alloy phase. Although this method can reduce the smelting temperature, the recovered tungsten, molybdenum, copper, iron and other metals are enriched together in the same alloy ingot. These metals have strong mutual solubility at high temperatures and easily form continuous solid solutions or stable intermetallic compounds. Moreover, their chemical properties are similar, making it difficult for conventional wet leaching technology to selectively dissolve and separate them. This increases the complexity of the process and the cost of recycling, and faces significant limitations in practical industrial applications. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, the purpose of this application is to provide a method for recovering valuable metals from tungsten smelting slag. This method not only reduces the smelting temperature, achieving efficient recovery of valuable metals, but also eliminates the need for additional fluxing agents and optimizes the metal distribution, thereby reducing recovery costs.

[0005] To achieve the above objectives, the method for recovering valuable metals from tungsten smelting slag provided in this application includes the following steps: (1) Tungsten smelting slag containing W, Ni, Co and optional Cu is mixed with molybdenum smelting slag containing Mo and Cu, carbonaceous reducing agent and pyrite to obtain a mixture; (2) The mixture is subjected to reduction sulfidation smelting to obtain a smelting product including an alloy phase, a matte phase and a slag phase; the alloy phase is enriched with W, Mo, Co and Ni, and the matte phase is enriched with Cu.

[0006] This application achieves synergistic smelting of tungsten smelting slag by introducing molybdenum smelting slag, carbonaceous reducing agents, and pyrite, resulting in a significant reduction in smelting temperature and effective recovery and controllable separation of valuable metals. Specifically, the molybdenum smelting slag acts as a slag-forming agent, significantly reducing the smelting temperature of tungsten smelting slag. The molybdenum smelting slag is rich in acidic oxides (such as SiO2 and FeO), which can neutralize the alkaline components (such as CaO) in the tungsten slag to form a low-melting-point eutectic slag system. Furthermore, the Na2O in the molybdenum smelting slag can further regulate the viscosity of the slag liquid, promoting the sedimentation of metal droplets. The Mo in the molybdenum slag readily forms a continuous solid solution with W and Fe in the mixture, which helps to enrich refractory metals. Thus, it not only improves the problems of refractory tungsten slag and difficult phase separation of slag and metal, but also simultaneously achieves the synergistic treatment of two types of waste slag. In addition, carbonaceous reducing agents can selectively reduce high-valence oxides of metals such as W, Mo, and Fe to elemental metals or metal carbides, and enrich them to form alloy phases with good sedimentation properties. Pyrite provides active sulfur and iron sources through thermal decomposition. The sulfur source released reacts with copper, which has a strong affinity for sulfur, to form stable sulfides, thereby forming an independent matte phase. This successfully achieves the efficient separation of copper from the alloy phase and improves the distribution of valuable metals.

[0007] In some embodiments of this application, the tungsten smelting slag comprises, by mass percentage: 1%~5% W, 2%~5% Co, 2%~5% Ni, 1%~5% Mn, 1%~5% Cu, 5%~15% Fe, 10%~20% Ca, 5%~10% Si, 3%~8% Ti, 3%~8% P, 1%~5% Cr, 1%~5% Na, 1%~5% Mg, 1%~5% Al, and 20%~35% O.

[0008] Furthermore, the molybdenum smelting slag comprises: 1%~5% Mo, 5%~15% Cu, 25%~35% Fe, 15%~25% Si, 10%~20% Na, 1%~5% Ca, 1%~5% Al and 15%~30% O.

[0009] In some embodiments of this application, the mass ratio of tungsten smelting slag to molybdenum smelting slag is 1:(0.5~2). Controlling the ratio within this range can, on the one hand, avoid the limited reduction in the melting point of the system and poor slag phase fluidity due to too low a content of molybdenum smelting slag; on the other hand, it can prevent the slag basicity from being too low due to too high a content of molybdenum smelting slag, thereby avoiding the rise in smelting temperature and excessively high melt viscosity.

[0010] In some embodiments of this application, the amount of the carbonaceous reducing agent is 7 to 22 parts by weight relative to 100 parts by weight of the tungsten smelting slag. This range of dosage can both promote the sufficient reduction and enrichment of the metal oxide in the alloy phase and avoid metal volatilization loss that may be caused by excessive reducing agent.

[0011] In some embodiments of this application, the carbonaceous reducing agent is selected from at least one of coke, pulverized coal, charcoal, activated carbon, graphite, and carbon black.

[0012] In some embodiments of this application, the amount of pyrite used is 10 to 40 parts by weight relative to 100 parts by weight of the tungsten smelting slag.

[0013] In some embodiments of this application, the temperature of the reduction vulcanization melting is 1300~1500℃. Further, the temperature of the reduction vulcanization melting is ≤1400℃.

[0014] In some embodiments of this application, the holding time for the reduction sulfidation smelting is 1 to 5 hours.

[0015] In some embodiments of this application, the reduction sulfidation smelting is carried out in the presence of an inert gas selected from argon and / or nitrogen.

[0016] In some embodiments of this application, the alloy phase comprises, by mass percentage, 2% to 6% W, 3.5% to 12% Mo, 5% to 12% Co, 40% to 65% Fe, 4% to 12% Ni and 0.1% to 4.5% Cu.

[0017] In some embodiments of this application, the matte phase comprises 12% to 28% S, 25% to 60% Cu, and 18% to 55% Fe by mass percentage.

[0018] Furthermore, based on the total mass of Cu in the alloy phase and the matte phase, the mass content of Cu in the matte phase is ≥90%.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein: Figure 1 This is a photograph of the smelting product after the slag phase was removed in Example 1; Figure 2Energy dispersive spectroscopy (EDS) diagrams of the alloy phase and matte phase in the smelting product prepared in Example 1. Figure 3 Energy dispersive spectroscopy (EDS) chromatogram of the alloy phase in the smelting product prepared for Comparative Example 1. Figure 4 This is a photograph of the smelting product obtained in Comparative Example 2 after the slag phase has been removed. Detailed Implementation

[0021] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0022] The "scope" disclosed in this application is defined in the form of a lower limit and / or an upper limit, whereby a given scope is defined by selecting a lower limit and / or an upper limit. This type of scope may or may not include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an undefined scope, and any lower limit can be combined with other lower limits to form an undefined scope, similarly, any upper limit can be combined with any other upper limit to form an undefined scope. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and can be combined with any other point or single value, or with other lower or upper limits, to form an undefined scope.

[0023] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0024] In the following text, for ease of description, "tungsten smelting slag" and "tungsten slag" have the same meaning, and "molybdenum smelting slag" and "molybdenum slag" have the same meaning.

[0025] This application provides a method for recovering valuable metals from tungsten smelting slag, comprising the following steps: (1) Tungsten smelting slag containing W, Ni, Co and optional Cu is mixed with molybdenum smelting slag containing Mo and Cu, carbonaceous reducing agent and pyrite to obtain a mixture; (2) The mixture is subjected to reduction sulfidation smelting to obtain a smelting product including an alloy phase, a matte phase and a slag phase; the alloy phase is enriched with W, Mo, Co and Ni, and the matte phase is enriched with Cu.

[0026] Tungsten smelting slag suffers from high melting points, leading to high smelting temperatures and difficulties in slag-metal separation. Molybdenum smelting slag, on the other hand, often contains MoS2 and intermetallic alloy phases. Conventional wet extraction methods are ineffective at separating the non-water-soluble molybdenum phase. Thermal sulfidation reduction processes result in the co-enrichment of sulfides and reduced metals in the same phase, with Cu and Mo mutually encapsulating each other, making phase separation impossible and increasing subsequent processing costs and separation difficulty. The method in this application addresses this by co-treating both types of slag. Utilizing the SiO2 and Na2O components in the molybdenum smelting slag, the smelting temperature of the tungsten slag is reduced, improving melt fluidity. Furthermore, the high miscibility of W and Mo and the strong affinity of Cu for sulfur facilitate the separation of Mo and Cu. During smelting, Mo is directionally enriched in the alloy phase along with W, Co, and Ni, while Cu is distributed in the matte phase. This optimizes the distribution of valuable metals in the product phase, significantly improving metal recovery efficiency and economics.

[0027] In some embodiments, the tungsten smelting slag, by mass percentage, comprises: 1%~5% W, 2%~5% Co, 2%~5% Ni, 1%~5% Mn, 1%~5% Cu, 5%~15% Fe, 10%~20% Ca, 5%~10% Si, 3%~8% Ti, 3%~8% P, 1%~5% Cr, 1%~5% Na, 1%~5% Mg, 1%~5% Al, and 20%~35% O. Preferably, the molybdenum smelting slag, by mass percentage, comprises: 1%~5% Mo, 5%~15% Cu, 25%~35% Fe, 15%~25% Si, 10%~20% Na, 1%~5% Ca, 1%~5% Al, and 15%~30% O. Tungsten smelting slag contains a large amount of high-melting-point substances such as phosphates and calcium silicates, along with high-melting-point oxides such as Al2O3 and Cr2O3. This results in a high overall liquidus temperature and increased viscosity in the slag system. Not only does it require a high temperature to achieve melting and flow, but it also makes it difficult for the metal droplets formed after reduction to settle effectively, ultimately causing difficulties in separating the alloy phase from the slag phase. Therefore, using molybdenum smelting slag rich in Na, Si, and Al can adjust the acid-base ratio of the slag system and reduce the liquidus temperature and viscosity.

[0028] In this application, the tungsten smelting slag may be, for example, the leaching slag produced after extracting valuable metals from tungsten waste using a combined pyrometallurgical-hydrometallurgical process. The molybdenum smelting slag may be, for example, the smelting slag produced after extracting molybdenum through molybdenite oxidation roasting-acid leaching or the alkaline leaching slag produced during molybdate production.

[0029] In this application, the metal elements in tungsten smelting slag and molybdenum smelting slag can be determined by X-ray spectroscopy (XRF), the oxygen content can be determined by oxygen and nitrogen analyzer, and the S and C contents can be obtained by sulfur and carbon analyzer.

[0030] In some embodiments, the particle size distribution of the tungsten smelting slag can be 10~100. The particle size distribution of the molybdenum smelting slag can be 10~100. .

[0031] In step (1), the amount of molybdenum smelting slag can be determined based on tungsten smelting slag, aiming to effectively reduce the smelting temperature of the tungsten smelting slag by utilizing its fluxing components. As some embodiments, the mass ratio of the tungsten smelting slag to the molybdenum smelting slag is 1:(0.5~2), for example, 1:0.5, 1:0.7, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc. In this way, the total recovery rate of valuable metals can be increased while reducing the smelting temperature.

[0032] As some preferred examples, the mass content of Ca in the mixture is 10% to 15%, and the mass content of Si is 8% to 12%.

[0033] In this application, the carbonaceous reducing agent can selectively reduce high-valence metal oxides in smelting slag to elemental metals or metal carbides. This application does not particularly limit the type of carbonaceous reducing agent and it can be any carbon-containing material capable of achieving the above-mentioned reduction effect. As some examples, the carbonaceous reducing agent can be at least one of coke, pulverized coal, charcoal, activated carbon, graphite, and carbon black. The carbonaceous reducing agent is usually in powder form; this application also refers to powdered carbonaceous reducing agent as carbon powder, and the particle size of the carbon powder can be, for example, 10~100. .

[0034] In step (1), as some embodiments, the amount of carbonaceous reducing agent used is 7 to 22 parts by weight relative to 100 parts by weight of the tungsten smelting slag, for example, 7 parts by weight, 10 parts by weight, 11 parts by weight, 13 parts by weight, 15 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, etc.

[0035] In this application, the pyrite can be used as a sulfiding agent to provide a sulfur source and an iron source during the smelting process. The sulfur source reacts with copper to generate stable sulfides, and the iron source can promote the enrichment and sedimentation of metals.

[0036] In step (1), as some embodiments, the amount of pyrite used relative to 100 parts by weight of the tungsten smelting slag is 8 to 40 parts by weight, for example, 8 parts by weight, 10 parts by weight, 11 parts by weight, 13 parts by weight, 15 parts by weight, 20 parts by weight, 22 parts by weight, 25 parts by weight, 30 parts by weight, 32 parts by weight, 36 parts by weight, 40 parts by weight, etc. In order to improve the recovery rate of valuable metals and promote the enrichment of copper in the matte phase, while suppressing the distribution of other valuable metals (such as molybdenum) in the matte phase as much as possible, the amount of pyrite used is preferably 15 to 30 parts by weight.

[0037] In some embodiments, the pyrite grain size can be, for example, 1 to 100. .

[0038] This application does not impose any particular limitation on the mixing method in step (1), as long as the components can be fully and uniformly mixed to facilitate the smooth progress of the reaction in the subsequent reduction sulfidation smelting process. The mixing can be carried out mechanically using a ball mill, or by grinding in a mortar.

[0039] In step (2), by smelting the mixture, valuable metals can undergo reduction and sulfidation reactions, thereby becoming enriched in the alloy phase and matte phase, respectively. The smelting temperature is mainly determined by the melting point of the mixture, and is usually controlled within a range of 100-200°C higher than its melting point. With the same mixture composition, a higher smelting temperature is more conducive to the melting of slag and the aggregation and separation of the metal phase, but excessively high temperatures may lead to increased volatilization loss of valuable metals and a significant increase in energy consumption. Therefore, as some implementation methods, the reduction-sulfidation smelting temperature is 1300-1500°C, for example, 1300°C, 1320°C, 1350°C, 1380°C, 1400°C, 1500°C, etc. Further, the reduction-sulfidation smelting temperature is not higher than 1400°C.

[0040] In some embodiments, the reduction sulfidation melting time (i.e., the holding time at the reduction sulfidation melting temperature) can be 1 to 5 hours, such as 1 hour, 2 hours, 2.5 hours, 3 hours, 4 hours, 5 hours, etc. Too short a melting time may lead to incomplete reaction, with valuable metals not being fully reduced and sulfidized; too long a melting time will result in excessive energy consumption. Preferably, the reduction sulfidation melting time is 2 to 4 hours.

[0041] In step (2), the reduction sulfidation smelting can be carried out in the presence of an inert gas. The inert gas is selected from at least one of argon and nitrogen. Alternatively, the reduction sulfidation smelting can be carried out in a smelting furnace.

[0042] According to some specific implementation methods, step (2) includes the following process: (2-1) The mixture is loaded into the corundum crucible, and the filling volume can usually account for 80% to 90% of the volume of the corundum crucible. Then it is transferred to the melting furnace and heated to 1250 to 1500°C at a rate of 5 to 10°C / min under an argon atmosphere, and held at this temperature for 1 to 3 hours. Subsequently, the smelting furnace was naturally cooled to room temperature to obtain smelting products with alloy phase, matte phase and slag phase in the lower, middle and upper layers, respectively; (2-2) Remove the slag phase from the smelting product to obtain an alloy phase enriched with valuable metals and a matte phase; Optionally, step (2) further includes: (2-3) Separate the alloy phase and the matte phase.

[0043] In some embodiments, after reduction sulfidation smelting, the components in the tungsten and molybdenum smelting slag form a three-phase stratification based on density differences: metal oxides are reduced and mutually dissolved to form a high-density alloy phase, which deposits at the bottom; sulfide-loving Cu combines with S to form sulfides, and this matte phase, with a lower density, is distributed above the alloy phase; the top is composed of various oxides and silicates forming the slag phase. Alternatively, mechanical means such as hammering or peeling can be used to separate or remove the three phases. Typically, the three phases of the smelting product can satisfy the following conditions: the alloy phase is enriched with high-density metals such as W, Mo, Co, and Ni, and may also contain elements such as Fe, P, C, and Cr; the matte phase is enriched with Cu, and may also contain elements such as S, Fe, Na, Cr, and Mn. The slag phase mainly contains elements such as Na, Mg, Al, Si, Ca, Ti, and O.

[0044] In some embodiments, the alloy phase comprises, by mass percentage, 2% to 6% W, 3.5% to 12% Mo, 5% to 12% Co, 40% to 65% Fe, 4% to 12% Ni and 0.1% to 4.5% Cu.

[0045] In some embodiments, the matte phase comprises 12% to 28% S, 25% to 60% Cu, and 18% to 55% Fe by mass percentage.

[0046] The valuable metals recovered by the method of this application are mainly concentrated in the alloy phase and the matte phase. The valuable metals in the alloy phase can be separated by methods such as selective oxidation, wet leaching or electrolysis; while the copper in the matte phase can be further recovered by wet processes such as pyrometallurgical blowing or "leaching-electrowinning".

[0047] In some embodiments, the method of this application achieves a recovery rate of not less than 75% for W, Co, Ni, and Cu. Preferably, the mass content of Cu in the matte phase is ≥90%, based on the total mass of Cu in the alloy phase and the matte phase.

[0048] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0049] In the following examples and comparative examples, unless otherwise specified, all percentages are percentages by mass.

[0050] The carbon powder used is carbon black.

[0051] The composition of tungsten smelting slag is as follows: W 1.5%, Co 3.4%, Ni 3.5%, Cu 4.1%, Fe 6.8%, Ca 16.2%, Si 6.7%, Ti 4.8%, P 4.3%, Cr 4.7%, Na 2.0%, Mg 3.7%, Al 2.7%, Mn 1.7%, C 2.0%, and O 31.9%.

[0052] The composition of molybdenum smelting slag is: Mo 2.5%, Cu 9.8%, Fe 25.4%, Si 15.4%, Na 13.9%, Ca 9.8%, Al 2.9%, and O 20.3%.

[0053] Example 1 (1) Place 100g of tungsten smelting slag, 100g of molybdenum smelting slag, 12g of carbon powder and 20g of pyrite in a mortar and mix them evenly to obtain a mixture.

[0054] (2) The mixture is loaded into a corundum crucible (crucible size: diameter 55mm, height 120mm, thickness 3mm, the same below), transferred to a melting furnace, and melted at 1400℃ at a rate of 10℃ / min under an argon atmosphere, and held at this temperature for 2h.

[0055] Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0056] Figure 1 The images show the front view (left) and cross-section (right) of the two-phase product, revealing a clear boundary and distinct layering between the alloy phase and the matte phase. Figure 2 (a) and (b) are the results of energy dispersive spectroscopy (EDS) elemental analysis of the alloy phase and the matte phase, respectively: the metal elements contained in the alloy phase include Fe, Co, Ni, W, Mo, Cr and Cu; while the matte phase mainly contains Cu, S, O, Fe, Na, Cr and Mn, but the content of Cu in the alloy phase is very low, and it is mainly enriched in the matte phase.

[0057] Example 2 Valuable metals in tungsten smelting slag were recovered according to the method in Example 1, except that the mass of pyrite was adjusted to 10g, thereby obtaining an alloy phase and matte phase enriched with valuable metals.

[0058] Example 3 The valuable metals in tungsten smelting slag were recovered according to the method in Example 1, except that the mass of pyrite was adjusted to 30g, thereby obtaining an alloy phase and matte phase enriched with valuable metals.

[0059] Example 4 The valuable metals in tungsten smelting slag were recovered according to the method in Example 1, except that the smelting temperature was adjusted to 1350°C and the holding time was adjusted to 2.5h, thereby obtaining an alloy phase and matte phase enriched with valuable metals.

[0060] Example 5 (1) Mix 120g of tungsten smelting slag, 80g of molybdenum smelting slag, 12g of carbon powder and 20g of pyrite in a mortar until uniform to obtain a mixture.

[0061] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1450°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0062] Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0063] Examples 6-7 The valuable metals in tungsten smelting slag were recovered according to the method in Example 1, except that the holding time of smelting was adjusted to 1 hour and 3 hours respectively, so as to obtain alloy phases and matte phases enriched with valuable metals.

[0064] Example 8 (1) 70g of tungsten smelting slag, 126g of molybdenum smelting slag, 14g of carbon powder and 20g of pyrite are placed in a mortar and mixed evenly to obtain a mixture.

[0065] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1300°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0066] Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0067] Example 9 (1) 90g of tungsten smelting slag, 117g of molybdenum smelting slag, 14g of carbon powder and 20g of pyrite are placed in a mortar and mixed evenly to obtain a mixture.

[0068] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1330°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0069] Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0070] Comparative Example 1 (1) Place 100g of tungsten smelting slag and 12g of carbon powder in a mortar and mix them evenly to obtain a mixture.

[0071] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1550°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0072] The furnace was then naturally cooled to room temperature. The resulting smelting product consisted of two phases: an alloy phase in the lower layer and a slag phase in the upper layer. The slag phase was separated to obtain an alloy phase enriched with valuable metals. No matte phase was formed in this comparative example. Figure 3 The figure shows the EDS analysis results of the alloy phase. As can be seen from the figure, all the valuable metals are concentrated in the alloy phase.

[0073] Comparative Example 2 (1) Mix 100g of tungsten smelting slag, 12g of carbon powder and 20g of pyrite in a mortar until uniform to obtain a mixture.

[0074] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1500°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0075] The furnace was then naturally cooled to room temperature, and the resulting smelting product consisted of two phases: an alloy phase in the lower layer and a slag phase in the upper layer. The slag phase was then separated. Figure 4 The images show top view (left) and cross-section (right) of the product after the slag phase was separated. It can be seen that the product does not have a layered matte phase.

[0076] Comparative Example 3 (1) Mix 100g of tungsten smelting slag, 100g of molybdenum smelting slag and 12g of carbon powder in a mortar until uniform to obtain a mixture.

[0077] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1400°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0078] The furnace was then naturally cooled to room temperature, and the resulting smelting product consisted of two phases: an alloy phase in the lower layer and a slag phase in the upper layer (without matte phase formation). The slag phase was then separated to obtain the alloy phase.

[0079] Comparative Example 4 (1) Mix 100g of tungsten smelting slag, 100g of molybdenum smelting slag, 12g of carbon powder and 20g of sulfur in a mortar to obtain a mixture.

[0080] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1400°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours.

[0081] Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0082] Example 10 (1) Mix 50g of tungsten smelting slag, 100g of molybdenum smelting slag, 11g of carbon powder and 20g of pyrite in a mortar until uniform to obtain a mixture.

[0083] (2) The mixture is loaded into a corundum crucible, transferred to a melting furnace, heated to 1300°C at a rate of 10°C / min under an argon atmosphere, and held at that temperature for 2 hours. Subsequently, the smelting furnace was naturally cooled to room temperature to obtain a three-phase smelting product with an alloy phase, a matte phase, and a slag phase in the lower, middle, and upper layers, respectively. The slag phase was separated to obtain a two-phase product with an alloy phase and a matte phase enriched with valuable metals.

[0084] The main operating conditions for the above embodiments and comparative examples are shown in Table 1.

[0085] Table 1

[0086] Note: In Table 1, sulfur was used instead of pyrite in Comparative Example 2.

[0087] Test case The test cases are used to illustrate the recovery effects of the above embodiments and comparative examples.

[0088] The recovery rate of valuable metals was calculated by XRF analysis of the metal element content in the alloy phase and matte phase using the following formula.

[0089] 1. The formulas for calculating the recovery rates of W, Co, and Ni are as follows:

[0090] In the formula, M alloy The total mass of the alloy phase obtained after melting. M w For the quality of tungsten smelting slag, w i1 Represents element iMass fraction in the alloy phase w i2 Represents element i Mass fraction of elements in tungsten smelting slag i It represents W, Co, and Ni.

[0091] 2. The formula for calculating the recovery rate of Mo is:

[0092] In the formula, M alloy The total mass of the alloy phase obtained after melting. M Mo To ensure the quality of the molybdenum smelting slag used, w Mo1 This indicates the mass fraction of Mo in the alloy phase. w Mo2 This indicates the mass fraction of Mo in molybdenum smelting slag.

[0093] 3. The formula for calculating the Cu recovery rate is:

[0094] In the formula, M alloy and M S The values ​​represent the masses of the alloy phase and matte phase obtained after smelting, respectively. M w and M Mo The masses of tungsten smelting slag and molybdenum smelting slag are respectively. w Cu1 、w Cu2 , w Cu3 and w Cu4 These represent the mass fraction of Cu in the alloy phase, matte phase, tungsten smelting slag, and molybdenum smelting slag, respectively.

[0095] The results are shown in Table 2.

[0096] Table 2

[0097] Table 3

[0098] Note: "Alloy Cu / Matture Cu" refers to the mass ratio of Cu in the alloy phase to Cu in the matte phase.

[0099] Based on the data in Tables 1-3, it can be seen that compared with Comparative Examples 1-4, Examples 1-10 can achieve a higher recovery rate of valuable metals, and the copper recovered is mainly distributed in the matte phase, accounting for more than 90%.

[0100] Comparing Example 1 with Comparative Examples 1-3, it can be seen that when molybdenum slag and / or pyrite are not used to treat tungsten slag, the obtained smelting products do not show obvious matte phase formation. Combined with Table 2, it can be seen that the copper recovered in Comparative Examples 1-3 remains mostly in the alloy phase (i.e., optimized alloy recovery distribution cannot be achieved), and the total recovery rate of valuable metals is also too low (<74%). In Comparative Example 4, sulfur was used instead of pyrite. Although alloy and matte phases were also obtained, the recovered copper was mainly concentrated in the alloy phase, and the total recovery rate of valuable metals was low.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not 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. These 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, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for recovering valuable metals from tungsten smelting slag, characterized in that, include: (1) Tungsten smelting slag containing W, Ni, Co and optional Cu is mixed with molybdenum smelting slag containing Mo and Cu, carbonaceous reducing agent and pyrite to obtain a mixture; (2) The mixture is subjected to reduction sulfidation smelting to obtain a smelting product including an alloy phase, a matte phase and a slag phase, wherein the alloy phase is enriched with W, Mo, Co and Ni, and the matte phase is enriched with Cu.

2. The recycling method according to claim 1, characterized in that, The mass ratio of tungsten smelting slag to molybdenum smelting slag is 1:(0.5~2).

3. The recycling method according to claim 1 or 2, characterized in that, The tungsten smelting slag comprises, by mass percentage: 1%~5% W, 2%~5% Co, 2%~5% Ni, 1%~5% Mn, 1%~5% Cu, 5%~15% Fe, 10%~20% Ca, 5%~10% Si, 3%~8% Ti, 3%~8% P, 1%~5% Cr, 1%~5% Na, 1%~5% Mg, 1%~5% Al, and 20%~35% O.

4. The recycling method according to any one of claims 1-3, characterized in that, The molybdenum smelting slag comprises, by mass percentage: 1%~5% Mo, 5%~15% Cu, 25%~35% Fe, 15%~25% Si, 10%~20% Na, 5%~15% Ca, 1%~5% Al and 15%~30% O.

5. The recycling method according to any one of claims 1-4, characterized in that, The amount of carbonaceous reducing agent used is 7 to 22 parts by weight relative to 100 parts by weight of the tungsten smelting slag.

6. The recycling method according to any one of claims 1-5, characterized in that, The carbonaceous reducing agent is selected from at least one of coke, pulverized coal, charcoal, activated carbon, graphite, and carbon black.

7. The recycling method according to any one of claims 1-6, characterized in that, The amount of pyrite used is 8 to 40 parts by weight relative to 100 parts by weight of the tungsten smelting slag.

8. The recycling method according to any one of claims 1-7, characterized in that, The temperature of the reduction sulfidation smelting is 1300~1500℃, preferably ≤1400℃; Preferably, the reduction sulfidation smelting time is 1 to 5 hours.

9. The recycling method according to any one of claims 1-8, characterized in that, The reduction sulfidation smelting is carried out in the presence of an inert gas, which is selected from argon and / or nitrogen.

10. The recycling method according to any one of claims 1-9, characterized in that, The alloy phase comprises, by mass percentage, 2% to 6% W, 3.5% to 12% Mo, 5% to 12% Co, 40% to 65% Fe, 4% to 12% Ni and 0.1% to 4.5% Cu; Preferably, the matte phase comprises 12% to 28% S, 25% to 60% Cu, and 18% to 55% Fe by mass percentage; Preferably, based on the total mass of Cu in the alloy phase and the matte phase, the mass content of Cu in the matte phase is ≥90%.

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