A method for collecting platinum group metals by pyrometallurgy of bismuth and recovering them by vacuum distillation

Abstract

The present application provides a method for recovering platinum group metals by combining bismuth pyrometallurgical trapping and vacuum distillation, which includes the following steps: using at least one of metallic bismuth and bismuth compounds as a trapping agent, subjecting a raw material containing platinum group metals to high-temperature smelting through bismuth pyrometallurgical trapping to obtain a melt; cooling and separating the melt to obtain a noble bismuth alloy and a slag phase; subjecting the noble bismuth alloy to vacuum distillation to obtain metallic bismuth and a platinum group metal concentrate, so as to recover metallic bismuth from the noble bismuth alloy. The method provided by the present invention has the advantages of environmental friendliness, low reaction temperature, high efficiency in recovering platinum group metals, recyclability of bismuth resources, and resource cost savings, laying a foundation for the total quality recovery of platinum group metals in raw materials containing platinum group metals.

Description

Technical Field

[0001] This application relates to the technical field of platinum group metal enrichment, and particularly to a method for jointly recovering platinum group metals by bismuth pyrometallurgical capture and vacuum distillation. Background Art

[0002] Platinum group metals (PGMs) include platinum, palladium, rhodium, ruthenium, iridium and osmium, and have excellent physical and chemical properties such as high temperature resistance, corrosion resistance and high catalytic activity, and are widely used in the fields of automobiles, petroleum, chemical industry, electronic components, aerospace and environmental protection. China is the largest consumer of platinum group metals in the world, with an annual demand of more than 150t, accounting for about 30-35% of the global total. However, the annual output of platinum group metals in China is only about 3t, and a large amount of imports are needed. Among them, the waste generated after the consumption of platinum group metal products is rich in platinum group metals. If the platinum group metals in it can be efficiently recovered, it will effectively alleviate the current situation of the imbalance between supply and demand of platinum group metals in China and promote the green, healthy and high-quality development of the platinum group metal industry in China.

[0003] The enrichment of platinum group metals is the most important link in the entire recovery process, mainly including wet dissolution of the carrier and pyrometallurgical enrichment, etc. The general operation steps of wet enrichment are as follows: First, the waste containing platinum group metals is ground, and then treated with an acid solution to dissolve the carrier or dissolve the platinum group metals to achieve separation. However, there are problems in the wet recovery of platinum group metals such as low recovery rate, generally not exceeding 95%; large amount of strong acid used, resulting in a poor on-site operation environment; low concentration of platinum group metal ions and difficult to enrich; large amount of acidic wastewater and difficult to treat, resulting in relatively prominent environmental protection problems. In the process of researchers' efforts to eliminate the above defects in the wet dissolution of the carrier process, the pyrometallurgical enrichment technology of platinum group metals has been gradually developed. The main principle of pyrometallurgical enrichment is that platinum group metals have a high affinity with base metals and can form alloys at high temperatures, while the carrier enters the slag phase, thus achieving the purpose of platinum group metal enrichment. After pyrometallurgical enrichment, the grade of platinum group metals is increased, and then connected with wet treatment to obtain a platinum group metal solution with a higher concentration, making it more convenient for separation and recovery.

[0004] Currently, the main pyrometallurgical enrichment processes include lead capture, copper capture, iron capture, matte capture, and bismuth capture, etc. The lead capture method has the advantages of simple operation, low smelting temperature, and high recovery rate, but it has the disadvantages of long operation time, serious lead dust pollution, and low rhodium recovery rate; the copper capture method is mainly applied in many Western countries and has the advantages of simple process, good capture effect, and can be grafted onto copper smelters. However, precious metals generally need to be separated and refined from copper anode slime, and there are disadvantages such as long process flow, serious backlog of precious metals, and long production cycle; the iron capture method is mainly used by Tanaka in Japan, Johnson-Matthey in the UK, and Sino-Platinum Metals Yimen Company in China. It has the characteristics of easy availability of raw materials and high capture efficiency. However, it also has the disadvantages of high capture temperature, expensive plasma smelting furnace equipment, short service life of plasma guns, and easy formation of ferrosilicon alloy, resulting in difficulty in dissolution in the follow-up; the matte capture method mainly uses sulfur nickel, copper nickel sulfide, etc. to recover platinum group metals in spent catalysts, but the obtained precious metal alloy cannot be separated by pyrometallurgy. Generally, wet processes are used to separate collectors such as copper, nickel, and matte, and the process flow is complex and long.

[0005] Among them, bismuth capture has the advantages of no pollution, low reaction temperature, good capture effect, etc., which is in line with the orientation of China's sustainable development and is bound to become the core technology for enriching platinum group metals in the future. However, at present, bismuth capture is mainly used as a bismuth assay method to detect and analyze the content of platinum group metals in fewer types of ores or catalysts, and there is no industrial application case for recovering platinum group metal-containing waste materials as pyrometallurgical capture. And currently, bismuth capture also has problems such as large consumption of bismuth, long process due to the separation of metallic bismuth and platinum group metals by acid dissolution or cupellation, large bismuth loss, and difficulty in recycling. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method for jointly recovering platinum group metals by bismuth pyrometallurgical capture and vacuum distillation, which has the advantages of environmental friendliness, low reaction temperature, high efficiency in recovering platinum group metals, recyclable bismuth resources, and saving resource costs.

[0007] The technical solution of the present invention is as follows:

[0008] A method for jointly recovering platinum group metals by bismuth pyrometallurgical capture and vacuum distillation includes the following steps:

[0009] Using at least one of metallic bismuth and bismuth compounds as a collector, and performing high-temperature smelting on the raw material containing platinum group metals through bismuth pyrometallurgical capture to obtain a melt;

[0010] Cooling and separating the melt to obtain a noble bismuth alloy and a slag phase;

[0011] Performing vacuum distillation on the noble bismuth alloy to obtain metallic bismuth and a platinum group metal concentrate, so as to recover metallic bismuth from the noble bismuth alloy.

[0012] Optionally, the vacuum distillation of the bismuth-rich alloy to obtain metallic bismuth and a platinum group metal concentrate includes:

[0013] Distilling the bismuth-rich alloy under a vacuum of 20 Pa - 40 Pa and at a temperature of 1000 °C - 1100 °C for 0.5 h - 2 h to obtain metallic bismuth and a platinum group metal concentrate.

[0014] Optionally, after the vacuum distillation of the bismuth-rich alloy to obtain metallic bismuth and a platinum group metal concentrate, the following steps are further included:

[0015] Performing vacuum distillation on the slag phase to obtain metallic bismuth and a secondary slag phase, so as to recover metallic bismuth.

[0016] Optionally, the mass ratio of the mass of bismuth in the collector to the mass of the raw material is 0.1 - 2.

[0017] Optionally, the bismuth compound includes bismuth oxide.

[0018] Optionally, using at least one of metallic bismuth and a bismuth compound as a collector, and performing high-temperature smelting on a raw material containing platinum group metals by bismuth pyrometallurgical capture to obtain a melt, including:

[0019] Adding the collector, slag former, flux, and reducing agent to the raw material and mixing evenly to obtain a mixed material;

[0020] Performing high-temperature smelting on the mixed material to obtain the melt.

[0021] Optionally, the raw material includes one or more of waste automotive exhaust catalysts, waste petrochemical catalysts, waste fine chemical catalysts, platinum group metal alloy materials, platinum group metal-containing waste materials, and waste electrical components.

[0022] Optionally, the slag former includes at least one of calcium oxide, calcium carbonate, calcium hydroxide, sodium carbonate, sodium bicarbonate, and sodium hydroxide; the flux includes at least one of borax and calcium fluoride; the reducing agent includes at least one of activated carbon, bituminous coal, coke, and starch.

[0023] Optionally, after the vacuum distillation of the bismuth-rich alloy to obtain metallic bismuth and a platinum group metal concentrate, the following steps are further included:

[0024] Separating and purifying the platinum group metal concentrate to obtain platinum group metals.

[0025] Optionally, the performing high-temperature smelting on the mixed material to obtain the melt includes:

[0026] Smelting the mixed material at 900 °C - 1100 °C for 0.5 - 2 h to obtain the melt.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] The present invention provides a method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation, which includes the following steps: using at least one of metallic bismuth and bismuth compounds as a capture agent, subjecting a raw material containing platinum group metals to high-temperature smelting through bismuth pyrometallurgical capture to obtain a melt; cooling and separating the melt to obtain a noble bismuth alloy and a slag phase; subjecting the noble bismuth alloy to vacuum distillation to obtain metallic bismuth and a platinum group metal concentrate, so as to recover metallic bismuth from the noble bismuth alloy. By adopting the technical solution of the present application, using metallic bismuth and bismuth compounds as capture agents and adopting bismuth pyrometallurgical capture of platinum group metals has the characteristics of being green and environmentally friendly, having a low reaction temperature, and good capture effect; at the same time, subjecting the noble bismuth alloy formed by bismuth and platinum group metals to vacuum distillation to obtain two target products, namely a high-purity platinum group metal concentrate and metallic bismuth, with a high recovery rate of platinum group metals; recycling metallic bismuth as a capture agent overcomes the defect of large consumption of capture agents in traditional technologies and effectively saves energy; it lays a foundation for the total recovery of platinum group metals in raw materials containing platinum group metals. Description of the Drawings

[0029] In order to more clearly illustrate the technical solution of the present application, the drawings required for the description of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 is a flowchart of the steps of the method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation according to an embodiment of the present application;

[0031] Figure 2 is a flowchart of the steps of the method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation according to another embodiment of the present application;

[0032] Figure 3 is a process flowchart of the method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation according to still another embodiment of the present application. Detailed Embodiments

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present application belong to the scope of protection of the present application.

[0034] In the related art, the process of bismuth pyrometallurgical capture of platinum group metals is still in the laboratory research stage, and there is an urgent need to develop a new technology that can utilize the advantages of bismuth capture to recover platinum group metals from industrial waste.

[0035] Referring to Figure 1 as shown, Figure 1 FIG. is a flow chart of the steps of the method for recovering platinum group metals by bismuth pyrometallurgical capture combined with vacuum distillation shown in the present invention, which includes the following steps:

[0036] S1. Using at least one of metallic bismuth and bismuth compounds as a collector, subjecting the raw material containing platinum group metals to high-temperature smelting by bismuth pyrometallurgical capture to obtain a melt;

[0037] S2. Cooling and separating the melt to obtain a noble bismuth alloy and a slag phase;

[0038] S3. Subjecting the noble bismuth alloy to vacuum distillation to obtain metallic bismuth and a platinum group metal concentrate, so as to recover metallic bismuth from the noble bismuth alloy.

[0039] The bismuth pyrometallurgical capture in this application refers to the pyrometallurgical enrichment process using bismuth as a collector in the platinum group metal enrichment process. The principle of the pyrometallurgical enrichment process is that platinum group metals form alloys with base metals, and through high-temperature reactions, the materials containing platinum group metals are separated from other substances, thereby forming an alloy phase and a slag phase. In this application, the base metals are metallic bismuth and bismuth compounds, and the bismuth element has a high affinity for platinum group metals and can effectively capture platinum group metals to form an alloy of bismuth and platinum group metals. Optionally, the collector can be metallic bismuth or a bismuth compound or a mixture of metallic bismuth and bismuth compounds.

[0040] Preferably, the bismuth compound includes bismuth oxides, such as bismuth trioxide.

[0041] The raw material containing platinum group metals can be industrial waste generated in the fields of automobiles, petroleum, chemical engineering, electronic components, aerospace, and environmental protection. Of course, it is also applicable to products containing platinum group metals in ores and catalysts. Specifically, the raw material is one or more of waste automobile exhaust catalysts, waste petrochemical catalysts, waste fine chemical catalysts, platinum group metal alloy materials, platinum group metal-containing waste, and waste electrical components. According to statistics, the above raw materials are the main secondary resource materials containing platinum group metals in our country, and the total amount of platinum group metals generated in the waste each year can reach more than 50t. Since the sources of waste containing platinum group metals are mostly from the environment after waste acquisition, or the original factories usually have multiple products, and various waste materials rich in platinum group metals are stacked together. Due to different environments and different sources of raw materials, the present invention does not limit the combination form of the raw materials. It should be understood that the compositions of the slag phase and the alloy obtained by the bismuth pyrometallurgical capture process both depend on the composition of the raw materials, so the present invention also does not limit the compositions of the noble bismuth alloy and the slag phase.

[0042] After the raw material preparation is completed, the above-mentioned raw materials and the collector are subjected to a pyrometallurgical enrichment process to obtain a molten metal mixed melt. The metal mixed solution is the alloy melt and the slag melt formed in the pyrometallurgical enrichment process. Since the alloy solution and the slag melt are not compatible, due to the action of gravity, the alloy melt undergoes gravitational sedimentation. After a period of cooling and separation, a completely separated bismuth-rich alloy and slag phase are obtained.

[0043] By subjecting the bismuth-rich alloy to vacuum distillation, bismuth metal has a high volatility under vacuum conditions while platinum group metals are not easily volatilized. Therefore, the separation of bismuth metal and platinum group metals is achieved. On the one hand, bismuth metal is recycled as a collector, solving the current dilemmas such as high consumption, high loss, high cost, and lack of resources of the collector. On the other hand, high-grade platinum group metals are obtained, which can be directly used for subsequent separation and purification to obtain various precious metals. On the third hand, the process maturity of using bismuth element for pyrometallurgical recovery of platinum group metals is improved. The separation of bismuth and platinum group metals by vacuum distillation belongs to physical separation, and the recovery rate of platinum group metals is close to 100%. Therefore, the method provided by the present invention can lay a foundation for the full-quality recovery of platinum group metals in secondary resource materials in the future with high efficiency, greenness, and environmental protection.

[0044] Preferably, the bismuth-rich alloy is subjected to vacuum distillation to obtain bismuth metal and a platinum group metal concentrate, including: distilling the bismuth-rich alloy under the conditions of a vacuum degree of 20 Pa - 40 Pa and a temperature of 1000 °C - 1100 °C for 0.5 h - 2 h to obtain bismuth metal and a platinum group metal concentrate. In the present invention, bismuth metal and platinum group metals are separated by vacuum distillation. Therefore, the vacuum distillation conditions are key parameters affecting the recovery efficiency of bismuth metal and platinum group metals in the present invention. The vacuum distillation conditions include vacuum degree, vacuum temperature, and distillation time. Through long-term research and based on professional knowledge, the inventor knows that during the vacuum distillation process, when the vacuum degree, volatilization temperature, and volatilization time change within the parameter range, the volatilization rate of bismuth first increases and then levels off. Therefore, the present invention limits the vacuum distillation conditions to distilling for 0.5 h - 2 h under the conditions of a vacuum degree of 20 Pa - 40 Pa and a temperature of 1000 °C - 1100 °C. Within this range, the volatilization rate of bismuth continuously increases to achieve the full separation of bismuth metal and platinum group metal concentrate. As a specific explanation of this embodiment, based on the environmentally friendly characteristics of bismuth metal and the large difference in volatility with platinum group metals, the present application is applied to the vacuum distillation process, with an environmentally friendly operation environment and high operability. For the other lead capture, copper capture, and sulfur capture in the pyrometallurgical enrichment process, the volatilization of lead and sulfur causes environmental changes, and the volatilization of copper is difficult, and none of them are applicable to the method provided by the present invention.

[0045] In another embodiment, the mass ratio of the mass of bismuth in the collector to the mass of the raw material is 0.1 - 2. The collector has an affinity for platinum group metals, and the content of the collector is proportional to the content of the platinum group metals to be captured. Therefore, the key parameter affecting the recovery efficiency of metallic bismuth and platinum group metals in the present invention also includes the addition amount of the collector. The collector used in the present invention is at least one of metallic bismuth and bismuth compounds. When only metallic bismuth or a bismuth compound is used, the mass ratio of metallic bismuth or the bismuth compound to the raw material is 0.1 - 2. When both bismuth and a bismuth compound are used simultaneously, the total mass ratio of metallic bismuth and the bismuth compound to the raw material is 0.1 - 2.

[0046] In another embodiment, as shown in Figure 2 shown, Figure 2 is the process flow chart of the method for recovering platinum group metals by the combined pyrometallurgical capture and vacuum distillation of bismuth shown in the present invention. In addition to the above steps S1 - step S3, it also includes step S4 and step S5.

[0047] Among them, after subjecting the noble bismuth alloy to vacuum distillation to obtain metallic bismuth and a platinum group metal concentrate, the following steps are further included:

[0048] S4. Subject the slag phase to vacuum distillation to obtain metallic bismuth and a secondary slag phase, so as to recover metallic bismuth.

[0049] It can be understood that step S4 does not necessarily need to be carried out after step S3, and they can also be carried out simultaneously. Considering the need to use a vacuum distillation device simultaneously, it is usually selected to carry out step S4 after step S3. Figure 2 An exemplary process flow chart for recovering metallic bismuth from both the slag phase and the noble bismuth alloy is given. In this embodiment, it is inevitable that the slag phase prepared by pyrometallurgical enrichment will carry a small amount of metallic bismuth. The source of metallic bismuth in the slag phase is that when metallic bismuth or a bismuth compound is used as the collector, the bismuth compound is also reduced to metallic bismuth in the pyrometallurgical enrichment process. Therefore, the remaining metallic bismuth that has not fully adhered to the platinum group metals is mixed into the slag phase. Through vacuum distillation of the slag phase, the metallic bismuth with a lower volatility is separated from the slag phase, and the unvaporized forms a secondary slag phase. Through further treatment of the slag phase, the recovery rate of metallic bismuth in the present invention approaches 100%. During the vacuum distillation operation process, no auxiliary materials are consumed, no harmful flue gas is generated, the equipment has a high degree of automation, high production efficiency, and is environmentally friendly, while realizing the recovery of both metallic bismuth and platinum group metals.

[0050] Moreover, the secondary slag phase recovered in the present invention does not contain available metallic bismuth and platinum group metals, and the secondary slag phase can be used as a building material in the field of engineering construction. The method provided by the present invention has a short process flow, simple operation, low raw material cost, and no heavy metal pollution to the environment, and has great environmental and economic benefits, meeting the requirements of current green metallurgy for clean production.

[0051] Among them, after subjecting the bismuth-rich alloy to vacuum distillation to obtain metallic bismuth and a platinum group metal concentrate, the following steps are further included:

[0052] S5. Separating and purifying the platinum group metal concentrate to obtain platinum group metals.

[0053] By further separating and purifying the platinum group metal concentrate, noble metal simple substances can be obtained and are respectively used in various industries. The separation and purification process of platinum group metals includes pickling, extraction, dissolution and precipitation, etc. The subsequent separation and purification belongs to the prior art and will not be elaborated in this application too much.

[0054] In another embodiment, at least one of metallic bismuth and bismuth compounds is used as a collector, and the raw material containing platinum group metals is subjected to high-temperature smelting by bismuth pyrometallurgical collection to obtain a melt, including: adding the collector, slag-forming agent, flux and reducing agent to the raw material and mixing evenly to obtain a mixed material; subjecting the mixed material to high-temperature smelting to obtain a melt.

[0055] In the pyrometallurgical enrichment process of platinum group metals, the reducing agent can generate platinum group metals in the raw material from oxides to simple substances and reduce bismuth oxide to simple substances. Metallic bismuth effectively captures platinum group metals to form a metal-metal bismuth-rich alloy; the slag-forming agent mixes substances other than the bismuth-rich alloy in the melt system to form a slag phase; the flux reduces the melting point and viscosity of the slag phase, so that the slag phase has good fluidity, so that the bismuth-rich alloy settles from the melt under the action of gravity.

[0056] Therefore, the key parameters affecting the recovery efficiency of metallic bismuth and platinum group metals in the present invention also include the addition amount of the flux, the addition amount of the reducing agent and the addition amount of the slag-forming agent. Preferably, the addition amount of the slag-forming agent is preferably controlled to make the alkalinity in the melt be 0.8-1.1; the mass ratio of the flux to the raw material varies within the range of 0.05-0.2; the mass ratio of the reducing agent to the raw material varies within the range of 0.05-0.2. The addition amounts of the above additives can effectively promote or exert their functions within the parameter limit range. Of course, the parameters affecting the recovery efficiency are also related to the conditions of high-temperature smelting. Correspondingly, the mixed material is smelted at 900°C-1100°C for 0.5-2 h to obtain a melt.

[0057] As a further improvement of this embodiment, the slag-forming agent includes at least one of calcium oxide, calcium carbonate, calcium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide; the flux includes at least one of borax and calcium fluoride; the reducing agent includes at least one of activated carbon, bituminous coal, coke and starch.

[0058] Therefore, the present invention adopts the method of bismuth pyrometallurgical capture combined with vacuum distillation, uses bismuth as a capture agent, and waste containing platinum group metals as raw materials. By controlling the addition amounts of the capture agent, slag-forming agent, flux, and reducing agent, as well as conditions such as the smelting temperature, smelting time, vacuum degree of vacuum distillation, volatilization temperature, and its volatilization time, the efficient capture and separation of platinum group metals by metallic bismuth are realized step by step. At the same time, a platinum group metal concentrate with a recovery rate close to 100% and metallic bismuth are obtained.

[0059] Based on the above conditions, the present invention will be further demonstrated by Examples 1 - 8 below.

[0060] Refer to Figure 3 as shown Figure 3 is the process flow chart of the method for recovering platinum group metals by bismuth pyrometallurgical capture combined with vacuum distillation of the present application. In the specific implementation manner, first, select secondary resource materials containing platinum group metals. The sources of such materials include any one of waste automotive exhaust catalysts, waste petrochemical catalysts, waste fine chemical catalysts, platinum group metal alloy materials, waste containing platinum group metals, and waste electrical components. First, the raw materials are crushed and ground finely to facilitate the acceleration of the reaction process. Secondly, four ingredients, namely a capture agent, a flux, a slag-forming agent, and a reducing agent, are added to the raw materials, and after mixing evenly, high-temperature smelting is carried out. After the smelting is completed, clarification and separation are carried out to form a slag phase and a noble bismuth alloy, and the slag phase and the noble bismuth alloy ( Figure 3 slag-gold separation in it) are subjected to vacuum distillation to recover metallic bismuth for recycling, and a secondary slag phase and a platinum group metal (PGMs) concentrate are obtained. Among them, the secondary slag phase is used for building materials, and the platinum group metal (PGMs) concentrate is used for recycling in the factory.

[0061] Example 1:

[0062] Take 200 g of waste automotive exhaust catalyst as the raw material and 20 g of metallic bismuth as the capture agent to conduct a recovery test on the precious metals in the raw material. The main components and contents of the raw material are Al 2 O 3 (38.26%), SiO 2 (24.17%), MgO (8.97%), Pt (68 g / t), Pd (2848 g / t), Rh (310 g / t).

[0063] The raw materials are ground to a particle size of 44 μm - 1 mm; 20 g of bismuth metal, 76 g of calcium oxide, 75 g of sodium carbonate, 15 g of borax, 5 g of calcium fluoride, and 20 g of carbon powder are proportioned and mixed evenly, and then placed in an intermediate frequency furnace and heated and melted at 900 °C for 0.5 h; after the melting is completed, the melt is cooled, and the slag phase and the noble bismuth alloy are separated; the noble bismuth alloy is placed in a vacuum distillation furnace and volatilized at a volatilization temperature of 1000 °C and a vacuum degree of 20 Pa for 0.5 h, and after the reaction is completed, the bismuth metal and the platinum group metals (PGMs) concentrate are collected; the slag phase is placed in a vacuum distillation furnace and volatilized at a temperature of 1000 °C and a vacuum degree of 20 Pa for 0.5 h, and the bismuth metal and the secondary slag phase are collected.

[0064] The contents of platinum group metals and bismuth metal in the platinum group metals concentrate, bismuth metal and secondary slag phase are analyzed by chemical element detection, and the recovery rate is calculated. The recovery rate of platinum group metal platinum is 99.02%, the recovery rate of palladium is 99.11%, the recovery rate of rhodium is 98.52%, and the recovery rate of bismuth is 99.53%.

[0065] Example 2:

[0066] 200 g of waste automobile exhaust catalyst is used as the raw material, and 20 g of bismuth trioxide is used as the collector to recover the precious metals in the raw material. The main components and contents of the raw material are the same as those in Example 1.

[0067] The raw materials are ground to a particle size of 44 μm - 1 mm; 20 g of bismuth oxide, 140 g of calcium hydroxide, 12 g of sodium bicarbonate, 30 g of borax, 5 g of calcium fluoride, and 30 g of carbon powder are proportioned and mixed evenly, and then placed in an intermediate frequency furnace and heated and melted at 1100 °C for 1.5 h; after the melting is completed, the melt is cooled, and the slag phase and the noble bismuth alloy are separated; the noble bismuth alloy is placed in a vacuum distillation furnace and volatilized at a volatilization temperature of 1050 °C and a vacuum degree of 40 Pa for 1.5 h, and after the reaction is completed, the bismuth metal and the platinum group metals (PGMs) concentrate are collected; the slag phase is placed in a vacuum distillation furnace and volatilized at a temperature of 1050 °C and a vacuum degree of 40 Pa for 1.5 h, and the bismuth metal and the secondary slag phase are collected.

[0068] The contents of platinum group metals and bismuth in the platinum group metals concentrate, bismuth metal and secondary slag phase are analyzed by chemical element detection, and the recovery rate is calculated. The recovery rate of platinum group metal platinum is 99.34%, the recovery rate of palladium is 99.42%, the recovery rate of rhodium is 98.55%, and the recovery rate of bismuth is 99.69%.

[0069] Example 3:

[0070] 200 g of waste petrochemical catalyst is used as the raw material, and 100 g of bismuth metal is used as the collector to recover the precious metals in the raw material, and the main components and contents of the raw material are Al 2 O3 (78.76%) and Pd (2021 g / t).

[0071] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 100 g of metallic bismuth, 150 g of calcium carbonate, 15 g of sodium bicarbonate, 10 g of borax, 2 g of calcium fluoride, and 40 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1000 °C for 1 h; after the melting is completed, cool the melt and separate the slag phase from the noble bismuth alloy; place the noble bismuth alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1100 °C and a vacuum degree of 30 Pa for 1 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1100 °C and a vacuum degree of 30 Pa for 1 h, and collect the metallic bismuth and the secondary slag phase.

[0072] Conduct chemical element detection and analysis on the content of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth and secondary slag phase, and calculate the recovery rate. The recovery rate of platinum group metal palladium is 99.51%, and the recovery rate of bismuth is 99.81%.

[0073] Example 4:

[0074] Use 200 g of waste petrochemical catalyst as raw material and 120 g of bismuth trioxide as a collector to conduct a recovery test on the precious metals in the raw material, where the main components and contents of the raw material are the same as those in Example 3.

[0075] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 120 g of bismuth trioxide, 130 g of calcium hydroxide, 20 g of sodium carbonate, 8 g of borax, 5 g of calcium fluoride, and 50 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1000 °C for 2 h; after the melting is completed, cool the melt and separate the slag phase from the noble bismuth alloy; place the noble bismuth alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1100 °C and a vacuum degree of 30 Pa for 2 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1100 °C and a vacuum degree of 30 Pa for 1 h, and collect the metallic bismuth and the secondary slag phase.

[0076] Conduct chemical element detection and analysis on the content of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth and secondary slag phase, and calculate the recovery rate. The recovery rate of platinum group metal palladium is 99.76%, and the recovery rate of bismuth is 99.75%.

[0077] Example 5:

[0078] Use 200 g of waste fine chemical catalyst as raw material and 120 g of bismuth trioxide as a collector to conduct a recovery test on the total noble metals (platinum group metals) in the raw material.

[0079] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 120 g of bismuth oxide, 130 g of calcium hydroxide, 10 g of sodium bicarbonate, 30 g of borax, 5 g of calcium fluoride, and 30 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1000 °C for 1.5 h; after the melting is completed, cool the melt and separate the slag phase from the noble bismuth alloy; place the noble bismuth alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1000 °C and a vacuum degree of 40 Pa for 1.5 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction ends; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1100 °C and a vacuum degree of 40 Pa for 1 h, and collect the metallic bismuth and the secondary slag phase.

[0080] Conduct chemical element detection and analysis on the content of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth, and secondary slag phase, and calculate the recovery rate. The total recovery rate of platinum group metals is 99.61%, and the recovery rate of bismuth is 99.58%.

[0081] Example 6:

[0082] Use 200 g of waste fine chemical catalyst as the raw material and 80 g of metallic bismuth as the collector to conduct a recovery test on the total noble metals (platinum group metals) in the raw material.

[0083] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 80 g of bismuth, 130 g of calcium oxide, 10 g of sodium carbonate, 20 g of borax, 10 g of calcium fluoride, and 50 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1100 °C for 1.5 h; after the melting is completed, cool the melt and separate the slag phase from the noble bismuth alloy; place the noble bismuth alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1100 °C and a vacuum degree of 40 Pa for 2 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction ends; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1100 °C and a vacuum degree of 40 Pa for 2 h, and collect the metallic bismuth and the secondary slag phase.

[0084] Conduct chemical element detection and analysis on the content of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth, and secondary slag phase, and calculate the recovery rate. The total recovery rate of platinum group metals is 99.33%, and the recovery rate of bismuth is 99.49%.

[0085] Example 7:

[0086] Use 200 g of platinum group metal alloy waste as the raw material and 150 g of bismuth trioxide as the collector to conduct a recovery test on the total noble metals (platinum group metals) in the raw material.

[0087] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 150 g of bismuth oxide, 100 g of calcium hydroxide, 15 g of sodium hydroxide, 30 g of borax, 10 g of calcium fluoride, and 20 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1100 °C for 2 h; after the melting is completed, cool the melt and separate the slag phase from the bismuth-rich alloy; place the bismuth-rich alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1000 °C and a vacuum degree of 40 Pa for 2 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1000 °C and a vacuum degree of 40 Pa for 2 h, and collect the metallic bismuth and the secondary slag phase.

[0088] Conduct chemical element detection and analysis on the contents of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth, and secondary slag phase, and calculate the recovery rate. The total recovery rate of platinum group metals is 99.60%, and the recovery rate of bismuth is 99.57%.

[0089] Example 8:

[0090] Use 200 g of platinum group metals alloy waste as raw materials and 200 g of metallic bismuth as a collector to conduct a recovery test on the total noble metals (platinum group metals) in the raw materials.

[0091] Grind the raw materials to a particle size of 44 μm - 1 mm; weigh 200 g of metallic bismuth, 150 g of calcium hydroxide, 10 g of sodium hydroxide, 25 g of borax, 5 g of calcium fluoride, and 40 g of carbon powder, mix them evenly, place them in an intermediate frequency furnace, and heat and melt at 1000 °C for 1 h; after the melting is completed, cool the melt and separate the slag phase from the bismuth-rich alloy; place the bismuth-rich alloy in a vacuum distillation furnace and volatilize at a volatilization temperature of 1100 °C and a vacuum degree of 20 Pa for 0.5 h, and collect the metallic bismuth and platinum group metals (PGMs) concentrate after the reaction; place the slag phase in a vacuum distillation furnace and volatilize at a temperature of 1100 °C and a vacuum degree of 20 Pa for 0.5 h, and collect the metallic bismuth and the secondary slag phase.

[0092] Conduct chemical element detection and analysis on the contents of platinum group metals and bismuth in the platinum group metals concentrate, metallic bismuth, and secondary slag phase, and calculate the recovery rate. The total recovery rate of platinum group metals is 99.83%, and the recovery rate of bismuth is 99.66%.

[0093] It can be seen from Examples 1 - 8 that the method for recovering platinum group metals from secondary resources by combining bismuth pyrometallurgical capture and vacuum distillation provided by the present invention can efficiently recover platinum group metals from secondary resources. The total recovery rate of platinum group metals and the recovery rate of metallic bismuth are close to 100%, greatly improving the resource utilization rate and laying a foundation for the total quality recovery of platinum group metals from secondary resources. The process of this method is simple to operate, the required raw materials are widely sourced and low in cost, the experiment is easy to operate, and the requirements for equipment are low, with low energy consumption and environmental friendliness, having huge environmental and economic benefits and meeting the requirements of current green metallurgy for clean production.

[0094] It should be understood that although the preferred embodiments of the embodiments of the present application have been described in the specification of the present application, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0095] The above has introduced in detail a method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation provided by the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, based on the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation, characterized in that, it comprises the following steps: Adding a collector, a slag former, a flux and a reducing agent to the raw materials and mixing them evenly to obtain a mixed material; using metallic bismuth as the collector, smelting the mixed material containing platinum group metals at 900°C - 1100°C for 0.5 - 2 h by bismuth pyrometallurgical capture to obtain a melt; the raw materials include one or more of waste automobile exhaust catalysts, waste petrochemical catalysts, waste fine chemical catalysts, platinum group metal alloy materials, platinum group metal-containing waste materials and waste electrical components; Cooling and separating the melt to obtain a noble bismuth alloy and a slag phase; Distilling the noble bismuth alloy under the conditions of a vacuum degree of 20 Pa - 40 Pa and a temperature of 1100°C for 0.5 h to obtain metallic bismuth and a platinum group metal concentrate, so as to recover metallic bismuth from the noble bismuth alloy; Performing vacuum distillation on the slag phase to obtain metallic bismuth and a secondary slag phase, so as to recover metallic bismuth from the slag phase; Using the metallic bismuth recovered from the noble bismuth alloy and the metallic bismuth recovered from the slag phase together as a collector for bismuth pyrometallurgical capture; Separating and purifying the platinum group metal concentrate to obtain platinum group metals.

2. The method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation according to claim 1, characterized in that, the mass ratio of bismuth in the collector to the mass of the raw materials is 0.1 - 2.

3. The method for recovering platinum group metals by combining bismuth pyrometallurgical capture and vacuum distillation according to claim 1, characterized in that, the slag former includes at least one of calcium oxide, calcium carbonate, calcium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide; the flux includes at least one of borax and calcium fluoride; the reducing agent includes at least one of activated carbon, bituminous coal, coke and starch.

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