A method for recovering platinum group noble metals from spent catalysts using matte

Abstract

The application discloses a method for recovering platinum group noble metals from waste catalysts by using copper matte, adopts copper matte as a capturing agent raw material, and alkali metal in a basicity-doped slagging agent is doped into a molten slag to form a compound in a smelting process, so as to separate base metal impurities in the copper matte to obtain alkali metal-doped cuprous sulfide, and platinum group metals in the catalyst are simultaneously captured, the key is to avoid the generation of sulfur dioxide and reduce environmental pollution; the separated impurities in the copper matte are slagged with the basicity-doped slagging agent and a catalyst carrier.

Description

Technical Field

[0001] This invention relates to the field of rare and precious metal smelting, and more specifically, to a method for recovering platinum group precious metals (PGMs) from spent catalysts using copper matte. Background Technology

[0002] Waste automotive exhaust catalysts are an important secondary resource for recovering platinum group metals (PGMs), and are hailed as "moving, high-quality urban PGM mines." Currently used automotive exhaust catalysts mostly use cordierite ceramics (2MgO·2Al2O3·5SiO2 or 2FeO·2Al2O3·5SiO2) as a carrier. During the high-temperature catalytic oxidation-reduction of harmful gases such as CO, CH, and NOx in automotive exhaust, the pyrometallurgical enrichment process exhibits significant advantages in terms of throughput, metal recovery rate, and raw material adaptability due to factors such as the gradual infiltration of PGM particles from the carrier surface, the transformation of the Al2O3 coating into a glaze that encapsulates the PGM particles, and the oxidation of the PGMs. This makes it the most promising process method for application.

[0003] Pyrometallurgical enrichment processes can be categorized into lead capture, copper capture, iron capture, bismuth capture, and matte capture, depending on the selected scavenger. Lead is an excellent scavenger for many precious metals, exhibiting high capture efficiency for platinum and palladium, but its affinity for rhodium is less than ideal. Lead capture requires relatively low smelting temperatures, typically around 1100℃, but lead is highly toxic and causes significant environmental pollution. Copper and iron capture require higher smelting temperatures, generally between 1200-1650℃, resulting in higher energy consumption and equipment requirements. The subsequent separation of the scavenger alloy often necessitates pulverizing the alloy or using it as an anode for electrolytic separation, leading to a relatively long process. Bismuth is green and non-toxic, possessing excellent affinity for precious metals and serving as a good scavenger for many. Bismuth capture, like lead capture, can be smelted at relatively low temperatures (around 1100℃), but bismuth oxide has a high boiling point (1890℃), making traditional ash blowing processes inefficient for bismuth separation. Matte is a miscible metal sulfide. Molten matte exhibits metalloid properties, and elemental sulfur has a strong affinity for noble metals, enabling it to efficiently capture them. Pyrometallurgical copper and nickel smelting practices show that during the smelting process, the vast majority of noble metals in the concentrate enter the matte phase and are enriched. Matte is also commonly used as a collector in fire assay analysis for platinum group metals, effectively enriching trace amounts of these metals. Common matte collectors include nickel matte, copper matte, and iron matte.

[0004] In the technical solution of patent application number 201710856842.0, Ni3S2 is used as a collector. Platinum group metals in the catalyst are collected by microwave heating at 1050-1200℃. Residual platinum group metals are recovered by flotation of the slag. The matte is then ground and leached with sulfuric acid or hydrofluoric acid at 160-170℃ under oxygen pressure, achieving a platinum, palladium, and rhodium recovery rate exceeding 98%. In the technical solution of patent application number 201510797358.6, high-nickel matte produced by a nickel smelter is used as a collector. Calcium oxide and silicon dioxide are added, and the matte is smelted at 1400-1450℃ for 1 hour to obtain matte mainly composed of metallic nickel. The collection rates of platinum and palladium reach over 99%, and the collection rate of rhodium is over 95%. The matte is then leached with sulfuric acid under pressure at 160-170℃ for 6-8 hours to separate the nickel.

[0005] In the technical solution of patent application number 201310300130.2, copper concentrate with a copper content greater than 60% is used as the collector raw material, and calcium oxide and silicon dioxide are used as auxiliary materials. Platinum group metals in the exhausted catalyst are captured by smelting at 1250-1450℃, with more than 98.5% of the precious metals enriched in the copper matte phase. In the technical solution of patent application number 202010550572.2, waste automotive exhaust catalyst is mixed with copper-containing hazardous waste and granulated. The copper matte is then smelted in an oxygen-enriched environment at 1200-1300℃ to capture precious metals.

[0006] In the technical solution of patent application number 201911145621.8, ferrous disulfide is preferably used to smelt and form matte at 1100-1700℃ to capture platinum, palladium, and rhodium from waste automotive exhaust catalysts. The alloy matte is pulverized in hot water and dissolved and purified with dilute acid to obtain platinum group metal enriched slag. In the technical solution of patent application number 202110881695.9, after calcining and ball milling pretreatment of the catalyst, carbonaceous reducing agent and ferrous sulfate are added as capturing agents, and iron matte is formed by reduction smelting at 1350℃-1400℃ to capture platinum and rhenium in the catalyst, with a platinum recovery rate greater than 99.5%.

[0007] However, copper matte, iron matte, and nickel matte are not easily soluble in acid and all require oxygen pressure leaching or pretreatment. Furthermore, impurities such as sulfur, lead, and silicon in precious matte tend to precipitate and remain in enriched slag, leading to a decrease in the grade of platinum group metals and hindering subsequent refining and purification. Pyrometallurgical blowing processes can ideally remove impurities such as sulfur, lead, and silicon. However, the crude metal produced by blowing requires techniques such as oxidized ash blowing, electrolysis, or oxygen pressure leaching to achieve matrix separation. Moreover, the blowing process inevitably brings problems such as sulfur dioxide and heavy metal dust.

[0008] In summary, current matte collection processes generally suffer from problems such as high smelting temperatures, easy SO2 pollution, or difficulty in separating matte from platinum group metals. Summary of the Invention

[0009] 1. The problem to be solved

[0010] To address the problems inherent in existing matte trapping processes, this invention provides a method for recovering platinum group metals from spent catalysts using copper matte.

[0011] 2. Technical Solution

[0012] The technical solution adopted in this invention is as follows:

[0013] [1] A method for recovering platinum group metals from spent catalysts using copper matte includes the following steps:

[0014] S1. Ingredients

[0015] A mixture is obtained by mixing a catalyst, a scavenging agent, a reducing agent, and an alkali-doped slagging agent, and then a protective agent is applied to the surface of the resulting mixture; wherein,

[0016] The trapping agent is copper matte, and the amount of the trapping agent is 0.07-0.14 times the mass of the catalyst;

[0017] The alkali-doped slag-forming agent includes alkali metals and boron-containing substances; the amount of the alkali-doped slag-forming agent is 1.0-2.5 times the mass of the catalyst.

[0018] S2. Preparation and smelting of alkali metal copper matte

[0019] The ingredients in S1 are subjected to high-temperature smelting treatment, which results in the formation of matte phase and smelting slag.

[0020] The high-temperature treatment temperature shall not exceed 950°C;

[0021] In fact, compared with other matte collection methods, the technical solution of this invention directly selects copper matte produced by pyrometallurgical copper smelting as the raw material for the collector. The novel collector formed during the smelting process, alkali metal-doped cuprous sulfide (i.e., matte), has a lower melting point than copper matte and other metal matte. This is the key to reducing the smelting temperature and achieving the collection of platinum group metals in waste catalysts at a lower temperature. Furthermore, by utilizing the strong affinity of matte for precious metals, a high precious metal collection efficiency can be achieved.

[0022] Furthermore, generally, the lower the amount of precipitant used, the better it helps to improve the grade of platinum group metals in matte and increase the enrichment ratio. However, there is a risk of incomplete precipitation of platinum group metals. Therefore, for catalysts with high grades of platinum group metals, a relatively low enrichment factor should usually be selected. It is worth noting, however, that the novel alkali metal-doped cuprous sulfide precipitant formed in this invention has high precipitation efficiency. Therefore, even if the amount of precipitant used is lower than that of common precipitants, an ideal precipitation rate can still be guaranteed.

[0023] Furthermore, the matte is an intermediate product of pyrometallurgical copper smelting, and is a eutectic of cuprous sulfide and ferrous sulfide; common matte has a Cu content of 45-72% and an iron content of 5%-30%.

[0024] In the smelting process, alkali metal ions from the alkali-doped slag-forming agent enter the matte to form sulfides and fix sulfur ions, which is key to avoiding the generation of sulfur dioxide and reducing environmental pollution. In this process, impurity elements such as iron, silicon, calcium, lead, arsenic, zinc, and aluminum in the matte are also effectively separated to obtain alkali metal-doped cuprous sulfide with extremely low impurity elements, while simultaneously and efficiently capturing platinum group metals in the raw materials. The impurity elements separated from the matte, together with the alkali-doped slag-forming agent and catalyst carrier, form slag and achieve separation from the matte phase.

[0025] Furthermore, the alkali metal in the alkali-doped slag-forming agent is arbitrarily selected from substances containing lithium and / or sodium and / or potassium; more specifically, the sodium- and / or potassium-containing substances in the alkali-doped slag-forming agent include any one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0026] The boron-containing substance in the alkali-doped slag-forming agent includes any one or more of borax and sodium metaborate.

[0027] Furthermore, the smelting slag is a seven-element oxide slag, wherein the oxides are Na2O, K2O, FeO, MgO, Al2O3, SiO2, and B2O3;

[0028] Alternatively, a six-element oxide slag type, wherein the oxide is Na2O, FeO, MgO, Al2O3, SiO2, or B2O3.

[0029] Further, the basicity M of the smelting slag is 0.5 to 0.9; preferably 0.6 to 0.8. The basicity (M) of the smelting slag is the ratio of the mass percentage of the simplest basic stable oxide to the simplest acid stable oxide in the slag.

[0030] It is worth noting that during the batching process of S1, it is necessary to consider how to strictly control the basicity (M) of the smelting slag. The study found that the basicity (M) of the smelting slag affects the fluidity of the smelting slag. If the basicity (M) of the smelting slag is too high or too low, it will cause the smelting slag to be too viscous or too thin, both of which will affect the recovery rate of platinum group metals. When the viscosity of the smelting slag is too high, the collector and platinum group metals are easily entrained and lost. When the viscosity of the smelting slag is too low, the collector agglomerates too quickly and settles before it has sufficient contact with the platinum group metals, which affects the collection efficiency. Thin slag will cause serious erosion and corrosion of refractory materials and reduce their service life.

[0031] Furthermore, the reducing agent includes carbohydrates, preferably one or a mixture of several of flour, starch, sucrose, glucose, etc.; the amount of the reducing agent is 0.2-0.8 times the mass of the trapping agent.

[0032] Furthermore, the protective agent is generally a mixture of sodium carbonate and borax in a certain proportion.

[0033] Furthermore, in S2, the high-temperature melting treatment is carried out at a temperature of 850-950°C, preferably 880-920°C, and is held at that temperature for 30-60 minutes.

[0034] While ensuring the separation of slag and matte, the shortest possible heat preservation time should be selected to save energy, reduce corrosion of refractory materials, and prevent matte from oxidizing due to excessive contact with air.

[0035] Furthermore, in step S2, the ingredients from step S1 are first placed in an environment preheated to 600-700°C, and then heated at a uniform rate to 850-950°C for 10-30 minutes for high-temperature heat preservation treatment.

[0036] The higher the initial smelting temperature, the faster the material heats up, the more vigorous the reaction, the more thoroughly the furnace charge is agitated, the more complete the contact between platinum group metals in the furnace charge and the collector, and the higher the recovery rate. However, excessively vigorous reactions pose a risk of slag overflow from the furnace. The selection of initial temperature and heating rate should take into account the amount of furnace charge, the composition of the batch, and the reaction conditions in the furnace. Under the premise of ensuring safety, the highest possible initial temperature and the fastest heating rate should be selected to shorten the smelting time and improve the production efficiency per unit time.

[0037] Furthermore, platinum group metals can be separated by a simple wet process; the wet process includes high-temperature roasting and acid leaching.

[0038] Furthermore, the catalyst is an automotive exhaust purification catalyst with cordierite (2MgO·2Al2O3·5SiO2 or 2FeO·2Al2O3·5SiO2) as the support and platinum group metals (mainly platinum, palladium, and rhodium) as the active components.

[0039] Beneficial effects

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] 1) This invention uses copper matte as the raw material for the slag trap. During the smelting process, alkali metals from the alkali-doped slag-forming agent enter the matte to form compounds. Base metal impurities in the copper matte are separated to prepare alkali metal-doped cuprous sulfide, while simultaneously trapping platinum group metals in the catalyst. Crucially, this avoids the generation of sulfur dioxide, reducing environmental pollution. The impurities separated from the copper matte, along with the alkali-doped slag-forming agent and catalyst support, form slag. The novel alkali metal-doped cuprous sulfide slag trap has a lower melting point than copper matte and other metal mattes, allowing for smelting at lower temperatures and utilizing the affinity of matte for precious metals to achieve efficient trapping. In particular, alkali metal-doped cuprous sulfide is easily processed by wet methods, achieving a high enrichment of platinum group metals.

[0042] Furthermore, using matte as the scavenging agent results in fewer impurities, making it easier to obtain high-quality enriched precious metal matte. By adding alkali metal dopants, iron and other base metal impurities in the molten matte can be effectively separated, resulting in alkali metal-doped cuprous sulfide with extremely low impurity content.

[0043] 2) This invention uses alkali metal-doped cuprous sulfide as a collector and adopts an optimized slag-forming and batching scheme to achieve the collection of platinum group metals in waste automobile exhaust catalysts at a lower temperature, with a smelting temperature far lower than that of traditional matte collection and base metal collection.

[0044] By utilizing the affinity of molten metal sulfides for noble metals, high collection efficiency can be achieved with low agent consumption, and the platinum group metal grade can be enriched by 10-20 times.

[0045] Furthermore, alkali metal-doped cuprous sulfide contains almost no impurities such as iron, lead, or silicon, and platinum group metals can be separated through a simple wet process, resulting in a short and efficient subsequent treatment.

[0046] 3) The slag formation, impurity removal, smelting and enrichment process of this invention is carried out in a reducing atmosphere, so the sulfides do not oxidize and almost no sulfur dioxide is produced, making it clean, green and environmentally friendly. Attached Figure Description

[0047] Figure 1 This is a process flow diagram of the technical solution in an embodiment of the present invention. Detailed Implementation

[0048] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field;

[0049] The essential features and significant effects of the present invention can be seen from the following embodiments. The described embodiments are some, but not all, of the embodiments of the present invention. Therefore, they do not limit the present invention in any way. Any non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are within the protection scope of the present invention.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0051] In the following embodiments,

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0055] 1) Ingredients

[0056] After a waste automobile exhaust catalyst is crushed and ground, 100.00g is weighed and poured into a clay crucible. 14.00g of copper matte powder, 50g of borax, 50g of sodium metaborate, 50g of sodium carbonate, and 8.00g of flour are added and stirred thoroughly. The protective agent is composed of sodium carbonate and borax in a mass ratio of 100:81. 5g of the protective agent is weighed and evenly covered on the surface of the furnace charge. The six-component basicity M of the smelting slag is 0.55.

[0057] Table 1. Main components and platinum group metal grades of a waste automotive catalyst.

[0058] grade 34.12 45.23 8.03 21.24 2424 54.38

[0059] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0060] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0061] Place the prepared crucible into a muffle furnace preheated to 650°C, and heat it to 900°C at a uniform rate for 20 minutes. Hold the temperature for 50 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0062] The total grade of platinum group metals in the alkali metal-doped cuprous sulfide (hereinafter referred to as "precious matte") obtained by the embodiment is about 2.5%, the enrichment ratio is about 10:1, and the recovery rates of Pt, Pd, and Rh are 95.67%, 96.14%, and 95.33%, respectively.

[0063] Table 2. Main components (wt%) of copper matte and noble matte in Example 1

[0064] copper matte 65.43 21.17 0.10 0.02 7.95 0.11 0.04 1.26 Noble Lace 68.10 19.44 10.48 0.03 0.0524 0.15 0.185 0.14

[0065] 3) Weigh 100.00g of precious matte. After roasting and acid leaching, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0066] Example 2

[0067] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0068] 1) Ingredients

[0069] After being crushed and ground, 100.00g of a waste automobile exhaust catalyst was weighed and poured into a clay crucible. Then, 14.00g of copper matte powder, 50g of sodium metaborate, 30g of sodium carbonate, 30g of potassium carbonate, and 10.00g of starch were added and stirred thoroughly. The protective agent was composed of sodium carbonate and borax in a 2:1 mass ratio. 5g of the protective agent was weighed and evenly covered on the surface of the furnace charge. The basicity M of the smelting slag in this batching scheme is 0.64.

[0070] Table 3. Main components and platinum group metal grades of a certain waste automobile catalyst.

[0071] grade 36.30 44.40 5.31 715.2 1875 120.6

[0072] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0073] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0074] Place the prepared crucible into a muffle furnace preheated to 700°C, and heat it to 880°C at a uniform rate for 10 minutes. Hold the temperature for 30 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0075] The total grade of platinum group metals in the noble matte obtained by this embodiment is approximately 2.7%, with an enrichment ratio of approximately 10:1. The recovery rates are 95.39% for Pt, 95.82% for Pd, and 94.76% for Rh.

[0076] Table 4. Main components (wt%) of copper matte and noble matte in Example 2

[0077] copper matte 67.47 20.35 0.12 0.50 7.40 0.17 0.06 1.86 Noble Lace 69.68 18.54 9.37 0.70 0.0325 0.11 0.0719 0.13

[0078] 3) Weigh 100.00g of precious matte, and after simple roasting and acid leaching treatment, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0079] Example 3

[0080] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0081] 1) Ingredients

[0082] After being crushed and ground, 100.00g of a waste automobile exhaust catalyst was weighed and poured into a clay crucible. 7.78g of copper matte powder, 30g of borax, 50g of potassium carbonate, 30g of potassium bicarbonate, and 3.00g of sucrose were added and stirred thoroughly. The protective agent was composed of sodium carbonate and borax in a mass ratio of 25:11. 5g of the protective agent was weighed and evenly covered on the surface of the furnace charge. The basicity M of the smelting slag in this batching scheme is 0.66.

[0083] Table 5. Main components and platinum group metal grades of a certain waste automobile catalyst.

[0084] grade 40.53 36.12 11.08 363.8 982.5 196.7

[0085] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0086] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0087] Place the prepared crucible into a muffle furnace preheated to 650°C, and heat it to 950°C at a uniform rate for 30 minutes. Hold the temperature for 60 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0088] The total grade of platinum group metals in the noble matte obtained by this embodiment is approximately 2.8%, with an enrichment ratio of approximately 18:1. The recovery rates are 95.35% for Pt, 96.01% for Pd, and 95.21% for Rh.

[0089] Table 6. Main components (wt%) of copper matte and noble matte in Example 3.

[0090] copper matte 66.69 19.47 0.21 0.61 7.20 0.27 0.1 1.61 Noble Lace 69.01 17.78 7.58 2.47 0.0424 0.09 0.100 0.12

[0091] 3) Weigh 100.00g of precious matte, and after simple roasting and acid leaching treatment, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0092] Example 4

[0093] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0094] 1) Ingredients

[0095] After being crushed and ground, 100.00g of a waste automobile exhaust catalyst was weighed and poured into a clay crucible. 7.00g of copper matte powder, 30g of borax, 10g of sodium carbonate, 50g of sodium bicarbonate, 50g of potassium bicarbonate, and 4.00g of glucose were added and stirred thoroughly. The protective agent, composed of sodium carbonate and borax in a mass ratio of 100:39, was weighed out and evenly covered on the surface of the furnace charge. The basicity M of the smelting slag in this batching scheme is 0.73.

[0096] Table 7. Main components and platinum group metal grades of a certain waste automobile catalyst.

[0097]

[0098]

[0099] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0100] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0101] Place the prepared crucible into a muffle furnace preheated to 600°C, and heat it to 850°C at a uniform rate for 30 minutes. Hold the temperature for 40 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0102] The total grade of platinum group metals in the noble matte obtained by this embodiment is approximately 2.7%, with an enrichment ratio of approximately 20:1. The recovery rates are 96.20% for Pt, 96.16% for Pd, and 95.77% for Rh.

[0103] Table 8. Main components (wt%) of copper matte and noble matte in Example 4.

[0104] copper matte 62.52 20.44 0.32 0.21 8.48 0.3 0.13 1.23 Noble Lace 67.64 19.51 9.52 1.07 0.377 0.07 0.396 0.11

[0105] 3) Weigh 100.00g of precious matte, and after simple roasting and acid leaching treatment, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0106] Example 5

[0107] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0108] 1) Ingredients

[0109] After being crushed and ground, 100.00g of a waste automobile exhaust catalyst was weighed and poured into a clay crucible. Then, 11.67g of copper matte powder, 100g of borax, 100g of sodium carbonate, 20g of sodium bicarbonate, 20g of potassium bicarbonate, 3.00g of flour, and 3.00g of starch were added and stirred thoroughly. The protective agent, composed of sodium carbonate and borax in a mass ratio of 25:14, was weighed out and evenly covered on the surface of the furnace charge. The basicity M of the smelting slag in this batching scheme is 0.79.

[0110] Table 9. Main Components and Platinum Group Metal Grades of a Waste Automobile Catalyst

[0111] grade 32.78 40.44 4.76 737.1 1356 246.4

[0112] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0113] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0114] Place the prepared crucible into a muffle furnace preheated to 600°C, and heat it to 950°C at a uniform rate for 20 minutes. Hold the temperature for 20 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0115] The total grade of platinum group metals in the noble matte obtained by this embodiment is approximately 2.8%, with an enrichment ratio of approximately 12:1. The recovery rates are 95.35% for Pt, 96.78% for Pd, and 94.83% for Rh.

[0116] Table 10. Main components (wt%) of copper matte and noble matte in Example 5

[0117] copper matte 60.55 21.54 0.24 0.33 8.82 0.16 0.05 1.22 Noble Lace 64.91 20.38 10.68 0.37 0.0314 0.13 0.124 0.18

[0118] 3) Weigh 100.00g of precious matte, and after simple roasting and acid leaching treatment, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0119] Example 6

[0120] This invention discloses a method for preparing alkali metal-doped cuprous sulfide to capture platinum group metals from waste automotive exhaust catalysts by smelting copper matte, comprising:

[0121] 1) Ingredients

[0122] After a waste automobile exhaust catalyst is crushed and ground, 100g is weighed and poured into a clay crucible. Then, 9.33g of copper matte powder, 40g of borax, 20g of sodium metaborate, 60g of sodium carbonate, 1.00g of flour, and 1.00g of glucose are added and stirred thoroughly. The protective agent is composed of sodium carbonate and borax in a mass ratio of 100:53. 5g of the protective agent is weighed and evenly covered on the surface of the furnace charge. The basicity M of the smelting slag in this batching scheme is 0.61.

[0123] Table 11 Main Components and Platinum Group Metal Grades of a Waste Automobile Catalyst

[0124] grade 32.52 37.34 8.91 537.6 1261 186.1

[0125] Note: Platinum group metal grade unit: ppm; SiO2, Al2O3, MgO content unit: wt%.

[0126] 2) Preparation and smelting of alkali metal-doped cuprous sulfide

[0127] Place the prepared crucible into a muffle furnace preheated to 700°C, and heat it to 920°C at a uniform rate for 20 minutes. Hold the temperature for 45 minutes. After holding, quickly transfer the melt to a preheated mold. After the melt cools, separate the slag phase.

[0128] The total grade of platinum group metals in the noble matte obtained by this embodiment is approximately 3.0%, with an enrichment ratio of approximately 15:1. The recovery rates are 95.11% for Pt, 96.50% for Pd, and 95.45% for Rh.

[0129] Table 12. Main components (wt%) of copper matte and noble matte in Example 6.

[0130] copper matte 71.78 19.56 0.22 0.24 6.26 0.12 0.05 1.75 Noble Lace 70.01 16.83 9.87 0.05 0.509 0.11 0.0612 0.11

[0131] 3) Weigh 100.00g of precious matte, and after simple roasting and acid leaching treatment, the leaching residue rate is 1.1%, the sulfation conversion rate reaches more than 98%, and the platinum group metals are enriched more than 90 times.

[0132] Comparative Example 1

[0133] This comparative example is basically the same as Example 1, except that:

[0134] The hexabasic acidity M of the obtained smelting slag is 0.4.

[0135] Specifically, in step one, after coarse and fine crushing of a certain waste automobile exhaust catalyst (the main components and platinum group metal content are shown in Table 1), 100.00g of the catalyst is weighed and poured into a clay crucible. Then, 14.00g of copper matte powder, 120g of borax, 30g of sodium metaborate, 20g of sodium carbonate, and 8.00g of flour are added and stirred thoroughly.

[0136] The rest is the same as in Example 1.

[0137] Table 13. Main components (wt%) of noble sulfur in Comparative Example 1

[0138] Noble Lace 67.20 18.22 0.12 0.03 0.078 0.22 0.09 1.02

[0139] The total grade of platinum group metals in the precious matte obtained by the comparative scheme was about 2.5%, with an enrichment ratio of about 10:1. However, the separation effect of slag and matte was not good, with a small amount of matte entrained in the slag. The matte recovery rate was lower than that of Example 1, resulting in a decrease in the recovery rate of platinum group metals: Pt recovery rate 88.73%, Pd recovery rate 89.38%, and Rh recovery rate 88.56%.

[0140] Comparative Example 2

[0141] This comparative example is basically the same as Example 1, except that:

[0142] The hexabasic acidity M of the obtained smelting slag is 1.0.

[0143] Specifically, in step one, a certain waste automobile exhaust catalyst (the main components and platinum group metal content are shown in Table 1) is coarsely crushed and finely crushed, and 100.00g is weighed and poured into a clay crucible. 14.00g of copper matte powder, 20g of borax, 100g of sodium metaborate, 150g of sodium carbonate, and 8.00g of flour are added and stirred thoroughly.

[0144] The rest is the same as in Example 1.

[0145] Table 14. Main components (wt%) of noble sulfur in Comparative Example 2

[0146] Noble Lace 64.10 19.00 0.12 0.03 0.23 0.21 0.02 0.36

[0147] The total grade of platinum group metals in the precious matte obtained by the comparative scheme was about 2.5%, with an enrichment ratio of about 10:1. However, the separation effect of slag and matte was not good, with a small amount of matte entrained in the slag. The matte recovery rate was lower than that of Example 1, resulting in a decrease in the recovery rate of platinum group metals: Pt recovery rate 90.35%, Pd recovery rate 91.78%, and Rh recovery rate 90.63%.

[0148] Note: In all the above examples and comparative examples, water of crystallization is not included in the calculation of each salt.

[0149] It should be noted that other catalysts containing precious metals can also be treated using the method of this invention. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A process for the recovery of platinum group noble metals from spent catalysts with matte, characterized in that, Includes the following steps: S1. Ingredients A mixture is obtained by mixing a catalyst, a scavenging agent, a reducing agent, and an alkali-doped slagging agent, and then a protective agent is applied to the surface of the resulting mixture; wherein, The trapping agent is copper matte, and the amount of the trapping agent is 0.07-0.14 times the mass of the catalyst; The alkali-doped slag-forming agent includes alkali metals and boron-containing substances; the amount of the alkali-doped slag-forming agent is 1.0-2.5 times the mass of the catalyst. S2. Smelting and Capturing The ingredients in S1 are subjected to high-temperature treatment, which results in the formation of matte phase and smelting slag. The high-temperature treatment temperature shall not exceed 950°C.

2. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 1, characterized in that, The copper matte has a Cu content of 45-72% and an iron content of 5%-30%.

3. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 1, characterized in that, The alkali-containing metal in the alkaline doping slag-forming agent includes any one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. The boron-containing substance in the alkali-doped slag-forming agent includes any one or more of borax and sodium metaborate.

4. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 3, characterized in that, The smelting slag is a seven-element oxide slag, and the oxides are Na2O, K2O, FeO, MgO, Al2O3, SiO2, and B2O3. Alternatively, a six-element oxide slag type, wherein the oxide is Na2O or K2O, FeO, MgO, Al2O3, SiO2, or B2O3.

5. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 4, characterized in that, The basicity M of the smelting slag is 0.5 to 0.

9.

6. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 4, characterized in that, The basicity M of the smelting slag is 0.6 to 0.

8.

7. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 1, characterized in that, The reducing agent includes carbohydrates; the amount of the reducing agent is 0.2-0.8 times the mass of the trapping agent.

8. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 1, characterized in that, The protective agent is a mixture of sodium carbonate and borax.

9. The method for recovering platinum group metals from spent catalysts using copper matte according to any one of claims 1 to 6, characterized in that, In S2, the high-temperature treatment is carried out at a temperature of 850-950℃ and is held for 30-60 minutes.

10. The method for recovering platinum group metals from spent catalysts using copper matte according to claim 7, characterized in that, In step S2, the ingredients from step S1 are first placed in an environment preheated to 600-700°C, and then heated at a uniform rate to 850-950°C for 10-30 minutes for heat preservation.

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