A process for the solid state sulphidation-flotation enrichment of palladium from spent alumina-supported palladium catalysts

Abstract

The application discloses a method for solid-state sulfidation-flotation enrichment of palladium of waste alumina carrier palladium catalyst, which comprises the following steps: mixing, crushing and roasting a waste alumina carrier palladium catalyst, a trapping agent ferrous sulfate or nickel sulfate and a reducing agent charcoal powder at a temperature of 600-1000 DEG C; grinding the roasted sample with a ball mill by adding water; putting the ground ore slurry into a flotation tank; adding a collecting agent and a foaming agent; introducing air into the flotation tank; and obtaining a concentrate, a tailing and a middling through roughing, twice scavenging and twice cleaning. The enrichment ratio of the metal palladium in the concentrate can reach 8.53-9.13. The method has the advantages of a short technological process, a large enrichment ratio, a stable enrichment effect, a large processing capacity, a small difficulty in waste liquid treatment, a low roasting temperature, environmental friendliness, a low requirement for the high-temperature resistance and acid and alkali resistance of equipment, and easy industrialization.

Description

Technical Field

[0001] This invention belongs to the field of platinum group metals recycling technology, and relates to a method for solid-state sulfidation-flotation enrichment of palladium using a waste alumina-supported palladium catalyst. Background Technology

[0002] Currently, the main methods for enriching palladium from spent alumina-supported palladium catalysts include hydrometallurgical processes, pyrometallurgical processes, combined pyrometallurgical and hydrometallurgical processes, and supercritical processes. Among these, the pyrometallurgical process involves adding other fluxes to the catalyst and treating it at high temperatures to separate the platinum group metals from the support, thereby purifying the enriched product. Pyrometallurgical processes have the advantages of simple technology and high metal recovery rates, but they require sophisticated equipment and consume a lot of energy. Hydrometallurgical processes can be divided into selective carrier dissolution, platinum group metal dissolution, total dissolution, and bioleaching. Hydrometallurgical processes have the advantages of low cost and high recovery rates, but the resulting wastewater is difficult to treat, the composition of the solution is complex, and some reagents are highly toxic (e.g., cyanide used in cyanide leaching is highly toxic and requires strict control, making management difficult). The combined pyrometallurgical and hydrometallurgical process combines pyrometallurgical and hydrometallurgical methods, including pyrometallurgical enrichment, separation of precious and base metals, leaching of precious metals, reduction precipitation, and refining purification to obtain sponge palladium. This process is complex, and the treatment of waste residue and wastewater is difficult. Supercritical processes offer advantages such as rapid reaction rates and the absence of secondary pollution, but they require sophisticated equipment and are difficult to industrialize. Therefore, there is a need to develop a method for the solid-state sulfidation-flotation enrichment of palladium from waste alumina-supported palladium catalysts. This method features a simple process flow, minimal waste residue and liquid treatment, low calcination temperature, environmental friendliness, low requirements for equipment's high-temperature resistance and acid / alkali tolerance, and is easily industrially feasible. Summary of the Invention

[0003] The purpose of this invention is to provide a method for solid-state sulfidation-flotation enrichment of palladium catalysts on waste alumina carriers, which has a simple process flow, low difficulty in treating waste residue and waste liquid, low roasting temperature, environmental friendliness, low requirements for equipment to withstand high temperatures and acid and alkali resistance, and is easy to achieve industrial production.

[0004] To achieve the above objectives, the present invention provides a method for solid-state sulfidation-flotation enrichment of palladium from waste alumina-supported palladium catalyst, comprising the following steps:

[0005] (1) The waste alumina palladium catalyst, scavenger and charcoal powder are mixed and crushed in a sealed pulverizer. The crushed sample is then placed in a crucible resistance furnace for low-temperature calcination.

[0006] (2) Add water to the roasted sample and grind it with a ball mill. Put the ground slurry into the flotation cell, add the collector and frother, then introduce air into the flotation cell, turn on the scraper, and scrape off the roughing foam.

[0007] (3) Add the collector and frother to the flotation cell, stir, open the air valve to introduce air, and then open the scraper to scrape the first froth.

[0008] (4) Add the collector and frother to the flotation cell again, stir, open the air valve to introduce air, open the scraper to scrape the second flotation foam, and the flotation cell contains tailings.

[0009] (5) After the tailings in the flotation cell are discharged, the foam from the roughing, scavenging, and scavenging processes is put back into the flotation cell, stirred, and then the air valve is opened to introduce air. The scraper is then turned on to scrape the first finely selected foam, and the flotation cell contains middlings.

[0010] (6) After the middlings in the flotation cell are discharged, the foam from the first cleaning is put back into the flotation cell, stirred, and then the air valve is opened to introduce air. Then the scraper is started to remove the foam from the second cleaning. The flotation cell contains concentrate.

[0011] (7) After the concentrate in the flotation cell is discharged, it is filtered and dried to obtain a concentrate enriched with palladium.

[0012] Further, in step (1), the catching agent is ferrous sulfate or nickel sulfate, and the amount of catching agent added is 1.2 to 2 times the weight ratio of the waste alumina palladium catalyst. The reducing agent is charcoal powder, and the amount of charcoal powder added is 0.12 to 0.2 times the weight ratio of the waste alumina palladium catalyst.

[0013] Further, the pulverized sample from step (1) is subjected to low-temperature calcination in a crucible resistance furnace at a temperature of 600-1000℃ for 0.5-2.5h.

[0014] Furthermore, in step (2), the volume ratio of roasted ore to water is 2:1.

[0015] Furthermore, in steps (2), (3), (4), (5), and (6), the collector is a xanthate solution with a concentration of 2%, and the foaming agent is No. 2 oil.

[0016] Working principle of this invention:

[0017] This invention involves adding ferrous sulfate or nickel sulfate to waste alumina palladium catalyst and calcining it at 600-800℃. The resulting ferrous sulfide or nickel sulfide acts as a collector, enriching palladium in the ferrous sulfide or nickel sulfide. The reaction is as follows:

[0018] FeSO4 + 4C = FeS↓ + 4CO↑ (2-1)

[0019] FeSO4 + 2C = FeS↓ + 2CO2↑ (2-2)

[0020] NiSO4 + 4C = NiS↓ + 4CO↑ (2-3)

[0021] NiSO4 + 2C = NiS↓ + 2CO2↑ (2-4)

[0022] Next, the calcined sample was ground with water using a ball mill and placed in a flotation cell. Collectors and frothers were added, and air was then introduced into the flotation cell. The hydrophobic end of the frother was on the air-facing side of the gas-liquid interface, while the hydrophilic end remained in the solution, forming bubbles. The collector adsorbed onto the surface of the solid mineral powder. During flotation, the bubbles carried the palladium-containing mineral powder out, which was collected by a scraper and container, achieving palladium enrichment. X-ray analysis of the final product showed that the final phase of the sample with added ferrous sulfate was Al2O3, with Fe... 1-x S, C; the final phase of the sample with added nickel sulfate was Al2O3, C, Ni3S2.

[0023] The main innovation of this invention lies in:

[0024] This method discloses a solid-state sulfidation-flotation enrichment method for palladium from waste alumina-supported palladium catalyst. First, a collector and charcoal powder are added to the catalyst for low-temperature calcination (600-1000℃). Compared to traditional pyrometallurgical processes (melting temperature 1250-1350℃), the temperature is reduced by 350-650℃, lowering energy consumption and significantly reducing the equipment's high-temperature resistance requirements. Furthermore, the reagents used in this invention are non-toxic and do not involve harsh environments such as strong acids or alkalis. The resulting wastewater and waste liquid can be recycled, making it environmentally friendly and energy-saving. The collectors and frothers involved are inexpensive and widely available, enabling highly efficient palladium capture with an enrichment ratio of 8.53-9.13. The process is also simple, with stable enrichment effects, large processing capacity, and mature equipment, making industrial-scale production easily achievable. Attached Figure Description

[0025] Figure 1 A process flow diagram for the solid-state sulfidation-flotation enrichment of palladium using waste alumina-supported palladium catalyst;

[0026] Figure 2 The XRD diffraction pattern of the sample after calcination with ferrous sulfate;

[0027] Figure 3 The XRD diffraction pattern of the sample after calcination with nickel sulfate; Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific examples: Example

[0029] Referring to the attached diagram, the conditions are as follows: Weigh 1000g of waste alumina-supported palladium catalyst, add ferrous sulfate at a weight ratio of 1.2 times that of the waste palladium catalyst, and charcoal powder at a weight ratio of 0.12 times that of the waste palladium catalyst. Mix and pulverize the mixture, then place it in a crucible resistance furnace for roasting at 650℃ for 0.5 hours. Place the roasted sample and water (33.4% water, 66.6% ore) in a ball mill and grind for 5 minutes. After sedimentation, pour off the supernatant. Place the precipitated slurry into a flotation cell, turn on the main shaft and stir for 1 minute, add 55ml of xanthate solution, stir for 3 minutes, add 0.98ml of No. 2 oil, stir for 1 minute, then open the air valve and start the scraper. Use a container to catch the foam. After 3 minutes, close the scraper and air valve to complete the roughing process. Add 27ml of collector to the flotation cell and stir for 3 minutes. Add 0.49ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher foam. After 2 minutes, close the air valve and scraper to complete the first scavenging. Add 13ml of collector to the flotation cell again and stir for 3 minutes. Add 0.25ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher and first scavenging. After 1 minute, close the air valve and scraper to complete the second scavenging. Filter and dry the tailings in the flotation cell and place them in a sealed bag with a label. Put the foam from the rougher, first scavenging, and second scavenging back into the flotation cell, turn on the main shaft and stir for 3 minutes. Open the air valve and scraper and collect the foam in another container. After 3 minutes, close the air valve and scraper to complete the first cleaning. Transfer the middlings from the flotation cell to another container. The foam from the first selection was put back into the flotation cell and stirred for 3 minutes. Then the air valve and scraper were turned on, and another container was used to catch the foam. After 3 minutes of selection, the air valve and scraper were turned off to complete the second selection. The concentrate in the flotation cell was filtered and dried to obtain a concentrate enriched with palladium. The palladium enrichment ratio was calculated to be 8.74. Example

[0030] Referring to the attached diagram, the conditions are as follows: Weigh 2500g of waste alumina-supported palladium catalyst, add nickel sulfate at a ratio of 1.4 times the weight of the waste palladium catalyst, and charcoal powder at a ratio of 0.14 times the weight of the waste palladium catalyst. Mix and pulverize the mixture, then place it in a crucible resistance furnace for roasting at 800℃ for 1 hour. Place the roasted sample and water (33.4% water, 66.6% ore) in a ball mill and grind for 5 minutes. After sedimentation, pour off the supernatant. Place the precipitated slurry into a flotation cell, turn on the main shaft and stir for 1 minute. Add 82ml of xanthate solution and stir for 3 minutes. Add 1.48ml of No. 2 oil and stir for 1 minute. Then, open the air valve and turn on the scraper. Use a container to catch the foam. After 3 minutes, close the scraper and air valve to complete the roughing process. Add 41ml of collector to the flotation cell and stir for 3 minutes. Add 0.74ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher foam. After 2 minutes, close the air valve and scraper to complete the first scavenging. Add 21ml of collector to the flotation cell again and stir for 3 minutes. Add 0.37ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher and first scavenging foam. After 1 minute, close the air valve and scraper to complete the second scavenging. Filter and dry the tailings in the flotation cell and place them in a sealed bag with a label. Put the foam from the rougher, first scavenging, and second scavenging back into the flotation cell, turn on the main shaft and stir for 3 minutes. Open the air valve and scraper and collect the foam in another container. After 3 minutes, close the air valve and scraper to complete the first cleaning. Transfer the middlings from the flotation cell to another container. The foam from the first selection was put back into the flotation cell and stirred for 3 minutes. Then the air valve and scraper were turned on, and another container was used to catch the foam. After 3 minutes of selection, the air valve and scraper were turned off to complete the second selection. The concentrate in the flotation cell was filtered and dried to obtain a concentrate enriched with palladium. The palladium enrichment ratio was calculated to be 8.92. Example

[0031] Referring to the attached diagram, the conditions are as follows: Weigh 2000g of waste alumina-supported palladium catalyst, add ferrous sulfate at a weight ratio of 1.6 times that of the waste palladium catalyst, and charcoal powder at a weight ratio of 0.16 times that of the waste palladium catalyst. Mix and pulverize the mixture, then place it in a crucible resistance furnace for roasting at 950℃ for 1.5 hours. Place the roasted sample and water (33.4% water, 66.6% ore) in a ball mill and grind for 5 minutes. After sedimentation, pour off the supernatant. Place the precipitated slurry into a flotation cell, turn on the main shaft and stir for 1 minute. Add 110ml of xanthate solution and stir for 3 minutes. Add 1.96ml of No. 2 oil and stir for 1 minute. Then, open the air valve and turn on the scraper. Use a container to catch the foam. After 3 minutes, close the scraper and air valve to complete the roughing process. Add 27ml of collector to the flotation cell and stir for 3 minutes. Add 0.98ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher foam. After 2 minutes, close the air valve and scraper to complete the first scavenging. Add 13ml of collector to the flotation cell again and stir for 3 minutes. Add 0.49ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher and first scavenging foam. After 1 minute, close the air valve and scraper to complete the second scavenging. Filter and dry the tailings in the flotation cell and place them in a sealed bag with a label. Put the foam from the rougher, first scavenging, and second scavenging back into the flotation cell, turn on the main shaft and stir for 3 minutes. Open the air valve and scraper and collect the foam in another container. After 3 minutes, close the air valve and scraper to complete the first cleaning. Transfer the middlings from the flotation cell to another container. The foam from the first selection was put back into the flotation cell and stirred for 3 minutes. Then the air valve and scraper were turned on, and another container was used to catch the foam. After 3 minutes of selection, the air valve and scraper were turned off to complete the second selection. The concentrate in the flotation cell was filtered and dried to obtain a concentrate enriched with palladium. The palladium enrichment ratio was calculated to be 9.13. Example

[0032] Referring to the attached diagram, the conditions are as follows: Weigh 3500g of waste alumina-supported palladium catalyst, add nickel sulfate at a ratio of 1.8 times the weight of the waste palladium catalyst, and charcoal powder at a ratio of 0.18 times the weight of the waste palladium catalyst. Mix and pulverize the mixture, then place it in a crucible resistance furnace for roasting at 850℃ for 2.0 hours. Place the roasted sample and water (33.4% water, 66.6% ore) in a ball mill and grind for 5 minutes. After sedimentation, pour off the supernatant. Place the precipitated slurry into a flotation cell, turn on the main shaft and stir for 1 minute. Add 82ml of xanthate solution and stir for 3 minutes. Add 1.47ml of No. 2 oil and stir for 1 minute. Then, open the air valve and turn on the scraper. Use a container to catch the foam. After 3 minutes, close the scraper and air valve to complete the roughing process. Add 41ml of collector to the flotation cell and stir for 3 minutes. Add 0.74ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher foam. After 2 minutes, close the air valve and scraper to complete the first scavenging. Add 20ml of collector to the flotation cell again and stir for 3 minutes. Add 0.37ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher and first scavenging foam. After 1 minute, close the air valve and scraper to complete the second scavenging. Filter and dry the tailings in the flotation cell and place them in a sealed bag with a label. Put the foam from the rougher, first scavenging, and second scavenging back into the flotation cell, turn on the main shaft and stir for 3 minutes. Open the air valve and scraper and collect the foam in another container. After 3 minutes, close the air valve and scraper to complete the first cleaning. Transfer the middlings from the flotation cell to another container. The foam from the first selection was put back into the flotation cell and stirred for 3 minutes. Then the air valve and scraper were turned on, and another container was used to catch the foam. After 3 minutes of selection, the air valve and scraper were turned off to complete the second selection. The concentrate in the flotation cell was filtered and dried to obtain a concentrate enriched with palladium. The palladium enrichment ratio was calculated to be 8.69. Example

[0033] Referring to the attached diagram, the conditions are as follows: Weigh 2000g of waste alumina-supported palladium catalyst, add ferrous sulfate at twice the weight ratio of the waste palladium catalyst, and charcoal powder at 0.2 times the weight ratio of the waste palladium catalyst. Mix and pulverize the mixture, then place it in a crucible resistance furnace for roasting at 950℃ for 2.5 hours. Place the roasted sample with water (33.4% water, 66.6% ore) in a ball mill and grind for 5 minutes. After sedimentation, pour off the supernatant. Place the precipitated slurry into a flotation cell, turn on the main shaft and stir for 1 minute. Add 110ml of xanthate solution and stir for 3 minutes. Add 1.96ml of No. 2 oil and stir for 1 minute. Then, open the air valve and turn on the scraper. Use a container to catch the foam. After 3 minutes, close the scraper and air valve to complete the roughing process. Add 55ml of collector to the flotation cell and stir for 3 minutes. Add 0.98ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher foam. After 2 minutes, close the air valve and scraper to complete the first scavenging. Add 27ml of collector to the flotation cell again and stir for 3 minutes. Add 0.49ml of No. 2 oil and stir for 1 minute. Open the air valve and scraper to mix the foam with the rougher and first scavenging. After 1 minute, close the air valve and scraper to complete the second scavenging. Filter and dry the tailings in the flotation cell and place them in a sealed bag with a label. Put the foam from the rougher, first scavenging, and second scavenging back into the flotation cell, turn on the main shaft and stir for 3 minutes. Open the air valve and scraper and collect the foam in another container. After 3 minutes, close the air valve and scraper to complete the first cleaning. Transfer the middlings from the flotation cell to another container. The foam from the first selection was put back into the flotation cell and stirred for 3 minutes. Then the air valve and scraper were turned on, and another container was used to catch the foam. After 3 minutes of selection, the air valve and scraper were turned off to complete the second selection. The concentrate in the flotation cell was filtered and dried to obtain a concentrate enriched with palladium. The palladium enrichment ratio was calculated to be 8.53.

Claims

1. A method for solid state sulfidation-flotation enrichment of palladium from spent alumina support palladium catalysts, characterized in that, The following steps are taken: (1) The waste alumina palladium catalyst, the trapping agent, and the charcoal powder are mixed and then put into a sealed pulverizer for pulverization. The trapping agent is ferrous sulfate or nickel sulfate, and the trapping agent is added in an amount of 1.2-2 times the weight of the waste alumina palladium catalyst. The charcoal powder is added in an amount of 0.12-0.2 times the weight of the waste alumina palladium catalyst. The pulverized sample is placed in a crucible electric resistance furnace and calcined at 600-800°C for 0.5-2.5h to perform a solid-state sulfidation reaction, so that the trapping agent reacts with the reducing agent to form ferrous sulfide or nickel sulfide to achieve trapping of palladium; (2) Water is added to the calcined sample and ground by a ball mill. The volume ratio of the calcined ore to water is 2:

1. The ground ore slurry is put into a flotation tank, and a collecting agent and a foaming agent are added. The collecting agent is a xanthate solution with a concentration of 2%, and the foaming agent is No. 2 oil. Air is introduced into the flotation tank, the scraper is turned on, and the roughing froth is scraped; (3) The collecting agent and the foaming agent are added to the flotation tank, stirred, and then air is introduced through the air valve. The scraper is turned on to scrape the first scavenging froth; (4) The collecting agent and the foaming agent are added to the flotation tank again, stirred, and then air is introduced through the air valve. The scraper is turned on to scrape the second scavenging froth, and the flotation tank is the tailings; (5) After the tailings in the flotation tank are discharged, the roughing, the first scavenging, and the second scavenging froths are put back into the flotation tank, stirred, and then air is introduced through the air valve. The scraper is turned on to scrape the first cleaning froth, and the flotation tank is the middlings; (6) After the middlings in the flotation tank are discharged, the first cleaning froth is put back into the flotation tank, stirred, and then air is introduced through the air valve. The scraper is turned on to scrape the second cleaning froth, and the flotation tank is the concentrate; (7) The concentrate in the flotation tank is discharged, filtered, and dried to obtain the concentrate enriched in metallic palladium.

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