New Application of Copper Dross

Abstract

The present invention discloses a new application of copper dross. Copper dross is the dross produced by adding sulfur to remove copper or separating copper by liquid-liquid separation during the pyrometallurgical refining of crude lead. In the present invention, the powder of spent automotive exhaust catalysts is mixed with copper dross, CaO, borax, and Na2CO3, and then subjected to high-temperature smelting to obtain a slag phase and a matte phase respectively, with the platinum group elements enriched in the matte phase. The present invention innovatively uses the heavy metal hazardous waste copper dross as a collector to capture the platinum group metals in the spent automotive exhaust catalysts. The capture rates of platinum, palladium, and rhodium can reach over 98%, realizing the efficient capture of platinum group metals and the recycling of industrial waste, reducing the industrial cost, treating solid waste, and having good industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of platinum group metal recovery, and specifically relates to a new application of copper dross as a collector for platinum group metals in spent automotive exhaust catalysts. Background Art

[0002] Platinum group metals (PGMs) are important strategic resources in China and are widely used in modern industry. China's annual production of platinum group metals is only about 3 tons, but the annual demand for platinum group metals exceeds 180 tons, highly relying on imports.

[0003] With the increasing consumption of primary resources of platinum group metals, industrial waste catalysts with complex compositions as secondary resources have become the main raw material sources for platinum group metal supply. Automotive exhaust catalysts are the largest application field of platinum group metals. Automotive exhaust catalysts use cordierite as a carrier, with TiO2, ZrO2, and CeO2 as promoters in the raw materials, and platinum group metals such as platinum, palladium, and rhodium as active components evenly distributed in the carrier. Spent automotive exhaust catalysts have become the main "mines" for extracting platinum group metals. Efficiently recovering platinum group metals from spent automotive exhaust catalysts is of extremely important significance for solving the contradiction between the scarcity of natural resources of platinum group metals and the growing demand. Moreover, these waste materials contain a large amount of organic wastes such as carbon deposits and sludge, as well as heavy metals such as lead. Without treatment, they are likely to cause serious environmental pollution. Therefore, recovering platinum group metals from spent automotive exhaust catalysts not only meets the need for comprehensive resource utilization but also meets the requirement for eliminating environmental pollution.

[0004] In summary, there are problems such as resource waste and environmental pollution in the treatment of spent automotive exhaust catalysts. Independently developing low-cost and efficient platinum group metal recovery technologies is an urgent need in the platinum group metal industry. Using heavy metal hazardous waste to capture platinum group metals in spent automotive exhaust catalysts not only reduces environmental pollution but also brings actual economic benefits. However, existing methods have problems such as low recovery rate of platinum group metals, high cost, and environmental pollution. Based on this, an application of using copper dross to capture platinum group metals in spent automotive exhaust catalysts is proposed, and this method has not been reported yet. Summary of the Invention

[0005] Aiming at the problems of low recovery rate of platinum group metals, high cost, environmental pollution, and reuse of industrial heavy metal hazardous waste in the existing methods, the present invention provides a new application of using copper dross as a collector to capture platinum group metals in spent automotive exhaust catalysts.

[0006] The present invention innovatively uses copper dross as a collector. Copper dross is a waste material produced by adding sulfur to remove copper or melting and separating copper during the pyrometallurgical refining of crude lead, and it has a significant capture effect on platinum group metals. Using copper dross to smelt and capture platinum group metals in spent automotive exhaust catalysts can replace pure lead sulfide collectors, achieving efficient recovery of platinum group metals while reducing the recovery cost and realizing the recycling of industrial waste.

[0007] The present invention is achieved through the following technical solutions:

[0008] A new application of copper dross as a collector for enriching platinum group metals in spent automotive exhaust catalysts. The copper dross can enrich the platinum group metals in the spent automotive exhaust catalysts.

[0009] The copper dross is the dross produced by adding sulfur to remove copper or separating copper by liquidation in the pyrometallurgical refining of crude lead.

[0010] The specific steps of the application are as follows:

[0011] (1) Weigh copper dross, spent automotive exhaust catalyst powder, CaO, borax, and Na2CO3, mix them, and place the mixture in a graphite crucible.

[0012] (2) Move the crucible in step (1) to the furnace cavity of a high-frequency induction melting furnace and cover it with a corundum crucible.

[0013] (3) Turn on the high-frequency induction melting furnace in step (2) and conduct high-temperature melting.

[0014] (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. Let the graphite crucible stand in the furnace cavity for 10 minutes and then take it out. Cool it to room temperature until the material is completely cooled and solidified, and then pour it out. Separate the slag and matte phases of the material to obtain a slag phase and a matte phase, and the platinum group elements are enriched in the matte phase.

[0015] The mass fractions of each part in the mixture in step (1) are as follows: 40 - 50% copper dross, 20 - 25% spent automotive exhaust catalyst powder, 5 - 15% CaO, 21 - 26% borax, and 2 - 5% Na2CO3.

[0016] The high-temperature melting in step (3) is to raise the temperature to 1200 - 1400 °C for high-temperature melting, and the heat preservation time is 40 - 60 minutes. The beneficial effects of the present invention:

[0017] (1) The present invention reduces the melting temperature, does not require an additional reducing agent, and has a high degree of separation between the slag phase and the matte phase.

[0018] (2) The present invention innovatively uses copper dross as a collector to achieve efficient recovery of platinum, palladium, and rhodium in spent automotive exhaust catalysts, effectively solving the problem of high collector cost and enabling the rational recycling of industrial waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the XRD pattern of the copper dross raw material in Example 2 of the present invention;

[0020] Figure 2 It is the separation diagram of the slag and matte phases in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The following combines specific embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention, but the protection scope of the present invention is not limited to the content described.

[0022] The copper dross used in the embodiment is the dross produced by pyrometallurgical refining of crude lead with sulfur addition to remove copper or liquation to remove copper. The copper dross contains elements such as Pb, S, Te, Cu, Sn, Bi, Se that have an affinity for platinum group metals. Among them, the contents of Pb and PbS are the highest, and they have a significant trapping effect on platinum group metals.

[0023] The spent automotive exhaust catalyst used in the embodiment has high contents of platinum, palladium, and rhodium.

[0024] Example 1

[0025] (1) Weigh 40 g of copper dross, 23.91 g of spent automotive exhaust catalyst, 8.58 g of calcium oxide, 25.29 g of borax, and 2.22 g of anhydrous sodium carbonate. After mixing all the materials evenly, put them into a graphite crucible. A total of 100 g of materials are put into the graphite crucible, and the slag basicity is 0.58; (2) Move the crucible in step (1) to the furnace cavity of a high-frequency induction melting furnace and cover it with a corundum crucible.

[0026] (3) Turn on the high-frequency induction melting furnace in step (2). The heating current of the high-frequency induction melting furnace during high-temperature melting is as follows: First, adjust the current to 300 A and heat for 10 minutes. Then, increase the current of the induction melting furnace by 200 A every 10 minutes until it reaches 900 A and no longer increases. Control the temperature at 1200 °C and keep it for 60 min for high-temperature melting. The materials in the crucible will completely melt and react; (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. The graphite crucible is left to stand in the furnace cavity for 10 minutes and then taken out. After cooling to room temperature until the materials are completely cooled and solidified, pour them out to obtain a slag with obvious glass phase and a matte phase enriched with platinum, palladium, and rhodium. The boundary between the slag and matte phases is obvious, and the two phases are easy to separate.

[0027] After testing, the grades of platinum, palladium, and rhodium in the spent automotive exhaust catalyst are 92 g / t, 1458 g / t, and 293 g / t respectively. The element contents in the copper dross are Pb 62.89%, S 11.42%, Te 9.27%, Cu 5.56%, Sn 4.96%, Bi 2.23%, Se 1.91% respectively. The recovery rates of platinum, palladium, and rhodium trapped by the copper dross reach 95.09%, 95.78%, and 95.99% respectively. The results show that it is feasible to use copper dross as a trapping agent to recover platinum group metals from the tailings of spent automotive exhaust catalysts.

[0028] Example 2

[0029] (1) Weigh 40 g of copper dross, 23.50 g of spent automotive exhaust catalysts, 8.60 g of calcium oxide, 25.50 g of borax, and 2.40 g of anhydrous sodium carbonate. After mixing all the materials evenly, put them into a graphite crucible. A total of 100 g of materials are put into the graphite crucible, and the slag basicity is 0.59; (2) Move the crucible in step (1) to the furnace cavity of a high-frequency induction melting furnace and cover it with a corundum crucible;

[0030] (3) Turn on the high-frequency induction melting furnace in step (2). When performing high-temperature melting, the heating current of the high-frequency induction melting furnace is as follows: First, adjust the current to 300 A and heat for 10 minutes. Then, increase the current of the induction melting furnace by 200 A every 10 minutes until it reaches 900 A and no longer increases. Control the temperature at 1300 °C and keep it warm for 60 min to perform high-temperature melting. The materials in the crucible will completely melt and react; (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. Let the graphite crucible stand in the furnace cavity for 10 minutes and then take it out. Cool it to room temperature until the materials are completely cooled and solidified, and then pour them out to obtain slag with obvious glass phase and matte phase enriched with platinum, palladium, and rhodium. The boundary between the slag and matte phases is obvious, and the two phases are easy to separate.

[0031] After testing, the grades of platinum, palladium, and rhodium in the spent automotive exhaust catalysts are 106 g / t, 1545 g / t, and 347 g / t respectively. The XRD pattern of the copper dross raw material is as Figure 1 shown. It can be seen from the figure that the content of Pb and PbS in the copper dross raw material is high. The element contents in the copper dross are Pb 59.51%, S 10.55%, Te 8.43%, Cu 3.43%, Sn 6.10%, Bi 1.23%, and Se 1.17% respectively. Figure 2 This is the separation diagram of the slag phase and the matte phase. It can be seen from the figure that the difference between the slag phase and the matte phase is obvious and they are easy to separate. By calculation, the recovery rates of platinum, palladium, and rhodium reach 100%, 98.73%, and 98.35% respectively. The material ratio of this group of experiments can capture all the platinum metals in the tail slag.

[0032] Example 3

[0033] (1) Weigh 45 g of copper dross, 20.00 g of spent automotive exhaust catalysts, 8.50 g of calcium oxide, 24.50 g of borax, and 2.00 g of anhydrous sodium carbonate. After mixing all the materials evenly, put them into a graphite crucible. A total of 100 g of materials are put into the graphite crucible, and the slag basicity is 0.64; (2) Move the crucible in step (1) to the furnace cavity of a high-frequency induction melting furnace and cover it with a corundum crucible;

[0034] (3) Turn on the high-frequency induction melting furnace in step (2). During high-temperature melting, the heating current of the high-frequency induction melting furnace is as follows: First, adjust the current to 300 A and heat for 10 minutes. Then, increase the current of the induction melting furnace by 200 A every 10 minutes until it no longer increases at 900 A. Control the temperature at 1300 °C and keep it warm for 60 minutes for high-temperature melting. The materials in the crucible will completely melt and react. (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. Let the graphite crucible stand in the furnace cavity for 10 minutes and then take it out. Cool it at room temperature until the materials are completely cooled and solidified, and then pour them out to obtain slag with obvious glass phase and matte phase enriched with platinum, palladium, and rhodium. The boundary between the slag and matte phases is obvious, and the two phases are easy to separate.

[0035] After detection, the grades of platinum, palladium, and rhodium in the failed automotive exhaust catalyst are 106 g / t, 1545 g / t, and 347 g / t respectively. The element contents in the copper dross are Pb 59.51%, S 10.55%, Te 8.43%, Cu 3.43%, Sn 6.10%, Bi 1.23%, and Se 1.17% respectively. The recovery rates of platinum, palladium, and rhodium reach 79.06%, 91.25%, and 92.60% respectively. The melting parameters are the same as those in Example 2, but the results are different, indicating that when the experimental conditions such as time and temperature are the same, the capture rate at a slag basicity of 0.64 is lower than that at a basicity of 0.59, which shows that the burden slag type with a slag basicity of 0.59 is better.

[0036] Example 4

[0037] (1) Weigh 40 g of copper dross, 23.91 g of failed automotive exhaust catalyst, 8.58 g of calcium oxide, 25.29 g of borax, and 2.22 g of anhydrous sodium carbonate. After mixing all the materials evenly, put them into a graphite crucible. A total of 100 g of materials are put into the graphite crucible, and the slag basicity is 0.58. (2) Move the crucible in step (1) to the furnace cavity of the high-frequency induction melting furnace and cover it with a corundum crucible.

[0038] (3) Turn on the high-frequency induction melting furnace in step (2). During high-temperature melting, the heating current of the high-frequency induction melting furnace is as follows: First, adjust the current to 300 A and heat for 10 minutes. Then, increase the current of the induction melting furnace by 200 A every 10 minutes until it no longer increases at 900 A. Control the temperature at 1400 °C and keep it warm for 40 minutes for high-temperature melting. The materials in the crucible will completely melt and react. (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. Let the graphite crucible stand in the furnace cavity for 10 minutes and then take it out. Cool it at room temperature until the materials are completely cooled and solidified, and then pour them out to obtain slag with obvious glass phase and matte phase enriched with platinum, palladium, and rhodium. The boundary between the slag and matte phases is obvious, and the two phases are easy to separate.

[0039] After testing, the grades of platinum, palladium and rhodium in the failed automobile exhaust catalyst were 83g / t, 1320g / t and 274g / t respectively. The element contents in the copper slag were Pb60.60%, S10.22%, Te8.59%, Cu3.36%, Sn5.83%, Bi1.47% and Se1.50% respectively. The recovery rates of platinum, palladium and rhodium were 87.71%, 89.45% and 88.43% respectively. The data showed that most of the platinum group metals had been captured in the matte phase, but a small amount of platinum group metals still remained in the slag phase.

[0040] Example 5

[0041] (1) Weigh 40 g of copper scum and put it into the bottom of a graphite crucible; weigh 23.91 g of spent automobile exhaust catalyst, 8.58 g of calcium oxide, 25.29 g of borax, and 2.22 g of anhydrous sodium carbonate, mix them evenly, and put them into a graphite crucible, placing them on the top of the copper scum. A total of 100 g of materials are put into the graphite crucible, and the slag basicity is 0.58;

[0042] (2) moving the crucible in step (1) into the furnace chamber of a high-frequency induction melting furnace and covering it with a corundum crucible;

[0043] (3) The high-frequency induction melting furnace in step (2) is turned on. During high-temperature melting, the heating current of the high-frequency induction melting furnace is: first adjust the current to 300A, heat for 10 minutes, then increase the current of the induction melting furnace by 200A every 10 minutes until it reaches 900A and no longer increases. The temperature is controlled at 1400°C and the insulation time is 40 minutes. High-temperature melting is performed and the material in the crucible is completely melted and reacted. (4) After the melting and insulation are completed, the high-frequency induction melting furnace is turned off. The graphite crucible is taken out after being allowed to stand in the furnace chamber for 10 minutes. It is cooled to room temperature until the material is completely cooled and solidified and then poured out to obtain a slag with a clear glass phase and a matte phase enriched with platinum, palladium and rhodium. The boundary between the slag and matte phases is obvious and the two phases are easy to separate.

[0044] After testing, the grades of platinum, palladium and rhodium in the failed automobile exhaust catalyst are 92g / t, 1458g / t and 293g / t respectively, the element contents in the copper slag are Pb62.89%, S11.42%, Te9.27%, Cu5.56%, Sn4.96%, Bi2.23% and Se1.91% respectively, and the recovery rates of platinum, palladium and rhodium are 36.69%, 38.15% and 44.78% respectively. The capture effect of Example 4 is better than that of Example 5, indicating that the capture effect of smelting in a way that the copper slag is fully mixed with the ingredients is better than the capture effect of placing the copper slag at the bottom of the ingredients.

Claims

1. New application of copper dross as a collector for platinum group metals in spent automotive exhaust catalysts, and the specific steps are as follows: (1) Weigh copper dross, spent automotive exhaust catalyst powder, CaO, borax, and Na2CO3, mix them, and place the mixture in a graphite crucible; the copper dross is the dross produced by adding sulfur to remove copper or melting and separating copper during pyrometallurgical refining of crude lead. (2) Move the crucible in step (1) to the furnace cavity of a high-frequency induction melting furnace and cover it with a corundum crucible. (3) Turn on the high-frequency induction melting furnace in step (2) and conduct high-temperature melting. (4) After the melting and heat preservation are completed, turn off the high-frequency induction melting furnace. Take out the graphite crucible after it has been stationary in the furnace cavity for 10 minutes, cool and solidify it at room temperature, separate the material slag and matte phases, and obtain a slag phase and a matte phase. The platinum group elements are enriched in the matte phase. The mass fractions of each part in the mixture in step (1) are as follows: 40 - 50% copper dross, 20 - 25% spent automotive exhaust catalyst powder, 5 - 15% CaO, 21 - 26% borax, 2 - 5% Na2CO3.

2. The application according to claim 1, wherein The high-temperature melting temperature in step (3) is 1200 - 1400 °C, and the heat preservation time is 40 - 60 minutes.

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