A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment.

Abstract

This invention discloses a method for removing SnPbFe impurities from platinum group metal-rich copper anode mud by heat treatment, comprising the following steps: (1) mixing platinum group metal-rich copper anode mud with acidic oxides and copper to obtain a mixture; (2) heat-treating the mixture obtained in step (1) and then cooling it to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities. Compared with the technical route of sulfuric acid copper removal-wet impurity removal for anode mud produced by copper smelting, the method of removing SnPbFe impurities from platinum group metal-rich copper anode mud of this invention by heat treatment uses acidic oxides to remove SnPbFe impurities in one process and efficiently recover PtPdRh from the anode mud, with a short process flow and high impurity removal efficiency.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy, and particularly relates to a method for removing impurities from copper anode mud. Background Technology

[0002] Platinum group metals (PGMs) comprise six elements: platinum, palladium, rhodium, osmium, ruthenium, and iridium, and are widely used in chemical and manufacturing industries. Recovering PGMs from secondary resources such as spent catalysts and electronic waste is an effective way to address the shortage of PGM resources. Platinum (Pt), palladium (Pd), and rhodium (Rh) from PGMs are primarily used in automotive exhaust catalysts. With the increasing number of scrapped vehicles, the recovery of Pt, Pd, and Rh from spent automotive exhaust catalysts has received widespread attention.

[0003] Among the many methods for recovering PtPdRh, the pyrometallurgical enrichment-electrolysis-anode slime separation and purification process using copper as a collector has high feasibility and economy. Unlike copper smelting processes that use ore as raw material, the raw materials for this process are secondary resources such as depleted catalysts with high platinum group metal content and electronic waste. The anode slime generated by copper electrolysis has the following characteristics: (1) The PGM content of copper anode slime (traditional copper anode slime) obtained by copper smelting processes of ore is <0.5%, while the PGM content of copper anode slime (platinum group metal-rich copper anode slime) obtained by this process is higher, generally >1%; (2) Pyrometallurgical enrichment generally co-processes depleted catalysts and electronic waste, and there are more types of raw materials than ore. Impurities such as SnPbFe in electronic waste enter the copper, resulting in a higher impurity content in the copper anode slime obtained by electrolysis.

[0004] Table 1 shows a comparison of the composition of traditional copper anode slime and platinum group metal-rich copper anode slime. Due to fluctuations in ore composition, the composition of anode slime produced by different copper smelters varies, but the SnFe impurity content is generally lower than that of platinum group metal-rich copper anode slime. Traditional copper anode slime is typically treated by sulfuric acid leaching to remove copper, followed by the addition of acid to dissolve the residue, and PtPdRh is extracted from the solution in stages. For platinum group metal-rich copper anode slime, if the traditional wet processing technology is used, a large amount of SnFe impurities will enter the wet process, increasing the difficulty of PtPdRh purification and reducing the efficiency of wet purification. Furthermore, the PtPdRh content in platinum group metal-rich anode slime is high; if the traditional long-process technology is used, the precious metal recovery cycle will be longer, and costs will increase.

[0005] Table 1: Comparison of the composition (wt%) of anode slime obtained from copper smelting and anode slime obtained from secondary resource recovery

[0006]

[0007] Patent CN115323187A proposes a method for removing SnPbFe impurities from platinum group metal anode mud by hydrochloric acid leaching and iron powder reduction. Compared with traditional wet treatment processes, this method has the advantages of short process and high impurity removal efficiency. However, this method still generates a large amount of acidic wastewater, requiring additional wastewater treatment equipment. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome the shortcomings and defects mentioned in the background art above, and to provide a method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment with a short process flow and high impurity removal efficiency. To solve the above technical problem, the technical solution proposed by this invention is as follows:

[0009] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0010] (1) Mix the platinum group metal-rich copper anode mud with acidic oxides and copper to obtain a mixture;

[0011] (2) The mixture obtained in step (1) is heated and then cooled to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities.

[0012] In the above-mentioned method for removing SnPbFe impurities from platinum group metal-rich copper anode mud by heat treatment, preferably, the platinum group metal-rich copper anode mud is obtained by using copper as a collector, enriching secondary resources containing platinum group metals by pyrolysis to obtain a copper alloy, and then electrolyzing the resulting copper anode mud.

[0013] In the above method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment, preferably, the sum of the masses of Pt, Pd, and Rh in the platinum group metal-rich copper anode slime accounts for 5-60% of the dry weight of the platinum group metal-rich copper anode slime.

[0014] In the above-described method for removing SnPbFe impurities from platinum group metal-rich copper anode sludge via heat treatment, preferably, the acidic oxide is silicon dioxide, and borax is added along with the silicon dioxide, with a mass ratio of silicon dioxide to borax of (0.2-0.9):1. Silicon dioxide is an acidic oxide, while SnPbFe oxides are mostly basic oxides. Silicon dioxide can be mixed with basic oxides to remove them. Adding borax helps lower the melting point and viscosity of the reaction system. If the mass ratio of silicon dioxide to borax is too low, it will not effectively remove impurities; if the mass ratio is too high, it will increase the viscosity of the impurity removal system and worsen the impurity removal effect. The mass ratio of silicon dioxide to borax needs to be reasonably controlled to ensure that they form a low-melting-point, low-viscosity slag at the heating temperature.

[0015] In the above method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment, preferably, the mass ratio of the total mass of silica and borax to the dry weight of the platinum group metal-rich copper anode slime is (0.5-1.5):1. If the amount of silica and borax is too small, the impurities will not be effectively removed; if the amount of silica and borax is too large, the amount of anode slime processed in a crucible of the same volume will be reduced, thus decreasing efficiency.

[0016] In the above-described method for removing SnPbFe impurities from platinum group metal-rich copper anode slime via heat treatment, preferably, the copper is copper granules (preferably elemental copper) with a particle size of 0.1-5 mm, and the mass ratio of the copper granules to the dry weight of the platinum group metal-rich copper anode slime is (0.2-0.9):1. Too small a copper particle size increases cost and is less conducive to the recovery of PtPdRh from the anode slime. Too little copper granules cannot sufficiently enrich the platinum group metals, resulting in some PtPdRh residue; too much copper granules will increase cost.

[0017] In the above method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment, preferably, the heat treatment temperature is 1200-1400℃ and the time is 2-4 hours. If the heat treatment temperature is too low, a high concentration of PtPdRh will remain in the slag, reducing the direct recovery rate; if the heat treatment temperature is too high, energy consumption will increase. If the holding time is too short, a high concentration of PtPdRh will remain in the slag; if the holding time is too long, costs will increase.

[0018] In the above-described method for removing SnPbFe impurities from platinum group metal-rich copper anode sludge by heat treatment, preferably, the reaction vessel during heat treatment is a clay crucible, no carbonaceous reducing agent is added to the mixture, and the heat treatment is carried out in air. The purpose of not using a reducing atmosphere in this invention is to prevent the oxides of SnPbFe impurities in the slag from being reduced into the alloy, thereby reducing the impurity removal efficiency.

[0019] The inventors are dedicated to developing a pyrometallurgical enrichment-electrolysis-anode slime separation and purification process using copper as a trap. The target resources for recovery include secondary resources such as spent catalysts and electronic waste. They deeply understand the contradiction between the broad raw material adaptability of pyrometallurgical enrichment and the low-impurity requirements of hydrometallurgical processes. For the copper anode slime rich in platinum group metals generated during the recovery of secondary resources, there is an urgent need for a highly efficient and low-cost method to remove impurities such as Sn, Pb, and Fe from the anode slime in a single process, obtaining a low-impurity residue as raw material for subsequent hydrometallurgical processes, thereby improving the efficiency of precious metal purification. To address the aforementioned problems, this invention proposes the following principle: First, copper anode sludge rich in platinum group metals is mixed with acidic oxides and copper to obtain a mixture. This mixture is then heated. During the heating process, SnPbFe impurities in the copper anode sludge are oxidized in air, generating corresponding alkaline oxides that combine with the acidic oxide silica, thus removing the impurities. Adding borax facilitates the action of silica, and the synergistic effect of both enhances the impurity removal efficiency. A portion of the PtPdRh in the copper anode sludge settles due to gravity, while the remainder is absorbed by the molten copper dripping down, forming an alloy at the bottom of the crucible, further enriching the precious metals relative to the anode sludge. Using this treatment method, efficient impurity removal and precious metal enrichment can be achieved in one step.

[0020] The present invention provides a method for removing SnPbFe impurities from copper anode mud rich in platinum group metals by heat treatment to obtain an alloy with highly enriched PtPdRh and low impurity content. This alloy can be water-quenched and powdered, and then used as a raw material for acid dissolution, thereby improving the efficiency of wet purification of PtPdRh.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1. The method of removing SnPbFe impurities from copper anode mud rich in platinum group metals by heat treatment in this invention is compared with the technical route of sulfuric acid copper removal-wet impurity removal for anode mud produced by copper smelting. This invention uses acidic oxides to remove SnPbFe impurities in one process and efficiently recover PtPdRh from the anode mud. The process is short and the impurity removal efficiency is high.

[0023] 2. The method of removing SnPbFe impurities from copper anode mud rich in platinum group metals by heat treatment of the present invention uses pyrometallurgical treatment of anode mud, but does not require oxygen blowing, the process is simple and the treatment cost is reduced. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The images show the alloy containing platinum group metals obtained in Example 1 and the slag containing SnPbFe impurities (the top image is the slag, and the bottom image is the alloy). Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0029] Example 1:

[0030] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0031] (1) Mix 150g (dry weight) of platinum group metal-rich copper anode mud (see Table 4 for composition, the same below), 70g of silicon dioxide (industrial grade), 82g of borax, and 100g of copper particles (average particle size 2mm) evenly, and then add it to a clay crucible (silicon oxide and aluminum oxide are the main components).

[0032] (2) Place the crucible in a resistance heating furnace and heat it in air at 1300℃ for 4 hours, then air cool it.

[0033] (3) After cooling, the crucible is removed to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities.

[0034] (4) Chemical analysis was performed on the slag and alloy, and the results are shown in Tables 3 and 4 below. In actual operation, due to the high enrichment of PtPdRh in the alloy, considering the sampling cost and the fact that comparing the composition of the slag can clarify the influence of different experimental factors, this embodiment only performs chemical analysis on the slag. In addition, because the distribution of elements in the slag is uneven, the results of chemical analysis of a sample (a small random piece) of slag are qualitative analyses and are only used to reflect the changing trends of the content of each element in the slag.

[0035] The slag and alloy obtained in Example 1 are as follows Figure 1 As shown, the slag and alloy separation effect is good, and there are no obvious residual copper particles in the slag.

[0036] Example 2:

[0037] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0038] (1) Mix 150g (dry weight) of platinum group metal-rich copper anode mud, 30g of silicon dioxide (industrial grade), 122g of borax, and 100g of copper particles (average particle size 2mm) evenly, and then add them to a clay crucible (with silicon dioxide and aluminum oxide as the main components).

[0039] (2) Place the crucible in a resistance heating furnace and heat it in air at 1300℃ for 4 hours, then air cool it.

[0040] (3) After cooling, the crucible is removed to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities.

[0041] (4) Chemical analysis of the slag and alloy was performed, and the results are shown in Tables 3 and 4 below.

[0042] Example 3:

[0043] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0044] (1) Mix 150g (dry weight) of platinum group metal-rich copper anode mud, 70g of silicon dioxide (industrial grade), 82g of borax, and 100g of copper particles (average particle size 2mm) evenly, and then add them to a clay crucible (with silicon dioxide and aluminum oxide as the main components).

[0045] (2) Place the crucible in a resistance heating furnace and heat it in air at 1300℃ for 2 hours, then air cool it.

[0046] (3) After cooling, the crucible is removed to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities.

[0047] (4) Chemical analysis of the slag and alloy was performed, and the results are shown in Tables 3 and 4 below.

[0048] Example 4:

[0049] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0050] (1) Mix 150g (dry weight) of platinum group metal-rich copper anode mud, 70g of silicon dioxide (industrial grade), 82g of borax, and 30g of copper particles (average particle size 2mm) evenly, and then add them to a clay crucible (with silicon dioxide and aluminum oxide as the main components).

[0051] (2) Place the crucible in a resistance heating furnace and heat it in air at 1300℃ for 4 hours, then air cool it.

[0052] (3) After cooling, the crucible was removed to obtain an alloy containing platinum group metals (about 61g) and slag containing SnPbFe impurities.

[0053] (4) Chemical analysis of the slag and alloy was performed, and the results are shown in Tables 3 and 4 below.

[0054] Comparative Example 1:

[0055] A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment includes the following steps:

[0056] (1) Mix 150g (dry weight) of platinum group metal-rich copper anode mud, 70g of silicon dioxide (industrial grade), 82g of borax, and 0g (average particle size 2mm) of copper particles evenly, and then add them to a clay crucible (with silicon dioxide and aluminum oxide as the main components).

[0057] (2) Place the crucible in a resistance heating furnace and heat it in air at 1300℃ for 4 hours, then air cool it.

[0058] (3) After cooling, the crucible is removed to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities.

[0059] (4) Chemical analysis of the slag and alloy was performed, and the results are shown in Tables 3 and 4 below.

[0060] The experimental conditions for the five groups of experiments are shown in Table 2, and the experimental results are shown in Table 3. A comparison of the composition of the platinum group metal-rich copper anode sludge and the treated alloy is shown in Table 4. The results show that SnPbFe impurities, mainly present in the slag, were removed. Comparing Example 1 and Example 2, it can be seen that increasing the borax ratio can reduce the precious metal content in the slag, and increasing the borax ratio can reduce the slag viscosity, which is beneficial for the precious metals in the slag to settle to the bottom of the alloy (but at this time, the amount of silica still needs to meet the requirements). Comparing Example 2 and Example 3, it can be seen that extending the heating time can reduce the precious metal content in the slag, which is related to the faster element diffusion rate at high temperatures. Comparing Examples 1, 4, and Comparative Example 1, it can be seen that reducing the amount of copper particles will increase the precious metal content in the slag; therefore, a certain amount of copper particles needs to be added to ensure the recovery of precious metals.

[0061] As shown in Table 4, the SnPbFe impurity content in the alloy is reduced after treatment, and the noble metal PtPdRh is further enriched. The solution obtained after acid dissolution of the alloy has less impurity content, which is conducive to improving the efficiency of PtPdRh separation and purification.

[0062] Table 2: Experimental conditions of Examples 1-4 and Comparative Example 1

[0063]

[0064]

[0065] Table 3: Experimental results of Examples 1-4 and Comparative Example 1

[0066] Cu Si Sn Pb Fe Au Ag Pd Pt Rh ％ ％ ％ ％ ％ ppm ppm ppm ppm ppm Example 1 Slag Composition 23.2 18.1 0.5 <0.01％ 1.1 <2 650 54 <2 8 Example 2 Slag Composition 25.7 13.7 0.5 <0.01％ 1.0 2 500 32 14 11 Example 3 Slag Composition 22.4 17.9 0.5 <0.01％ 1.2 <2 540 120 4 17 Example 4 Slag Composition 16.2 20.9 0.5 0.02 1.2 1000 55000 13300 1000 3000 Comparative Example 1 Slag Components 12.7 21.7 0.6 0.03 1.3 1000 69000 31600 1300 9000

[0067] Table 4: Composition comparison of copper anode slime and treated alloy in Example 4

[0068]

Claims

1. A method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment, characterized in that, Includes the following steps: (1) Mix the platinum group metal-rich copper anode mud with acidic oxides and copper to obtain a mixture; (2) Heat the mixture obtained in step (1) and then cool it to obtain an alloy containing platinum group metals and slag containing SnPbFe impurities; The sum of the masses of Pt, Pd, and Rh in platinum group metal-rich copper anode slime accounts for 5-60% of the dry weight of the platinum group metal-rich copper anode slime. The acidic oxide is silicon dioxide, and borax is added when silicon dioxide is added, with the mass ratio of silicon dioxide to borax being (0.2-0.9):1; The total mass ratio of silica and borax to the dry weight of platinum group metal-rich copper anode slime is (0.5-1.5):1; The reaction vessel used for the heat treatment is a clay crucible, and no carbonaceous reducing agent is added to the mixture. The heat treatment is carried out in air.

2. The method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment according to claim 1, characterized in that, The copper anode mud rich in platinum group metals is obtained by using copper as a collector, enriching secondary resources containing platinum group metals through pyrometallurgy to obtain copper alloys, and then electrolyzing them to obtain copper anode mud.

3. The method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment according to claim 1 or 2, characterized in that, The copper used is copper granules with a particle size of 0.1-5 mm. The mass ratio of the copper granules to the dry weight of the platinum group metal-rich copper anode slime is (0.2-0.9):

1.

4. The method for removing SnPbFe impurities from platinum group metal-rich copper anode slime by heat treatment according to claim 1 or 2, characterized in that, The heat treatment is performed at a temperature of 1200-1400℃ for 2-4 hours.

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