Method for enriching platinum group metal secondary resources through electromagnetic field

Abstract

The invention relates to a method for enriching platinum group metal secondary resources through an electromagnetic field, and belongs to the technical field of platinum group metal resource recovery. The method comprises the following steps: uniformly mixing the platinum group metal-containing waste material, a trapping agent, a reducing agent, an additive and a binder to obtain a mixture; carrying out wet grinding on the mixture to obtain a wet-ground mixture, pelletizing the wet-ground mixture, and drying to obtain platinum group metal waste pellets; under the protective atmosphere, the platinum group metal containing waste pellets are subjected to electromagnetic enrichment, and reduced pellets are obtained; and iron alloy-PGMs in the reduced pellets are recycled through a magnetic separation method, and enrichment of platinum group metal is achieved. By means of the electromagnetic effect of the electromagnetic field, iron alloy grains of the trapping agent rapidly migrate and grow due to electromagnetic force in the reduction process, meanwhile, the grain size of the trapping agent is greatly increased, the collecting capacity of the trapping agent on PGMs is improved, the recovery rate of the PGMs is increased, and the solid-state method for recovering platinum group metal secondary resources has the practical application value.

Description

Technical Field

[0001] The invention relates to a method for enriching secondary resources of platinum group metals using an electromagnetic field, belonging to the technical field of platinum group metal resource recovery. Background Art

[0002] Platinum group metals (PGMs) have stable chemical properties, excellent catalytic activity, and excellent electrical and thermal conductivity. They are widely used in automotive exhaust purification, electronics, chemical catalysis, and aerospace. PGMs are relatively abundant in secondary resources, especially in spent automotive exhaust catalysts, petrochemical waste catalysts, and fine chemical waste catalysts, with PGM content far exceeding that of their original ore, making them highly valuable for recycling.

[0003] Currently developed spent automotive catalysts basically use pyrometallurgical smelting enrichment processes to recover platinum group metals, but the existing pyrometallurgical enrichment technology still has problems such as long enrichment cycle, high energy consumption, and low PGMs content in ferroalloys. Summary of the Invention

[0004] In view of the existing technology of using pyrometallurgical smelting enrichment process to recover platinum group metals, which has problems such as long enrichment cycle, high energy consumption, and low PGMs content in ferroalloys, the present invention proposes a method for enriching secondary resources of platinum group metals using electromagnetic field. During the electromagnetic field enrichment process, the electromagnetic effect promotes the migration and growth of ferroalloy collector grains (iron Fe, nickel Ni, cobalt Co, manganese Mn), thereby enhancing the collector's ability to capture platinum group metals; a composite collector composed of iron concentrate and waste ternary precursor is used, and the coupling effect between iron Fe, nickel Ni, cobalt Co, and manganese Mn can be utilized to enhance the electromagnetic enrichment effect.

[0005] A method for enriching secondary resources of platinum group metals using an electromagnetic field, comprising the following steps: (1) uniformly mixing platinum group metal-containing waste, a collector, a reducing agent, an additive, and a binder to obtain a mixture; (2) wet-grinding the mixture to obtain a wet-grinded mixture, pelletizing the wet-grinded mixture, and drying the mixture to obtain pellets containing platinum group metal waste; (3) Under a protective atmosphere, the platinum group metal waste pellets are electromagnetically enriched in a temperature-controlled electromagnetic field induction heating furnace to obtain reduced pellets; (4) Magnetic separation is used to recover ferroalloy-PGMs from the reduced pellets to achieve the enrichment of platinum group metals.

[0006] Preferably, the platinum group metal-containing waste material in step (1) is automobile exhaust waste catalyst, petrochemical waste catalyst or fine chemical waste catalyst containing platinum group metals.

[0007] Preferably, the collector in step (1) is composed of iron concentrate and waste ternary precursor powder containing nickel, cobalt, and manganese, and the mass ratio of iron concentrate to waste ternary precursor powder is 39 - 49:1; the reducing agent is coke powder or anthracite, the additive is one or more of quicklime, limestone, slaked lime, borax, and sodium carbonate, and the binder is one or more of inorganic binders or organic binders.

[0008] More preferably, the waste ternary precursor powder is one or more of NCM811 precursor, NCM622 precursor, and NCM523 precursor, the inorganic binder is water glass and / or bentonite, and the organic binder is one or more of humic acid, sodium carboxymethyl cellulose, starch, and dextrin.

[0009] Preferably, the mass ratio of the collector to the platinum group metal-containing waste is 1.5 - 2:1, the mass ratio of the platinum group metal-containing waste to the reducing agent is 4 - 4.5:1, the mass ratio of the platinum group metal-containing waste to the additive is 11 - 15:1, and the mass ratio of the platinum group metal-containing waste to the binder is 30 - 35:1.

[0010] The strength of the platinum group metal-containing waste pellets in step (2) is not less than 200 N / P.

[0011] Preferably, the method of electromagnetic enrichment in step (3) specifically includes: Under an electromagnetic field frequency of 10 - 30 kHz, the temperature is increased from 400 - 600 °C to 700 - 900 °C to achieve variable-temperature electromagnetic enrichment for 20 - 30 min; in this low-temperature stage, the low-frequency electromagnetic field has a stronger penetration depth and can act more effectively on the interior of the reduced pellets, enabling a large amount of primary crystals of metallic ferroalloy to be generated on the surface of the collector, laying a foundation for the subsequent stage; Under an electromagnetic field frequency of 40 - 60 kHz, the temperature is increased from 700 - 900 °C to 1100 - 1300 °C to achieve variable-temperature electromagnetic enrichment for 20 - 30 min; in this medium-temperature stage, the ferroalloy grains of the collector begin to grow rapidly, and the medium frequency provides moderate electromagnetic force and magnetic force, accelerating the migration of particles in the ferroalloy grains and achieving the rapid growth of ferroalloy grains and the efficient collection of PGMs; Under an electromagnetic field frequency of 80 - 100 kHz, isothermal electromagnetic enrichment is carried out at a temperature of 1100 - 1300 °C for 80 - 180 min; in this high-temperature constant-stability stage, the high-frequency electromagnetic field can generate a stronger local electromagnetic force density, causing the ferroalloy grains generated in the low and medium magnetic fields to migrate and aggregate, enabling the ferroalloy grains to fully grow to the target size (tens or even hundreds of microns), and at the same time ensuring that there is sufficient time for PGMs to reach the distribution equilibrium in the ferroalloy phase through diffusion, achieving deep collection; The electromagnetic field frequency is reduced to 60 - 70 kHz, and electromagnetic enrichment is carried out at a constant temperature of 1100 - 1300 °C for 50 - 60 min; within this high-temperature and constant-stability stage, the grains have fully grown. Moderately reducing the frequency (while still maintaining stirring) allows the PGMs to settle in the ferroalloy grains, and enables the ferroalloy grains to continue to aggregate and grow, creating a more favorable phase distribution for subsequent magnetic separation (larger particles are easier to separate), stabilizing the grain structure, reducing internal defects, and ensuring the full and uniform homogenization of PGMs in the ferroalloy phase.

[0012] In the step (4), the grain size of the ferroalloy - PGMs is 50 - 200 μm.

[0013] The principle of the electromagnetic field enrichment of platinum group metal secondary resources in the present invention: The low capture efficiency of the collector leads to a low recovery rate of platinum group metals. The low content of platinum group metals in ferroalloys is one of the main problems faced by the pyrometallurgical enrichment of platinum group metal secondary resources. Electromagnetic field enrichment promotes the growth of ferroalloy collector grains (Fe / Ni / Co / Mn) through the electromagnetic effect of the electromagnetic field; the alternating electromagnetic field generates an induced current inside the collector grains. The induced current is perpendicular to the magnetic field direction and interacts with the alternating electromagnetic field to generate an electromagnetic force (Lorentz force). In addition, the ferroalloy grains of the collector will be magnetized in the magnetic field, and the magnetized ferroalloy grains will be subjected to a magnetic force when interacting with the magnetic field. Due to the different electrical conductivities and magnetic susceptibilities of the ferroalloy grains of the collector and non-metal grains, the magnitudes and directions of the electromagnetic force and magnetic force received in the electromagnetic field are different. The ferroalloy grains of the collector migrate and aggregate under the action of the electromagnetic force and magnetic force in the electromagnetic field. The migration and aggregation enable the ferroalloy grains to better capture platinum group metals during the movement process. In the absence of the action of the electromagnetic field, the ferroalloy grains only grow at fixed positions and do not have the process of migration and aggregation. Therefore, the capture effect on platinum group metals is poor, resulting in a low recovery rate of platinum group metals; the size of the collector grains aggregated in the electromagnetic field is larger than that of the ferroalloy grains without the action of the electromagnetic field. The larger-sized ferroalloy grains are more easily recovered in the magnetic separation process, making the recovery rate of platinum group metals by the electromagnetic field enrichment method higher than that of the non-electromagnetic enrichment method; electromagnetic enrichment realizes the increase in the size and migration and aggregation of the ferroalloy grains of the collector, significantly improves the collection effect of the collector, increases the content of platinum group metals in the ferroalloy, and improves the recovery rate of the Fe - PGMs alloy in the magnetic separation stage.

[0014] During the electromagnetic enrichment process, the ferroalloy grains (Fe / Ni / Co / Mn) of the collector are preferentially generated at the lattice defects of magnetite. In the initial stage of enrichment, there are many generation sites of the ferroalloy grains of the collector, and the grain structure is fragile. Therefore, low electromagnetic field frequency and variable-temperature electromagnetic enrichment are required to ensure the large-scale generation of the primary crystals of the collector during low-temperature enrichment. As the electromagnetic enrichment temperature increases, the ferroalloy grains of the collector continue to grow. At this time, high electromagnetic field frequency and constant-temperature electromagnetic enrichment are beneficial to the rapid growth and migration and aggregation of the collector grains, and improve the collection efficiency of the collector grains for platinum group metals.

[0015] The mechanism chain of the present invention for enriching platinum group metals from secondary resources by electromagnetic field is as follows: alternating electromagnetic field → generating Lorentz force (electromagnetic force) → driving the movement of ferroalloy grains → significantly increasing the contact frequency between ferroalloy grains → providing kinetic energy to overcome the aggregation resistance → efficient aggregation → significant increase in the size of ferroalloy grains → significantly increasing the contact opportunity between ferroalloy and PGMs particles / atoms → strengthening the diffusion and mass transfer of PGMs into ferroalloy grains → significantly improving the collection ability and dissolution rate of ferroalloy grains for PGMs → finally forming large-sized ferroalloy grains rich in PGMs → efficient separation by magnetic separation → realizing the high-recovery enrichment of platinum group metals.

[0016] The beneficial effects of the present invention are as follows: (1) The present invention uses a composite collector composed of iron concentrate and waste ternary precursor, and the coupling effect between metals such as iron, nickel, cobalt, and manganese can improve the electromagnetic enrichment effect; (2) The present invention uses the electromagnetic field enrichment method to recover platinum group metals from platinum group metal-containing waste. High-efficiency enrichment of platinum group metals by the collector can be achieved at a low temperature range of 1100 - 1300 °C (the traditional smelting enrichment temperature is 1400 - 1600 °C), which can significantly reduce the energy consumption during the platinum group metal enrichment process, improve the platinum group metal enrichment efficiency and the content of platinum group metals in ferroalloy, and increase the recovery rate of platinum group metals; (3) Using the traditional enrichment method of heating platinum group metal-containing waste without electromagnetic field, the collector grains are generated and grow at the lattice defects of magnetite, and there is no process of migration and aggregation, so the growth of grain size is limited; while under the action of electromagnetic field, the collector grains are affected not only by thermal energy but also by electromagnetic force and magnetic force, and the collector grains grow due to migration and aggregation; it has an obvious improvement effect on the collection and recovery of platinum group metals. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the device for enriching platinum group metals from secondary resources by electromagnetic field; Figure 2 It is a comparison chart of the grain size of the collector in Comparative Example 1 and Example 3, (a) without the action of electromagnetic field, (b) with the action of electromagnetic field; Figure 3 It is a statistical chart of the grain size of the collector in Comparative Example 1; Figure 4 It is a statistical chart of the grain size of the collector enriched by electromagnetic field in Example 3. Detailed Embodiments

[0018] The following further elaborates the present invention in detail in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0019] The schematic diagram of the device for enriching platinum group metals from secondary resources by electromagnetic field of the present invention is shown in Figure 1, in a protective atmosphere, the platinum group metal-containing waste pellets are reduced to pellets by electromagnetic enrichment (using a temperature and electromagnetic field controllable induction heating furnace); when an alternating electromagnetic field is applied, since the collector ferroalloy produced by reduction is a good conductor, while the surrounding slag phase is an insulator (or has extremely poor conductivity), the electromagnetic field will exert an electromagnetic effect on the ferroalloy grains. According to the Lorentz force law, a strong electromagnetic force is generated inside and around each conductive ferroalloy grain. The direction of the electromagnetic force is alternating (depending on the direction of the electromagnetic field), but its net effect is to drive the migration movement of the ferroalloy grains; the Lorentz force acts on the ferroalloy grains, causing adjacent ferroalloy grains to aggregate and contact; this movement is not an isolated behavior of a single grain. A large number of grains are simultaneously affected by the force and move, resulting in migration and aggregation within the entire melt, significantly increasing the collision frequency and contact opportunities between different ferroalloy grains, and between ferroalloy grains and dispersed PGMs particles / atoms; when two ferroalloy grains come into contact, the energy barrier formed by overcoming the surface tension merges into a larger grain; the grains are more likely to overcome the surface tension resistance during collision under the drive of the electromagnetic force, significantly improving the aggregation efficiency; reducing the physical barriers to aggregation and collection; the collision and aggregation cause the originally small ferroalloy grains to grow into larger grains, thus significantly increasing the grain size; and the dispersed PGMs atoms or tiny particles are more easily "captured" by the moving ferroalloy grains. Once in contact with the surface of the ferroalloy grains, the PGMs will quickly dissolve into the molten ferroalloy phase (trapping). The electromagnetic force accelerates the diffusion of PGMs within the ferroalloy, making its distribution more uniform, avoiding local saturation, significantly improving the collecting ability of the collector (ferroalloy) for PGMs, increasing the transfer rate and degree of PGMs from the slag phase to the alloy phase, and ensuring that more PGMs are "collected" into the grown collector ferroalloy grains.

[0020] Example 1: In this example, the platinum group metal-containing waste is a PGMs-containing waste catalyst, and the PGMs-containing waste catalyst contains 78 g / t of Pt, 1596 g / t of Pd, and 207 g / t of Rh; A method for enriching platinum group metal secondary resources by electromagnetic field, the specific steps are as follows: (1) Mix the platinum group metal-containing waste (PGMs-containing waste catalyst), collector (the mass ratio of iron concentrate to waste ternary precursor powder is 49:1), reducing agent (coke powder), additive (quicklime), and binder (sodium carboxymethyl cellulose and starch) evenly to obtain a mixture; based on the mass of the mixture being 100%, the PGMs-containing waste catalyst in the mixture accounts for 35 wt%, the collector accounts for 53 wt%, the reducing agent accounts for 8 wt%, the additive accounts for 3 wt%, and the binder accounts for 1 wt%; the waste ternary precursor powder is NCM523; (2) Wet grind the mixture for 10 min to obtain a wet-ground mixture. The wet-ground mixture is pelletized under a pressure of 500 MPa (pellet diameter: 10 - 14 mm), and then dried to obtain a pellet of platinum group metal-containing waste (drop strength: 12 times / 1 m, compressive strength: 241 N / P). (3) Under a protective atmosphere (nitrogen), the pellet of platinum group metal-containing waste is subjected to electromagnetic enrichment (using a temperature and electromagnetic field controllable induction heating furnace) to obtain a reduced pellet, and the pulverization rate of the reduced pellet is 7.6%. The method of electromagnetic enrichment specifically includes: At an electromagnetic field frequency of 10 kHz, increase the temperature from 400 °C to 700 °C to achieve variable-temperature electromagnetic enrichment for 20 min. At an electromagnetic field frequency of 40 kHz, increase the temperature from 700 °C to 1100 °C to achieve variable-temperature electromagnetic enrichment for 30 min. At an electromagnetic field frequency of 80 kHz, carry out isothermal electromagnetic enrichment at a temperature of 1100 °C for 80 min. Reduce the electromagnetic field frequency to 60 kHz, and carry out isothermal electromagnetic enrichment at a temperature of 1100 °C for 50 min. (4) After the reduced pellet is cooled to room temperature, grind it in a ball mill for 20 min, and use magnetic separation (a dry electromagnetic separator with a magnetic field intensity of 1 T) to recover ferroalloy-PGMs in the reduced pellet, thereby achieving the enrichment of platinum group metals. After detection, in this example, the average grain size of ferroalloy-PGMs is 71.64 μm, the recovery rate of metallic iron is 95.26%, the recovery rate of Pt is 97.86%, the comprehensive recovery rate of nickel, cobalt, and manganese is 91.55%, the recovery rate of Pd is 96.47%, and the recovery rate of Rh is 97.68%.

[0021] Example 2: In this example, the platinum group metal-containing waste is a PGMs-containing waste catalyst, and the PGMs-containing waste catalyst contains 69 g / t of Pt, 1745 g / t of Pd, and 238 g / t of Rh. A method for enriching platinum group metal secondary resources by electromagnetic field, the specific steps are as follows: (1) Mix the platinum group metal-containing waste (PGMs-containing waste catalyst), collector (the mass ratio of iron concentrate to waste ternary precursor powder is 47:1), reducing agent (coke powder), additive (quicklime and borax), and binder (sodium silicate) evenly to obtain a mixture. Based on the mass of the mixture being 100%, the PGMs-containing waste catalyst in the mixture accounts for 33 wt%, the collector accounts for 55 wt%, the reducing agent accounts for 8 wt%, the additive accounts for 3 wt%, and the binder accounts for 1 wt%. The waste ternary precursor powder is NCM622. (2)Wet grind the mixture for 10 min to obtain a wet-ground mixture. The wet-ground mixture is pelletized under a pressure of 500 MPa (pellet diameter: 10 - 14 mm), and then dried to obtain a pellet of platinum group metal-containing waste (drop strength: 11 times / 1 m, compressive strength: 217 N / P). (3)Under a protective atmosphere (argon), the pellet of platinum group metal-containing waste is subjected to electromagnetic enrichment (using a temperature and electromagnetic field controllable induction heating furnace) to obtain a reduced pellet, and the pulverization rate of the reduced pellet is 8.5%. The method of electromagnetic enrichment specifically includes: At an electromagnetic field frequency of 20 kHz, increase the temperature from 500 °C to 900 °C to achieve variable-temperature electromagnetic enrichment for 30 min; At an electromagnetic field frequency of 50 kHz, increase the temperature from 900 °C to 1200 °C to achieve variable-temperature electromagnetic enrichment for 20 min; At an electromagnetic field frequency of 90 kHz, keep the temperature at 1200 °C for constant-temperature electromagnetic enrichment for 140 min; Reduce the electromagnetic field frequency to 60 kHz, and keep the temperature at 1200 °C for constant-temperature electromagnetic enrichment for 50 min; (4)After the reduced pellet is cooled to room temperature, grind it in a ball mill for 20 min, and use magnetic separation (a dry electromagnetic separator with a magnetic field strength of 1 T) to recover ferroalloy-PGMs in the reduced pellet, realizing the enrichment of platinum group metals. After detection, in this example, the average grain size of ferroalloy-PGMs is 93.06 μm, the recovery rate of metallic iron is 97.17%, the recovery rate of Pt is 98.81%, the comprehensive recovery rate of nickel, cobalt, and manganese is 95.72%, the recovery rate of Pd is 96.73%, and the recovery rate of Rh is 97.95%.

[0022] Example 3: In this example, the platinum group metal-containing waste is a PGMs-containing waste catalyst, and the PGMs-containing waste catalyst contains 73 g / t of Pt, 1556 g / t of Pd, and 197 g / t of Rh; A method for enriching platinum group metal secondary resources by electromagnetic field, the specific steps are as follows: (1)Mix the platinum group metal-containing waste (PGMs-containing waste catalyst), collector (the mass ratio of iron concentrate to waste ternary precursor powder is 39:1), reducing agent (anthracite), additive (quicklime and sodium carbonate), and binder (humic acid and dextrin) evenly to obtain a mixture. Based on the mass of the mixture being 100%, the PGMs-containing waste catalyst in the mixture accounts for 30 wt%, the collector accounts for 60 wt%, the reducing agent accounts for 7 wt%, the additive accounts for 2 wt%, and the binder accounts for 1 wt%. The waste ternary precursor powder is NCM811; (2) Wet grind the mixture for 10 min to obtain a wet-ground mixture. Pellets (with a diameter of 10 - 14 mm) are formed by pressing the wet-ground mixture under a pressure of 500 MPa, and then dried to obtain pellets of platinum group metal-containing waste (the drop strength is 12 times / 1 m, and the compressive strength is 228 N / P). (3) Under a protective atmosphere (argon), the pellets of platinum group metal-containing waste are subjected to electromagnetic enrichment (using a temperature and electromagnetic field controllable induction heating furnace) to obtain reduced pellets, and the powdering rate of the reduced pellets is 8.7%. The method of electromagnetic enrichment specifically includes: At an electromagnetic field frequency of 30 kHz, heat up from a temperature of 600 °C to 900 °C to achieve variable-temperature electromagnetic enrichment for 30 min; At an electromagnetic field frequency of 60 kHz, heat up from a temperature of 900 °C to 1300 °C to achieve variable-temperature electromagnetic enrichment for 30 min; At an electromagnetic field frequency of 100 kHz, carry out isothermal electromagnetic enrichment at a temperature of 1300 °C for 180 min; Reduce the electromagnetic field frequency to 70 kHz, and carry out isothermal electromagnetic enrichment at a temperature of 1300 °C for 60 min; (4) After the reduced pellets are cooled to room temperature, grind them in a ball mill for 20 min, and use magnetic separation (a dry electromagnetic separator with a magnetic field intensity of 1 T) to recover ferroalloy-PGMs in the reduced pellets, realizing the enrichment of platinum group metals. After detection, the average grain size of ferroalloy-PGMs in this example is 142.57 μm (see Figure 2 and 4 ), the recovery rate of metallic iron is 98.15%, the recovery rate of Pt is 98.85%, the comprehensive recovery rate of nickel, cobalt, and manganese is 96.28%, the recovery rate of Pd is 97.21%, and the recovery rate of Rh is 98.03%.

[0023] Comparative Example 1: The platinum group metal-containing waste in this comparative example is a PGMs-containing waste catalyst, and the PGMs-containing waste catalyst contains Pt 73 g / t, Pd 1556 g / t, and Rh 197 g / t; The method for enriching platinum group metal secondary resources without electromagnetic field is as follows: (1) Mix the platinum group metal-containing waste (PGMs-containing waste catalyst), collector (the mass ratio of iron concentrate to waste ternary precursor powder is 39:1), reducing agent (anthracite), additive (quicklime and sodium carbonate), and binder (humic acid and dextrin) evenly to obtain a mixture; based on the mass of the mixture being 100%, the PGMs-containing waste catalyst in the mixture accounts for 30 wt%, the collector accounts for 60 wt%, the reducing agent accounts for 7 wt%, the additive accounts for 2 wt%, and the binder accounts for 1 wt%; the waste ternary precursor powder is NCM811. (2)Wet grind the mixture for 10 min to obtain a wet-ground mixture. The wet-ground mixture is pelletized under a pressure of 500 MPa (pellets with a diameter of 10 - 14 mm), and then dried to obtain platinum group metal-containing waste pellets (the drop strength is 12 times / 1 m, and the compressive strength is 228 N / P). (3)Under a protective atmosphere (argon), heat the platinum group metal-containing waste pellets in a muffle furnace to a temperature of 1300 °C and keep them at a constant temperature for enrichment for 240 min to obtain reduced pellets, and the pulverization rate of the reduced pellets is 8.9%. (4) After the reduced pellets are cooled to room temperature, grind them in a ball mill for 20 min, and use magnetic separation (a dry electromagnetic separator with a magnetic field strength of 1 T) to recover ferroalloy-PGMs in the reduced pellets to achieve the enrichment of platinum group metals. After detection, the average grain size of ferroalloy-PGMs in this example is 49.51 μm (see Figure 2 and 3 ), the recovery rate of metallic iron is 93.18%, the recovery rate of Pt is 95.21%, the comprehensive recovery rate of nickel, cobalt, and manganese is 89.44%, the recovery rate of Pd is 93.24%, and the recovery rate of Rh is 94.87%. Platinum group metals are rare and precious metals with high value (the prices of Pt and Pd > 200 yuan / g). From the results of Example 3 and Comparative Example 1, it can be concluded that the electromagnetic enrichment has a higher recovery rate of platinum group metals than the conventional pyrometallurgical enrichment, and has obvious economic benefits.

[0024] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A method for enriching platinum group metal secondary resources by electromagnetic field, characterized in that, The specific steps are as follows: (1) Mix the platinum group metal-containing waste, collector, reducing agent, additive, and binder evenly to obtain a mixture; (2) Wet grind the mixture to obtain a wet-ground mixture, pelletize the wet-ground mixture, and dry it to obtain a platinum group metal-containing waste pellet; (3) Under a protective atmosphere, the platinum group metal-containing waste pellet is electromagnetically enriched to obtain a reduced pellet; The method of electromagnetic enrichment specifically includes: At an electromagnetic field frequency of 10 - 30 kHz, heat from a temperature of 400 - 600 °C to 700 - 900 °C to achieve variable-temperature electromagnetic enrichment for 20 - 30 min; At an electromagnetic field frequency of 40 - 60 kHz, heat from a temperature of 700 - 900 °C to 1100 - 1300 °C to achieve variable-temperature electromagnetic enrichment for 20 - 30 min; At an electromagnetic field frequency of 80 - 100 kHz, perform constant-temperature electromagnetic enrichment at a temperature of 1100 - 1300 °C for 80 - 180 min; Reduce the electromagnetic field frequency to 60 - 70 kHz, and perform constant-temperature electromagnetic enrichment at a temperature of 1100 - 1300 °C for 50 - 60 min; (4) Use magnetic separation to recover ferroalloy-PGMs in the reduced pellet to achieve the enrichment of platinum group metals.

2. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, wherein: In step (1), the platinum group metal-containing waste is an automotive exhaust waste catalyst, petrochemical waste catalyst, or fine chemical waste catalyst containing platinum group metals.

3. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, wherein: In step (1), the collector is composed of iron concentrate and waste ternary precursor powder containing nickel, cobalt, and manganese, and the mass ratio of iron concentrate to waste ternary precursor powder is 39 - 49:1; the reducing agent is coke powder or anthracite, the additive is one or more of quicklime, limestone, slaked lime, borax, and sodium carbonate, and the binder is one or more of inorganic binders or organic binders.

4. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 3, characterized in that: The waste ternary precursor powder is one or more of NCM811 precursor, NCM622 precursor, and NCM523 precursor. The inorganic binder is water glass and / or bentonite, and the organic binder is one or more of humic acid, sodium carboxymethylcellulose, starch, and dextrin.

5. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, characterized in that: The mass ratio of the collector to the platinum group metal-containing waste is 1.5 - 2:1, the mass ratio of the platinum group metal-containing waste to the reducing agent is 4 - 4.5:1, the mass ratio of the platinum group metal-containing waste to the additive is 11 - 15:1, and the mass ratio of the platinum group metal-containing waste to the binder is 30 - 35:

1.

6. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, wherein: In step (2), the strength of the platinum group metal-containing waste pellet is not less than 200 N / P.

7. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, wherein: In step (3), the pulverization rate of the reduced pellet is not higher than 20%.

8. The method for enriching platinum group metal secondary resources by electromagnetic field according to claim 1, wherein: In step (4), the grain size of ferroalloy-PGMs in the reduced pellet is 50 - 200 μm.

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