A method for extracting iron from copper tailings

Abstract

A method for extracting iron from copper tailings belongs to the field of copper tailings recovery and treatment, and comprises the following steps: step one, collecting copper tailings for crushing; step two, adding a reducing agent and an additive to the crushed copper tailings of step one for fully mixing; step three, feeding the mixed material of step two into a sealed kiln for sealed reduction; step four, taking out the mixed material after the reduction operation of step three is completed and crushing again; step five, performing magnetic separation on the crushed mixed material of step four to obtain iron powder; and step six, recycling the remaining material after the magnetic separation of step five. The low-temperature reduction method of the present application has a lower temperature than the traditional smelting method, so that the generated iron powder and slag remain in a solid state during the reduction process, avoiding the problems of ring formation in the sealed kiln and the difficulty in discharging the material from the rotary hearth furnace, thereby reducing energy consumption and improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of copper tailings recycling and treatment, specifically a method for extracting iron from copper tailings. Background Technology

[0002] As the world's largest producer and consumer of refined copper, my country has maintained its position as the world's largest producer of copper for many years. In 2024, my country's refined copper production exceeded 13 million tons, accounting for about 45% of global production. More than 90% of this refined copper is produced through pyrometallurgical processes. Each ton of copper produced generates approximately 2-3 tons of smelting slag, with an average annual increase of nearly 30 million tons of copper slag nationwide (with "potential iron resources" of about 12 million tons). The total historical stockpiles have reached hundreds of millions of tons.

[0003] On the other hand, my country's steel industry is highly dependent on imported iron ore. In 2024, my country imported 1.237 billion tons of iron ore (up 4.9% year-on-year, accounting for 72% of global imports), with an import value of 940.631 billion yuan, a record high. This situation highlights the significant challenges facing my country's strategic mineral resource security.

[0004] Copper tailings, after being depleted by flotation, is a secondary resource with significant recycling value. Its iron content is generally as high as 40%-45%, exceeding the average grade of domestic iron ore (between 20%-30%), effectively making it a "man-made rich iron ore." Nearly 12 million tons of "potential iron resources" are found in newly added copper tailings each year. Furthermore, copper tailings are rich in various valuable metals such as copper, zinc, and aluminum. Against this backdrop, promoting the resource utilization of bulk industrial solid wastes such as copper tailings not only has environmental benefits but also strategic significance for alleviating dependence on imported iron ore resources and enhancing supply chain security. Currently, magnetic separation is the most economical and efficient method for iron enrichment and recovery due to its simple operation and large processing capacity. However, since the iron in copper tailings is mainly found in chemically stable fir olivine (Fe2SiO4), which has weak magnetism, magnetic separation cannot effectively enrich, recover, and separate the iron from the copper tailings. Moreover, fir olivine is difficult to reduce economically and efficiently using traditional metallurgical processes. Therefore, although copper slag contains huge iron resources, it is considered an "unconventional resource" and "has no utilization value" until a breakthrough in extraction technology is achieved.

[0005] Currently, domestic and international methods for treating copper slag mainly include physical beneficiation, pyrometallurgical depletion, and hydrometallurgical extraction. However, no breakthroughs have been achieved in the efficient extraction of iron and the synergistic recovery of multiple metals, especially in balancing economic and environmental benefits. With increasingly stringent environmental policies and a growing scarcity of mineral resources in my country, promoting the resource utilization of copper slag has become an urgent need for achieving the green and low-carbon transformation of the non-ferrous metals industry.

[0006] Globally, the comprehensive utilization of copper slag is a common challenge faced by countries and regions with concentrated copper smelting (such as China, Chile, Peru, India, and Japan). Domestically, dozens of refined copper production enterprises, including Jiangxi Copper, Tongling Nonferrous Metals, and Yunnan Copper, have accumulated a massive amount of copper slag, which continues to increase annually. Achieving large-scale disposal and high-value utilization of copper slag not only helps enterprises fulfill their environmental responsibilities but also opens up new resource channels, improves economic efficiency, and aligns with the national strategic direction of circular economy development and "zero-waste city" construction. Summary of the Invention

[0007] This invention provides a method for extracting iron from copper tailings, thereby overcoming the deficiencies in the prior art.

[0008] This invention is achieved through the following technical solution:

[0009] A method for extracting iron from copper tailings includes the following steps:

[0010] Step 1: Collect copper tailings and crush them;

[0011] Step 2: Add the reducing agent and additives to the copper tailings powder crushed in Step 1 and mix thoroughly;

[0012] Step 3: The mixture obtained in Step 2 is sent into a sealed kiln for sealing and reduction;

[0013] Step 4: After the restoration operation in Step 3 is completed, take out the mixture and crush it again;

[0014] Step 5: Perform magnetic separation on the pulverized mixture from Step 4 to obtain iron powder;

[0015] Step Six: Recycle and reuse the remaining material after magnetic separation in Step Five.

[0016] In the method for extracting iron from copper tailings as described above, in step one, the copper tailings are pulverized by a ball mill and then passed through a 200-mesh sieve for later use. If there is any material that has not passed through the sieve, it is retained and mixed with the next batch before being pulverized again.

[0017] In the method for extracting iron from copper tailings as described above, the mass ratio of copper tailings powder, reducing agent, and additives in step two is 10:4-6:1-2. The copper tailings powder, reducing agent, and additives are weighed according to the ratio and added to a mixer, which is then mixed and stirred at a speed of 300-400 r / min for 10-15 min.

[0018] In the method for extracting iron from copper tailings as described above, the reducing agent in step two is any one or any two or more of fine coal powder, anthracite powder, and petroleum coke powder mixed in any proportion.

[0019] In the method for extracting iron from copper tailings as described above, the auxiliary agent in step two includes the following substances in parts by weight: 1-2 parts manganese dioxide, 3-5 parts magnesium oxide, 15-20 parts sodium silicate, 10-15 parts calcium carbonate, and 6-10 parts sodium borate.

[0020] The method for extracting iron from copper tailings as described above, specifically step three, involves: mixing the copper tailings powder, reducing agent, and additives as described in step two, pressing the mixture into a block with dimensions of 8*6*2cm, and then feeding it into a sealed kiln. A protective gas is then introduced to expel air from the kiln. The temperature is then raised to 1000-1100℃ and maintained for 20-30 minutes. The volatile vapors are extracted and recovered. The temperature is then maintained while a protective gas is continuously introduced to increase the pressure inside the sealed kiln to 2.3-2.5MPa, which is maintained for 40-50 minutes. The volatile vapors are then extracted and recovered. Heating is then stopped, and the kiln is cooled to room temperature.

[0021] In the method for extracting iron from copper tailings as described above, the protective gas in step three is nitrogen, the heating rate of the sealed kiln is 10-15℃ / min, and the heating energy of the sealed kiln includes electricity, coal, and natural gas. After the first steam extraction and cooling in step three, a zinc-containing mixture is obtained, and after the second steam extraction and cooling in step three, a lead-containing mixture is obtained.

[0022] In the method for extracting iron from copper tailings as described above, in step four, the mixed material is fed into a ball mill for crushing and then passed through a 500-mesh sieve for later use. If there is still residual material on the sieve, it is sent to a crushing device of corresponding volume according to its weight for further crushing until all materials have passed through the sieve.

[0023] In the method for extracting iron from copper tailings as described above, step five involves three magnetic separation operations: the magnetic field strength of the first magnetic separation is 500 Gauss, and the rotation speed of the drum magnetic separator is 100 r / min; the magnetic field strength of the second magnetic separation is 1000 Gauss, and the rotation speed of the drum magnetic separator is 150 r / min; and the magnetic field strength of the third magnetic separation is 1500 Gauss, and the rotation speed of the drum magnetic separator is 200 r / min.

[0024] In the method for extracting iron from copper tailings as described above, the remaining materials in step six can be recycled from the main raw materials of mineral soil conditioners, as well as cement admixtures, concrete admixtures, and road construction and backfill materials.

[0025] The advantages of this invention are:

[0026] The present invention uses a low-temperature reduction method, which is lower than the traditional smelting and smelting method. This method keeps the iron powder and slag generated during the reduction process in a solid state, avoiding the ring formation problem that is easy to occur in sealed kiln smelting and reduction and the difficulty of discharging material in rotary hearth furnace. This reduces energy consumption and improves production efficiency.

[0027] In this invention, pulverized coal is used as a reducing agent, thus eliminating the need for coke as a reducing agent and avoiding the environmental pollution caused by coke smelting. At the same time, due to the lower smelting temperature, the generation of harmful gases (such as NO2 and SO2) is reduced. Compared with the traditional smelting method, waste gas emissions are reduced, and cooling water consumption is reduced, thus reducing water resource consumption and wastewater treatment pressure.

[0028] In this invention, the additives are a combination of manganese dioxide, magnesium oxide, sodium silicate, calcium carbonate, and sodium borate. Magnesium oxide and sodium silicate can form low-melting-point substances with silicates, improving the meltability and fluidity of the material and increasing the reduction rate of iron. Manganese dioxide can accelerate the reduction reaction process and shorten the reaction time. The carbon dioxide produced by the decomposition of calcium carbonate at high temperatures can regulate the atmosphere inside the kiln. Sodium borate can act as a flux and reduce viscosity, synergistically improving the reduction effect. The combined use of these additives can effectively destroy the crystal structure of fir olivine, promote the dissociation of iron from silicate minerals, and reduce the activation energy of the reduction reaction. This allows the fir olivine, which is originally difficult to reduce, to be efficiently reduced at lower temperatures. This solves the technical problem of the stable occurrence of iron in copper tailings and the difficulty of reduction in traditional processes, facilitating subsequent magnetic separation and improving the recovery rate of iron.

[0029] This invention is highly adaptable to heat sources and can select electricity, coal or natural gas as energy sources according to actual conditions, which is highly flexible. This diversified energy selection not only reduces production costs, but also optimizes resource allocation according to local conditions and enhances the applicability of the technology.

[0030] This invention can also separate zinc and lead elements with high purity by recovering the vapor in the reduction process, realizing the recycling of zinc and lead elements while removing lead elements, so that the residue can be used as the main raw material for mineral soil conditioners. Attached Figure Description

[0031] 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.

[0032] Figure 1 This is a flowchart of the present invention;

[0033] Figure 2 This is the detection result of Embodiment 1 of the present invention;

[0034] Figure 3 This is the detection result of Embodiment 2 of the present invention;

[0035] Figure 4 This is the detection result of Embodiment 3 of the present invention;

[0036] Figure 5 This is the XRD detection result of Embodiment 3 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, a method for extracting iron from copper tailings includes the following steps:

[0039] Step 1: Collect copper tailings and crush them;

[0040] Step 2: Add the reducing agent and additives to the copper tailings powder crushed in Step 1 and mix thoroughly;

[0041] Step 3: The mixture obtained in Step 2 is sent into a sealed kiln for sealing and reduction;

[0042] Step 4: After the restoration operation in Step 3 is completed, take out the mixture and crush it again;

[0043] Step 5: Perform magnetic separation on the pulverized mixture from Step 4 to obtain iron powder;

[0044] Step Six: Recycle and reuse the remaining material after magnetic separation in Step Five.

[0045] Specifically, in step one of this embodiment, the copper tailings are pulverized by a ball mill and then passed through a 200-mesh sieve for later use. If there is any material that has not passed through the sieve, it is retained and mixed with the next batch before being pulverized again.

[0046] Specifically, in step two of this embodiment, the mass ratio of copper tailings powder, reducing agent, and additives is 10:4-6:1-2. The copper tailings powder, reducing agent, and additives are weighed according to the ratio and added to a mixer, which is then mixed and stirred at a speed of 300-400 r / min for 10-15 min.

[0047] More specifically, the reducing agent in step two of this embodiment is any one or any two or more of fine coal powder, anthracite powder, and petroleum coke powder mixed in any proportion.

[0048] More specifically, the additives in step two of this embodiment include the following substances in parts by weight: 1-2 parts manganese dioxide, 3-5 parts magnesium oxide, 15-20 parts sodium silicate, 10-15 parts calcium carbonate, and 6-10 parts sodium borate.

[0049] More specifically, the specific operation of step three in this embodiment is as follows: After the copper tailings powder, reducing agent and additives are mixed in step two, they are pressed into a block with a length, width and height of 8*6*2cm and then sent into a sealed kiln. Then, protective gas is introduced to exhaust the air in the sealed kiln. Then, the temperature is raised to 1000-1100℃ and maintained for 20-30 minutes. The volatile vapors are extracted and recovered. Then, the temperature is maintained while protective gas is continuously introduced to increase the pressure in the sealed kiln to 2.3-2.5MPa and maintained for 40-50 minutes. The volatile vapors are extracted and recovered. Then, heating is stopped and the kiln is cooled to room temperature.

[0050] Furthermore, in this embodiment, the protective gas in step three is nitrogen, the heating rate of the sealed kiln is 10-15℃ / min, and the heating energy of the sealed kiln includes electricity, coal, and natural gas. In step three, the zinc-containing mixture is obtained after the first steam extraction and cooling, and the lead-containing mixture is obtained after the second steam extraction and cooling.

[0051] Furthermore, in step four of this embodiment, the mixed materials are fed into a ball mill for pulverization and then passed through a 500-mesh sieve for later use. If there are still residual materials on the sieve, they are sent to a pulverizing device of corresponding volume according to their weight for further pulverization until all materials have passed through the sieve.

[0052] Furthermore, in step five of this embodiment, three magnetic separation operations are performed. The magnetic field strength of the first magnetic separation is 500 Gauss, and the rotation speed of the drum magnetic separator is 100 r / min; the magnetic field strength of the second magnetic separation is 1000 Gauss, and the rotation speed of the drum magnetic separator is 150 r / min; the magnetic field strength of the third magnetic separation is 1500 Gauss, and the rotation speed of the drum magnetic separator is 200 r / min.

[0053] Furthermore, the remaining materials in step six of this embodiment can be recycled from the main raw materials of mineral soil conditioners, as well as cement admixtures, concrete admixtures, and road construction and backfill materials. The remaining materials in this invention undergo deep processing via a sealed kiln calcination process, resulting in chemically stable, fine-grained, and low-harmful-impurity content. Their main components are mineral elements such as silicon, aluminum, and calcium, further compounded with organic matter, humus, and microorganisms, achieving a perfect combination of "mineral nutrient supplementation" and "organic ecological conditioning." The remaining materials in this invention can be directly sold to downstream enterprises in the cement admixture, concrete admixture, and road construction and backfill material sectors. By replacing some of the original materials, production costs are reduced by 30% compared to traditional materials, not only reducing the consumption of natural resources but also lowering carbon emissions by 50-70%.

[0054] Example 1

[0055] Step 1: Collect copper tailings and crush them in a ball mill, then pass them through a 200-mesh sieve for later use. If there are any unscreened materials, retain them and mix them with the next batch before crushing them again.

[0056] Step 2: The copper tailings powder crushed in Step 1, along with refined coal powder and additives (the weight parts of each substance are: 1 part manganese dioxide, 3 parts magnesium oxide, 15 parts sodium silicate, 10 parts calcium carbonate, and 6 parts sodium borate), are weighed according to a mass ratio of 10:4:1 and added to a mixer. The mixture is stirred at a speed of 300 r / min for 15 min.

[0057] Step 3: After the copper tailings powder, refined coal powder, and additives from Step 2 are mixed, they are pressed into blocks with dimensions of 8*6*2cm and then fed into a sealed kiln. Nitrogen gas is then introduced to purge the air from the sealed kiln. The temperature is then raised to 1000℃ at a rate of 10-15℃ / min. The heating energy source for the sealed kiln is electricity, coal, or natural gas. The temperature is maintained for 30 minutes, and the volatile vapors are extracted for zinc recovery. The temperature is then maintained while nitrogen gas is continuously introduced to increase the pressure inside the sealed kiln to 2.3MPa and maintained for 50 minutes. The volatile vapors are then extracted for lead recovery. Heating is then stopped, and the kiln is cooled to room temperature.

[0058] Step 4: After the restoration operation in Step 3 is completed, take out the mixture and send it into a ball mill for crushing and then pass it through a 500-mesh sieve for later use. If there are still residual materials on the sieve, send them into a crushing device of the corresponding volume according to their weight to continue crushing until all materials have passed through the sieve.

[0059] Step 5: The pulverized mixture from Step 4 is subjected to three magnetic separation operations. The first magnetic separation uses a magnetic field strength of 500 Gauss and a drum separator speed of 100 r / min; the second magnetic separation uses a strength of 1000 Gauss and a drum separator speed of 150 r / min; the third magnetic separation uses a strength of 1500 Gauss and a drum separator speed of 200 r / min. The separated materials are then mixed to obtain iron powder. The iron content of the iron powder is analyzed, and the results are as follows. Figure 2 As shown.

[0060] Example 2

[0061] Step 1: Collect copper tailings and crush them in a ball mill, then pass them through a 200-mesh sieve for later use. If there is any material that does not pass through the sieve, retain it and mix it with the next batch before crushing it again.

[0062] Step 2: The copper tailings powder crushed in Step 1, the reducing agent (coal powder and anthracite powder mixed in a 1:1 mass ratio) and the additives (the weight parts of each substance are: 2 parts manganese dioxide, 5 parts magnesium oxide, 20 parts sodium silicate, 15 parts calcium carbonate, and 10 parts sodium borate) are weighed in a mixer at a mass ratio of 10:6:2 and mixed and stirred at a speed of 400 r / min for 10 min.

[0063] Step 3: After the copper tailings powder, refined coal powder, and additives from Step 2 are mixed, they are pressed into blocks with dimensions of 8*6*2cm and then fed into a sealed kiln. Nitrogen gas is then introduced to purge the air from the sealed kiln. The temperature is then raised to 1100℃ at a rate of 10-15℃ / min. The heating energy source for the sealed kiln is electricity, coal, or natural gas. The temperature is maintained for 20 minutes, and the volatile vapors are extracted for zinc recovery. The temperature is then maintained while nitrogen gas is continuously introduced to increase the pressure inside the sealed kiln to 2.5MPa and maintained for 40 minutes. The volatile vapors are then extracted for lead recovery. Heating is then stopped, and the kiln is cooled to room temperature.

[0064] Step 4: After the restoration operation in Step 3 is completed, take out the mixture and send it into a ball mill for crushing and then pass it through a 500-mesh sieve for later use. If there are still residual materials on the sieve, send them into a crushing device of the corresponding volume according to their weight to continue crushing until all materials have passed through the sieve.

[0065] Step 5: The pulverized mixture from Step 4 is subjected to three magnetic separation operations. The first magnetic separation uses a magnetic field strength of 500 Gauss and a drum separator speed of 100 r / min; the second magnetic separation uses a strength of 1000 Gauss and a drum separator speed of 150 r / min; the third magnetic separation uses a strength of 1500 Gauss and a drum separator speed of 200 r / min. The separated materials are then mixed to obtain iron powder. The iron content of the iron powder is analyzed, and the results are as follows. Figure 3 As shown.

[0066] Example 3

[0067] Step 1: Collect copper tailings and crush them in a ball mill, then pass them through a 200-mesh sieve for later use. If there is any material that does not pass through the sieve, retain it and mix it with the next batch before crushing it again.

[0068] Step 2: The copper tailings powder crushed in Step 1, the reducing agent (coal powder, anthracite powder and petroleum coke powder mixed in a mass ratio of 1:1:1) and the additives (the weight parts of each substance are: manganese dioxide 1.5 parts, magnesium oxide 4 parts, sodium silicate 18 parts, calcium carbonate 13 parts, sodium borate 8 parts) are weighed in a mass ratio of 10:5:1.5 and added to the mixer. The mixture is stirred at a speed of 350 r / min for 10-15 min.

[0069] Step 3: After the copper tailings powder, refined coal powder, and additives from Step 2 are mixed, they are pressed into blocks with dimensions of 8*6*2cm and then fed into a sealed kiln. Nitrogen gas is then introduced to purge the air from the sealed kiln. The temperature is then raised to 1050℃ at a rate of 13 m / min. The heating energy sources for the sealed kiln are electricity, coal, and natural gas. The temperature is maintained for 25 minutes, and the volatile vapors are extracted for zinc recovery. The temperature is then maintained while nitrogen gas is continuously introduced to increase the pressure inside the sealed kiln to 2.4 MPa and maintained for 45 minutes. The volatile vapors are then extracted for lead recovery. Heating is then stopped, and the kiln is cooled to room temperature.

[0070] Step 4: After the restoration operation in Step 3 is completed, take out the mixture and send it into a ball mill for crushing and then pass it through a 500-mesh sieve for later use. If there are still residual materials on the sieve, send them into a crushing device of the corresponding volume according to their weight to continue crushing until all materials have passed through the sieve.

[0071] Step 5: The pulverized mixture from Step 4 is subjected to three magnetic separation operations. The first magnetic separation uses a magnetic field strength of 500 Gauss and a drum separator speed of 100 r / min; the second magnetic separation uses a strength of 1000 Gauss and a drum separator speed of 150 r / min; the third magnetic separation uses a strength of 1500 Gauss and a drum separator speed of 200 r / min. The separated materials are then mixed to obtain iron powder. The iron content of the iron powder is analyzed and XRD is performed. The results are as follows: Figure 4 and Figure 5 As shown.

[0072] Depend on Figures 2-4 It can be seen that the total iron content extracted from copper tailings in Examples 1-3 of the present invention is all above 88%, and can even exceed 93%, and the metallic iron content is also above 85%. Figure 5 The product prepared in Example 3 can be shaped to ensure that the main substance is iron. Therefore, the present invention uses a low-temperature reduction method to efficiently recover iron from copper tailings, thereby solving the technical problems of stable iron content and high reduction difficulty in copper tailings in traditional processes.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting iron from copper tailings, characterized in that: Includes the following steps: Step 1: Collect copper tailings and crush them; Step 2: Add the reducing agent and additives to the copper tailings powder crushed in Step 1 and mix thoroughly; Step 3: The mixture obtained in Step 2 is sent into a sealed kiln for sealing and reduction; Step 4: After the restoration operation in Step 3 is completed, take out the mixture and crush it again; Step 5: Perform magnetic separation on the pulverized mixture from Step 4 to obtain iron powder; Step Six: Recycle and reuse the remaining material after magnetic separation in Step Five; In step one, the copper tailings are crushed by a ball mill and then passed through a 200-mesh sieve for later use. If there is any material that has not passed through the sieve, it is retained and mixed with the next batch before being crushed again. The mass ratio of copper tailings powder, reducing agent and additives in step two is 10:4-6:1-2. The copper tailings powder, reducing agent and additives are weighed according to the ratio and added to the mixer and mixed and stirred at a speed of 300-400 r / min for 10-15 min. The reducing agent in step two is any one or any two or more of the following: fine coal powder, anthracite powder, and petroleum coke powder, in any proportion. The auxiliary agent in step two includes the following substances in parts by weight: 1-2 parts manganese dioxide, 3-5 parts magnesium oxide, 15-20 parts sodium silicate, 10-15 parts calcium carbonate, and 6-10 parts sodium borate. The specific operation of step three is as follows: After mixing the copper tailings powder, reducing agent and additives in step two, press the mixture into a block with a length, width and height of 8*6*2cm and then send it into a sealed kiln. Then, a protective gas is introduced to exhaust the air in the sealed kiln. Then, the temperature is raised to 1000-1100℃ and maintained for 20-30 minutes. The volatile vapors are extracted and recovered. Then, the temperature is maintained while the protective gas is continuously introduced to increase the pressure in the sealed kiln to 2.3-2.5MPa and maintained for 40-50 minutes. The volatile vapors are extracted and recovered. Then, heating is stopped and the kiln is cooled to room temperature. The protective gas in step three is nitrogen, the heating rate of the sealed kiln is 10-15℃ / min, and the heating energy of the sealed kiln includes electricity, coal and natural gas. After the first steam extraction and cooling in step three, a zinc-containing mixture is obtained, and after the second steam extraction and cooling in step three, a lead-containing mixture is obtained. In step four, the mixed materials are fed into a ball mill for crushing and then passed through a 500-mesh sieve for later use. If there are still residual materials on the sieve, they are sent to a crushing device of the corresponding volume according to their weight for further crushing until all materials have passed through the sieve. In step five, three magnetic separation operations are performed. The magnetic field strength of the first magnetic separation is 500 Gauss, and the rotation speed of the drum magnetic separator is 100 r / min. The magnetic field strength of the second magnetic separation is 1000 Gauss, and the rotation speed of the drum magnetic separator is 150 r / min. The magnetic field strength of the third magnetic separation is 1500 Gauss, and the rotation speed of the drum magnetic separator is 200 r / min. The remaining materials in step six are recycled as the main raw materials for mineral soil conditioners, as well as cement admixtures, concrete admixtures, and road construction and backfill materials.

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