Collaborative recovery method for directionally converting SO2 into waste tire cord steel wires

Abstract

The invention provides a collaborative recovery method for directionally converting SO2 into waste tire cord steel wires, and belongs to the technical field of solid waste recycling. According to the collaborative recovery method provided by the invention, the granular waste tire cord steel is roasted in an SO2 / O2 / N2 mixed atmosphere and an air atmosphere in sequence, and then the valuable metal components copper, zinc and iron in the waste tire cord steel wire are directionally converted into copper sulfate, zinc sulfate and iron oxide through further leaching and magnetic separation processes. According to the method, efficient recovery and resource utilization of valuable metal components of copper, zinc and iron in the waste tire cord steel wires are achieved, an innovative solution is provided for high-value utilization of the waste tire cord steel wires, and the method has good application prospects and social and ecological benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and particularly relates to a synergistic recovery method for the directional conversion of SO2 into waste tire cord steel wire. Background Art

[0002] With the rapid development of the global automotive industry, the generation of waste tires is also increasing continuously. According to statistics, the global annual output of waste tires is as high as hundreds of millions. In China, about 20 million tons of waste tires were generated in 2022, and it is increasing rapidly at a rate of 8% to 10% per year. Waste tires not only occupy a large amount of land resources, but also are difficult to degrade due to their three-dimensional cross-linked network structure, becoming one of the main sources of solid waste pollution.

[0003] As the tire cord steel wire, which is the tire skeleton material, accounts for 15%-20% of the total tire mass, its main component is high-carbon steel (Fe content > 98%), and it also contains alloy elements such as copper and zinc. Traditional landfill or incineration disposal methods not only cause waste of rubber and metal resources in tires, but also the pollutants such as dioxins generated by the combustion of waste tires bring serious environmental risks and pose a serious threat to human life and health. In addition, through the high-temperature recovery process, the performance of the cord steel wire in waste tires drops sharply and it is difficult to meet the performance requirements of cord steel wire.

[0004] Waste tire cord steel wire is a solid metal product generated during the crushing process of waste tires. Due to the existence of the cord steel wire coating (copper-zinc alloy), it is difficult to directly apply waste tire cord steel wire to the steel smelting process. At present, waste tire cord steel wire is mainly used in the field of low-end steel products and is simply reprocessed into metal abrasives such as steel cut wire shots and casting sand shots, which weakens the environmental protection attributes and economic value of waste tire cord steel wire. Therefore, there is an urgent need for a recovery technology to achieve the full-component recovery and resource utilization of waste tire cord steel wire.

[0005] In CN100369820C, a multi-step process is adopted to recycle the steel wire in waste tires. First, the surface brass coating is removed by an electrochemical method or a chemical method, then an acid dissolution is carried out to prepare a ferrous salt solution, further impurity removal by filtration is carried out, and finally high-purity iron oxide is prepared by drying and calcination. However, this recycling process has long and cumbersome operation steps, and a high-concentration strong acid is used in the leaching process, and a relatively high calcination temperature is adopted in the calcination process, which not only increases the cost and energy consumption of subsequent treatment, but also causes serious corrosion to the treatment equipment, making the economic benefit of the entire process of recycling waste tire cord steel wire poor and difficult to mass-produce. In CN111349750A, the waste tire cord steel wire is melted into molten steel, then processed into steel shots by a forming device, and finally finished cast steel shots are obtained through heat treatment. Although this recycling process has a simple process flow and low energy consumption. However, this recycling process is carried out at a high temperature, which exacerbates the heat loss of the metal components of the cord steel wire; at the same time, after melting, the high-carbon steel is reduced to ordinary cast steel, and the loss of product added value is serious. In addition, due to the presence of the coating copper and zinc components, it will also cause an increase in the brittleness of the finished cast steel shots, making it difficult to meet the development needs of green manufacturing and resource recycling industries. CN103436899B uses a strongly alkaline mixed solution of ammonia water, sodium nitrite, and deionized water to remove the surface coating of waste tire steel cord under the conditions of heating and oxygen passing. However, sodium nitrite not only has a high price, but also has chemical toxicity and is unstable itself, and is prone to explosion under certain environments, increasing the instability and danger of the recycling process. Therefore, there is an urgent need for a method that can efficiently recycle and utilize waste tire cord steel wire at present. Summary of the Invention

[0006] The present invention provides a synergistic recycling method for SO2-directed conversion of waste tire cord steel wire. This method realizes the directional conversion, gradient separation, and resource utilization of valuable metal components copper, zinc, and iron in waste tire cord steel wire through the SO2-directed conversion process, provides an innovative solution for the high-value utilization of waste tire cord steel wire, and has good application prospects, social and ecological benefits.

[0007] In order to achieve the above object, the present invention provides a synergistic recycling method for SO2-directed conversion of waste tire cord steel wire. By roasting the granular waste tire cord steel successively in a SO2 / O2 / N2 mixed atmosphere and an air atmosphere, the directional conversion of valuable metal components copper, zinc, and iron in the waste tire cord steel wire into copper sulfate, zinc sulfate, and iron oxide is realized.

[0008] Preferably, when carrying out the temperature-controlled roasting process in the SO2 / O2 / N2 mixed atmosphere, the volume concentration ratio of SO2 is 20% - 60%, the volume concentration ratio of O2 is 20% - 40%, and the rest is N2.

[0009] Preferably, when the roasting process is carried out in a SO2 / O2 / N2 mixed atmosphere, the roasting reaction temperature is 400 - 600 °C, and the roasting reaction time is 30 - 90 min.

[0010] Preferably, when the oxidative roasting process is carried out in an air atmosphere, the roasting reaction temperature is 600 - 700 °C, and the roasting reaction time is 20 - 60 min.

[0011] Preferably, the particle size D90 of the granular waste tire cord steel is ≤ 500 μm.

[0012] Preferably, the specific steps for realizing the directional conversion of valuable metal components copper, zinc, and iron in the waste tire cord steel into copper sulfate, zinc sulfate, and iron oxide are as follows:

[0013] The roasting slag obtained from the roasting process is stirred and leached by a water leaching process. After solid-liquid separation and washing, a first filtrate containing copper sulfate and zinc sulfate and a first filter residue containing iron oxide are obtained;

[0014] Zinc powder is added to the first filtrate for copper replacement precipitation. After pressure filtration separation, crude copper and a zinc sulfate solution are obtained, and the first filter residue is subjected to magnetic separation to enrich the iron oxide component to obtain iron concentrate.

[0015] Preferably, in the water leaching process, the mass ratio of the roasting slag to water is 1:3 - 1:10, and heating leaching is carried out within the temperature range of 50 - 100 °C for 20 - 60 min.

[0016] Preferably, in the copper replacement precipitation process, zinc powder is added to the first filtrate for replacement reaction according to the molar ratio of zinc powder to copper ions in the solution of 1.1 - 1.5:1.

[0017] Preferably, in the copper replacement precipitation process, the copper precipitation reaction temperature is 40 - 60 °C, and the reaction time is 20 - 60 min.

[0018] Preferably, the copper component is recovered in the form of copper powder, and the iron component is recovered in the form of iron oxide, wherein the purity of the crude copper > 98.2%, and the purity of the iron oxide > 98.8%.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0020] 1. First, the present invention realizes the directional conversion of valuable metal components copper, zinc, and iron in waste tire cord steel through a two-stage roasting process under different atmospheres (the first stage is a mixed atmosphere of SO2 / O2 / N2, and the second stage is an air atmosphere): the copper and zinc components in the coating are converted into copper sulfate and zinc sulfate; the iron component in the matrix is converted into iron oxide; then, through a further water leaching process, the efficient separation of water-soluble copper sulfate, zinc sulfate, and iron oxide is achieved. In addition, the deep separation of copper and zinc ions in the solution is realized through a zinc powder replacement reaction, obtaining crude copper powder and zinc sulfate solution; finally, iron concentrate is obtained through a magnetic separation process, and the recycling of the iron component in blast furnace ironmaking is also realized. Through the above SO2 directional conversion collaborative recovery process, the cascade classification and high-value recovery of three types of valuable metal components (copper, zinc, and iron) in waste tire cord steel are realized.

[0021] 2. The process flow provided by the present invention is simple to operate, with low comprehensive treatment costs and cost savings, and is suitable for application and promotion in industrial production. At the same time, through the SO2 directional conversion - collaborative separation process, the present invention constructs a full-component recovery and resource utilization system for waste tire cord steel, provides reliable technical support for the large-scale recovery of waste tire cord steel, and promotes the transformation and upgrading of the waste tire resource industry towards high efficiency, cleanliness, and high value. Brief Description of the Drawings

[0022] Figure 1 It is a schematic flow chart of the collaborative recovery method for SO2 directional conversion of waste tire cord steel provided by an embodiment of the present invention. Detailed Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] As Figure 1 shown, the collaborative recovery method for SO2 directional conversion of waste tire cord steel includes the following steps:

[0026] The waste tire cord steel is processed by a shearing crusher to obtain particulate materials with a particle size D90 ≤ 500 μm;

[0027] Spread the granular material evenly in a quartz boat of a tube furnace, introduce a mixed gas of SO2 / O2 / N2 (volume ratio 60%:20%:20%), heat it to 500 °C at a rate of 10 °C / min and keep it at a constant temperature for 60 minutes. The copper and zinc components in the waste tire cord steel are respectively converted into CuSO4 and ZnSO4, and the iron component is directionally converted into ferric sulfate and iron oxide. Then, switch the atmosphere of the tube furnace to an air atmosphere, heat it to 630 °C at a rate of 5 °C / min and keep it at a constant temperature for 60 minutes, and ferric sulfate is directionally converted into Fe3O4;

[0028] After calculation, in the whole roasting process, the conversion rate of copper sulfate is 98.6%; the conversion rate of zinc sulfate is 98.8%; the conversion rate of iron oxide is 99.1%.

[0029] Mix the roasted slag with deionized water at 70 °C according to a solid-liquid ratio of 1:5, leach it by mechanical stirring (rotation speed 400 rpm / min) for 45 minutes, and then separate it by a plate and frame filter press to obtain the first filtrate and the first filter residue;

[0030] Add zinc powder to the first filtrate according to a Zn:Cu molar ratio of 1.2:1, stir and react at 60 °C for 30 minutes, and obtain crude copper powder and zinc sulfate solution by centrifugal separation;

[0031] Perform magnetic separation on the first filter residue to obtain iron concentrate and non-magnetic tailings.

[0032] After the waste tire cord steel is recycled, the zinc component is recycled in the form of zinc sulfate solution; the copper component is recycled in the form of copper powder; the iron component is recycled in the form of iron oxide. Among them, the purity of crude copper > 98.7%; the purity of iron oxide > 99.0%.

[0033] Example 2

[0034] The method for synergistic recovery of waste tire cord steel by SO2 directional conversion includes the following steps:

[0035] Process the waste tire cord steel with a shearing crusher to obtain granular materials with a particle size D90 ≤ 500 μm;

[0036] Spread the granular material evenly in a quartz boat of a tube furnace, introduce a mixed gas of SO2 / O2 / N2 (volume ratio 40%:40%:20%), heat it to 550 °C at a rate of 10 °C / min and keep it at a constant temperature for 80 minutes. The copper and zinc components in the waste tire cord steel are respectively converted into CuSO4 and ZnSO4, and the iron component is directionally converted into ferric sulfate and iron oxide. Then, switch the atmosphere of the tube furnace to an air atmosphere, heat it to 650 °C at a rate of 5 °C / min and keep it at a constant temperature for 45 minutes, and ferric sulfate is directionally converted into Fe3O4;

[0037] After calculation, during the entire roasting process, the conversion rate of copper sulfate is 98.7%; the conversion rate of zinc sulfate is 98.6%; the conversion rate of iron oxide is 99.3%.

[0038] Mix the roasted slag with deionized water at 80°C according to a solid-liquid ratio of 1:8, and leach for 60 minutes by mechanical stirring (rotation speed 450 rpm / min), then separate through a plate and frame filter press to obtain the first filtrate and the first filter residue;

[0039] Add zinc powder to the first filtrate according to a Zn:Cu molar ratio of 1.3:1, stir and react at 60°C for 30 minutes, and obtain crude copper powder and zinc sulfate solution through centrifugal separation;

[0040] Perform magnetic separation on the first filter residue to obtain iron concentrate and non-magnetic tailings.

[0041] After the waste tire cord steel wire is recycled, the zinc component is recycled in the form of zinc sulfate solution; the copper component is recycled in the form of copper powder; the iron component is recycled in the form of iron oxide. Among them, the purity of crude copper > 98.5%; the purity of iron oxide > 99.0%.

[0042] Example 3

[0043] The synergistic recovery method for the SO2-directed conversion of waste tire cord steel wire includes the following steps:

[0044] Process the waste tire cord steel wire through a shear crusher to obtain granular materials with a particle size D90 ≤ 500 μm;

[0045] Lay the granular materials flat in a quartz boat of a tubular furnace, introduce a SO2 / O2 / N2 mixed gas (volume ratio 55%:20%:25%), heat up to 450°C at a rate of 10°C / min and keep it constant for 90 minutes. The copper and zinc components in the waste tire cord steel wire are respectively converted into CuSO4 and ZnSO4, and the iron component is directionally converted into iron sulfate and iron oxide; then, switch the atmosphere of the tubular furnace to air atmosphere, heat up to 600°C at a rate of 5°C / min and keep it constant for 60 minutes, and the iron sulfate is directionally converted into Fe3O4;

[0046] After calculation, during the entire roasting process, the conversion rate of copper sulfate is 98.2%; the conversion rate of zinc sulfate is 98.0%; the conversion rate of iron oxide is 97.5%.

[0047] Mix the roasted slag with deionized water at 60°C according to a solid-liquid ratio of 1:10, and leach for 45 minutes by mechanical stirring (rotation speed 600 rpm / min), then separate through a plate and frame filter press to obtain the first filtrate and the first filter residue;

[0048] Add zinc powder to the first filtrate according to a Zn:Cu molar ratio of 1.2:1, stir and react at 50°C for 30 minutes, and obtain crude copper powder and zinc sulfate solution through centrifugal separation;

[0049] The first filter residue is subjected to magnetic separation to obtain iron concentrate and non-magnetic tailings.

[0050] After the waste tire cord steel wire is recycled, the zinc component is recovered in the form of zinc sulfate solution; the copper component is recovered in the form of copper powder; the iron component is recovered in the form of iron oxide. Among them, the purity of crude copper > 98.2%; the purity of iron oxide > 99.0%.

[0051] Example 4

[0052] The synergistic recovery method for the SO2-directed conversion of waste tire cord steel wire includes the following steps:

[0053] The waste tire cord steel wire is treated by a shearing crusher to obtain particulate materials with a particle size D90 ≤ 500 μm;

[0054] The particulate materials are spread flat in a quartz boat of a tubular furnace, and a mixed gas of SO2 / O2 / N2 (volume ratio 30%:40%:30%) is introduced, heated to 450 °C at a rate of 10 °C / min and kept at a constant temperature for 60 minutes. The copper and zinc components in the waste tire cord steel wire are respectively converted into CuSO4 and ZnSO4, and the iron component is directionally converted into ferric sulfate and iron oxide; then, the atmosphere in the tubular furnace is switched to an air atmosphere, heated to 650 °C at a rate of 5 °C / min and kept at a constant temperature for 60 minutes, and the ferric sulfate is directionally converted into Fe3O4;

[0055] After calculation, during the entire roasting process, the conversion rate of copper sulfate is 97.2%; the conversion rate of zinc sulfate is 97.6%; the conversion rate of iron oxide is 99.3%.

[0056] The roasted slag is mixed with deionized water at 60 °C according to a solid-liquid ratio of 1:5, leached by mechanical stirring (rotation speed 450 rpm / min) for 40 minutes, and then separated by a plate and frame filter press to obtain the first filtrate and the first filter residue;

[0057] Zinc powder is added to the first filtrate according to a Zn:Cu molar ratio of 1.1:1, and stirred and reacted at 60 °C for 30 minutes, and then centrifuged to obtain crude copper powder and zinc sulfate solution;

[0058] The first filter residue is subjected to magnetic separation to obtain iron concentrate and non-magnetic tailings.

[0059] After the waste tire cord steel wire is recycled, the zinc component is recovered in the form of zinc sulfate solution; the copper component is recovered in the form of copper powder; the iron component is recovered in the form of iron oxide. Among them, the purity of crude copper > 98.2%; the purity of iron oxide > 99.0%.

[0060] Example 5

[0061] The synergistic recovery method for the SO2-directed conversion of waste tire cord steel wire includes the following steps:

[0062] The waste tire cord steel wires are processed by a shearing crusher to obtain granular materials with a particle size D90 ≤ 500 μm;

[0063] The granular materials are spread flat in a quartz boat of a tubular furnace, and a mixed gas of SO2 / O2 / N2 (volume ratio 20%:40%:40%) is introduced. It is heated to 550 °C at a rate of 10 °C / min and kept at a constant temperature for 90 minutes. The copper and zinc components in the waste tire cord steel wires are respectively converted into CuSO4 and ZnSO4, and the iron component is directionally converted into ferric sulfate and iron oxide; then, the atmosphere of the tubular furnace is switched to an air atmosphere, heated to 620 °C at a rate of 5 °C / min and kept at a constant temperature for 45 minutes, and the ferric sulfate is directionally converted into Fe3O4;

[0064] After calculation, during the entire roasting process, the conversion rate of copper sulfate is 95.9%; the conversion rate of zinc sulfate is 96.2%; the conversion rate of iron oxide is 99.1%.

[0065] The roasted slag is mixed with deionized water at 70 °C according to a solid-liquid ratio of 1:8, leached for 50 minutes by mechanical stirring (rotation speed 400 rpm / min), and then separated by a plate and frame filter press to obtain the first filtrate and the first filter residue;

[0066] Zinc powder is added to the first filtrate according to a Zn:Cu molar ratio of 1.2:1, and stirred and reacted at 60 °C for 30 minutes, and then separated by centrifugation to obtain crude copper powder and zinc sulfate solution;

[0067] The first filter residue is subjected to magnetic separation to obtain iron concentrate and non-magnetic tailings.

[0068] After the waste tire cord steel wires are recycled, the zinc component is recycled in the form of zinc sulfate solution; the copper component is recycled in the form of copper powder; the iron component is recycled in the form of iron oxide. Among them, the purity of the crude copper > 98.3%; the purity of the iron oxide > 98.8%.

[0069] Comparative Example 1

[0070] The recycling treatment process is the same as that in Example 1, except that when roasting in the mixed atmosphere of SO2 / O2 / N2, the volume ratio of the mixed gas SO2 / O2 / N2 is 15%:45%:40%. After two-step roasting, the conversion rate of copper sulfate is only 82.1%; the conversion rate of zinc sulfate is only 81.6%; the conversion rate of iron oxide is 97.5%.

[0071] Comparative Example 2

[0072] The recycling process is the same as that of Example 3, except that the temperature during the oxidative roasting process in an air atmosphere is 720 °C. After the two-step roasting process, the conversion rate of copper sulfate is only 76.2%; the conversion rate of zinc sulfate is only 76.5%; the conversion rate of iron oxide is only 80.1%. After the subsequent leaching - copper precipitation - magnetic separation process, the purity of the crude copper decreases and can only reach 93.3%.

[0073] Comparative Example 3

[0074] The recycling process is the same as that of Example 4, except that the temperature during the roasting process in a SO2 / O2 / N2 mixed atmosphere is 300 °C. After the two-step roasting process, the conversion rate of copper sulfate is only 53.1%; the conversion rate of zinc sulfate is only 51.6%; the conversion rate of iron oxide is 98.8%. However, the excessively low roasting temperature in the first roasting process results in the loss of copper and zinc components, which enter the tailings.

Claims

1. A method for the coordinated recovery of waste tire cord steel wire by directional conversion of SO2, characterized in that: The granular waste tire cord steel is subjected to a roasting process in a SO2 / O2 / N2 mixed atmosphere and an air atmosphere in turn, and then subjected to further leaching and magnetic separation processes, so as to achieve a directional conversion of the valuable metal components copper, zinc and iron in the waste tire cord steel wire into copper sulfate, zinc sulfate and iron oxide.

2. The collaborative recycling method according to claim 1, characterized in that: When the temperature-controlled roasting process is carried out in a SO2 / O2 / N2 mixed atmosphere, the volume concentration of SO2 accounts for 20% to 60%, the volume concentration of O2 accounts for 20% to 40%, and the rest is N2.

3. The collaborative recycling method according to claim 2, characterized in that: When the calcination process is carried out in a SO2 / O2 / N2 mixed atmosphere, the calcination reaction temperature is 400-600°C and the calcination reaction time is 30-90 minutes.

4. The collaborative recycling method according to claim 1, characterized in that: When the oxidation roasting process is carried out in an air atmosphere, the roasting reaction temperature is 600-700° C. and the roasting reaction time is 20-60 minutes.

5. The collaborative recycling method according to any one of claims 1 to 4, characterized in that: The particle size D90 of the granular waste tire cord steel is ≤500 μm.

6. The collaborative recycling method according to claim 5, characterized in that: The directional conversion of the valuable metal components copper, zinc and iron in the waste tire cord steel wire into copper sulfate, zinc sulfate and iron oxide specifically includes the following steps: The calcined slag obtained in the calcination process is stirred and leached through a water leaching process, and after solid-liquid separation and washing, a first filtrate containing copper sulfate and zinc sulfate and a first filtrate residue containing iron oxide are obtained; Zinc powder is added to the first filtrate to replace copper precipitation, and crude copper and zinc sulfate solution are obtained by filter pressing and separation, and the first filter residue is magnetically separated to enrich the iron oxide component to obtain iron concentrate.

7. The collaborative recycling method according to claim 6, characterized in that: In the water leaching process, the mass ratio of roasted slag to water is 1:3 to 1:10, and the leaching is carried out by heating at a temperature range of 50 to 100° C. for 20 to 60 minutes.

8. The collaborative recycling method according to claim 6, characterized in that: In the copper replacement step, zinc powder is added to the first filtrate at a molar ratio of zinc powder to copper ions in the solution of 1.1 to 1.5:1 to carry out a replacement reaction.

9. The collaborative recycling method according to claim 8, characterized in that: In the replacement copper deposition process, the copper deposition reaction temperature is 40 to 60° C. and the reaction time is 20 to 60 minutes.

10. The collaborative recycling method according to any one of claims 1 to 9, characterized in that: The copper component is recovered in the form of copper powder, the iron component is recovered in the form of iron oxide, and the zinc component is recovered in the form of zinc sulfate solution, wherein the purity of crude copper is greater than 98.2%, and the purity of iron oxide is greater than 98.8%.

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