Method for multi-metal reinforced separation of high-tin tailings and preparation of high-quality iron powder

Abstract

The invention discloses a method for multi-metal reinforced separation of high-tin tailings and preparation of high-quality iron powder, and belongs to the technical field of efficient recycling of metal mineral resources. The method comprises the following steps: uniformly mixing the high-tin tailings with a first reducing agent to prepare pellets, drying the pellets, mixing the pellets with a second carbonaceous reducing agent, heating to 950-1100 DEG C, keeping the temperature for 20-150 minutes to obtain flue gas and roasting slag, and cooling the flue gas to obtain flue dust containing tin, arsenic, lead and zinc; and then the roasting slag is subjected to water-cooling ore grinding and then is subjected to magnetic separation, and high-quality iron powder can be obtained. The volatilization rates of tin, arsenic, lead and zinc are gt; the iron grade is gt; the recovery rate is 98% and gt; the method has the advantages that the problem of the high-tin-content tin tailing tin and arsenic reinforced separation and iron deep reduction industry is solved, efficient comprehensive recovery of valuable components and high-valued utilization of tin tailing resources are achieved, safe supply of tin resources in the world is guaranteed, and the method is of great significance to green and sustainable development of the tin industry.

Description

Technical Field

[0001] The invention relates to a method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder, belonging to the technical field of efficient recovery and reuse of metal mineral resources. Background Art

[0002] Tin is a vital strategic resource and an indispensable rare metal in my country. The latest data from the USGS indicates that global tin reserves are approximately 4.6 million tons. Based on an average annual refined tin production of 300,000 tons, this only covers the next 15-16 years of demand. China's tin ore resources are relatively abundant, with approximately 1.1 million tons of reserves (Yunnan accounts for approximately 44.7% of the country's total reserves), primarily in the form of placer and vein tin ores. However, China's tin dependence on foreign suppliers reaches 30-40%. With the long-term exploitation of tin ore, primary resources have become increasingly scarce, with the mining grades of placer and vein tin falling to 0.009-0.03% and 0.5%, respectively. The development and utilization of tin ore has generated and stockpiled large quantities of tin tailings worldwide. Process mineralogy studies have shown that tin tailings typically contain iron, arsenic, lead, zinc, and sulfur, with a tin content of 0.2-0.8%, primarily in the form of fine-grained cassiterite, densely associated with iron ore, with poor monomer dissociation. Yunnan Tin Group (Holdings) Co., Ltd. alone boasts 300 million tons of tin tailings reserves, with reserves exceeding 40 and 40 million tons of tin and iron, respectively, with an economic value exceeding 100 billion yuan. After pretreatment, tin, iron, arsenic, lead, and zinc can be efficiently enriched, with tin content reaching 0.4%-1.2%, but this is difficult to use within existing tin smelting processes.

[0003] Low-grade tin resource disposal processes primarily include beneficiation, combined beneficiation and smelting, and roasting. Because cassiterite is brittle and finely embedded, beneficiation often employs a combination of staged grinding with gravity separation, flotation, and magnetic separation. This process can enrich tin to 3-40% for use in fuming furnaces or Ausmelt reduction smelting. While this method offers advantages such as low processing costs and simple operation, it also carries drawbacks such as low valuable metal recovery, high environmental hazards from secondary tailings storage, and low economic returns. The combined smelting process (CN116889925A, a tin tailings classification pre-enrichment - classification sorting recovery of tin and iron) obtains tin and iron co-associated minerals and strong magnetic separation iron concentrate by combining classification - gravity separation - strong magnetic separation. The tin and iron co-associated minerals are reduced and roasted at 650 ° C and 10 wt% addition to convert Fe2O3 into Fe3O4. The roasted products are separated by magnetic separation to obtain tin-rich medium ore with an iron grade of 61.16% and a comprehensive recovery rate of 23.00% and a tin grade of 3.53% and a recovery rate of 67.1%. The strong magnetic separation concentrate is reduced and roasted at a temperature of 700 ° C and 15% lignite addition, and then ground and weak magnetic separation is performed to obtain an iron grade of 60.34% and a comprehensive recovery rate of 48.02%. Since tin and arsenic easily react with ferroferric oxide (Fe3O4) in the magnetic separation concentrate to form tin / arsenic iron spinel Fe at low temperature, the tin and arsenic can be separated by calcination. x(Sn, As) 3-x O4, resulting in the inability to achieve efficient separation of tin, arsenic and iron in the magnetization roasting process in the combined beneficiation and smelting process. The tin (>0.3%) and arsenic in the iron concentrate obtained from the tin, arsenic and iron co-existing minerals seriously exceed the standard, resulting in the unusable iron concentrate (the steel industry requires a tin content of <0.08%) and a waste of tin resources. More importantly, the iron content of the iron concentrate is only 60-65%, and its economic value is relatively low. Due to the high pollution of chlorination roasting, it cannot be used in industry. The current roasting process includes reduction roasting and sulfide roasting. Reduction roasting (CN102965522B, a method for separating and recovering tin from tin-containing tailings in mineral processing) is heated at 850℃~1000℃ in a weak reducing atmosphere (the volume concentration of CO CO / (CO+CO2) is 20%~50%), and the tin in the tailings is reduced and volatilized into the flue gas, but this method is only suitable for tailings with a tin content of <0.3% and a recovery rate of <75%, and the iron cannot be recycled. Sulfidation roasting (CN103088181B, a method for producing sponge iron from high-iron, low-tin ores by direct reduction via sulfidation volatilization) processes high-iron, low-tin ores (Sn: <0.4%) at 1000-1300°C, producing a sponge iron content of 90-92%. More importantly, when the tin and arsenic content of the ore is high, the tin and arsenic content of the sponge iron increases significantly, making it difficult to utilize.

[0004] In summary, tin, arsenic and iron have similar physical and chemical properties. Existing technologies make it difficult to achieve efficient separation of tin, arsenic and iron in high-tin tin tailings (Sn: 0.4%-1.2%), resulting in the enrichment of tin and arsenic in iron products, causing waste of tin resources and poor product quality and low value, making it difficult to industrialize. At present, the utilization rate of tin tailings is extremely low, and they are dumped in the open air environment of tailings ponds, occupying a large amount of land resources. At the same time, harmful elements such as arsenic, lead, and zinc in the mines will also pollute surrounding water bodies, soil and crops. Therefore, there is an urgent need to break through the bottleneck of efficient utilization of tin and iron in high-tin tin tailings and improve the availability of global tin resources, which is of great significance to the green and sustainable development of the tin industry. Summary of the Invention

[0005] In order to overcome the problems in the background technology, the purpose of the present invention is to provide a method for the enhanced separation of multiple metals in high-tin tin tailings and the preparation of high-quality iron powder. The core of the present invention is based on the different reduction and volatilization characteristics of tin, arsenic, and iron. By coupling the key parameters such as the type, mixing ratio, addition method, and temperature of the carbonaceous reducing agent, arsenic and tin are volatilized before FeO is reduced to Fe, and the problem of tin industry that tin, arsenic and iron are enhanced and separated in the same process to coordinate the deep reduction of iron (FeO is reduced to Fe) is overcome. At the same time, valuable metals such as lead and zinc can be recovered simultaneously. The smoke dust efficiently enriched with tin, lead, zinc and arsenic can be used as a high-quality tin raw material, and compared with iron concentrate and sponge iron, the metal iron powder obtained by this patent has a high grade and low impurity content, realizing the high-value utilization of tin tailings and having great promotion and application.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for preparing high-quality iron powder by enhanced separation of multiple metals from high-tin tin tailings comprises the following steps:

[0008] (1) mixing high-tin tin tailings with a first reducing agent to form pellets, drying the pellets, mixing them with a second reducing agent, heating them to 950-1100° C., and keeping the temperature for 20-150 minutes to obtain flue gas and roasted slag, and cooling the flue gas to obtain smoke containing tin, arsenic, lead, and zinc;

[0009] (2) The roasted slag is water-cooled and ground, and then magnetically separated to obtain high-quality iron powder.

[0010] Preferably, the high-tin tin tailings contain 0.4-1.2 wt% tin, 5-50 wt% iron, 0.1-3 wt% arsenic, 0.1-5 wt% lead, and 0.1-5 wt% zinc.

[0011] Preferably, the mass ratio of the high-tin tin tailings to the first reducing agent is 100:(5-15).

[0012] Preferably, the first reducing agent includes reducing agent A and reducing agent B; reducing agent A is a reducing agent with a carbon dioxide reaction rate greater than 25% in the temperature range of 600-900°C, such as waste activated carbon, waste engine oil, biomass oil, bituminous coal or blue carbon, and has a particle size of less than 150 mesh. Reducing agent B is a reducing agent with a carbon dioxide reaction rate less than 20% in the temperature range of 900-1100°C, such as petroleum coke, coke or defluorinated aluminum electrolysis waste cathode carbon, and has a particle size including coarse and fine particle sizes, the coarse particle size is 50-120 mesh, the fine particle size is 200-400 mesh, and the mass ratio of coarse particle size to fine particle size is (20-70):(80-30).

[0013] The carbon dioxide reactivity refers to the chemical reactivity of carbon materials such as coal to carbon dioxide, and is expressed by the carbon dioxide reduction rate.

[0014] Preferably, the mass ratio of the reducing agent A to the reducing agent B is (5-25):(95-75).

[0015] Preferably, the second reducing agent is a reducing agent with a carbon content of >75%, including at least one of bituminous coal, semi-coke, petroleum coke, coke, and defluorinated aluminum electrolysis waste cathode carbon, with a particle size of 2.5 cm to 200 mesh, and the mass ratio of pellets to the second carbonaceous reducing agent is 100:(5 to 50).

[0016] Preferably, the particle size of the roasted slag after grinding is less than 200 mesh, and the magnetic field strength of the magnetic separation is 70-140 kA / m.

[0017] Preferably, the grade of the high-quality iron powder is greater than 98%.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention adopts a simple, efficient, safe and low-cost method for the enhanced separation of multiple metals from high-tin tin tailings to prepare high-quality iron powder, overcoming the industry's difficult problem of efficient separation of tin, lead and zinc in 0.4% to 1.2% tin tailings and coordinated deep reduction of iron. The method achieves a tin recovery rate of >95%, breaking through the bottleneck of the mainstream tin tailings beneficiation process that is difficult to solve, which is the fine and dense coexistence of acid-soluble tin and cassiterite, and significantly improving the recovery rate by 15-50%.

[0020] (2) The present invention uses a first carbonaceous reducing agent and a second carbonaceous reducing agent, and cooperates with the roasting temperature and time to achieve high-value utilization of iron, deeply reducing the iron in the high-tin tin tailings to elemental Fe, and the iron grade in the metallic iron is greater than 98% and the recovery rate is greater than 80%, and the content of impurity elements such as tin, arsenic, and sulfur is less than 0.02%, 0.05%, and 0.05%. After magnetic separation, it is processed into high-quality iron powder (Fe:>98%), which is significantly improved compared with the traditional iron ore preparation as iron concentrate (Fe: 60-70%). At the same time, the recovery rates of lead, zinc, and arsenic are all greater than 90%, and the associated valuable components and harmful components such as reduced arsenic are recovered. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0022] Example 1

[0023] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder comprises the following steps:

[0024] (1) The composition of high-tin tin tailings is as follows:

[0025] Table 1 Main chemical composition of a high-tin tin tailings

[0026]

[0027] (2) The 100 wt% high-tin tin tailings were mixed with 1.5 wt% semi-coke and 6.5 wt% petroleum coke to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 20 wt% of bituminous coal and heated to 1050°C at a heating rate of 20°C / min and kept warm for 70 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead and zinc.

[0028] (3) The roasted slag in step (2) is water-cooled and ground to -400 mesh and then subjected to weak magnetic separation (70kA / m) to obtain high-quality iron powder and tailings.

[0029] Calculated recoveries of tin, arsenic, lead, and zinc reached 95.41%, 94.26%, 98.21%, and 90.25%, respectively. The high-quality iron powder had a grade of 98.15% and a recovery rate of 77.21%. The impurity contents of tin, arsenic, lead, and zinc in the high-quality iron powder were <0.02%, 0.05%, 0.03%, and 0.04%, respectively. These results demonstrate that enhanced separation of tin, lead, and zinc from tin tailings facilitates high-value iron reuse and reduces arsenic-containing waste. The tin enrichment ratio in the tin, lead, zinc, and arsenic-containing dust is >10, making it suitable as a high-quality raw material for current tin smelting.

[0030] Example 2

[0031] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder comprises the following steps:

[0032] (1) 100 wt% high-tin tin tailings were mixed with 1 wt% bituminous coal and 8 wt% coke to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 20 wt% semi-coke and heated to 1000 ℃ at a heating rate of 30 ℃ / min and kept at this temperature for 150 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead and zinc.

[0033] (2) The roasted slag in step (1) is water-cooled and ground to -250 mesh and then subjected to weak magnetic separation (140 kA / m) to obtain high-quality iron powder and tailings.

[0034] Calculated recoveries of tin, arsenic, lead, and zinc reached 94.12%, 95.14%, 99.11%, and 92.43%, respectively. The high-quality iron powder had a grade of 98.01% and a recovery rate of 82%. The impurity contents of tin, arsenic, lead, and zinc in the high-quality iron powder were <0.02%, 0.05%, 0.03%, and 0.04%, respectively. These results demonstrate that enhanced separation of tin, lead, and zinc from tin tailings facilitates high-value iron reuse and reduces arsenic-containing waste. The tin enrichment ratio in the tin, lead, zinc, and arsenic-containing dust is >10, making it suitable as a high-quality raw material for current tin smelting.

[0035] Example 3

[0036] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder comprises the following steps:

[0037] (1) 100 wt% high-tin tin tailings were mixed with 1.1 wt% bituminous coal and 13 wt% coke to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 5 wt% defluorinated aluminum electrolysis waste cathode carbon and heated to 1100 °C at a heating rate of 5 °C / min and kept warm for 20 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead and zinc.

[0038] (2) The roasted slag in step (1) is water-cooled and ground to -250 mesh and then subjected to weak magnetic separation (100 kA / m) to obtain high-quality iron powder and tailings.

[0039] Calculated recoveries of tin, arsenic, lead, and zinc reached 95.44%, 96.12%, 98.86%, and 90.12%, respectively. The high-quality iron powder had a grade of 98.75% and a recovery rate of 84.12%. The impurity contents of tin, arsenic, lead, and zinc in the high-quality iron powder were <0.02%, 0.03%, 0.02%, and 0.03%, respectively. These results demonstrate that enhanced separation of tin, lead, and zinc from tin tailings facilitates high-value iron reuse and reduces arsenic-containing waste. The tin enrichment ratio in the tin, lead, zinc, and arsenic-containing dust is >10, making it suitable as a high-quality raw material for current tin smelting.

[0040] Comparative Example 1

[0041] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of iron powder comprises the following steps:

[0042] (1) 100 wt% high-tin tin tailings and 10 wt% petroleum coke were uniformly mixed to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 20 wt% of bituminous coal and heated to 1050°C at a heating rate of 20°C / min and kept at this temperature for 70 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead, and zinc.

[0043] (2) In step (2), the roasted slag is water-cooled and ground to -400 mesh and then subjected to weak magnetic separation (70 kA / m) to obtain iron powder and tailings.

[0044] The calculated recoveries of tin, arsenic, lead, and zinc were 68.13%, 74.12%, 94.86%, and 87.12%, respectively. The iron powder grade was 96.05% with a recovery rate of 78%. The results showed that it was difficult to efficiently separate iron and arsenic from iron, resulting in a reduced iron grade and excessive tin and arsenic impurity content in the metallic iron powder, making it difficult to use.

[0045] Comparative Example 2

[0046] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of iron powder comprises the following steps:

[0047] (1) 100 wt% high-tin tin tailings and 10 wt% semi-coke were uniformly mixed to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 20 wt% of bituminous coal and heated to 1050 °C at a heating rate of 20 °C / min and kept at this temperature for 70 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead and zinc.

[0048] (2) The roasted slag in step (1) is water-cooled and ground to -400 mesh and then subjected to weak magnetic separation (70 kA / m) to obtain iron powder and tailings.

[0049] The calculated recoveries of tin, arsenic, lead, and zinc were 55.13%, 34.12%, 92.86%, and 85.12%, respectively. The iron powder grade was 83.14% with a recovery rate of 72%. The results showed that it was difficult to efficiently separate iron and arsenic from iron, resulting in a reduced iron grade and excessive tin and arsenic impurity content in the metallic iron powder, making it difficult to use.

[0050] Comparative Example 3

[0051] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of iron powder comprises the following steps:

[0052] (1) 100 wt% high-tin tin tailings were mixed with 1.5 wt% lignite + 6.5 wt% petroleum coke to form pellets, which were dried. Then, 100 wt% of the pellets were mixed with 20 wt% lignite and heated to 1050 ℃ at a heating rate of 20 ℃ / min and kept warm for 70 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead and zinc.

[0053] (2) The roasted slag in step (1) is water-cooled and ground to -400 mesh and then subjected to weak magnetic separation (70 kA / m) to obtain high-quality iron powder and tailings.

[0054] The calculated recoveries of tin, arsenic, lead and zinc were 92.44%, 91.21%, 94.86% and 78.21% respectively, but the iron powder grade was 77.23% and the recovery rate was 64.12%. However, the tin enrichment ratio in the tin, lead, zinc and arsenic-containing smoke was only 5, which significantly reduced the quality of the tin smelting raw materials.

[0055] Comparative Example 4

[0056] A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of iron powder comprises the following steps:

[0057] (1) 100 wt% high-tin tin tailings and 30 wt% bituminous coal were uniformly mixed to form pellets, dried, and then heated to 1050°C at a heating rate of 20°C / min and kept warm for 70 min. The flue gas was cooled to obtain smoke containing tin, arsenic, lead, and zinc.

[0058] (2) The roasted slag in step (1) was water-cooled and ground to -250 mesh before being subjected to weak magnetic separation (0.3×10 5 A / m) separation can obtain iron powder and tailings.

[0059] The calculated recoveries of tin, arsenic, lead, and zinc were 51.13%, 38.12%, 93.86%, and 78.12%, respectively. The iron powder grade was 93.15% and the recovery rate was 84.12%. It was difficult to separate tin, arsenic, and iron, and the quality of the metallic iron powder was poor.

[0060] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder, characterized by: The steps include: (1) mixing high-tin tin tailings with a first reducing agent to form pellets, drying the pellets, mixing them with a second reducing agent, heating them to 900-1100° C., and keeping the temperature for 20-150 minutes to obtain flue gas and roasted slag, and cooling the flue gas to obtain smoke containing tin, arsenic, lead, and zinc; (2) The roasted slag is water-cooled and ground, and then magnetically separated to obtain high-quality iron powder.

2. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The high-tin tin tailings contain 0.4-1.2 wt% tin, 5-50 wt% iron, 0.1-3 wt% arsenic, 0.1-5 wt% lead, and 0.1-5 wt% zinc.

3. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The mass ratio of the high-tin tin tailings to the first reducing agent is 100:(5-15).

4. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The first reducing agent includes reducing agent A and reducing agent B; the reducing agent A is a reducing agent with a carbon dioxide reaction rate greater than 25% in the temperature range of 600-900°C; the reducing agent B is a reducing agent with a carbon dioxide reaction rate less than 20% in the temperature range of 900-1100°C; the mass ratio of reducing agent A to reducing agent B is (5-25):(95-75).

5. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The particle size of the reducing agent A is less than 150 mesh; the particle size of the reducing agent B includes a coarse particle size and a fine particle size, the coarse particle size is 50-120 mesh, the fine particle size is 200-400 mesh, and the mass ratio of the coarse particle size to the fine particle size is (20-70):(80-30).

6. The method for preparing high-quality iron powder from high-tin tin tailings by enhanced separation of multiple metals according to claim 1, characterized in that: The second reducing agent has a carbon content greater than 75% and a particle size of 2.5 cm to 200 meshes; the mass ratio of the pellets to the second reducing agent is 100:(5-50).

7. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The particle size of the roasted slag after grinding is less than 200 meshes, and the magnetic field intensity of the magnetic separation is 70-140 kA / m.

8. The method for enhanced separation of multiple metals from high-tin tin tailings and preparation of high-quality iron powder according to claim 1, characterized in that: The grade of the high-quality iron powder is greater than 98%.

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