Method for high-tin tin tailings polymetallic enhanced separation and preparation of high-quality iron powder

Abstract

The application discloses a method for high-tin tin tailing multi-metal reinforced separation and preparation of high-quality iron powder, and belongs to the technical field of efficient recovery and reuse of metal mineral resources.The high-tin tin tailing is uniformly mixed with a first reducing agent to prepare pellets, the pellets are dried, mixed with a second carbonaceous reducing agent, heated to 950-1100 DEG C and kept for 20-150 min to obtain flue gas and roasting slag, and the flue gas is cooled to obtain tin, arsenic, lead and zinc dust; then the roasting slag is ground by water cooling and subjected to magnetic separation, so that high-quality iron powder is obtained.The volatilization rates of tin, arsenic, lead and zinc are all greater than 90%, the iron grade is greater than 98%, and the recovery rate is greater than 75%, thus breaking through the industry difficulty of tin, arsenic reinforced separation and iron deep reduction of tin tailing with high tin content, realizing efficient comprehensive recovery of valuable components and high-value utilization of tin tailing resources, guaranteeing the safe supply of world tin resources, and having important significance for green and sustainable development of the tin industry.

Description

TECHNICAL FIELD

[0001] The application relates to a method for high-tin tin tailing polymetallic intensified separation and preparation of high-quality iron powder, and belongs to the technical field of efficient recycling of metal mineral resources. BACKGROUND

[0002] Tin is an important strategic resource in China and is an indispensable key rare metal. During the development and utilization of tin mines, a large amount of tin tailings is produced and stored all over the world. Process mineralogy results show that tin tailings usually contain iron, arsenic, lead, zinc and sulfur components, and the tin content is 0.2-0.8%, mainly in the form of fine-grained cassiterite, which is densely intergrown with iron ore and has poor monomer dissociation degree. After pretreatment, tin, iron, arsenic, lead and zinc can be efficiently enriched, and the tin content is enriched to 0.4%-1.2%, but it is difficult to use in the existing tin smelting process.

[0003] The disposal process of low-grade tin resources mainly includes two categories of beneficiation method, combined method of beneficiation and smelting, and roasting process. Because tin is brittle and has fine embedded particle size, the beneficiation method often adopts combined process of stage grinding and gravity separation, flotation and magnetic separation, which can enrich the tin grade to 3-40%, and is used for smelting in a smoke furnace or an ausmelt reduction, which has the advantages of low processing cost, simple operation, etc., but also has the disadvantages of low recovery rate of valuable metals, high environmental hazards of secondary tailings storage, low economic benefits, etc. The combined process of beneficiation and smelting (CN116889925A, a tin tailing classification pre-concentration-classification separation and recovery of tin and iron) obtains tin-iron co-associated minerals and strong magnetic separation iron concentrate through classification-gravity separation-strong magnetic separation. The tin-iron co-associated minerals are reduced and roasted at 650 DEG C and 10wt% addition to convert Fe2O3 into Fe3O4, and the roasting product is separated by magnetic separation to obtain iron concentrate with an iron grade of 61.16%, a comprehensive recovery rate of 23.00%, tin-rich middlings with 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 DEG C and 15% lignite addition, and ground-weakly magnetically separated to obtain iron concentrate with an iron grade of 60.34% and a comprehensive recovery rate of 48.02%. Because tin and arsenic are easy to form tin / arsenic iron spinel Fe x (Sn, As) 3-xO4, resulting in the inability of the magnetization roasting process in the combined smelting to achieve efficient separation of tin, arsenic and iron, and the tin content (>0.3%) and arsenic content in the obtained iron concentrate of tin-arsenic-iron associated minerals being seriously over-standard, resulting in the inability of the iron concentrate powder to be used (the steel industry requires the tin content to be <0.08%) and the waste of tin resources. More importantly, the iron content of the iron concentrate powder is only 60-65%, and the economic value is low. Because the chlorination roasting is highly polluting, it cannot be applied in industry, and the current roasting processes include reduction roasting and sulfidation roasting. The reduction roasting (CN102965522B, a method for separating and recovering tin from a tin-containing tailing) is heated at 850-1000°C under a weak reduction atmosphere (the volume concentration of CO in CO / (CO+CO2) is 20%-50%) to reduce and volatilize the tin in the tailing into the flue gas, but this method is only suitable for tailings with a tin content of <0.3% and the recovery rate is <75%, and the iron cannot be recycled. The sulfidation roasting (CN103088181B, a method for obtaining sponge iron by treating high-iron low-tin ore through sulfidation volatilization direct reduction) is used to treat high-iron low-tin ore (Sn: <0.4%) at 1000-1300°C, and the obtained sponge content is 90-92%. More importantly, when the tin and arsenic contents in the ore are high, the tin and arsenic contents in the sponge iron are also significantly increased, which makes it difficult to utilize.

[0004] In summary, the physicochemical properties of tin, arsenic and iron are similar, and the existing technology is 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 the iron product, causing waste of tin resources and poor product quality and low value, and being difficult to be industrialized. At present, the utilization rate of tin tailings is very low, and they are discarded in the open environment of the tailings pond, occupying a large amount of land resources, and the harmful elements such as arsenic, lead and zinc in the ore also pollute the surrounding water, soil and crops. Therefore, it is urgent to break through the bottleneck of efficient utilization of tin and iron in high-tin tin tailings, and to improve the availability of world tin resources, which is of great significance to the green and sustainable development of the tin industry. SUMMARY

[0005] In order to overcome the problems in the background art, the purpose of the present application is to provide a method for multi-metal enhanced separation and preparation of high-quality iron powder from high-tin tin tailings, which is based on the different reduction and volatilization characteristics of tin, arsenic and iron phases, and through the coupling of key parameters such as the type, mixing ratio, addition method and temperature of carbonaceous reducing agent, the volatilization of arsenic and tin is controlled before FeO is reduced to Fe, and the problems of simultaneous separation of tin and arsenic and deep reduction of iron (FeO is reduced to Fe) in the tin industry are solved, and valuable metals such as lead and zinc can be recovered at the same time. The efficient enrichment of tin, lead, zinc and arsenic in the flue dust can be used as high-quality tin raw material, and compared with the iron concentrate and sponge iron, the iron powder obtained by the present application has high grade and low impurity content, realizing the high-value utilization of tin tailings, and having great popularization and application.

[0006] In order to achieve the above-mentioned purpose, the present application realizes the following technical scheme:

[0007] A method for preparing high-quality iron powder by high-tin tin tailings multi-metal enhanced separation, comprising the following steps:

[0008] (1) uniformly mixing the high-tin tin tailings with a first reducing agent to form pellets, drying the pellets and mixing with a second reducing agent to heat to 950-1100°C and hold for 20-150 min to obtain flue gas and roasting slag, and cooling the flue gas to obtain tin, arsenic, lead, zinc-containing dust;

[0009] (2) after the roasting slag is ground by water cooling and then subjected to magnetic separation, high-quality iron powder can be obtained.

[0010] Preferably, the high-tin tin tailings contain 0.4-1.2wt% tin, 5-50wt% iron, 0.1-3wt% arsenic, 0.1-5wt% lead, and 0.1-5wt% 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 comprises a reducing agent A and a reducing agent B; the reducing agent A is a reducing agent with a carbon dioxide reaction rate >25% in the temperature range of 600-900°C, such as waste activated carbon, waste engine oil, biomass oil, bituminous coal, or semi-coke, etc., with a particle size <150 mesh. The reducing agent B is a reducing agent with a carbon dioxide reaction rate <20% in the temperature range of 900-1100°C, such as petroleum coke, coke, or defluorinated aluminum electrolysis waste cathode carbon, with a particle size comprising coarse and fine particle sizes, the coarse particle size being 50-120 mesh, and the fine particle size being 200-400 mesh, and the mass ratio of the coarse particle size to the fine particle size being (20-70):(80-30).

[0013] The carbon dioxide reaction rate refers to the chemical reactivity of carbon materials such as coal to carbon dioxide, which is represented 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 >75%, comprising 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-200 mesh, and the mass ratio of the pellets to the second carbonaceous reducing agent being 100:(5-50).

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

[0017] Preferably, the high-quality iron powder has a grade >98%.

[0018] The beneficial effects of the present application are as follows:

[0019] (1) The present application uses a simple, efficient, safe and low-cost method of high-tin tin tailings multi-metal enhanced separation to prepare high-quality iron powder, which solves the problem of efficient separation of tin, lead and zinc in 0.4% to 1.2% tin tailings and deep reduction of iron industry. The tin recovery rate is > 95%, which breaks through the bottleneck of acid-soluble tin and tin stone micro-fine and dense symbiosis in the mainstream mineral processing joint process, and significantly improves 15-50%.

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

[0021] The present application will be further described in detail below in conjunction with specific examples, but the scope of protection of the present application is not limited thereto.

[0022] Example 1

[0023] A high-tin tin tailings multi-metal enhanced separation and preparation method of high-quality iron powder, comprising the following steps:

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

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

[0026]

[0027] (2) The above 100wt% high-tin tin tailings are mixed with 1.5wt% of lanthanum carbon and 6.5wt% of petroleum coke to make pellets, dried, and then 100wt% of the pellets are mixed with 20wt% of bituminous coal at a heating rate of 20℃ / min to 1050℃ and kept for 70min, and the flue gas is cooled to obtain tin, arsenic, lead and zinc dust.

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

[0029] The calculated recovery rates of tin, arsenic, lead, and zinc are 95.41%, 94.26%, 98.21%, and 90.25%, respectively, the grade of high-quality iron powder is 98.15%, and the recovery rate is 77.21%, the content of impurity elements such as tin, arsenic, lead, and zinc in the high-quality iron powder is less than 0.02%, 0.05%, 0.03%, and 0.04%, respectively. The results show that the tin tailings are subjected to strengthened separation of tin, lead, and zinc and simultaneous high-value reuse of iron, and the amount of arsenic-containing waste is reduced. The tin enrichment ratio in the tin, lead, zinc, and arsenic-containing flue dust is greater than 10, which can be used as a high-quality raw material for current tin smelting.

[0030] Example 2

[0031] A method for high-tin tin tailings multi-metal strengthened separation and preparation of high-quality iron powder, comprising the following steps:

[0032] (1) 100wt% high-tin tin tailings are uniformly mixed with 1wt% bituminous coal + 8wt% coke to form pellets, which are dried, and then 100wt% of the pellets are mixed with 20wt% of semicoke at a temperature increasing rate of 30℃ / min to 1000℃ and kept for 150min, and the flue gas is cooled to obtain tin, arsenic, lead, and zinc-containing flue dust.

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

[0034] The calculated recovery rates of tin, arsenic, lead, and zinc are 94.12%, 95.14%, 99.11%, and 92.43%, respectively, the grade of high-quality iron powder is 98.01%, and the recovery rate is 82%, the content of impurity elements such as tin, arsenic, lead, and zinc in the high-quality iron powder is less than 0.02%, 0.05%, 0.03%, and 0.04%, respectively. The results show that the tin tailings are subjected to strengthened separation of tin, lead, and zinc and simultaneous high-value reuse of iron, and the amount of arsenic-containing waste is reduced. The tin enrichment ratio in the tin, lead, zinc, and arsenic-containing flue dust is greater than 10, which can be used as a high-quality raw material for current tin smelting.

[0035] Example 3

[0036] A method for high-tin tin tailings multi-metal strengthened separation and preparation of high-quality iron powder, comprising the following steps:

[0037] (1) 100wt% high-tin tin tailings are uniformly mixed with 1.1wt% bituminous coal + 13wt% coke to form pellets, which are dried, and then 100wt% of the pellets are mixed with 5wt% of defluorinated aluminum electrolysis waste cathode carbon at a temperature increasing rate of 5℃ / min to 1100℃ and kept for 20min, and the flue gas is cooled to obtain tin, arsenic, lead, and zinc-containing flue dust.

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

[0039] The calculated recoveries of tin, arsenic, lead, and zinc were 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 elements in the high-quality iron powder were <0.02%, 0.03%, 0.02%, and 0.03%, respectively. The results indicate that the enhanced separation of tin, lead, and zinc in tin tailings, combined with the high-value reuse of iron, simultaneously reduces the volume of arsenic-containing waste. The tin enrichment rate in the tin-, lead-, zinc-, and arsenic-containing flue dust is >10%, making it a high-quality raw material for current tin smelting processes.

[0040] Comparative Example 1

[0041] A method for polymetallic enhanced separation and iron powder preparation from high-tin tailings includes the following steps:

[0042] (1) 100wt% high-tin tailings and 10wt% petroleum coke are mixed evenly to form pellets, dried, and then 100wt% pellets are mixed with 20wt% bituminous coal and heated to 1050℃ at a heating rate of 20℃ / min and held for 70min. The flue gas is cooled to obtain tin, arsenic, lead and zinc dust.

[0043] (2) In step (2), the roasted slag is water-cooled and ground to -400 mesh and then separated by weak magnetic separation (70kA / 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, while the iron powder grade was 96.05% with a recovery rate of 78%. The results indicate that iron and arsenic are difficult to separate efficiently from iron, the iron grade of the metallic iron powder is reduced, and the content of tin and arsenic impurities exceeds the standard, making it unsuitable for application.

[0045] Comparative Example 2

[0046] A method for polymetallic enhanced separation and iron powder preparation from high-tin tailings includes the following steps:

[0047] (1) 100wt% high-tin tailings and 10wt% semi-coke are mixed evenly to form pellets, dried, and then 100wt% pellets are mixed with 20wt% bituminous coal and heated to 1050℃ at a heating rate of 20℃ / min and held for 70min. The flue gas is cooled to obtain tin, arsenic, lead and zinc dust.

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

[0049] The calculated recovery rates of tin, arsenic, lead, and zinc are 55.13%, 34.12%, 92.86%, and 85.12%, respectively, and the grade of the iron powder is 83.14% with a recovery rate of 72%. The results show that iron and arsenic are difficult to separate efficiently, the grade of the iron powder is reduced, the content of tin and arsenic impurities exceeds the standard, and the iron powder is difficult to apply.

[0050] Comparative Example 3

[0051] A method for high-tin tin tailings multi-metal enhanced separation and preparation of iron powder, comprising the following steps:

[0052] (1) 100wt% high-tin tin tailings are mixed with 1.5wt% of semi-coke and 6.5wt% of petroleum coke to form pellets, which are dried, and then 100wt% of the pellets are mixed with 20wt% of lignite at a temperature increasing rate of 20℃ / min to 1050℃ and kept for 70min, and the flue gas is cooled to obtain tin, arsenic, lead, and zinc-containing dust.

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

[0054] The calculated recovery rates of tin, arsenic, lead, and zinc are 92.44%, 91.21%, 94.86%, and 78.21%, respectively, but the grade of the iron powder is 77.23% with a recovery rate of 64.12%, and the tin enrichment ratio in the tin, lead, zinc, and arsenic-containing dust is only 5, significantly reducing the quality of the tin smelting raw material.

[0055] Comparative Example 4

[0056] A method for high-tin tin tailings multi-metal enhanced separation and preparation of iron powder, comprising the following steps:

[0057] (1) 100wt% high-tin tin tailings are mixed with 30wt% of bituminous coal to form pellets, which are dried, and then heated to 1050℃ at a temperature increasing rate of 20℃ / min and kept for 70min, and the flue gas is cooled to obtain tin, arsenic, lead, and zinc-containing dust.

[0058] (2) The roasting slag in step (1) is ground to-250 mesh by water cooling and then subjected to weak magnetic separation (0.3×10 5 A / m) to obtain iron powder and tailings.

[0059] The calculated recovery rates of tin, arsenic, lead, and zinc are 51.13%, 38.12%, 93.86%, and 78.12%, respectively, and the grade of the iron powder is 93.15% with a recovery rate of 84.12%. Tin and arsenic are difficult to separate, and the quality of the metallic iron powder is poor.

[0060] Finally, it should be noted that the above preferred embodiments are merely intended to illustrate the technical solutions of the present application, not to limit the present application. Even though the present application has been described in detail by the above preferred embodiments, those skilled in the art should understand that they can make various modifications in form and details without departing from the scope of the present application defined by the claims.

Claims

1. A method for high-tin tin-tailings polymetallic intensive separation and preparation of high-quality iron powder, characterized in that: The method comprises the following steps: ​ (1) mixing high-tin tin tailings with a first reducing agent to form pellets, drying the pellets, mixing the pellets with a second reducing agent, heating to 900-1100 DEG C and maintaining for 20-150 min to obtain flue gas and roasted slag, and cooling the flue gas to obtain tin, arsenic, lead and zinc-containing dust; (2) after water-cooling and grinding, the roasted slag is subjected to magnetic separation to obtain high-quality iron powder; The first reducing agent comprises a reducing agent A and a reducing agent B; the reducing agent A is a reducing agent with a carbon dioxide reaction rate > 25% in the temperature range of 600-900 DEG C; the reducing agent B is a reducing agent with a carbon dioxide reaction rate < 20% in the temperature range of 900-1100 DEG C; the mass ratio of the reducing agent A to the reducing agent B is (5-25):(95-75); the second reducing agent is a reducing agent with a carbon content > 75%, and the mass ratio of the pellets to the second reducing agent is 100:(5-50).

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

3. The method for multi-metal enhanced separation and preparation of high-quality iron powder from high-tin tin tailings 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 multi-metal enhanced separation and preparation of high-quality iron powder from high-tin tin tailings according to claim 1, characterized in that: The particle size of the reducing agent A is < 150 mesh; the particle size of the reducing agent B comprises 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).

5. The method for preparing high-quality iron powder by multi-metal enhanced separation of high-tin tin tailings according to claim 1, characterized in that: The particle size of the second reducing agent is 200 mesh-2.5 cm.

6. The method for high-tin cassiterite tailings polymetallic intensive separation and preparation of high-quality iron powder according to claim 1, characterized in that: After grinding, the particle size of the roasted slag is < 200 mesh, and the magnetic field strength of the magnetic separation is 70-140 kA / m.

7. The method for multi-metal enhanced separation and preparation of high-quality iron powder from high-tin tin tailings according to claim 1, characterized in that: The grade of the high-quality iron powder is > 98%.

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