A method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide

Abstract

The application discloses a method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide, and comprises the following steps: S1, crushing a screened manganese-containing mixed ore, a solvent and a carbonaceous reducing agent to a particle size required by a semi-closed ore-heating furnace, and then performing batching to obtain a mixture; S2, adding the mixture obtained in the step S1 into the semi-closed ore-heating furnace to perform a high-temperature reduction reaction; and S3, after the high-temperature reduction in the step S2, Li2O in spodumene is reduced to metallic lithium in the ore-heating furnace by C, but due to high smelting temperature, Li is volatilized to contact carbon dioxide and oxygen in the air, is reduced to Li2O and is enriched in the smoke dust ash, so that Li2O can be recovered from lithium-rich smoke dust ash collected from a smoke dust collection system of the semi-closed ore-heating furnace in the smelting process; meanwhile, the semi-closed ore-heating furnace can discharge the product low-aluminum micro-carbon manganese-silicon alloy and the slag which can be sold to a cement plant. The method solves the problems that in the prior art, when lithium-containing ores are used as raw materials to smelt manganese-silicon alloy, aluminum and carbon impurities are difficult to control, the grade of lithium recovery products is low, and subsequent treatment is complex.

Description

Technical Field

[0001] This invention patent belongs to the technical field of manganese silicon alloy smelting and comprehensive utilization of lithium resources, specifically relating to a method for preparing low-aluminum micro-carbon manganese silicon alloy and enriching lithium dioxide. Background Technology

[0002] Lithium is an important strategic metal, playing an irreplaceable role in lithium batteries, the nuclear industry, glass and ceramics, and lubricating greases. my country's lithium resources mainly consist of salt lake brines and lithium-bearing ores. Spodumene and lepidolite are important raw materials for lithium extraction. Some lithium-bearing ores, such as spodumene, often contain high levels of silicon and aluminum, making them potential raw materials for manganese-silicon alloys. However, traditional smelting processes for these complex resources often focus only on the extraction of the main metal, neglecting the synergistic utilization of multiple components. This leads to lithium resource loss, limited alloy quality, and low overall recovery rates. While existing technologies attempt to simultaneously recover manganese, silicon, and lithium through high-temperature reduction smelting, significant challenges remain in controlling the aluminum and carbon impurity content in the alloy and improving the purity of lithium concentrates.

[0003] Regarding the comprehensive utilization of manganese, silicon, and lithium-containing raw materials in the smelting of manganese-silicon alloys, prior art document CN114015873A discloses a method for preparing manganese-silicon alloys from lithium ore and enriching lithium. This method uses lithium ore as raw material and, through steps such as batching, agglomeration, and high-temperature reduction smelting, allows manganese and silicon to be reduced by carbon and incorporated into the alloy. Simultaneously, lithium volatilizes at high temperature and enters the flue gas, which is then collected by dust collectors to obtain lithium-containing dust. This achieves preliminary lithium enrichment during the preparation of manganese-silicon alloys. This method provides a useful reference for the synergistic recovery of multiple metal components from lithium-containing ores.

[0004] However, the methods disclosed in the aforementioned comparative documents still have significant shortcomings. First, lithium ore typically contains a certain amount of impurities such as Al₂O₃. Under carbothermic reduction conditions, some aluminum is reduced into the manganese-silicon alloy, resulting in a high aluminum content in the alloy, making it difficult to meet the quality requirements of low-aluminum manganese-silicon alloys. Second, to ensure the reduction rate of manganese and silicon, this method requires the addition of a large amount of carbonaceous reducing agent, and the melting endpoint is not easily controlled precisely, which can easily lead to carbon enrichment in the alloy, resulting in a high carbon content in the product and making it impossible to obtain a low-carbon manganese-silicon alloy. Third, the lithium enrichment product is mainly lithium-containing dust, in which lithium exists in complex forms, has a high impurity content, and a low Li₂O grade, making subsequent lithium extraction processes cumbersome and difficult to directly obtain high-grade lithium dioxide enrichment.

[0005] Therefore, there is an urgent need for a method that uses lithium-containing ore as raw material to simultaneously prepare low-alumina micro-carbon manganese silicon alloy and efficiently enrich lithium dioxide, so as to improve the quality of manganese silicon alloy, simplify the lithium recovery process and improve the utilization rate of lithium resources. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a method for preparing low-aluminum, low-carbon manganese-silicon alloys and enriching lithium dioxide. The aim is to effectively suppress the aluminum and carbon content in the manganese-silicon alloys by optimizing the raw material ratio, controlling the reducing atmosphere and temperature regime, and combining it with the flue gas capture system of a semi-closed submerged arc furnace, while simultaneously promoting the enrichment of lithium in the flue dust in the form of high-purity Li2O.

[0007] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: a method for preparing low-aluminum micro-carbon manganese silicon alloy and enriching lithium dioxide, specifically including the following steps:

[0008] S1. After crushing the screened manganese-containing mixed ore, solvent, and carbonaceous reducing agent to the particle size required for the semi-closed submerged arc furnace, the mixture is batched to obtain the mixed material.

[0009] S2. Add the mixture obtained in S1 to a semi-closed submerged arc furnace for high-temperature reduction reaction;

[0010] After high-temperature reduction by S2, Li2O in spodumene is reduced to metallic lithium by C in the submerged arc furnace. However, due to the high smelting temperature, Li volatilizes and comes into contact with carbon dioxide and oxygen in the air, and is reduced to Li2O and enriched in the flue dust. Thus, Li2O can be recovered from the lithium-rich flue dust collected by the semi-closed submerged arc furnace flue dust collection system during the smelting process. At the same time, the semi-closed submerged arc furnace can produce low-aluminum micro-carbon manganese silicon alloy and slag that can be sold to cement plants.

[0011] As a further preferred embodiment, the manganese-containing mixed ore in S1 is composed of sintered ore, bauxite, high-carbon slag, manganese-rich slag, and South African semi-carbonate, and the mass ratio of sintered ore, bauxite, high-carbon slag, manganese-rich slag, and South African semi-carbonate is 1:1:0.85:0.75:1.4, and the elemental composition and content percentage of the manganese-containing mixed ore are: Mn: 35%~40%, Fe: 4%~4.5%, P: 0.03%~0.06%, SiO2: 15%~18%, CaO: 5%~7%, MgO: 2.00%~2.15%, Al2O3: 4.5%~5%.

[0012] As a further preferred embodiment, the solvent in S1 is spodumene, and the elemental composition and percentage content of spodumene are SiO2: 65%~75%, Al2O3: 15%~25%, and Li2O: 1%~5%.

[0013] As a further preferred embodiment, the carbonaceous reducing agent in S1 includes, but is not limited to, one or more of bituminous coal, anthracite, coke, pre-calcined coke, and post-calcined coke in any proportion, and the percentage of carbon content in the carbonaceous reducing agent must be not less than 83%.

[0014] As a further preferred embodiment, in S1, the particle size of the manganese-containing mixed ore in the crushed mixture is [value missing], the particle size of the solvent is [value missing], and the particle size of the carbonaceous reducing agent is [value missing], and the mass ratio of the manganese-containing mixed ore, solvent, and carbonaceous reducing agent during batching is 1:0.4:0.32.

[0015] As a further preferred embodiment, during the screening and batching process in S1, the ratio of important elements in the mixture should be controlled as follows: Mn / Fe > 7.8, Mn / P > 557, Mn / SiO = 20.78, Si / Al = 3.98.

[0016] As a further preferred embodiment, the high-temperature reduction reaction in S2 is carried out at a temperature of 1450–1600°C for 2–3 hours, and a continuous feeding method is adopted to ensure the continuous progress of the reaction.

[0017] As a further preferred embodiment, the Li2O content in the lithium-rich flue dust collected by the semi-closed submerged arc furnace dust collection system in S3 can account for 7% to 7.5% of the total mass of the flue dust.

[0018] As a further preferred embodiment, the elemental composition and percentage content of the low-aluminum micro-carbon manganese silicon alloy obtained in step S3 are as follows: Mn: 60%~65%, Fe: 8%~8.5%, P: 0.05%~0.15%, Si: 29%~32%, C: 0.05%~0.15%, Al: 1%~2%.

[0019] The reaction processes involved in the smelting process of this invention are as follows:

[0020] aMnO + bSiO₂ + cAL₂O 3+d Li₂O + eFe₂O₃ + nC fMn+gSi+kFe+rP+hAL+iLi +gCO2

[0021] Li+O2 Li2O (enriched in smoke and dust)

[0022] Where: a, b, c, d, e, and n satisfy the mass ratio of manganese-containing mixed ore, solvent, and carbonaceous reducing agent as 1:0.4:0.32;

[0023] f, g, k, r, and h satisfy the elemental composition and percentage content of the low-aluminum micro-carbon manganese silicon alloy product as follows: Mn: 60%~65%, Fe: 8%~8.5%, P: 0.05%~0.15%, Si: 29%~32%, C: 0.05%~0.15%, Al: 1%~2%.

[0024] The beneficial effects of this invention are:

[0025] 1. By synergistically controlling the raw material composition and smelting process, the stable preparation of low-aluminum (Al ≤ 2%) and low-carbon (C ≤ 0.15%) manganese silicon alloys was successfully achieved, meeting the stringent requirements of high-end special steel smelting for alloy impurity content;

[0026] 2. By utilizing the flue gas capture system of a semi-closed submerged arc furnace, volatile lithium is efficiently enriched in the flue dust in the form of Li2O, with a Li2O grade of 7%~7.5%, which is significantly higher than that of lithium-containing dust obtained by traditional processes, providing high-quality raw materials for subsequent direct purification or wet leaching.

[0027] 3. By introducing lithium-containing ore as a solvent into the manganese-silicon alloy smelting system, the synergistic recovery of multiple components such as lithium, manganese, silicon, and iron was achieved, avoiding the loss of lithium resources and improving the overall resource utilization rate.

[0028] 4. The produced slag has stable composition and high vitrification degree, and can be directly used as cement admixture, realizing the resource utilization of solid waste, which is in line with the concept of green metallurgy and circular economy. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the method for producing low-carbon manganese-silicon alloy according to the present invention; Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] The inventors have discovered the following problems in the existing technology regarding the comprehensive utilization of manganese, silicon, and lithium-containing raw materials in manganese-silicon alloy smelting: When using manganese, silicon, and lithium-containing ores as raw materials for manganese-silicon alloy smelting, the inherent Al2O3 in the raw materials is difficult to completely suppress its reduction tendency under high-temperature carbothermic reduction conditions, resulting in a generally high aluminum content in the obtained alloy, failing to meet the industrial standards for low-aluminum manganese-silicon alloys. Simultaneously, to ensure sufficient reduction of manganese and silicon, excessive amounts of coke or coal-based reducing agents are usually added during the process, often resulting in a high carbon content in the alloy, making it difficult to achieve the low-carbon target. Furthermore, lithium volatilized into the flue gas mainly exists in the form of Li2O, LiF, or lithium silicate particles. The enriched material obtained after smelting and dust collection has a complex composition, with low Li2O grade and a large amount of impurity oxides, which not only increases the impurity removal burden of subsequent wet lithium extraction but also significantly reduces lithium recovery efficiency and product purity. These problems severely restrict the high-value and clean utilization of lithium-containing ore resources.

[0034] Therefore, as Figure 1 As shown, the inventors provide a method for preparing low-aluminum micro-carbon manganese-silicon alloys and enriching lithium dioxide, specifically including the following steps:

[0035] S1. After crushing the screened manganese-containing mixed ore, solvent, and carbonaceous reducing agent to the particle size required for the semi-closed submerged arc furnace, the mixture is batched to obtain the mixed material.

[0036] Furthermore, the manganese-containing mixed ore in S1 is composed of sintered ore, bauxite, high-carbon slag, manganese-rich slag, and South African semi-carbonate, and the mass ratio between the sintered ore, bauxite, high-carbon slag, manganese-rich slag, and South African semi-carbonate is 1:1:0.85:0.75:1.4, and the elemental composition and content percentage of the manganese-containing mixed ore are Mn: 35%~40%, Fe: 4%~4.5%, P: 0.03%~0.06%, SiO2: 15%~18%, CaO: 5%~7%, MgO: 2.00%~2.15%, Al2O3: 4.5%~5%.

[0037] Furthermore, the solvent in S1 is spodumene, and the elemental composition and percentage content of spodumene are SiO2: 65%~75%, Al2O3: 15%~25%, and Li2O: 1%~5%.

[0038] Furthermore, the carbonaceous reducing agent in S1 includes, but is not limited to, one or more of bituminous coal, anthracite, coke, pre-calcined coke, and post-calcined coke in any proportion, and the percentage of carbon content in the carbonaceous reducing agent must be no less than 83%.

[0039] Furthermore, in S1, the particle size of the manganese-containing mixed ore in the crushed mixture is [value missing], the particle size of the solvent is [value missing], and the particle size of the carbonaceous reducing agent is [value missing], and the mass ratio of the manganese-containing mixed ore, solvent, and carbonaceous reducing agent during batching is 1:0.4:0.32.

[0040] Furthermore, during the screening and batching process in S1, the ratio of important elements in the mixture must be controlled as follows: Mn / Fe > 7.8, Mn / P > 557, Mn / SiO = 20.78, and Si / Al = 3.98.

[0041] S2. Add the mixture obtained in S1 to a semi-closed submerged arc furnace for high-temperature reduction reaction;

[0042] Furthermore, the high-temperature reduction reaction in S2 is carried out at a temperature of 1450–1600°C for 2–3 hours, and a continuous feeding method is adopted to ensure the continuous progress of the reaction.

[0043] After high-temperature reduction by S2, Li2O in spodumene is reduced to metallic lithium by C in the submerged arc furnace. However, due to the high smelting temperature, Li volatilizes and comes into contact with carbon dioxide and oxygen in the air, and is reduced to Li2O and enriched in the flue dust. Thus, Li2O can be recovered from the lithium-rich flue dust collected by the semi-closed submerged arc furnace flue dust collection system during the smelting process. At the same time, the semi-closed submerged arc furnace can produce low-aluminum micro-carbon manganese silicon alloy and slag that can be sold to cement plants.

[0044] Furthermore, the Li2O content in the lithium-rich flue dust collected by the semi-closed submerged arc furnace dust collection system in S3 can account for 7% to 7.5% of the total mass of the flue dust.

[0045] Furthermore, the elemental composition and percentage content of the low-aluminum micro-carbon manganese silicon alloy obtained in step S3 are as follows: Mn: 60%~65%, Fe: 8%~8.5%, P: 0.05%~0.15%, Si: 29%~32%, C: 0.05%~0.15%, Al: 1%~2%.

[0046] The reaction processes involved in the smelting process of this invention are as follows:

[0047] aMnO + bSiO₂ + cAL₂O 3+d Li₂O + eFe₂O₃ + nC fMn+gSi+kFe+rP+hAL+iLi +gCO2

[0048] Li+O2 Li2O (enriched in smoke and dust)

[0049] Where: a, b, c, d, e, and n satisfy the mass ratio of manganese-containing mixed ore, solvent, and carbonaceous reducing agent as 1:0.4:0.32;

[0050] f, g, k, r, and h satisfy the elemental composition and percentage content of the low-aluminum micro-carbon manganese silicon alloy product as follows: Mn: 60%~65%, Fe: 8%~8.5%, P: 0.05%~0.15%, Si: 29%~32%, C: 0.05%~0.15%, Al: 1%~2%.

[0051] Based on this, the inventors have drawn the following conclusions:

[0052] This method effectively suppresses the reduction of aluminum into the alloy phase by optimizing the raw material ratio and smelting process, while precisely controlling the carbon potential to achieve a low-carbon target and promoting the selective volatilization and enrichment of lithium in the flue dust. Although the aluminum content in the resulting alloy is still in the range of 1% to 2%, not yet fully meeting the low-aluminum standard (Al ≤ 0.5%), and there is still room for improvement in the Li2O grade in the flue dust, it has made significant progress in impurity control and lithium enrichment efficiency compared to the prior art document CN114015873A. Further steps could be taken to further reduce the aluminum content of the alloy and increase the enrichment concentration of Li2O in the flue dust by adjusting the slag basicity, introducing composite additives, or optimizing the flue gas cooling path, thereby promoting the industrial application of this process.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing low-aluminum micro-carbon manganese silicon alloy and enriching lithium dioxide, characterized in that, Specifically, the following steps are included: S1. After crushing the screened manganese-containing mixed ore, solvent, and carbonaceous reducing agent to the particle size required for the semi-closed submerged arc furnace, the mixture is batched to obtain the mixed material. S2. Add the mixture obtained in S1 to a semi-closed submerged arc furnace for high-temperature reduction reaction; After high-temperature reduction by S2, Li2O in spodumene is reduced to metallic lithium by C in the submerged arc furnace. However, due to the high smelting temperature, Li volatilizes and comes into contact with carbon dioxide and oxygen in the air, and is reduced to Li2O and enriched in the flue dust. Thus, Li2O can be recovered from the lithium-rich flue dust collected by the semi-closed submerged arc furnace flue dust collection system during the smelting process. At the same time, the semi-closed submerged arc furnace can produce low-aluminum micro-carbon manganese silicon alloy and slag that can be sold to cement plants.

2. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The manganese-containing mixed ore in S1 consists of sintered ore, bauxite, high-carbon slag, manganese-rich slag, and South African semi-carbonate, with a mass ratio of 1:1:0.85:0.75:1.

4. The elemental composition and percentage content of the manganese-containing mixed ore are as follows: Mn: 35%~40%, Fe: 4%~4.5%, P: 0.03%~0.06%, SiO2: 15%~18%, CaO: 5%~7%, MgO: 2.00%~2.15%, Al2O3: 4.5%~5%.

3. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The solvent in S1 is spodumene, and the elemental composition and percentage content of spodumene are SiO2: 65%~75%, Al2O3: 15%~25%, and Li2O: 1%~5%.

4. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The carbonaceous reducing agent in S1 includes, but is not limited to, one or more of bituminous coal, anthracite, coke, pre-calcined coke, and post-calcined coke in any proportion, and the percentage of carbon content in the carbonaceous reducing agent must be no less than 83%.

5. The method for preparing low-aluminum micro-carbon manganese silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The particle size of the manganese-containing mixed ore in the crushed mixture in S1 is [value missing], the particle size of the solvent is [value missing], and the particle size of the carbonaceous reducing agent is [value missing]. The mass ratio of the manganese-containing mixed ore, solvent, and carbonaceous reducing agent during batching is 1:0.4:0.

32.

6. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: During the screening and batching process in S1, the ratio of important elements in the mixture must be controlled as follows: Mn / Fe > 7.8, Mn / P > 557, Mn / SiO = 20.78, Si / Al = 3.

98.

7. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The high-temperature reduction reaction in S2 is carried out at a temperature of 1450–1600°C for 2–3 hours, and is conducted using a continuous feeding method to ensure the continuous progress of the reaction.

8. The method for preparing low-aluminum micro-carbon manganese silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The Li2O content in the lithium-rich flue dust collected by the semi-closed submerged arc furnace dust collection system in S3 can account for 7% to 7.5% of the total mass of the flue dust.

9. The method for preparing low-aluminum micro-carbon manganese-silicon alloy and enriching lithium dioxide according to claim 1, characterized in that: The elemental composition and percentage content of the low-aluminum micro-carbon manganese silicon alloy obtained from the furnace in S3 are as follows: Mn: 60%~65%, Fe: 8%~8.5%, P: 0.05%~0.15%, Si: 29%~32%, C: 0.05%~0.15%, Al: 1%~2%.

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