Preparation method of industrial silicon and silicon-manganese intermediate alloy and metal manganese in combination

Abstract

The application provides a preparation method of industrial silicon and co-produced silicon-manganese intermediate alloy and metallic manganese, and relates to the technical field of metallic manganese production. The method comprises the following steps: crushing, screening and drying of silica and manganese oxide ore; reaction of silica powder, manganese oxide ore powder, composite reducing agent and quicklime flux; slagging, pouring and cooling after the reaction, casting of iron ingot mold, natural cooling and demolding to obtain Mn24Si70 alloy; the Mn24Si70 alloy contains 23%-25% of Mn, 69%-71% of Si, ≤1.8% of C and ≤0.12% of P; crushing of the Mn24Si70 alloy, adding of manganese-rich slag, Mn24Si70 alloy, quicklime flux and fluorite fluxing agent into a refining furnace for refining, slagging, pouring and cooling after the refining, casting of iron ingot mold, natural cooling and demolding to obtain metallurgical-grade metallic manganese blocks with Mn content ≥99%; therefore, the application first prepares Mn24Si70 alloy by using silica and manganese oxide ore, the Mn24Si70 alloy is a high-silicon reducing agent and can be sold or used for preparation of metallic manganese, thereby reducing the cost of purchased industrial silicon.

Description

Technical Field

[0001] This invention belongs to the field of metallic manganese production technology, specifically relating to an industrial silicon-manganese co-production intermediate alloy and a method for preparing metallic manganese. Background Technology

[0002] Currently, when producing metallic manganese, an electro-silicon thermal refining furnace is used alone. This method relies entirely on purchasing industrial silicon / high-silicon manganese reducing agent. The price of purchased raw materials is affected by the dual cycles of photovoltaic and ferroalloy production, making costs uncontrollable and preventing continuous production. At the same time, manganese slag and silicon-based dust are disposed of separately, resulting in low resource recovery rates.

[0003] In the prior art, Chinese invention application number 202210998134.1 discloses a process for producing metallic manganese using a large-scale submerged arc furnace, specifically including the following processing steps: S1, material conveying; S2, material batching; S3, material distribution; S4, material refining; and S5, material recovery. This invention can achieve the silicothermic preparation of metallic manganese using conventional material conveying equipment, batching equipment, distribution equipment, and a submerged arc furnace. The cost is low, and the equipment wear is extremely small compared to the traditional electrolytic method. However, this invention still requires the purchase of a composite deoxidizer for silicomanganese alloy during the preparation process, and the manganese slag and silicon dust are disposed of separately, resulting in a low resource recovery rate. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing industrial silicon-manganese intermediate alloy and metallic manganese, so as to prepare a high silicon reducing agent (Mn24Si70 alloy) without external purchase, and simultaneously use two solid wastes, manganese slag and silicon dust, to prepare two products, which can achieve continuous production and improve resource recovery rate.

[0005] A method for preparing an industrial silicon-manganese co-production intermediate alloy and metallic manganese includes the following steps: S1: Crush, sieve and dry silica and manganese oxide ore to obtain silica powder and manganese oxide ore powder; S2: Silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, the slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. The Mn24Si70 alloy contains 23%-25% Mn, 69%-71% Si, ≤1.8% C, and ≤0.12% P. S3: Crush the Mn24Si70 alloy, add the manganese-rich slag, crushed Mn24Si70 alloy, quicklime flux, fluorite flux, and silicon manganese powder into the refining furnace for refining. After refining, remove the slag, pour and cool, cast iron ingot mold, and demold naturally to obtain metallurgical grade manganese metal blocks with Mn content ≥99%.

[0006] Preferably, the composite reducing agent is one or two of semi-coke and charcoal, and the fixed carbon content in the composite reducing agent is ≥83%.

[0007] Preferably, the silica contains ≥99% SiO2 and ≤0.4% Al2O3, the manganese oxide ore contains ≥33% Mn and ≤0.15% P, and the quicklime flux contains ≥85% CaO.

[0008] Preferably, the mass ratio of silica, manganese oxide ore, composite reducing agent, and quicklime flux is 57-59:8.5-9.5:27.5-29.5:1-1.65.

[0009] Preferably, step S3 specifically includes the following steps: Pretreatment: The manganese-rich slag is melted, and the manganese melt with a Mn content greater than 45% and the Mn24Si70 alloy are mixed and stirred under argon to pre-reduce part of the MnO to obtain a pre-reduced molten solution. Refining: Mn24Si70 alloy, quicklime flux, and fluorite flux are added to the pre-reduced molten solution for refining. After refining, slag is removed, the solution is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain metallurgical grade manganese metal blocks with Mn content ≥99%, achieving deep dephosphorization and dealuminization.

[0010] Preferably, the alkalinity of the refining furnace slag is 1.8 to 2.2.

[0011] Preferably, the Mn24Si70 alloy is added in batches during the pretreatment and refining steps to avoid significant fluctuations in the molten pool temperature caused by the Mn24Si70 alloy and to improve the stability of the dephosphorization and dealuminization reaction.

[0012] Preferably, in the refining step, the mass ratio of the pre-reduced molten manganese slag, Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro powder is 61.7-66: 12.7-14.5: 30.7-35.5: 1-1.7: 1.5-3.5.

[0013] Preferably, in the pretreatment step, the mass ratio of the manganese-rich slag to the Mn24Si70 alloy is 2-3:1.

[0014] Preferably, in step S2, the temperature is a smelting temperature of 1780~1900℃ and the time is 90-120min; in step S3, the temperature is a smelting temperature of 1600~1680℃ and the time is 90-120min.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for preparing industrial silicon-manganese co-production intermediate alloy and metallic manganese. The method involves crushing, sieving, and drying silica and manganese oxide ore to obtain silica powder and manganese oxide ore powder. The silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. The Mn24Si70 alloy contains 23%-25% Mn and 1% Si. The alloy has a content of 69%-71%, a carbon content of ≤1.8%, and a phosphorus content of ≤0.12%. The Mn24Si70 alloy is crushed, and the manganese-rich slag, crushed Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro-powder are added to a refining furnace for refining. After refining, the slag is removed, the alloy is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain metallurgical-grade manganese metal blocks with a Mn content ≥99%. Therefore, this invention breaks the traditional complete dependence of manganese metal smelting on high-purity industrial silicon (or ferrosilicon alloy). By utilizing low-value silica and manganese oxide ore to pre-prepare a high-silicon intermediate alloy of Mn24Si70 with specific compositions, the "purchase of expensive reducing agents" model is transformed into a "self-made low-cost intermediate" model. Furthermore, the silicon content in the prepared Mn24Si70 alloy is as high as 69%-71%, far exceeding the silicon content of conventional silicon-manganese alloys. It can be sold directly to the market as a high-value-added product, or it can be used as an internal intermediate in the production of downstream metallic manganese, which reduces the cost of raw material procurement from the source, while making the production process highly flexible and responsive to the market.

[0016] Secondly, this invention introduces the Mn24Si70 alloy as a "raw material buffer" into the production chain. When the supply of high-quality industrial silicon is tight or its price fluctuates, the reserve of this intermediate alloy can effectively alleviate the raw material shortage and ensure the continuous and stable operation of subsequent manganese refining processes.

[0017] Furthermore, low-value byproducts of silicon-manganese micro-powder produced during silicon smelting and manganese-rich slag generated during the production of Mn24Si70 alloy are used as raw materials for refining; this achieves resource utilization of solid waste and reduces solid waste treatment costs. Simultaneously, when combined with Mn24Si70 containing 69%-71% high silicon, it not only enhances the driving force of the MnO reduction reaction but also replenishes manganese, significantly reducing the residual manganese content in the slag. The resulting metallurgical-grade manganese ingots have an Mn content exceeding 99%, meeting the stringent requirements for high-purity manganese metal in high-end special steel, non-ferrous alloys, and electronic materials industries.

[0018] Finally, by combining "primary smelting in an electric arc furnace" with "deep reduction in a refining furnace", the efficient recovery of manganese from ore to final metal products was achieved, and the overall manganese recovery rate was steadily increased to over 80%. Detailed Implementation

[0019] The technical solutions and effects of the embodiments of the present invention will be further described in detail below.

[0020] A method for preparing an industrial silicon-manganese co-production intermediate alloy and metallic manganese includes the following steps: S1: Crush, sieve and dry silica and manganese oxide ore to obtain silica powder and manganese oxide ore powder; S2: Silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, the slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. The Mn24Si70 alloy contains 23%-25% Mn, 69%-71% Si, ≤1.8% C, and ≤0.12% P. S3: The Mn24Si70 alloy is crushed, and the manganese-rich slag, crushed Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro powder are added to the refining furnace for refining. After refining, the slag is removed, the alloy is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain metallurgical grade manganese metal blocks with a Mn content ≥99%, so as to realize the closed-loop circulation within the plant. The ferrosilicon micro powder is a by-product of silicon smelting, and the manganese-rich slag is a high-manganese slag from manganese smelting.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for preparing industrial silicon-manganese intermediate alloy and metallic manganese by crushing, screening, and drying silica and manganese oxide ore to obtain silica powder and manganese oxide ore powder. The silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, the slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. The Mn24Si70 alloy has an Mn content of 23%-25%, a Si content of 69%-71%, a C content ≤1.8%, and a P content ≤0.12%. The Mn24Si70 alloy is crushed, and the manganese-rich slag, Mn24Si70 alloy, quicklime flux, fluorite flux, and ferromanganese micro powder are added to a refining furnace for refining. After refining, the slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. However, after demolding, metallurgical-grade manganese metal blocks with a Mn content ≥99% are obtained. Therefore, this invention first prepares Mn24Si70 alloy by using silica and manganese oxide ore. Mn24Si70 alloy is a high-silicon reducing agent that can be sold or used in the preparation of metallic manganese, which greatly reduces the cost of purchasing industrial silicon and allows for production to be selected according to market conditions. At the same time, the Mn24Si70 alloy buffers the raw material shortage and improves the stability of continuous production. Secondly, metallic manganese blocks are prepared by using silicon micro powder, a by-product of silicon smelting, and high-manganese slag from manganese smelting, which greatly improves the utilization rate of solid waste and reduces raw material costs. Finally, the Mn24Si70 prepared by this invention contains 69%-71% high silicon, and its reducing ability is much higher than that of conventional 6517 silicon-manganese, which improves the MnO reduction efficiency, reduces manganese ore consumption, and increases the overall manganese recovery rate to over 80%.

[0022] Furthermore, the particle size of the silica powder and manganese oxide ore powder is 20mm~80mm, and the moisture content is ≤0.5%.

[0023] Furthermore, in step S2: the furnace is tamped 40-60 minutes per time to clear the sintered crust around the electrodes and suppress the volatilization of SiO and MnO gas.

[0024] Furthermore, in step S2: the material layer thickness in the industrial silicon submerged arc furnace is 800mm~1100mm to ensure sufficient reaction.

[0025] Furthermore, the composite reducing agent is one or two of semi-coke and charcoal, and the fixed carbon content in the composite reducing agent is ≥83%.

[0026] Furthermore, the silica contains ≥99% SiO2 and ≤0.4% Al2O3, the manganese oxide ore contains ≥33% Mn and ≤0.15% P, and the quicklime flux contains ≥85% CaO, to ensure the manganese and silicon content in the prepared Mn24Si70.

[0027] Furthermore, the mass ratio of silica, manganese oxide ore, composite reducing agent, and quicklime flux is 57-59:8.5-9.5:27.5-29.5:1-1.65 to synergistically ensure the quality of the prepared Mn24Si70.

[0028] Furthermore, the crushed Mn24Si70 alloy is in the form of 10~80mm blocks.

[0029] Furthermore, step S3 specifically includes the following steps: Pretreatment: The manganese-rich slag is melted, and the manganese melt with a Mn content greater than 45% is mixed with Mn24Si70 alloy and stirred under argon to pre-reduce part of the MnO, thus obtaining a pre-reduced molten solution. By performing pretreatment in advance, temperature fluctuations are buffered, and the melt temperature is stabilized at 1550~1620℃. Preheating and buffering in advance stabilize the temperature, and at the same time, pre-reduce part of the manganese oxide, thereby improving refining efficiency, improving the dephosphorization and dealuminization effect of high-alkali slag, and stabilizing the Mn97 / Mn99 grade of metallic manganese. Refining: Mn24Si70 alloy, quicklime flux, and fluorite flux are added to the pre-reduced molten solution for refining. After refining, the slag is removed, the solution is poured and cooled, and cast into an iron ingot mold. After natural cooling and demolding, metallurgical grade manganese metal blocks with Mn content ≥99% are obtained, achieving deep dephosphorization and dealuminization. At the same time, the Mn24Si70 alloy replaces the purchased industrial silicon to reduce costs, while the 24% manganese in Mn24Si70 simultaneously replenishes the manganese source in the molten pool, reducing manganese ore consumption and improving manganese recovery rate. Through pretreatment and refining, the manganese content in the slag is replaced to below 5%.

[0030] The refining reaction is as follows: 2MnO + Si = 2Mn + SiO2.

[0031] Furthermore, the alkalinity of the refining furnace slag is 1.8 to 2.2, so that desulfurization can be carried out by chemical ion exchange reaction.

[0032] Furthermore, the Mn24Si70 alloy needs to be added in batches during the pretreatment and refining steps. By adding Mn24Si70 in batches, the reaction efficiency is improved on the one hand, and the heat released by the reduction reaction is balanced by the addition of cold Mn24Si70 to avoid the Mn24Si70 alloy causing large fluctuations in the molten pool temperature and improving the stability of the dephosphorization and dealuminization reaction.

[0033] Furthermore, in the refining step, the mass ratio of the pre-reduced molten manganese slag, Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro powder is 61.7-66: 12.7-14.5: 30.7-35.5: 1-1.7: 1.5-3.5.

[0034] Furthermore, in the pretreatment step, the mass ratio of the manganese-rich slag to the Mn24Si70 alloy is 2-3:1, preferably 2:1.

[0035] Furthermore, in S2, the temperature is a smelting temperature of 1780~1900℃ and the time is 90-120min; in S3, the temperature is a smelting temperature of 1600~1680℃ and the time is 90-120min. Example

[0036] S1: Silica (SiO2 content ≥99%, Al2O3 content ≤0.4%): 2280~2360kg; Manganese oxide ore (Mn content ≥33%, P content ≤0.15%): 330~370kg; Composite reducing agent (85% semi-coke + 15% charcoal, fixed carbon ≥83%): 1100~1170kg; Quicklime flux (CaO ≥85%): 40~65kg; Raw material pretreatment: Silica and manganese oxide ore are crushed and screened to a particle size of 20~80mm, washed with water to remove mud, dried to a moisture content of ≤0.5%, and stored in independent sealed silos to prevent cross-contamination between high-purity silicon and manganese dust.

[0037] S2: Furnace type: 25000kVA closed rotary industrial silicon submerged arc furnace; molten pool temperature: 1780~1900℃; electrode system: deep-buried electrode thick material layer smelting, material layer thickness 800~1100mm; furnace tamping frequency: 40~60min / time; furnace tapping cycle: 2.5~3.5h / furnace; Silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, the furnace is discharged through a simple slag-blocking channel, and thin silicate slag is manually removed. The mixture is then poured and cooled into an iron ingot mold with a thickness of 80-110 mm. After natural cooling for 3-4 hours, the ingot is demolded to obtain Mn24Si70 alloy. The Mn24Si70 alloy contains 23%-25% Mn, 69%-71% Si, 1.6% C, and 0.12% P.

[0038] S3: In the pretreatment step: the ratio of manganese-rich slag produced by the electric arc furnace to Mn24Si70 alloy is 2:1. In the refining step: pre-reduced molten manganese slag: 1850~1980kg; Mn24Si70 reducing agent: 380~430kg; quicklime flux: 920~1060kg; fluorite flux: 30~50kg; ferrosilicon micro powder: 50kg-100kg; slag basicity is 1.8~2.2.

[0039] Crushing: Mn24Si70 alloy is crushed and screened to obtain 10~80mm blocky Mn24Si70 alloy.

[0040] Pretreatment: The manganese-rich slag produced by the electric arc furnace is melted in a refining furnace. After melting, the manganese melt with a Mn content greater than 45% and a temperature of 1550~1620℃ is mixed with Mn24Si70 alloy in a shaker and stirred under argon to pre-reduce part of the MnO to obtain a pre-reduced molten solution. Refining: The pre-reduced molten solution is added to the refining furnace for melting, and then Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro powder are added for refining. The smelting temperature is 1600~1680℃; the single furnace smelting cycle is 90~120min; after refining, slag is removed, casting is poured and cooled, cast iron ingot mold is formed, and the ingot is naturally cooled and demolded to obtain metallurgical grade manganese metal blocks with Mn content ≥99%; the comprehensive manganese recovery rate is 85%.

[0041] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing an industrial silicon-manganese co-production master alloy and metallic manganese, characterized in that, Includes the following steps: S1: Crush, screen, and dry silica and manganese oxide ore to obtain silica powder and manganese oxide ore powder; S2: Silica powder, manganese oxide ore powder, composite reducing agent, and quicklime flux are added to an industrial silicon submerged arc furnace for reaction. After the reaction, the slag is removed, the mixture is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain manganese-rich slag and Mn24Si70 alloy. The Mn24Si70 alloy contains 23%-25% Mn, 69%-71% Si, ≤1.8% C, and ≤0.12% P. S3: Crush the Mn24Si70 alloy, add the manganese-rich slag, crushed Mn24Si70 alloy, quicklime flux, fluorite flux, and silicon manganese powder into the refining furnace for refining. After refining, remove the slag, pour and cool, cast iron ingot mold, and demold naturally to obtain metallurgical grade manganese metal blocks with Mn content ≥99%.

2. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 1, characterized in that, The composite reducing agent is one or two of semi-coke and charcoal, and the fixed carbon content in the composite reducing agent is ≥83%.

3. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 2, characterized in that, The silica contains ≥99% SiO2 and ≤0.4% Al2O3, the manganese oxide ore contains ≥33% Mn and ≤0.15% P, and the quicklime flux contains ≥85% CaO.

4. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 1, characterized in that, The mass ratio of silica, manganese oxide ore, composite reducing agent, and quicklime flux is 57-59: 8.5-9.5：27.5-29.5：1-1.65。 5. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 3, characterized in that, Step S3 specifically includes the following steps: Pretreatment: The manganese-rich slag is melted, and the manganese melt with a Mn content greater than 45% and the Mn24Si70 alloy are mixed and stirred under argon to pre-reduce part of the MnO to obtain a pre-reduced molten solution. Refining: Mn24Si70 alloy, quicklime flux, and fluorite flux are added to the pre-reduced molten solution for refining. After refining, slag is removed, the solution is poured and cooled, cast into an iron ingot mold, and then naturally cooled and demolded to obtain metallurgical grade manganese metal blocks with Mn content ≥99%, achieving deep dephosphorization and dealuminization.

6. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 5, characterized in that, The alkalinity of the refining furnace slag is 1.8~2.

2.

7. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 5, characterized in that, In both the pretreatment and refining steps, the Mn24Si70 alloy needs to be added in batches to avoid significant fluctuations in the molten pool temperature caused by the Mn24Si70 alloy and to improve the stability of the dephosphorization and dealuminization reaction.

8. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 5, characterized in that, In the refining step, the mass ratio of the pre-reduced molten manganese slag, Mn24Si70 alloy, quicklime flux, fluorite flux, and ferrosilicon micro powder is 61.7-66: 12.7-14.5: 30.7-35.5: 1-1.7: 1.5-3.

5.

9. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 5, characterized in that, In the pretreatment step, the mass ratio of the manganese-rich slag to the Mn24Si70 alloy is 2-3:

1.

10. The method for preparing industrial silicon-manganese co-production master alloy and metallic manganese as described in claim 1, characterized in that, In step S2, the temperature is a smelting temperature of 1780~1900℃ and the time is 90-120min. In step S3, the temperature is a smelting temperature of 1600~1680℃ and the time is 90-120min.