Process for the production of manganese-silicon alloys

Abstract

The application provides a preparation method of manganese-silicon alloy and belongs to the technical field of alloy processing. The method comprises the following steps: taking manganese ore raw materials to perform batching, crushing, and screening to obtain manganese ore powder and manganese ore blocks; taking coke to perform crushing and screening to obtain coke powder and coke blocks; mixing the manganese ore powder and the coke powder and pressing into raw material balls, then performing sintering, crushing after cooling to obtain sintered ore; mixing the sintered ore, the manganese ore blocks, the coke blocks, and silica, putting the obtained mixture into an electric arc furnace to perform smelting to obtain molten iron material; discharging the molten iron material into a molten iron ladle and performing blowing with a mixed gas of bottom-blown air and oxygen; after the blowing is completed, performing settling, slagging, casting, and cooling and solidification to form a cast slab, and the manganese-silicon alloy is obtained. The method uses semi-manganese carbonate ore as the main raw material, sintering the manganese ore powder and the coke powder into granular sintered ore material, optimizes the batch structure, increases the batching amount of semi-manganese carbonate ore, reduces the purchasing pressure of manganese ore, and reduces the production cost.

Description

Technical Field

[0001] This invention relates to the field of alloy processing technology, and in particular to a method for preparing a manganese-silicon alloy. Background Technology

[0002] Manganese silicon alloy is an alloy composed of manganese, silicon, iron, and small amounts of carbon and other elements. It is a widely used and produced ferroalloy. Manganese silicon alloy is a commonly used composite deoxidizer in steelmaking and a reducing agent in the production of metallic manganese using the low-carbon ferromanganese and electro-silicon thermal processes. Raw materials for producing manganese silicon alloy include manganese ore, manganese-rich slag, silica, and coke, which are smelted at high temperatures in a submerged arc furnace. The world's manganese ore reserves are approximately 1.7 billion tons, with over 95% concentrated in countries such as South Africa, Ukraine, Australia, Gabon, Brazil, and India. With the continuous expansion of manganese silicon alloy production capacity in recent years, the demand for manganese ore has also increased. Domestic manganese ore is becoming increasingly scarce, necessitating the use of imported manganese ore, which has a larger supply and relatively lower cost. Therefore, my country imports millions of tons of manganese ore annually to meet the needs of its national economic development.

[0003] In the production of ferromanganese alloys, it is widely believed in the industry that South African semi-carbonate manganese ore has poor anti-explosion properties during production. When the temperature reaches 900℃ in the furnace, the ore is prone to exploding, producing some powdery and small-particle ore. This affects the permeability of the furnace bed and disrupts the bed structure during smelting. Simultaneously, South African semi-carbonate ore itself has excessively high alkalinity. If the amount is too large, it will lead to excessively high alkalinity in the final slag, resulting in a large amount of final slag and impacting smelting power consumption. Therefore, most manufacturers only incorporate South African semi-carbonate ore at most 10-15% in the ore blending process. This leads to difficulties in process control, unabated pressure on manganese ore procurement, and high production costs. Furthermore, in the existing technology, the production process of ferromanganese alloys also suffers from incomplete smelting reactions and low raw material utilization. Summary of the Invention

[0004] This invention provides a method for preparing manganese-silicon alloy by optimizing batch structure, improving raw material ratio, and coordinating gradient heating smelting operation to increase the amount of semi-carbonate manganese ore, reduce production power consumption and production costs, and improve product consistency, thereby solving the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides a method for preparing a manganese-silicon alloy, comprising: 1) Batching: Take the various manganese ore raw materials and batch them, then crush and screen the resulting mixed raw materials to obtain manganese ore powder and manganese ore blocks; take coke and crush and screen it to obtain coke powder and coke blocks. 2) Sintering: Manganese ore powder is mixed with coke powder and pressed into raw material spheres. The raw material spheres are then added to a sintering machine for sintering. After cooling, they are crushed to obtain sintered ore. 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture, which is then put into an electric arc furnace for smelting to obtain molten iron. 4) Blowing: The molten iron is discharged into the ladle and blown using a mixture of bottom-blown air and oxygen; 5) Casting: After blowing is completed, the mixture is calmed, slag is removed, and then it is cast into a mold, cooled and solidified to form a billet, thus obtaining the manganese silicon alloy.

[0006] The manganese-silicon alloy of this invention uses semi-carbonate manganese ore as the main raw material, which is mixed with different manganese ore raw materials in a certain proportion. The manganese ore powder and coke powder are sintered into granular sintered ore for use. After adding coke blocks and silica as ingredients, it is obtained by smelting and blowing to remove carbon. In the above preparation process, the preparation method and raw material formula are optimized, which effectively increases the amount of imported South African semi-carbonate manganese ore to more than 45%. This makes the amount of semi-carbonate manganese ore used higher than that in the prior art, effectively reducing the pressure of manganese ore procurement, significantly improving the manganese element recovery rate, and reducing production costs.

[0007] Further preferably, the proportions of each manganese ore raw material and their mass percentages in the mixed raw materials are as follows: based on a total of 100%, South African semi-carbonate manganese ore 45-50%, Gabonese manganese ore 15-20%, manganese oxide ore 20-30%, and domestic manganese ore 5-10%. Semi-carbonate manganese ore has high basicity and good particle size. Some carbonates (such as MnCO3) can decompose spontaneously at high temperatures to produce MnO and carbon dioxide, reducing the total amount of MnO that needs to be reduced by carbon, thereby reducing the demand for coke. The CO2 produced by decomposition reacts with coke to generate CO, which can then participate in the indirect reduction of manganese oxides (such as MnO+CO→Mn+CO2), further reducing the amount of coke required for direct carbon reduction, thereby reducing the overall amount of coke used.

[0008] Further preferably, the manganese content in each manganese ore raw material is not less than 35% (mass fraction), and the moisture content is not more than 6%.

[0009] More preferably, the particle size of the manganese ore powder is less than 10 mm, and the particle size of the manganese ore block is 10-75 mm.

[0010] Further preferred embodiments include coke with a fixed carbon content ≥84%, ash content ≤10%, coke lumps with a particle size of 10-30mm, and coke powder with a particle size <10mm. The core role of coke in production is as a reducing agent and heat source. Simultaneously, coke forms a porous framework structure during smelting, maintaining material permeability, ensuring uniform gas flow distribution, and improving smelting efficiency and molten iron quality.

[0011] A further preferred embodiment is that the mass ratio of manganese ore powder to coke powder is (10-30):1.

[0012] A further preferred embodiment is a sintering temperature of 1150-1250℃ and a sintering time of 2-4h.

[0013] Further preferably, the diameter of the raw material spheres is 20-30mm, and the sintered ore is crushed to a particle size of 10-50mm. After sintering, the manganese ore powder and coke powder enrich the manganese content in the ore, increasing the overall manganese content fed into the electric arc furnace, greatly reducing the dependence on high-grade manganese ore. At the same time, it can also pre-process the semi-carbonate manganese ore powder into granules, preventing it from producing finer powder due to high-temperature cracking, which would affect the smelting atmosphere, improve the overall raw material structure, prevent powder from clogging the material layer and causing deterioration of permeability, ensure stable smelting operation, reduce the slag-to-iron ratio, and lower production power consumption.

[0014] A further preferred method is to use a mass ratio of mixed raw materials, coke, and silica of 100:(15-25):(19-22), resulting in a slag basicity of 0.6-0.9 after smelting. Mixing and proportioning sintered ore, manganese ore blocks, coke blocks, and silica of different particle sizes and compositions ensures sufficient contact between the materials and increases the porosity of the furnace charge structure. This creates pores that allow for air circulation, promoting efficient contact between reducing gas (CO) and the ore. This results in a more complete reaction between materials during smelting, improving reaction efficiency and increasing raw material utilization and manganese recovery, indirectly reducing coke consumption. Additionally, 1-5 wt% lime and fluorite can be added to the mixture to adjust the basicity of the furnace charge and slag. The specific amounts of these two materials are adjusted according to actual needs, aiming to control the slag basicity to 0.6-0.9. Suitable basicity helps promote the reduction reaction of manganese and silicon, reduces manganese loss, minimizes the entry of impurities into the alloy product, and ensures good slag fluidity.

[0015] Further preferably, the silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40 mm. Silica serves to provide a source of Si in the alloy and to regulate the basicity of the slag.

[0016] A further preferred method is to use a melting temperature of 1450-1650℃, employ an electric arc in a submerged arc furnace for heating, and a melting time of 4-6 hours. High-temperature melting can fully reduce manganese and silicon oxides, shorten reaction time, increase alloy yield, improve thermal energy utilization, reduce unit energy consumption, and ensure that the mixture is fully melted during the melting cycle, resulting in uniform diffusion of alloying elements, which helps reduce component segregation and improve product consistency.

[0017] Further optimized, the smelting process employs a gradient heating method: Stage I: heating to 500-650℃ and holding for 15-30 minutes; Stage II: continuing to heat to 1100-1200℃ and holding for 10-15 minutes; Stage III: continuing to heat to 1450-1650℃ and holding until the end of smelting. The holding in Stage I removes moisture and volatiles from the mixture, resulting in a more uniform temperature increase and preventing sudden heating that could cause cracking or component loss, thus ensuring the stability of the entire smelting process and the quality of the ferrosilicon alloy. Stage II triggers the initial reduction reaction of manganese / silicon oxides, and the holding time ensures sufficient penetration of reducing gas into the furnace charge. Stage III achieves complete alloy melting and component homogenization, reducing inclusions. This gradient stage setting avoids low smelting efficiency or product quality problems due to insufficient or excessive temperature, preventing unnecessary energy waste and reducing smelting costs. It also reduces thermal stress on the submerged arc furnace at high temperatures, lowering the risk of equipment wear and damage, thereby extending the equipment's service life.

[0018] A further preferred method is to use a blowing time of 20-40 minutes. The use of mixed gas can slow down the oxidation rate of elements in the target alloy (such as manganese and silicon), and also avoid the problem of a sudden temperature rise exceeding the safety threshold of the molten iron ladle due to oxidation. Simultaneously, mixed gas blowing reduces the amount of pure oxygen used, maintains decarburization efficiency, and reduces energy consumption and costs. During the blowing process, the mixed gas also acts as a stirrer, increasing the contact area between the mixed gas and the molten iron, causing residual carbon to be oxidized, reducing the carbon content in the molten iron, and achieving the purpose of decarburization and carbon reduction.

[0019] A further preferred method is the bottom blowing operation as follows: At the start of bottom blowing, the O2 flow rate is 100-400 L / h, and the air flow rate is 100-300 L / h. During the blowing process, the air flow rate is gradually reduced until the final 5-10 minutes when all-oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas remains stable at 0.6-0.7 MPa. This phased blowing with varying gas content also helps reduce the oxidation loss of manganese and silicon, and improves the recovery rate of target elements such as manganese and silicon. The bottom blowing should be just enough to cause the molten iron to churn, with the diameter of the churn point not exceeding 300 mm. This avoids excessive gas flow causing molten iron to splash outside the ladle, but also prevents the flow from being too weak, which could lead to surface crusting. A gas mixing device, commonly used in the art, is required between the air and oxygen sources and the oxygen lance to ensure that the gas flow entering the ladle is uniform in composition. Regulating valves are required between the air and oxygen sources and the gas mixing device, and between the gas mixing device and the oxygen lance, to control the gas flow rate in real time. Other specific operational matters of blowing are conventional techniques in the art and will not be elaborated here.

[0020] A further preferred embodiment is that the calming time is 10-15 minutes, and during the casting process, the iron material from one ladle is controlled to be cast within 15 minutes.

[0021] The method for preparing manganese-silicon alloy provided by this invention also has the following beneficial effects: 1) This method optimizes the proportion and preparation method of manganese ore raw materials, sintersting manganese ore powder and coke powder into granular sintered ore materials, optimizing the batch structure, reducing phenomena such as cracking and pulverization of manganese ore during the smelting process, and ultimately increasing the amount of semi-carbonate manganese ore to 45-50%, reducing the dependence on high-grade manganese oxide ore, alleviating the pressure of manganese ore procurement, and reducing production costs.

[0022] 2) After sintering, manganese ore powder and coke powder enrich the manganese content in the ore, increase the overall manganese content of the submerged arc furnace, prevent powder from clogging the material layer and causing deterioration of air permeability. Furthermore, after mixing and proportioning sintered ore, manganese ore blocks, coke blocks and silica with different particle sizes and composition contents, the furnace charge structure is optimized. The precise control of smelting operation parameters can effectively reduce the power consumption in the smelting process, ensure stable operation of smelting, reduce the slag-to-iron ratio, achieve lower unit product power consumption, improve energy utilization efficiency, and have the benefits of cost reduction and efficiency improvement.

[0023] 3) Optimizing and improving the particle size and sintering of coke and manganese ore raw materials makes the composition of raw materials entering the furnace more uniform and stable. Combined with slag basicity control and the use of gradient heating smelting method, it can avoid low smelting efficiency or product quality problems caused by insufficient or excessive temperature. It also reduces the loss of manganese in slag and significantly improves the manganese recovery rate. Compared with traditional processes, it has significantly improved the utilization rate of raw materials, reduced production costs, reduced composition fluctuations, and improved product consistency. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of the present invention.

[0025] The following examples use conventional instruments and equipment in the art. Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available and conform to conventional specifications in the art. Any techniques or conditions not specifically described in the following examples can be performed according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0026] It should be noted that, in this invention and the following embodiments, unless otherwise specified, concentration, ratio, etc. are all weight concentration, weight ratio, etc., "%" all represent weight percentage, and "parts" all represent weight parts. These are common writing habits used by those skilled in the art, and therefore will not be repeated in this invention.

[0027] As a preferred embodiment, a method for preparing a manganese-silicon alloy according to the present invention includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush and screen the resulting mixed raw material to obtain manganese ore powder with a particle size of less than 10 mm and manganese ore lumps with a particle size of 10-75 mm; take coke and crush and screen it to obtain coke powder with a particle size of <10 mm and coke lumps with a particle size of 10-30 mm.

[0028] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: Based on a total weight of 100%, South African semi-carbonate manganese ore 45-50%, Gabonese manganese ore 15-20%, manganese oxide ore 20-30%, and domestic manganese ore 5-10%. The fixed carbon content of the above coke is ≥84%, and the ash content is ≤10%. In each of the above manganese ore raw materials, the manganese content is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0029] 2) Sintering: Manganese ore powder and coke powder are mixed in a mass ratio of (10-30):1 and pressed into raw material spheres with a diameter of 20-30mm. The raw material spheres are then added to a sintering machine and sintered under the ignition of coal gas in a submerged arc furnace. The sintering temperature is controlled at 1150-1250℃ and the sintering time is 2-4h. After cooling, the sintered ore is crushed to a particle size of 10-50mm to obtain sintered ore.

[0030] 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at a temperature of 1450-1650℃ for 4-6 hours to obtain molten iron. The slag produced after smelting has a basicity of 0.6-0.9. The mass ratio of the mixed raw materials, coke, and silica is 100:(15-25):(19-22). The silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40mm.

[0031] The smelting process employed a gradient heating method: Stage I: heating to 500-650℃ and holding for 15-30 minutes; Stage II: continuing to heat to 1100-1200℃ and holding for 10-15 minutes; Stage III: continuing to heat to 1450-1650℃ and holding until the smelting process was completed.

[0032] 4) Blowing: The molten iron is discharged into the ladle and blown with a mixture of bottom blowing air and oxygen for 20-40 minutes. At the beginning of bottom blowing, the O2 flow rate is 100-400 L / h and the air flow rate is 100-300 L / h. During the blowing process, the air flow rate is gradually reduced until the last 5-10 minutes when all oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas is kept stable at 0.6-0.7 MPa.

[0033] 5) Casting: After blowing is completed, the material is cooled for 10-15 minutes, the slag is removed, and then the molten iron is poured into the mold within 15 minutes. After cooling and solidification, a billet is formed, which yields the manganese silicon alloy.

[0034] It should be noted that, in the specific implementation scheme and examples, the composition and mass fraction of each manganese ore raw material are as follows: The Gabonese manganese ore, by mass fraction, includes: manganese 40-47%, iron 3-6%, silicon dioxide 5-10%, calcium oxide 1.5-2%, magnesium oxide 0.5-0.6%, and aluminum oxide 6-7.5%.

[0035] The semi-carbonate manganese ore in South Africa, by mass fraction, includes: manganese 38-42%, iron 4-6%, carbon 8-12%, silicon dioxide 5-8%, calcium oxide 14-16%, magnesium oxide 2-3.5%, and aluminum oxide 0.2-0.5%.

[0036] Manganese oxide ore, by mass fraction, includes: manganese 35-37%, iron 7.5-10%, silicon dioxide 25-30%, calcium oxide 2-5%, magnesium oxide 0.5-1.5%, and aluminum oxide 5-7%.

[0037] Domestic manganese ore, by mass fraction, includes: manganese 35-38%, iron 10-12%, silicon dioxide 27-30%, calcium oxide 2-3%, magnesium oxide 0.5-1%, and aluminum oxide 3-5%.

[0038] The present invention will be further described in detail below with reference to embodiments. However, it should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0039] Example 1:

[0040] A method for preparing a manganese-silicon alloy includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush and screen the resulting mixed raw material to obtain manganese ore powder with a particle size of less than 10 mm and manganese ore lumps with a particle size of 10-75 mm; take coke and crush and screen it to obtain coke powder with a particle size of <10 mm and coke lumps with a particle size of 10-30 mm.

[0041] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: based on a total weight of 100%, South African semi-carbonate manganese ore 45%, Gabonese manganese ore 15%, manganese oxide ore 30%, and domestic manganese ore 10%. The fixed carbon content of the above coke is ≥84%, and the ash content is ≤10%. The manganese content of each of the above manganese ore raw materials is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0042] 2) Sintering: Manganese ore powder and coke powder are mixed in a mass ratio of 10:1 and pressed into raw material spheres with a diameter of 20 mm. The raw material spheres are then added to a sintering machine and sintered under the ignition of coal gas in a submerged arc furnace. The sintering temperature is controlled at 1150℃ and the sintering time is 2 hours. After cooling, the sintered ore is crushed to a particle size of 10-50 mm to obtain sintered ore.

[0043] 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at 1450℃ for 4 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. The mass ratio of the mixed raw materials, coke, and silica is 100:15:19. The silica contains ≥97% SiO2 and <2% P2O5, with a particle size of 15-40mm. A gradient heating method is used for smelting: Stage I: Heating to 500℃ and holding for 15 minutes; Stage II: Heating to 1100℃ and holding for 10 minutes; Stage III: Heating to 1450℃ and holding until smelting is complete.

[0044] 4) Blowing: The molten iron is discharged into the ladle and blown with a mixture of bottom blowing air and oxygen for 20 minutes. At the beginning of bottom blowing, the O2 flow rate is 100 L / h and the air flow rate is 100 L / h. During the blowing process, the air flow rate is gradually reduced until the last 5 minutes when all oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas is always kept stable at 0.6-0.7 MPa.

[0045] 5) Casting: After blowing is completed, the iron is calmed for 10 minutes, the slag is removed, and then the iron is poured into the mold within 15 minutes. After cooling and solidification, a billet is formed, which yields the manganese silicon alloy.

[0046] Example 2:

[0047] A method for preparing a manganese-silicon alloy includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush and screen the resulting mixed raw material to obtain manganese ore powder with a particle size of less than 10 mm and manganese ore lumps with a particle size of 10-75 mm; take coke and crush and screen it to obtain coke powder with a particle size of <10 mm and coke lumps with a particle size of 10-30 mm.

[0048] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: based on a total weight of 100%, South African semi-carbonate manganese ore 50%, Gabonese manganese ore 20%, manganese oxide ore 25%, and domestic manganese ore 5%. The fixed carbon content of the above coke is ≥84%, and the ash content is ≤10%. The manganese content of each of the above manganese ore raw materials is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0049] 2) Sintering: Manganese ore powder and coke powder are mixed in a mass ratio of 30:1 and pressed into raw material spheres with a diameter of 30mm. The raw material spheres are then added to a sintering machine and sintered under the ignition of coal gas in a submerged arc furnace. The sintering temperature is controlled at 1250℃ and the sintering time is 4h. After cooling, the sintered ore is crushed to a particle size of 10-50mm to obtain sintered ore.

[0050] 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at 1650℃ for 6 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. The mass ratio of the mixed raw materials, coke, and silica is 100:25:21. The silica contains ≥97% SiO2 and <2% P2O5, with a particle size of 15-40mm. A gradient heating method is used for smelting: Stage I: Heating to 650℃ and holding for 30 minutes; Stage II: Heating to 1200℃ and holding for 15 minutes; Stage III: Heating to 1650℃ and holding until smelting is complete.

[0051] 4) Blowing: The molten iron is discharged into the ladle and blown with a mixture of bottom blowing air and oxygen for 40 minutes. At the beginning of bottom blowing, the O2 flow rate is 400 L / h and the air flow rate is 300 L / h. During the blowing process, the air flow rate is gradually reduced until the last 10 minutes when all oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas is kept stable at 0.6-0.7 MPa.

[0052] 5) Casting: After blowing is completed, the iron is cooled for 15 minutes, the slag is removed, and then the iron is poured into the mold within 15 minutes. After cooling and solidification, a billet is formed, which yields the manganese silicon alloy.

[0053] Example 3:

[0054] A method for preparing a manganese-silicon alloy includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush and screen the resulting mixed raw material to obtain manganese ore powder with a particle size of less than 10 mm and manganese ore lumps with a particle size of 10-75 mm; take coke and crush and screen it to obtain coke powder with a particle size of <10 mm and coke lumps with a particle size of 10-30 mm.

[0055] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: Based on a total weight of 100%, South African semi-carbonate manganese ore 47%, Gabonese manganese ore 18%, manganese oxide ore 25%, and domestic manganese ore 10%. The fixed carbon content of the above coke is ≥84%, and the ash content is ≤10%. In each of the above manganese ore raw materials, the manganese content is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0056] 2) Sintering: Manganese ore powder and coke powder are mixed in a mass ratio of 15:1 and pressed into raw material spheres with a diameter of 25mm. The raw material spheres are then added to a sintering machine and sintered under the ignition of coal gas in a submerged arc furnace. The sintering temperature is controlled at 1200℃ and the sintering time is 2.5h. After cooling, the sintered ore is crushed to a particle size of 10-50mm to obtain sintered ore.

[0057] 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at 1500℃ for 4.5 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. The mass ratio of the mixed raw materials, coke, and silica is 100:17.5:20. The silica contains ≥97% SiO2 and <2% P2O5, with a particle size of 15-40mm. A gradient heating method is used for smelting: Stage I: Heating to 600℃ and holding for 25 minutes; Stage II: Heating to 1150℃ and holding for 15 minutes; Stage III: Heating to 1500℃ and holding until smelting is complete.

[0058] 4) Blowing: The molten iron is discharged into the ladle and blown with a mixture of bottom blowing air and oxygen for 30 minutes. At the beginning of bottom blowing, the O2 flow rate is 300 L / h and the air flow rate is 200 L / h. During the blowing process, the air flow rate is gradually reduced until the last 5 minutes when all oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas is always kept stable at 0.6-0.7 MPa.

[0059] 5) Casting: After blowing is completed, the iron is cooled for 15 minutes, the slag is removed, and then the iron is poured into the mold within 15 minutes. After cooling and solidification, a billet is formed, which yields the manganese silicon alloy.

[0060] Comparative Example 1: A method for preparing a manganese-silicon alloy includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush the resulting mixed raw material to obtain manganese ore mixed raw material with a particle size of less than 75mm; take coke and crush it to obtain coke raw material with a particle size of <30mm.

[0061] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: Based on a total weight of 100%, South African semi-carbonate manganese ore 47%, Gabonese manganese ore 18%, manganese oxide ore 25%, and domestic manganese ore 10%. The fixed carbon content of the above coke is ≥84%, and the ash content is ≤10%. In each of the above manganese ore raw materials, the manganese content is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0062] 2) Smelting: Manganese ore mixture, coke, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at 1500℃ for 4.5 hours to obtain molten iron. The slag produced after smelting has a basicity of 0.6-0.9. The mass ratio of manganese ore mixture, coke, and silica is 100:17.5:20. The silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40mm. A gradient heating method is used for smelting: Stage I: Heating to 600℃ and holding for 25 minutes; Stage II: Heating to 1150℃ and holding for 15 minutes; Stage III: Heating to 1500℃ and holding until smelting is complete.

[0063] 3) Blowing: Same as 4) in Example 3.

[0064] 4) Casting: Same as 5) in Example 3, to obtain manganese-silicon alloy. In this comparative example, the manganese ore mixture and coke were not graded and powdered for sintering. After crushing, they were directly fed into the electric arc furnace for smelting. During the smelting process, it was found that the amount of slag was significantly increased compared to Example 3, and the furnace temperature fluctuated more than in Example 3, which increased the smelting power consumption and cost.

[0065] Comparative Example 2: A method for preparing a manganese-silicon alloy includes the following steps: 1) Ingredients: Same as 1) in Example 3.

[0066] 2) Sintering: Manganese ore powder and coke powder are mixed in a mass ratio of 15:1 and pressed into raw material spheres with a diameter of 25mm to obtain spherical ore.

[0067] 3) Smelting: Spherical ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then smelted in a submerged arc furnace at 1500℃ for 4.5 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. The mass ratio of the mixed raw materials, coke, and silica is 100:17.5:20. The silica contains ≥97% SiO2 and <2% P2O5, with a particle size of 15-40mm. A gradient heating method is used for smelting: Stage I: Heating to 600℃ and holding for 25 minutes; Stage II: Heating to 1150℃ and holding for 15 minutes; Stage III: Heating to 1500℃ and holding until smelting is complete.

[0068] 4) Blowing: Same as 4) in Example 3.

[0069] 5) Casting: Same as 5) in Example 3.

[0070] Comparative Example 3: A method for preparing a manganese-silicon alloy includes the following steps: 1) Ingredients: Same as 1) in Example 3.

[0071] 2) Sintering: Same as 2) in Example 3.

[0072] 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture. This mixture is then fed into a submerged arc furnace for smelting. The temperature is raised to the smelting temperature of 1500℃ in one step, and the smelting time is 4.5 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. A gradient heating method is not used in the smelting process. The mass ratio of the mixed raw materials, coke, and silica is 100:17.5:20. The silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40mm. In this comparative example, no gradient heating was used during the smelting process, resulting in a significantly increased amount of slag compared to Example 3. The furnace temperature also fluctuated more significantly compared to Example 3, increasing smelting power consumption and costs.

[0073] 4) Blowing: Same as 4) in Example 3.

[0074] 5) Casting: Same as 5) in Example 3.

[0075] Comparative Example 4: A method for preparing a manganese-silicon alloy includes the following steps: 1) Ingredients: Same as 1) in Example 3.

[0076] 2) Sintering: Same as 2) in Example 3.

[0077] 3) Smelting: Same as 3) in Example 3.

[0078] 4) Casting: Pour the molten iron into the ladle, let it settle for 15 minutes, remove the slag, and then pour the poured iron into the mold within 15 minutes. Cool and solidify to form a billet, thus obtaining the manganese silicon alloy.

[0079] Comparative Example 5: A method for preparing a manganese-silicon alloy includes the following steps: 1) Batching: Take each manganese ore raw material according to the mass percentage and then crush the resulting mixed raw material to obtain manganese ore mixed raw material with a particle size of less than 75mm; take coke and crush it to obtain coke raw material with a particle size of <30mm.

[0080] The composition and mass percentage of each manganese ore in the mixed raw materials are as follows: 40% South African semi-carbonate manganese ore, 18% Gabonese manganese ore, 25% manganese oxide ore, and 10% domestic manganese ore (based on a 100% total weight). The fixed carbon content of the coke is ≥84%, and the ash content is ≤10%. The manganese content of each of the above manganese ore raw materials is not less than 35% (mass fraction), and the moisture content is not higher than 6%.

[0081] 2) Smelting: Manganese ore mixture, coke, and silica are mixed to obtain a mixture. This mixture is then fed into a submerged arc furnace for smelting. The temperature is raised to 1500℃ in one step, and the smelting time is 4.5 hours to obtain molten iron. The basicity of the slag obtained after smelting is 0.6-0.9. The mass ratio of manganese ore mixture, coke, and silica is 100:27.5:20. The silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40 mm.

[0082] 3) Pour the molten iron into the ladle, let it settle for 15 minutes, remove the slag, and then pour the poured iron into the mold within 15 minutes. Let it cool and solidify to form a billet, thus obtaining the manganese silicon alloy.

[0083] Following the methods described in Examples 1-3 and Comparative Examples 1-5, manganese-silicon alloys were prepared using raw materials from the same batch. The mass fraction of the chemical components was determined using the methods in GB / T4008-2024 "Manganese-Silicon Alloys". Each test sample group had three replicates, and the average value was taken. The results are shown in Table 1.

[0084] Table 1 (Unit: %)

[0085] As shown in the table above, the manganese-silicon alloy products in each embodiment are of excellent quality. The manganese, silicon, carbon, phosphorus, and sulfur contents all meet the Grade I requirements of FeMn65Si17, indicating superior quality. The manganese recovery rate can reach over 80%, demonstrating high resource utilization. Comparative Example 1 uses unscreened, mixed-size manganese ore and coke as raw materials. Similar to Comparative Example 2, the lack of sintering treatment for the powdered raw materials leads to an unbalanced furnace charge structure, resulting in poor slag fluidity and charge permeability, incomplete reaction, and lower reduction efficiency. Consequently, the amount of slag and its manganese content increase, smelting power consumption is high, and manganese recovery rate decreases. Comparative Example 3 does not employ gradient heating during smelting, resulting in low thermal efficiency and unstable furnace conditions, which exacerbates manganese loss. Therefore, the manganese content in the slag increases, smelting power consumption rises, and manganese recovery rate decreases. Comparative Example 4, due to the absence of blowing, has a high carbon content and poor decarburization effect. Comparative Example 5 represents a commonly used method in the prior art, which involves a high amount of coke and a low amount of semi-carbonate manganese ore in the raw manganese ore, resulting in unstable product quality. In summary, the method of this invention, by increasing the amount of semi-carbonate manganese ore and through synergistic optimization techniques, improves the overall product quality. Specifically, the carbon, phosphorus, and sulfur content meets the requirements for low-carbon manganese silicon alloys, thereby improving the purity of alloy products and deep-processed steel, and increasing the added value of the products.

[0086] It should be noted that some detailed steps of the operation are not described in this invention, but are prior art known to those skilled in the art, and therefore will not be repeated here. Furthermore, in this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0087] It should be noted that the detailed structure of some devices is not described in this invention, but is prior art known to those skilled in the art, and therefore will not be elaborated here. In this invention, structures and devices not specifically limited can be purchased commercially, and those skilled in the art only need to install and operate them according to the accompanying instruction manual, without requiring any creative effort from those skilled in the art.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. In this invention, not all possible combinations of the various technical features in each embodiment or implementation are described. As long as the combinations of these technical features do not contradict each other, the various technical features in each embodiment or implementation can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a manganese-silicon alloy, characterized in that, include: 1) Batching: Take the various manganese ore raw materials and batch them, then crush and screen the resulting mixed raw materials to obtain manganese ore powder and manganese ore blocks; take coke and crush and screen it to obtain coke powder and coke blocks. 2) Sintering: Manganese ore powder is mixed with coke powder and pressed into raw material spheres. The raw material spheres are then added to a sintering machine for sintering. After cooling, they are crushed to obtain sintered ore. 3) Smelting: Sintered ore, manganese ore blocks, coke blocks, and silica are mixed to obtain a mixture, which is then put into an electric arc furnace for smelting to obtain molten iron. 4) Blowing: The molten iron is discharged into the ladle and blown using a mixture of bottom-blown air and oxygen; 5) Casting: After blowing is completed, the mixture is calmed, slag is removed, and then it is cast into a mold, cooled and solidified to form a billet, thus obtaining the manganese silicon alloy.

2. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The manganese ore raw materials and their mass percentages in the mixed raw materials are as follows: based on a total of 100%, South African semi-carbonate manganese ore 45-50%, Gabonese manganese ore 15-20%, manganese oxide ore 20-30%, and domestic manganese ore 5-10%; the manganese content in each of the manganese ore raw materials is not less than 35%, and the moisture content is not more than 6%.

3. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The manganese ore powder has a particle size of less than 10 mm, and the manganese ore lumps have a particle size of 10-75 mm; the coke has a fixed carbon content of ≥84%, an ash content of ≤10%, a coke lumps particle size of 10-30 mm, and a coke powder particle size of <10 mm.

4. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The mass ratio of manganese ore powder to coke powder is (10-30):1; the sintering temperature is 1150-1250℃, and the sintering time is 2-4h; the diameter of the raw material spheres is 20-30mm, and the sintered ore is crushed to a particle size of 10-50mm.

5. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The mass ratio of the mixed raw materials, coke, and silica is 100:(15-25):(19-22), and the basicity of the slag obtained after smelting is 0.6-0.

9.

6. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The silica contains ≥97% SiO2, <2% P2O5, and has a particle size of 15-40 mm.

7. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The melting temperature is 1450-1650℃, and the electric arc of the electric arc furnace is used for heating. The melting time is 4-6 hours.

8. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The smelting process employs a gradient heating method: Stage I: Heat to 500-650℃ and hold for 15-30 minutes; Stage II: Continue heating to 1100-1200℃ and hold for 10-15 minutes; Stage III: Continue heating to 1450-1650℃ and hold until the smelting process is complete.

9. The method for preparing manganese-silicon alloy according to claim 1, characterized in that, The blowing time is 20-40 minutes.

10. The method for preparing manganese-silicon alloy according to any one of claims 1-9, characterized in that, The bottom blowing operation process is as follows: At the beginning of bottom blowing, the O2 flow rate is 100-400L / h and the air flow rate is 100-300L / h. During the blowing process, the air flow rate is gradually reduced until the final 5-10 minutes when full oxygen bottom blowing is used. During bottom blowing, the pressure of the mixed gas is always kept stable at 0.6-0.7MPa.

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