Silicon-manganese alloy smelting method

Abstract

The invention relates to the technical field of metallurgy and chemical industry, in particular to a silicon-manganese alloy smelting method which comprises the following steps of raw material pretreatment, gradient reduction smelting, tapping and refining and flue gas slag cooperative treatment. In the silicon-manganese alloy smelting process, lanthanum-cerium oxide in the rare earth composite material reacts with impurities such as sulfur, phosphorus and oxygen in a melt at high temperature to form a high-melting-point compound which is separated along with slag, the impurity content is effectively reduced, meanwhile, rare earth elements are segregated at the grain boundary, atomic diffusion migration is inhibited, the alloy grain size is remarkably refined, and the alloy yield is improved. And the rare earth composite material optimizes the alloy solidification structure through the double effects of chemical purification and physical modification, the problems of impurity segregation and insufficient toughness in the traditional silicon-manganese alloy smelting process are solved, and the mechanical property of the silicon-manganese alloy is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical chemistry, and specifically relates to a method for smelting ferrosilicon manganese alloy. Background Art

[0002] Ferrosilicon manganese alloy is an important deoxidizer and alloy additive in the steel industry. Its performance directly affects the strength, toughness and corrosion resistance of steel. It is an iron alloy with a wide range of uses and large output.

[0003] In the prior art, such as Chinese Patent Publication No. CN114908263A, a method for preparing ferrosilicon manganese alloy is disclosed. Specifically, it includes raw material preheating, precise batching and raw material mixing. After mixing, the raw materials are transported to a reaction furnace, an initiator is ignited, and the smelting of ferrosilicon manganese alloy is completed by using the high temperature generated by the initiator. After smelting, cooling, separation and post-treatment are carried out to complete the preparation of ferrosilicon manganese alloy. The heat in the smelting process of this invention comes from the heat generated by igniting the initiator, and electricity is not used as an energy source, which greatly reduces the electricity cost in the production process; at the same time, an electric furnace with a large volume and complex structure is not used as a reaction vessel, reducing the equipment and site investment in production. In addition, applying this invention can also improve the manganese recovery rate, and at the same time can reduce the mass fractions of elements such as carbon, phosphorus and sulfur.

[0004] Although the method for preparing ferrosilicon manganese alloy in the above patent has many advantages, however, in the traditional smelting process of ferrosilicon manganese alloy, the manganese recovery rate still needs to be further improved, so as to further reduce the mass fractions of carbon, sulfur and phosphorus. Otherwise, impurity elements such as carbon, sulfur and phosphorus will form impurity phases in the alloy, distributing in the grain boundaries and matrix, resulting in a decrease in grain boundary strength, easy initiation and propagation of cracks, and further reducing the mechanical properties such as tensile strength and toughness of the alloy.

[0005] Based on this, the present invention provides a method for smelting ferrosilicon manganese alloy. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for smelting ferrosilicon manganese alloy to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A method for smelting ferrosilicon manganese alloy, including the following steps:

[0008] Raw material pretreatment: Select manganese ore, silica, rare earth composite material and composite carbon. After crushing and mixing the manganese ore and silica, then add the rare earth composite material and mix to form an ore material;

[0009] Gradient reduction smelting: Layered charging is carried out in the order of composite carbon, ore material, and composite carbon. The thickness ratio of the composite carbon layer to the ore material layer is 1:(0.8 - 1.2). Control the electrode to insert 45 - 55% of the furnace height. Two-stage smelting is carried out at 1300 - 1600 °C. In the first stage, keep the temperature at 1300 - 1400 °C for 1 - 2 hours. In the second stage, raise the temperature to 1550 - 1600 °C and continue the reduction reaction for 3 - 4 hours to obtain a ferrosilicon manganese alloy melt;

[0010] Tapping and refining: Pour the melt into a ladle for refining, add a modifier accounting for 3 - 5% of the slag mass and stir for 10 - 15 minutes. Subsequently, blow argon at 8 - 12 L / min onto the melt surface for 3 - 5 minutes;

[0011] Synergistic treatment of flue gas and slag: 50 - 70% of the smelting flue gas is blown back to the periphery of the bottom electrode of the furnace after bag dust removal. The remaining flue gas waste heat is used for power generation and preheating combustion-supporting air. The furnace slag and dust removal ash are cold-pressed into pellets and then returned to the furnace.

[0012] Preferably, the mass ratio of silica to manganese ore is (3 - 4):(6 - 7). After being crushed, the particle size of the manganese ore is 5 - 30 mm, and the particle size of the silica after being crushed is 10 - 15 mm. Among them, the mass ratio of the rare earth composite material to silica is (5 - 8):100, and the mass ratio of silica to composite carbon is (2 - 3):(7 - 8).

[0013] Preferably, the rare earth composite material is obtained by flotation purification of lanthanum-cerium rare earth ore, and the mass ratio of lanthanum oxide to cerium oxide is (2.5 - 3.5):1.

[0014] Preferably, the preparation method of the rare earth composite material includes the following steps: Select lanthanum-cerium rare earth ore as the raw material, crush it to 80 - 100 mesh and then carry out flotation to obtain a concentrate with a rare earth oxide content ≥ 85%. Transfer the concentrate to a rotary kiln and calcine it at 950 - 1000 °C for 2 - 3 h under nitrogen protection to obtain a calcined ore powder. Then transfer it to an enamel reaction kettle and add industrial hydrochloric acid with a mass concentration of (10 - 15)%. Stir at 75 - 85 °C and 100 - 150 r / min for 4 - 5 h. Then carry out centrifugal filtration. Slowly add a 10% mass concentration of oxalic acid solution to the filtrate in a 60 °C water bath. After precipitation, age for 2 - 3 h to obtain a treated material. Calcinate the treated material at 650 - 750 °C for 3 - 4 h and then sieve to obtain a 200 - 300 mesh powder, which is the rare earth composite material.

[0015] Preferably, the liquid-solid ratio of the industrial hydrochloric acid to the calcined ore powder is (3 - 5):1, and the molar ratio of the oxalic acid solution to the filtrate is (1 - 2):1.

[0016] Preferably, the method for preparing the composite carbon comprises the following steps: selecting straw, bamboo chips and walnut shells as raw materials, mixing and pulverizing them, then carbonizing at a heating rate of 10 °C / min under nitrogen protection to 400 - 500 °C for 2 - 3 h to obtain a carbonized product, impregnating the carbonized product in a 5% by mass phosphoric acid solution for 2 - 3 h and then draining to obtain a modified product, then transferring it to an activation furnace and heating at a heating rate of 10 - 15 °C / min to 500 - 600 °C for activation for 1 - 2 h to obtain an activated product, and finally crushing and screening to obtain composite carbon with a particle size of 10 - 50 mm.

[0017] Preferably, the mass ratio of the straw, bamboo chips and walnut shells is 5:3:2, and the liquid-solid ratio of the carbonized product and the phosphoric acid solution is 2:1.

[0018] Preferably, the modifier is a composite powder obtained by premixing sodium carbonate and calcium oxide in a mass ratio of (4 - 4.5):5.

[0019] Preferably, the cold-pressed pellets use sodium silicate solution as a binder, with an addition amount of 3 - 5% of the mass of the slag, a cold pressing pressure of 15 - 20 MPa, and a pellet compressive strength ≥ 600 N.

[0020] Preferably, the heating rate of the two-stage smelting is as follows: the first stage is 10 - 12 °C / min, and the second stage is 12 - 15 °C / min.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. In the present invention, during the smelting of ferrosilicon manganese alloy, lanthanum and cerium oxides in the rare earth composite material react with impurities such as sulfur, phosphorus, and oxygen in the melt at high temperature to form high-melting-point compounds and separate with the slag, effectively reducing the impurity content. At the same time, rare earth elements segregate at the grain boundaries, inhibiting the diffusion and migration of atoms, significantly refining the alloy grain size. And the rare earth composite material optimizes the alloy solidification structure through the dual effects of chemical purification and physical modification, solving the problems of impurity segregation and insufficient toughness in the traditional ferrosilicon manganese alloy smelting process, and significantly improving the mechanical properties of ferrosilicon manganese alloy.

[0023] 2. In the present invention, during the smelting of ferrosilicon manganese alloy, a large number of microporous structures are formed after the carbonization and activation treatment of the composite carbon, and the specific surface area is much higher than that of traditional coke, greatly increasing the contact area with the ore and accelerating the reduction reaction of carbon and metal oxides. At the same time, the sulfur and phosphorus content of the biomass raw material is extremely low, avoiding the introduction of impurities, and the reducing gas generated during the carbonization process and the solid carbon form a synergistic effect, reducing the energy required for the reaction. Therefore, the composite carbon significantly improves the reduction efficiency, reduces the amount of reducing agent used and pollutant emissions by virtue of its high reaction activity and low impurity characteristics, effectively solving the problems of high energy consumption and heavy pollution in the traditional process.

[0024] 3. In the present invention, during the smelting of ferrosilicon manganese alloy, part of the smelting flue gas is blown back to the furnace bottom after dust removal. Carbon monoxide therein participates in secondary reduction as a gaseous reducing agent, improving the carbon utilization rate. The waste heat is used to preheat the combustion-supporting air, enhancing the smelting thermal efficiency. The slag and dust are cold-pressed into pellets and returned to the furnace after treatment, further increasing the manganese recovery rate and significantly reducing the solid waste emissions. In this smelting method, through the utilization of flue gas waste heat and the resource utilization of slag, a gas-solid resource circulation process is constructed, realizing the cascaded utilization of energy and pollutant reduction, solving the problems of resource waste and environmental pollution, and promoting the development of green metallurgy technology. Specific Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0026] Embodiment 1. This embodiment provides a method for smelting ferrosilicon manganese alloy, including the following steps:

[0027] Raw material pretreatment: Select manganese ore, silica, rare earth composite material, and composite carbon. After crushing the manganese ore and silica and mixing them, then add the rare earth composite material and mix to form an ore material.

[0028] Gradient reduction smelting: Layer the materials in the order of composite carbon, ore material, and composite carbon. The thickness ratio of the composite carbon and ore material layers is 1:0.8. Control the electrode to insert 45% of the furnace chamber height and perform two-stage smelting at 1300 - 1550 °C. In the first stage, keep the temperature at 1300 °C for 1 hour, and in the second stage, raise the temperature to 1550 °C and continue the reduction reaction for 3 hours to obtain a ferrosilicon manganese alloy melt.

[0029] Tapping and refining: Pour the melt into a refining ladle, add a modifier accounting for 3% of the slag mass and stir for 10 minutes, and then blow argon at 8 L / min on the melt surface for 3 minutes.

[0030] Flue gas and slag collaborative treatment: 50% of the smelting flue gas is blown back to the periphery of the bottom electrode of the furnace after bag dust removal. The remaining flue gas waste heat is used for power generation and preheating the combustion-supporting air. The slag and dust are cold-pressed into pellets and returned to the furnace.

[0031] Among them, the mass ratio of silica to manganese ore is 3:6. The particle size of the crushed manganese ore is 5 mm, and the particle size of the crushed silica is 10 mm. The mass ratio of the rare earth composite material to silica is 5:100, and the mass ratio of silica to composite carbon is 2:7.

[0032] Among them, the rare earth composite material is obtained by flotation and purification of lanthanum-cerium rare earth ore, and the mass ratio of lanthanum oxide to cerium oxide is 2.5:1.

[0033] Among them, the preparation method of rare earth composite material includes the following steps: Select lanthanum-cerium rare earth ore as raw material, crush it to 80 mesh and then carry out flotation to obtain concentrate with rare earth oxide content ≥ 85%. Transfer the concentrate to a rotary kiln, calcine it at 950 °C for 2 h under nitrogen protection to obtain calcined ore powder, then transfer it to an enamel reactor and add industrial hydrochloric acid with a mass concentration of 10%. Stir at 75 °C and 100 r / min for 4 h, then carry out centrifugal filtration. Slowly add oxalic acid solution with a mass concentration of 10% to the filtrate in a 60 °C water bath. After precipitation, age for 2 h to obtain treated material. Calcine the treated material at 650 °C for 3 h and then screen to obtain 200-mesh powder, which is the rare earth composite material.

[0034] Among them, the liquid-solid ratio of industrial hydrochloric acid to calcined ore powder is 3:1, and the molar ratio of oxalic acid solution to filtrate is 1:1.

[0035] Among them, the preparation method of composite carbon includes the following steps: Select straw, bamboo chips and walnut shells as raw materials, mix and crush them, then under nitrogen protection, heat them at a heating rate of 10 °C / min to 400 °C for carbonization treatment for 2 h to obtain carbonized material. Immerse the carbonized material in phosphoric acid solution with a mass fraction of 5% for 2 h and then drain it to obtain modified material. Then transfer it to an activation furnace and heat it at a heating rate of 10 °C / min to 500 °C for activation for 1 h to obtain activated material. Then crush and screen to obtain composite carbon with a particle size of 10 mm.

[0036] Among them, the mass ratio of straw, bamboo chips and walnut shells is 5:3:2, and the liquid-solid ratio of carbonized material to phosphoric acid solution is 2:1.

[0037] Among them, the modifier is a composite powder prepared by premixing sodium carbonate and calcium oxide according to a mass ratio of 4:5.

[0038] Among them, sodium silicate solution is used as the binder for cold-pressed pellets, the addition amount is 3% of the mass of the slag, the cold-pressing pressure is 15 MPa, and the compressive strength of the pellets ≥ 600 N.

[0039] Among them, the heating rate of two-stage smelting is: the first stage is 10 °C / min, and the second stage is 12 °C / min.

[0040] Example 2, a method for smelting ferrosilicon manganese alloy, includes the following steps:

[0041] Raw material pretreatment: Select manganese ore, silica, rare earth composite material and composite carbon. Crush and mix manganese ore and silica, and then add rare earth composite material to mix to form ore material;

[0042] Gradient reduction smelting: Charge the materials in layers in the order of composite carbon, ore materials, and composite carbon. The thickness ratio of the composite carbon layer to the ore material layer is 1:1.2. Control the electrode to insert 55% of the furnace height and conduct two-stage smelting at 1400 - 1600 °C. In the first stage, keep the temperature at 1400 °C for 2 hours, and in the second stage, raise the temperature to 1600 °C and continue the reduction reaction for 4 hours to obtain a silicon-manganese alloy melt;

[0043] Tapping and refining: Pour the melt into a ladle for refining, add a modifier accounting for 5% of the slag mass and stir for 15 minutes, and then blow argon at 12 L / min onto the melt surface for 5 minutes;

[0044] Co-treatment of flue gas and slag: After the smelting flue gas is dust-removed by a bag filter, 70% of it is blown back to the periphery of the bottom electrode of the furnace, and the heat of the remaining flue gas is used for power generation and preheating combustion-supporting air. The furnace slag and the dust-removing ash are cold-pressed into pellets and then returned to the furnace.

[0045] Among them, the mass ratio of silica to manganese ore is 4:7. After being crushed, the particle size of the manganese ore is 30 mm, and the particle size of the silica after being crushed is 15 mm. Among them, the mass ratio of the rare earth composite material to silica is 8:100, and the mass ratio of silica to composite carbon is 3:8.

[0046] Among them, the rare earth composite material is obtained by flotation and purification of lanthanum-cerium rare earth ore, and the mass ratio of lanthanum oxide to cerium oxide is 3.5:1.

[0047] Among them, the preparation method of the rare earth composite material includes the following steps: Select lanthanum-cerium rare earth ore as the raw material, crush it to 100 mesh and then conduct flotation to obtain a concentrate with a rare earth oxide content ≥ 85%. Transfer the concentrate to a rotary kiln and calcine it at 1000 °C for 3 h under nitrogen protection to obtain a calcined ore powder. Then transfer it to an enamel reaction kettle and add industrial hydrochloric acid with a mass concentration of 15%. Stir at 85 °C and 150 r / min for 5 h, then conduct centrifugal filtration. Slowly add an oxalic acid solution with a mass concentration of 10% to the filtrate in a 60 °C water bath. After precipitation, age for 3 h to obtain a treated material. Calcinate the treated material at 750 °C for 4 h and then sieve it to obtain a 300-mesh powder, which is the rare earth composite material.

[0048] Among them, the liquid-solid ratio of industrial hydrochloric acid to the calcined ore powder is 5:1, and the molar ratio of the oxalic acid solution to the filtrate is 2:1.

[0049] Among them, the preparation method of the composite carbon includes the following steps: Select straw, bamboo chips, and walnut shells as raw materials, mix and crush them, and then under nitrogen protection, heat them at a heating rate of 10 °C / min to 500 °C for carbonization treatment for 3 h to obtain a carbonized product. Immerse the carbonized product in a phosphoric acid solution with a mass fraction of 5% for 3 h and then drain it to obtain a modified product. Then transfer it to an activation furnace and heat it at a heating rate of 15 °C / min to 600 °C for activation for 2 h to obtain an activated product. Then crush and screen it to obtain composite carbon with a particle size of 50 mm.

[0050] Among them, the mass ratio of straw, bamboo chips and walnut shells is 5:3:2, and the liquid-solid ratio of the carbide and phosphoric acid solution is 2:1.

[0051] Among them, the modifier is a composite powder obtained by premixing sodium carbonate and calcium oxide in a mass ratio of 4.5:5.

[0052] Among them, sodium silicate solution is used as the binder for the cold-pressed pellets, the addition amount is 5% of the mass of the slag, the cold-pressing pressure is 20 MPa, and the compressive strength of the pellets is ≥600 N.

[0053] Among them, the heating rate of the two-stage smelting is: 12 °C / min in the first stage and 15 °C / min in the second stage.

[0054] Example 3, a method for smelting ferrosilicon manganese alloy, comprising the following steps:

[0055] Raw material pretreatment: Select manganese ore, silica, rare earth composite material and composite carbon. After crushing the manganese ore and silica and mixing them, then add the rare earth composite material and mix to form an ore material;

[0056] Gradient reduction smelting: Layer the materials in the order of composite carbon, ore material, and composite carbon. The thickness ratio of the composite carbon and ore material layers is 1:1. Control the electrode to insert 50% of the height of the furnace hearth. Carry out two-stage smelting at 1350-1580 °C. Keep the temperature at 1350 °C for 1.5 hours in the first stage, and raise the temperature to 1580 °C in the second stage and continue the reduction reaction for 3.5 hours to obtain a ferrosilicon manganese alloy melt;

[0057] Tapping and refining: Pour the melt into a ladle for refining, add a modifier accounting for 4% of the mass of the slag and stir for 12 minutes, and then blow argon at 10 L / min on the surface of the melt for 4 minutes;

[0058] Flue gas and slag co-treatment: After the smelting flue gas is bag-filtered, 60% of it is blown back to the periphery of the bottom electrode of the furnace. The remaining flue gas waste heat is used for power generation and preheating combustion-supporting air. The furnace slag and dust removal ash are cold-pressed into pellets and then returned to the furnace.

[0059] Among them, the mass ratio of silica and manganese ore is 3:7. After crushing, the particle size of the manganese ore is 20 mm, and the particle size of the silica after crushing is 12 mm. Among them, the mass ratio of the rare earth composite material to silica is 6:100, and the mass ratio of silica to composite carbon is 2:8.

[0060] Among them, the rare earth composite material is obtained by flotation purification of lanthanum-cerium rare earth ore, and the mass ratio of lanthanum oxide to cerium oxide is 3:1.

[0061] Among them, the preparation method of the rare earth composite material includes the following steps: Select lanthanum-cerium rare earth ore as the raw material, crush it to 90 mesh and then perform flotation to obtain concentrate with a rare earth oxide content of ≥85%. Transfer the concentrate to a rotary kiln, roast it at 980 °C for 2.5 h under nitrogen protection to obtain roasted ore powder, then transfer it to an enamel reaction kettle and add industrial hydrochloric acid with a mass concentration of 13%. Stir at 80 °C and 120 r / min for 4.5 h, then perform centrifugal filtration. Slowly add an oxalic acid solution with a mass concentration of 10% to the filtrate in a 60 °C water bath. After precipitation, age for 2.5 h to obtain the treated material. Calcinate the treated material at 700 °C for 3.5 h and then screen to obtain 250-mesh powder, which is the rare earth composite material.

[0062] Among them, the liquid-solid ratio of industrial hydrochloric acid to roasted ore powder is 4:1, and the molar ratio of oxalic acid solution to filtrate is 1.5:1.

[0063] Among them, the preparation method of the composite carbon includes the following steps: Select straw, bamboo chips and walnut shells as the raw materials, mix and crush them, then under nitrogen protection, heat them at a heating rate of 10 °C / min to 450 °C for carbonization treatment for 2.5 h to obtain carbonized products. Immerse the carbonized products in a phosphoric acid solution with a mass fraction of 5% for 2.5 h and then drain to obtain modified products. Then transfer them to an activation furnace and heat them at a heating rate of 12 °C / min to 550 °C for activation for 1.5 h to obtain activated products. Then crush and screen to obtain composite carbon with a particle size of 30 mm.

[0064] Among them, the mass ratio of straw, bamboo chips and walnut shells is 5:3:2, and the liquid-solid ratio of carbonized products to phosphoric acid solution is 2:1.

[0065] Among them, the modifier is a composite powder obtained by premixing sodium carbonate and calcium oxide according to a mass ratio of 4.2:5.

[0066] Among them, sodium silicate solution is used as the binder for the cold-pressed pellets, the addition amount is 4% of the mass of the slag, the cold-pressing pressure is 18 MPa, and the compressive strength of the pellets is ≥600 N.

[0067] Among them, the heating rate of the two-stage smelting is as follows: the first stage is 11 °C / min, and the second stage is 14 °C / min.

[0068] Comparative Example 1. The difference between this comparative example and Examples 1-3 is that: In this comparative example, traditional coke is used to replace the composite carbon during the smelting of ferrosilicon manganese alloy.

[0069] Comparative Example 2. The difference between this comparative example and Examples 1-3 is that: In this comparative example, no rare earth composite material is added during the smelting of ferrosilicon manganese alloy.

[0070] Comparative Example 3. The difference between this comparative example and Examples 1-3 is that: In this comparative example, traditional coke is used to replace the composite carbon and no rare earth composite material is added during the smelting of ferrosilicon manganese alloy.

[0071] Testing method:

[0072] Alloy properties: The grain size and inclusion distribution were observed by scanning electron microscopy (SEM); the tensile strength was tested by a universal testing machine.

[0073] Reduction efficiency: Calculate the manganese recovery rate (mass of Mn in manganese alloy / total mass of Mn in raw materials × 100%), and record the smelting power consumption (kWh / t).

[0074] Pollutant emissions: Detect the dust and CO concentrations in the flue gas.

[0075] Performance tests were carried out on the silicomanganese alloy smelting methods in Examples 1 - 3 and Comparative Examples 1 - 3, and the obtained test data are recorded in the following table:

[0076]

[0077] From the comparison of the data in the table, it can be seen that lanthanum and cerium oxides in the rare earth composite material react with impurities such as sulfur, phosphorus, and oxygen in the melt at high temperatures to form high - melting - point compounds and separate with the slag, effectively reducing the impurity content. At the same time, rare earth elements segregate at the grain boundaries, inhibiting the diffusion and migration of atoms, significantly refining the alloy grain size. At the same time, the test shows that the inclusion content in the comparative examples without adding rare earth composite materials far exceeds that in the examples, and the tensile strength of the alloy in the examples is significantly higher than that of the alloy in the comparative examples. This indicates that the rare earth composite material optimizes the alloy solidification structure through the dual effects of chemical purification and physical modification, solves the problems of impurity segregation and insufficient toughness in the traditional silicomanganese alloy smelting process, and significantly improves the mechanical properties of the silicomanganese alloy;

[0078] From the comparison of the data in the table, it can be seen that after the composite carbon is carbonized and activated, a large number of microporous structures are formed, and the specific surface area is much higher than that of traditional coke, greatly increasing the contact area with the ore and accelerating the reduction reaction of carbon and metal oxides. At the same time, the sulfur and phosphorus content of the biomass raw material is extremely low, avoiding the introduction of impurities, and the reducing gases generated during the carbonization process and solid carbon form a synergistic effect, reducing the energy required for the reaction. At the same time, the test shows that the manganese recovery rates in the comparative examples using traditional coke are all lower than those in the examples, the power consumption per ton of alloy is about 450 kWh higher, and the dust emission is nearly 3 times that of the examples. It can be seen that the composite carbon significantly improves the reduction efficiency, reduces the amount of reducing agent used and pollutant emissions, and effectively solves the problems of high energy consumption and heavy pollution in the traditional process;

[0079] It can be seen from the comparison of the data in the table that after the smelting flue gas is dust-removed, part of it is blown back to the furnace bottom. The carbon monoxide therein participates in the secondary reduction as a gaseous reducing agent, improving the carbon utilization rate. The waste heat is used to preheat the combustion-supporting air, enhancing the smelting thermal efficiency. The slag and dust-removing ash are cold-pressed into pellets and returned to the furnace after treatment, further increasing the manganese recovery rate and significantly reducing the solid waste discharge. At the same time, the test shows that the dust emission in the examples is much lower than that in the comparative examples. Moreover, in this smelting method, through the utilization of flue gas waste heat and the resource utilization of slag, a gas-solid resource circulation process is constructed, realizing the cascaded utilization of energy and the reduction of pollutants, solving the problems of resource waste and environmental pollution, and promoting the development of green metallurgy technology.

[0080] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0081] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not elaborate all the details, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art in the relevant technical field can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for smelting ferrosilicon manganese, characterized in that, It includes the following steps: Raw material pretreatment: Select manganese ore, silica, rare earth composite material and composite carbon. After crushing the manganese ore and silica and mixing them, then add the rare earth composite material to mix and form an ore material; Gradient reduction smelting: Layer the materials in the order of composite carbon, ore material, and composite carbon. The thickness ratio of the composite carbon layer to the ore material layer is 1:(0.8 - 1.2). Control the electrode to insert 45 - 55% of the furnace height. Conduct two-stage smelting at 1300 - 1600 °C. Keep the temperature at 1300 - 1400 °C for 1 - 2 hours in the first stage, and then raise the temperature to 1550 - 1600 °C and continue the reduction reaction for 3 - 4 hours to obtain a ferrosilicon alloy melt; Tapping and refining: Pour the melt into a ladle for refining, add a modifier accounting for 3 - 5% of the slag mass and stir for 10 - 15 minutes, and then blow argon at 8 - 12 L / min onto the melt surface for 3 - 5 minutes; Flue gas and slag collaborative treatment: After the smelting flue gas is bag-filtered, 50 - 70% of it is blown back to the periphery of the bottom electrode of the furnace. The remaining flue gas waste heat is used for power generation and preheating combustion-supporting air. The furnace slag and dust removal ash are cold-pressed into pellets and then returned to the furnace.

2. The ferrosilicon manganese smelting method according to claim 1, characterized in that The mass ratio of the silica to the manganese ore is (3 - 4):(6 - 7). After crushing, the particle size of the manganese ore is 5 - 30 mm, and the particle size of the silica after crushing is 10 - 15 mm. Among them, the mass ratio of the rare earth composite material to the silica is (5 - 8):100, and the mass ratio of the silica to the composite carbon is (2 - 3):(7 - 8).

3. The silicomanganese alloy smelting method according to claim 1, characterized in that, The rare earth composite material is prepared by flotation and purification of lanthanum-cerium rare earth ore, and the mass ratio of lanthanum oxide to cerium oxide is (2.5 - 3.5):

1.

4. The ferrosilicon manganese smelting method according to claim 1, characterized in that, The preparation method of the rare earth composite material includes the following steps: Select lanthanum-cerium rare earth ore as the raw material, crush it to 80 - 100 mesh and then conduct flotation to obtain a concentrate with a rare earth oxide content ≥ 85%. Transfer the concentrate to a rotary kiln and roast it at 950 - 1000 °C for 2 - 3 h under nitrogen protection to obtain a roasted ore powder. Then transfer it to an enamel reaction kettle and add industrial hydrochloric acid with a mass concentration of (10 - 15)%. Stir at 75 - 85 °C and 100 - 150 r / min for 4 - 5 h. Then conduct centrifugal filtration. Slowly add a 10% mass concentration of oxalic acid solution to the filtrate in a 60 °C water bath. After precipitation, age for 2 - 3 h to obtain a treated material. Calcinate the treated material at 650 - 750 °C for 3 - 4 h and then screen it to obtain a 200 - 300 mesh powder, which is the rare earth composite material.

5. The ferrosilicon manganese smelting method according to claim 4, characterized in that, The liquid-solid ratio of the industrial hydrochloric acid to the roasted ore powder is (3 - 5):1, and the molar ratio of the oxalic acid solution to the filtrate is (1 - 2):

1.

6. The silicomanganese alloy smelting method according to claim 1, characterized in that, The preparation method of the composite carbon includes the following steps: Select straw, bamboo chips and walnut shells as raw materials, mix and crush them, and then heat them to 400 - 500 °C at a heating rate of 10 °C / min for carbonization treatment for 2 - 3 h under nitrogen protection to obtain a carbonized product. Immerse the carbonized product in a 5% mass fraction of phosphoric acid solution for 2 - 3 h and then drain it to obtain a modified product. Then transfer it to an activation furnace and heat it to 500 - 600 °C at a heating rate of 10 - 15 °C / min for activation for 1 - 2 h to obtain an activated product. Then crush and screen it to obtain a composite carbon with a particle size of 10 - 50 mm.

7. The ferrosilicon manganese alloy smelting method according to claim 6, characterized in that, The mass ratio of the straw, bamboo chips and walnut shells is 5:3:2, and the liquid-solid ratio of the carbide and the phosphoric acid solution is 2:

1.

8. The silicomanganese alloy smelting method according to claim 1, characterized in that, The modifier is a composite powder obtained by premixing sodium carbonate and calcium oxide in a mass ratio of (4 - 4.5):

5.

9. The ferrosilicon manganese smelting method according to claim 1, characterized in that The cold-pressed pellets use sodium silicate solution as a binder, with an addition amount of 3 - 5% of the mass of the slag. The cold-pressing pressure is 15 - 20 MPa, and the compressive strength of the pellets is ≥600 N.

10. The ferrosilicon manganese alloy smelting method according to claim 1, characterized in that, The heating rate of the two-stage smelting is as follows: the first stage is 10 - 12 °C / min, and the second stage is 12 - 15 °C / min.

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