A method for smelting silicon-manganese alloys

Abstract

The present application relates to the technical field of metallurgical chemical industry, in particular to a silicon-manganese alloy smelting method, comprising the following steps: raw material pretreatment, gradient reduction smelting, tapping and refining, and flue gas slag cooperative treatment.In the silicon-manganese alloy smelting, lanthanum cerium oxides in the rare earth composite material react with impurities such as sulfur, phosphorus and oxygen in the melt at high temperature, forming high-melting-point compounds and separating with the molten slag, effectively reducing the impurity content, at the same time, the rare earth elements segregate at the grain boundaries, inhibiting atomic diffusion and migration, significantly refining the alloy grain size, and the rare earth composite material is optimized through the dual action of chemical purification and physical modification, solving the problems of impurity segregation and insufficient toughness in the traditional silicon-manganese alloy smelting process, and significantly improving the mechanical properties of the silicon-manganese alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical chemical industry, in particular to a silicon-manganese alloy smelting method. BACKGROUND

[0002] Silicon-manganese alloy is an important deoxidizer and alloy additive in the steel industry, and its performance directly affects the strength, toughness and corrosion resistance of steel, is a widely used and large output ferroalloy.

[0003] In the prior art, such as Chinese patent publication No. CN114908263A, a silicon-manganese alloy preparation method is disclosed, which specifically includes raw material preheating and accurate batching and raw material mixing, after mixing, the raw materials are transported to the reaction furnace, the initiator is ignited, and the initiator is used to initiate high temperature to complete the smelting of silicon-manganese alloy. After smelting, cooling, separation and post-treatment are carried out to complete the preparation of silicon-manganese alloy. The heat in the smelting process of the present application comes from the heat generated by igniting the initiator, and electric power is not used as energy, which greatly reduces the power cost in the production process; at the same time, the electric furnace with large volume and complex structure is not used as the reaction container, which reduces the investment of equipment and site for production. In addition, the application can also improve the manganese recovery rate, and can also reduce the mass fraction of carbon, phosphorus and sulfur and other elements.

[0004] Although the silicon-manganese alloy preparation method in the above-mentioned patent has many benefits, the manganese recovery rate in the traditional silicon-manganese alloy smelting process still needs to be further improved, so as to further reduce the mass fraction of carbon, sulfur and phosphorus, otherwise the impurity elements such as carbon, sulfur and phosphorus will form impurity phases in the alloy, distributed in the grain boundary and matrix, resulting in the decrease of grain boundary strength, the easy initiation and propagation of cracks, and thus the decrease of the mechanical properties such as tensile strength and toughness of the alloy.

[0005] Based on this, the present application provides a silicon-manganese alloy smelting method. SUMMARY

[0006] The purpose of the present application is to provide a silicon-manganese alloy smelting method to solve the problems raised in the above background.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a silicon-manganese alloy smelting method, comprising the following steps:

[0008] Raw material pretreatment: select manganese ore, silica, rare earth composite material and composite carbon, crush the manganese ore and silica, then mix them, and then add the rare earth composite material to form ore material;

[0009] Gradient reduction smelting: layered material according to the order of composite carbon, ore material, composite carbon, the thickness ratio of composite carbon and ore material layer is 1: (0.8-1.2), the electrode insertion height in the hearth is controlled to be 45-55%, two-stage smelting is carried out at 1300-1600℃, the first stage is 1300-1400℃ for 1-2 hours, the second stage is heated to 1550-1600℃ for 3-4 hours of reduction reaction, and the silicon-manganese alloy melt is obtained;

[0010] Tapping and refining: the melt is introduced into a ladle for refining, a modifier with a mass of 3-5% of the slag is added and stirred for 10-15 minutes, then 8-12L / min argon is blown into the melt surface for 3-5 minutes;

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

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

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

[0014] Preferably, the preparation method of the rare earth composite material comprises the following steps: selecting lanthanum-cerium rare earth ore as raw material, crushing to 80-100 mesh and then flotation to obtain a concentrate with a rare earth oxide content of ≥85%, transferring the concentrate to a rotary kiln, roasting at 950-1000℃ for 2-3h under nitrogen protection to obtain roasted ore powder, then transferring the roasted ore powder to an enamel reaction kettle and adding industrial hydrochloric acid with a mass concentration of (10-15)%, stirring at 75-85℃ and 100-150r / min for 4-5h, then centrifugal filtration, slowly adding 10% oxalic acid solution to the filtrate in a 60℃ water bath, aging the precipitate for 2-3h to obtain treated material, calcining the treated material at 650-750℃ for 3-4h, and sieving to obtain 200-300 mesh powder, which is the rare earth composite material.

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

[0016] Preferably, the composite carbon preparation method comprises the following steps: selecting straw, bamboo chips and walnut shells as raw materials, mixing and crushing, then carbonizing under nitrogen protection at a temperature increasing rate of 10 ℃ / min to 400-500 ℃ for 2-3 h to obtain carbonized substances, immersing the carbonized substances in a 5% mass fraction phosphoric acid solution for 2-3 h, then draining to obtain modified substances, then transferring into an activation furnace, heating at a temperature increasing rate of 10-15 ℃ / min to 500-600 ℃ for 1-2 h to obtain activated substances, and then 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 substances and the phosphoric acid solution is 2:1.

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

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

[0020] Preferably, the temperature increasing rate of the two-stage smelting is: 10-12 ℃ / min in the first stage and 12-15 ℃ / min in the second stage.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. In the present application, lanthanum cerium oxides in the rare earth composite material react with impurities such as sulfur, phosphorus and oxygen in the melt at high temperature during the smelting of silicon-manganese alloy, forming high-melting-point compounds and separating with the molten slag, effectively reducing the impurity content, and at the same time, the rare earth elements are segregated at the grain boundaries, inhibiting atomic diffusion and migration, and significantly refining the alloy grain size. The rare earth composite material optimizes the alloy solidification structure through the dual action of chemical purification and physical modification, solves the problems of impurity segregation and insufficient toughness in the traditional silicon-manganese alloy smelting process, and significantly improves the mechanical properties of silicon-manganese alloy.

[0023] 2. In the present application, a large number of microporous structures are formed after the composite carbon is carbonized and activated, 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 forms a synergistic effect with the solid carbon, reducing the energy required for the reaction. Therefore, the composite carbon significantly improves the reduction efficiency, reduces the amount of reducing agent and pollutant emissions, and effectively solves the problems of high energy consumption and heavy pollution in the traditional process.

[0024] 3、The present application, in the smelting of silicon-manganese alloy, part of the smelting flue gas is blown back to the furnace bottom after dust removal, the carbon monoxide therein participates in secondary reduction as a gaseous reducing agent, improving the carbon utilization rate, the waste heat is used for preheating combustion air, improving the smelting heat efficiency, the slag and dust removal ash are treated and then cold-pressed into pellets for return to the furnace, further improving the manganese recovery rate, and significantly reducing solid waste emissions, in the smelting method, the flue gas waste heat utilization and slag resourceization are combined to construct a gas-solid resource circulation process, realizing energy cascade utilization and pollutant emission reduction, solving the problems of resource waste and environmental pollution, and promoting the development of green metallurgical process. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment 1 provides a silicon-manganese alloy smelting method, comprising the following steps:

[0027] Raw material pretreatment: select manganese ore, silica, rare earth composite material and composite carbon, crush the manganese ore and silica, then mix them, and then add the rare earth composite material to form ore material;

[0028] Gradient reduction smelting: layer the composite carbon, ore material and composite carbon in sequence, the thickness ratio of the composite carbon layer to the ore material layer is 1:0.8, control the electrode insertion height in the furnace to be 45%, and carry out two-stage smelting at 1300-1550 DEG C, the first stage is 1300 DEG C for 1 hour, the second stage is to heat to 1550 DEG C for 3 hours of continuous reduction reaction, to obtain silicon-manganese alloy melt;

[0029] Tapping and refining: introduce the melt into a refining ladle, add 3% of the modified agent by mass of the slag, stir for 10 minutes, and then blow 8 L / min of argon gas onto the surface of the melt for 3 minutes;

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

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

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

[0033] The rare earth composite material preparation method comprises the following steps: selecting lanthanum-cerium rare earth ore as raw material, crushing to 80 meshes, and then flotation to obtain a concentrate with a rare earth oxide content of 85%; transferring the concentrate to a rotary kiln, roasting at 950 DEG C for 2h under nitrogen protection, obtaining a roasted ore powder, then transferring to a enamel reaction kettle and adding 10% industrial hydrochloric acid by mass concentration, stirring at 75 DEG C and 100r / min for 4h, then centrifugal filtration, slowly adding 10% oxalic acid solution by mass concentration to the filtrate in a 60 DEG C water bath, aging for 2h after precipitation to obtain a treated material, and sieving the treated material calcined at 650 DEG C for 3h to obtain a 200 mesh powder, which is the rare earth composite material.

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

[0035] The composite carbon preparation method comprises the following steps: selecting straw, bamboo chips and walnut shells as raw materials, mixing and crushing, then carbonizing at 400 DEG C under nitrogen protection at a temperature rising rate of 10 DEG C / min for 2h to obtain carbonized material, immersing the carbonized material in 5% phosphoric acid solution by mass fraction for 2h, then draining, obtaining modified material, then transferring into an activation furnace, activating at 500 DEG C at a temperature rising rate of 10 DEG C / min for 1h to obtain activated material, and then crushing and sieving to obtain composite carbon with a particle size of 10mm.

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

[0037] The modifier is a composite powder agent pre-mixed by sodium carbonate and calcium oxide at a mass ratio of 4:5.

[0038] The cold-pressed pellets use sodium silicate solution as a binder, and the addition amount is 3% of the mass of the slag, the cold-pressing pressure is 15MPa, and the pellet compressive strength is greater than or equal to 600N.

[0039] The temperature rising rate of the two-stage smelting is: 10 DEG C / min in the first stage and 12 DEG C / min in the second stage.

[0040] Example 2, a silicon-manganese alloy smelting method, comprising the following steps:

[0041] Raw material pretreatment: selecting manganese ore, silica, rare earth composite material and composite carbon, crushing the manganese ore and silica, mixing, then adding the rare earth composite material to form an ore material;

[0042] Gradient reduction smelting: layered distribution according to composite carbon, ore material, composite carbon, the thickness ratio of composite carbon and ore material layer is 1:1.2, control the electrode insertion into the furnace height of 55%, carry out two-stage smelting at 1400-1600 ℃, the first stage is 1400 ℃ for 2 hours, the second stage is heated to 1600 ℃ for 4 hours of reduction reaction, obtain silicon-manganese alloy melt;

[0043] Tapping and refining: the melt is introduced into the refining ladle, 5% of the modifier of the mass of the slag is added and stirred for 15 minutes, then 12 L / min of argon is blown into the melt surface for 5 minutes;

[0044] Flue gas slag cooperative treatment: 70% of the smelting flue gas after bag dust removal is blown back to the electrode periphery of the furnace bottom, the remaining flue gas waste heat is used for power generation and preheating combustion air, the slag and dust removal ash are cold pressed into pellets and returned to the furnace.

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

[0046] Among them, the rare earth composite material is prepared from lanthanum-cerium rare earth ore by flotation purification, 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: selecting lanthanum-cerium rare earth ore as raw material, crushing to 100 mesh and then flotation to obtain concentrate with rare earth oxide content ≥85%, transferring the concentrate to a rotary kiln, roasting at 1000 ℃ for 3h under nitrogen protection to obtain roasted ore powder, then transferring to a enamel reaction kettle and adding industrial hydrochloric acid with a mass concentration of 15%, stirring at 85 ℃ and 150 r / min for 5h, then centrifugal filtration, slowly adding oxalic acid solution with a mass concentration of 10% to the filtrate in a 60 ℃ water bath, aging for 3h after precipitation to obtain treated material, calcining the treated material at 750 ℃ for 4h and then sieving to obtain 300 mesh powder, which is the rare earth composite material.

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

[0049] Among them, the preparation method of the composite carbon includes the following steps: selecting straw, bamboo chips and walnut shells as raw materials, mixing and crushing, then carbonizing at 500 ℃ under nitrogen protection with a temperature rising rate of 10 ℃ / min for 3h to obtain carbonized material, immersing the carbonized material in a phosphoric acid solution with a mass fraction of 5% for 3h and then draining to obtain modified material, then transferring to an activation furnace and activating at 600 ℃ with a temperature rising rate of 15 ℃ / min for 2h to obtain activated material, then crushing and sieving to obtain composite carbon with a particle size of 50 mm.

[0050] The mass ratio of the straw, the bamboo chips and the walnut shell is 5:3:2, and the liquid-solid ratio of the carbonized product and the phosphoric acid solution is 2:1.

[0051] The modifier is a composite powder agent pre-mixed by sodium carbonate and calcium oxide at a mass ratio of 4.5:5.

[0052] The sodium silicate solution is used as the binder for the cold-pressed pellets, and the addition amount is 5% of the mass of the slag, and the cold-pressing pressure is 20 MPa, and the compressive strength of the pellets is greater than or equal to 600 N.

[0053] The heating rate of the two-stage smelting is: 12 ℃ / min in the first stage and 15 ℃ / min in the second stage.

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

[0055] Raw material pretreatment: select manganese ore, silica, rare earth composite material and composite carbon, crush the manganese ore and silica, then mix them, and then add the rare earth composite material to form ore material;

[0056] Gradient reduction smelting: layer the composite carbon, the ore material and the composite carbon in sequence, the thickness ratio of the composite carbon layer to the ore material layer is 1:1, control the electrode insertion height to be 50% of the furnace chamber height, and perform two-stage smelting at 1350-1580 ℃, the first stage is 1350 ℃ for 1.5 hours, and the second stage is to heat to 1580 ℃ for a reduction reaction of 3.5 hours to obtain a silicon-manganese alloy melt;

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

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

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

[0060] The rare earth composite material is prepared from a lanthanum-cerium rare earth ore by flotation purification, and the mass ratio of lanthanum oxide to cerium oxide is 3:1.

[0061] The rare earth composite material preparation method comprises the following steps: selecting a lanthanum-cerium rare earth ore as a raw material, crushing to 90 meshes, and then flotation to obtain a concentrate with a rare earth oxide content of greater than or equal to 85%; transferring the concentrate to a rotary kiln, roasting at 980 DEG C for 2.5 hours under nitrogen protection, obtaining a roasted ore powder, then transferring the roasted ore powder to an enamel reaction kettle and adding industrial hydrochloric acid with a mass concentration of 13%, stirring at 80 DEG C and 120 r / min for 4.5 hours, then centrifugal filtration, slowly adding an oxalic acid solution with a mass concentration of 10% to the filtrate in a 60 DEG C water bath, and aging for 2.5 hours after precipitation to obtain a treated material, and then sieving the treated material calcined at 700 DEG C for 3.5 hours to obtain a 250-mesh powder, which is the rare earth composite material.

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

[0063] The composite carbon preparation method comprises the following steps: selecting straw, bamboo chips and walnut shells as raw materials, mixing and crushing, then carbonizing at 450 DEG C for 2.5 hours under nitrogen protection with a temperature rising rate of 10 DEG C / min, obtaining carbonized material, then dipping the carbonized material in a phosphoric acid solution with a mass fraction of 5% for 2.5 hours and then draining, obtaining modified material, then transferring the modified material into an activation furnace and activating at 550 DEG C for 1.5 hours with a temperature rising rate of 12 DEG C / min, obtaining activated material, and then crushing and sieving to obtain composite carbon with a particle size of 30 mm.

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

[0065] The modifier is a composite powder agent prepared by premixing sodium carbonate and calcium oxide at a mass ratio of 4.2:5.

[0066] The cold-pressed pellets use a sodium silicate solution as a binder, and the addition amount is 4% of the mass of the slag, and the cold-pressing pressure is 18 MPa, and the pellet compressive strength is greater than or equal to 600 N.

[0067] The temperature rising rate of the two-stage smelting is: 11 DEG C / min in the first stage and 14 DEG C / min in the second stage.

[0068] Comparative Example 1, the difference between the comparative example 1 and the examples 1-3 is that the traditional coke is used instead of the composite carbon in the silicon-manganese alloy smelting process of the comparative example 1.

[0069] Comparative Example 2, the difference between the comparative example 2 and the examples 1-3 is that the rare earth composite material is not added in the silicon-manganese alloy smelting process of the comparative example 2.

[0070] Comparative Example 3, the difference between the comparative example 3 and the examples 1-3 is that the traditional coke is used instead of the composite carbon and the rare earth composite material is not added in the silicon-manganese alloy smelting process of the comparative example 3.

[0071] Test method:

[0072] Alloy performance: Grain size and inclusion distribution were observed by scanning electron microscope (SEM); tensile strength was tested by universal testing machine.

[0073] Reduction efficiency: Manganese recovery rate (Mn mass in manganese alloy / total Mn mass in raw material x 100%) was calculated, and power consumption (kWh / t) was recorded.

[0074] Pollutant emission: Dust and CO concentration in flue gas were detected.

[0075] The performance of the silicon-manganese alloy smelting methods in Examples 1-3 and Comparative Examples 1-3 was tested, and the test data obtained are recorded in the following table:

[0076]

[0077] As can be seen from the data in the table, lanthanum and cerium oxides in the rare earth composite 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 atomic diffusion and migration, significantly refining the grain size of the alloy. At the same time, tests show that the inclusion content in the comparative examples without adding rare earth composite is much higher than that in the examples, and the tensile strength of the alloy in the examples is significantly improved compared with that in the comparative examples. This shows that the rare earth composite optimizes the solidification structure of the alloy through chemical purification and physical modification, solves the problems of impurity segregation and insufficient toughness in the traditional silicon-manganese alloy smelting process, and significantly improves the mechanical properties of the silicon-manganese alloy.

[0078] As can be seen from the data in the table, a large number of microporous structures are formed after the composite carbon is carbonized and activated, 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 synergistic effect of the reducing gas generated during the carbonization process and the solid carbon reduces the energy required for the reaction. At the same time, tests show that the manganese recovery rate of the comparative examples using traditional coke is lower than that in the examples, the power consumption per ton of alloy is about 450 kilowatt-hours 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 and pollutant emissions, and effectively solves the problems of high energy consumption and heavy pollution in the traditional process;

[0079] As can be seen from the data in the table, part of the smelting flue gas after dust removal is blown back to the furnace bottom, and the carbon monoxide therein participates in secondary reduction as a gaseous reducing agent, improving the carbon utilization rate, and the waste heat is used to preheat combustion air, improving the smelting heat efficiency, and the slag and dust removal ash are treated and cold-pressed into pellets for recycling, further improving the manganese recovery rate and greatly reducing solid waste emissions. At the same time, tests show that the dust emission in the example is much lower than that in the comparative example, and in the smelting method, the gas-solid resource circulation process is constructed through the utilization of flue gas waste heat and slag resourceization, realizing energy cascade utilization and pollutant emission reduction, solving the problems of resource waste and environmental pollution, and promoting the development of green metallurgical process.

[0080] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like 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 application. In the present specification, the illustrative 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 any one or more embodiments or examples in a suitable manner.

[0081] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method of smelting a silicon-manganese alloy, characterized in that, It comprises the following steps: Raw material pretreatment: select manganese ore, silica, rare earth composite material and composite carbon, crush the manganese ore and silica, then mix them, and then add the rare earth composite material to form ore material; Gradient reduction smelting: layer the composite carbon, ore material and composite carbon in sequence, the thickness ratio of the composite carbon and ore material layer is 1:(0.8-1.2), control the electrode insertion height in the hearth to be 45-55%, and carry out two-stage smelting at 1300-1600℃, the first stage is 1300-1400℃ for 1-2 hours, the second stage is to raise the temperature to 1550-1600℃ for 3-4 hours of continuous reduction reaction, and obtain silicon-manganese alloy melt; Tapping and refining: introduce the silicon-manganese alloy melt into a ladle for refining, add a modifier with a mass of 3-5% of the slag, stir for 10-15 minutes, then blow 8-12L / min argon into the melt surface for 3-5 minutes; Flue gas and slag cooperative treatment: after the smelting flue gas is bag filtered, 50-70% of the flue gas is blown back to the electrode periphery of the furnace bottom, the remaining flue gas is used for power generation and preheating combustion air, and the slag and dust removal ash are cold-pressed into pellets and then returned to the furnace; The rare earth composite material is prepared from lanthanum-cerium rare earth ore by flotation purification, and the mass ratio of lanthanum oxide to cerium oxide is (2.5-3.5):1; The preparation method of the rare earth composite material comprises the following steps: selecting lanthanum-cerium rare earth ore as raw material, crushing to 80-100 mesh, and then flotation to obtain a concentrate with rare earth oxide content ≥85%, transferring the concentrate to a rotary kiln, roasting at 950-1000℃ for 2-3h under nitrogen protection, obtaining roasted ore powder, then transferring to a enamel reaction kettle and adding industrial hydrochloric acid with a mass concentration of 10-15%, stirring at 75-85℃ and 100-150r / min for 4-5h, then centrifugal filtration, slowly adding oxalic acid solution with a mass concentration of 10% to the filtrate in a 60℃ water bath, aging the precipitate for 2-3h to obtain treated material, calcining the treated material at 650-750℃ for 3-4h, and then sieving to obtain 200-300 mesh powder, which is the rare earth composite material; The preparation method of the composite carbon comprises the following steps: selecting straw, bamboo shavings and walnut shells as raw materials, mixing and crushing, then carbonizing at 400-500℃ under nitrogen protection with a temperature rising rate of 10℃ / min for 2-3h to obtain carbonized material, immersing the carbonized material in a phosphoric acid solution with a mass fraction of 5% for 2-3h, then draining, obtaining modified material, then transferring to an activation furnace, activating at 500-600℃ with a temperature rising rate of 10-15℃ / min for 1-2h, obtaining activated material, then crushing and sieving to obtain composite carbon with a particle size of 10-50mm.

2. The silicon-manganese alloy smelting method according to claim 1, characterized by, The mass ratio of the silica and manganese ore is (3-4):(6-7), the particle size of the crushed manganese ore is 5-30mm, the particle size of the crushed silica is 10-15mm, the mass ratio of the rare earth composite material to silica is (5-8):100, and the mass ratio of the silica to composite carbon is (2-3):(7-8).

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

1.

4. The silicon-manganese alloy smelting method of claim 1, wherein, The mass ratio of the straw, bamboo chips and walnut shell is 5:3:2, and the liquid-solid ratio of the carbonized product and the phosphoric acid solution is 2:

1.

5. The silicon-manganese alloy smelting method of claim 1, wherein, The modifier is a composite powder agent prepared by premixing sodium carbonate and calcium oxide at a mass ratio of (4-4.5):

5.

6. The silicon-manganese alloy smelting method of claim 1, wherein, The pellets use sodium silicate solution as a binder, and the addition amount is 3-5% of the mass of the slag, and the cold pressing pressure is 15-20 MPa, and the compressive strength of the pellets is greater than or equal to 600 N.

7. The silicon-manganese alloy smelting method of claim 1, wherein, The heating rate of the two-stage smelting is: 10-12 ℃ / min in the first stage and 12-15 ℃ / min in the second stage.

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