Method for producing high-carbon ferro-chrome by using coal instead of traditional reducing agent in ultrahigh proportion

Abstract

The invention belongs to the technical field of alloy smelting, and particularly relates to a method for producing high-carbon ferro-chrome by using coal instead of a traditional reducing agent in an ultrahigh proportion, and the method for producing the high-carbon ferro-chrome comprises the following steps: pretreating chromium ore to obtain a chromium raw material, and mixing silica and lime to obtain a solvent; mixing a chromium raw material, a reducing agent and a solvent to obtain a furnace charge; charging the furnace charge into a submerged arc furnace, starting the furnace by using an arc striking electrode, and rapidly starting arc and heating to promote the furnace charge to be preliminarily melted; and after the furnace burden is molten, the temperature in the furnace is maintained to be 1700-1800 K, and the reaction time is 2-3 h. According to the method, the reducing agent is prepared from the high-proportion low-phosphorus and low-sulfur carbonaceous components, the smelting temperature and the content of SiO2 in the slag are regulated and controlled, the content of Cr and the content of C in the high-carbon ferrochrome can be effectively increased, the use amount of the coke reducing agent is greatly reduced, and the problems that in the prior art, the cost of the coke reducing agent is high, and the reducibility is low are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy smelting, and specifically relates to a method for producing high-carbon ferrochrome by replacing a traditional reducing agent with coal in an ultra-high proportion. Background Art

[0002] As a key alloying agent in the steel industry, high carbon ferrochrome plays an indispensable role in improving the hardness, wear resistance and corrosion resistance of steel. It is widely used in the production process of many high-end steels such as ball steel, tool steel, die steel and high-speed steel. The production process of traditional high carbon ferrochrome has long relied on specific traditional reducing agents, such as metallurgical coke, semi-coke or other reducing agents containing a high proportion of metallurgical coke or / and semi-coke. However, semi-coke and metallurgical coke are both coke, which are deep-processed products of coal. The deep processing process will generate corresponding processing costs and pollutant treatment costs. In addition, there are the following problems that cannot be ignored in the application of metallurgical coke and semi-coke. On the one hand, coke-based reducing agents will release a large amount of carbon dioxide, sulfur dioxide, nitrogen oxides and other pollutants during combustion and reaction, which is incompatible with the era of low-carbon emission reduction and green manufacturing advocated by the world; on the other hand, in order to meet the requirements of environmental protection regulations, enterprises need to invest huge amounts of money to purchase environmental protection equipment and upgrade treatment processes, and production costs will further increase.

[0003] As a low-cost energy source with abundant reserves, coal has gradually attracted attention for its potential application in the metallurgical field. Compared with coke, coal has higher reactivity and lower cost. However, since coal contains more impurities (such as sulfur and phosphorus), direct use will lead to a decrease in product quality. Based on the above problems, this application document proposes a method for producing high carbon ferrochrome by replacing traditional reducing agents with coal in an ultra-high proportion to improve the problem of high cost of traditional reducing agents in the high carbon ferrochrome smelting process. Summary of the invention

[0004] The purpose of the present invention is to provide a method for producing high carbon ferrochrome by replacing traditional reducing agents with coal in an ultra-high proportion, by preparing the reducing agent with a high proportion of low phosphorus and low sulfur carbonaceous components, and controlling the smelting temperature and the SiO2 content in the slag. 2 The Cr and C contents in high carbon ferrochrome can be effectively increased by regulating the content, which greatly reduces the usage of coke-based reducing agents, gives full play to the advantages of abundant coal reserves, low cost and high reaction activity, and solves the problems of high cost and low reducibility of coke-based reducing agents in the prior art.

[0005] The technical solution adopted by the present invention is as follows: A method for producing high carbon ferrochrome by replacing traditional reducing agents with coal in an ultra-high proportion, comprising the following steps: S1: pre-treating chromium ore to obtain chromium raw materials, mixing silica and lime to obtain solvent; S2: Mixing a chromium raw material, a reducing agent and a solvent to obtain a furnace charge, wherein the weight ratio of the chromium raw material, the reducing agent and the solvent is 0.35-0.45:1:0.15-0.25, and the reducing agent includes the following components in weight ratio: 30%-60% of extra-low sulfur coal, 30%-65% of anthracite, and 5%-10% of metallurgical coke, and the fixed carbon content of the extra-low sulfur coal and the anthracite is greater than 85%; S3: Load the charge into the ore-fired furnace, start the furnace with an arc-starting electrode, the starting voltage is 100-120V, the current is 25000-35000A, and the arc is started quickly to raise the temperature, so as to promote the initial melting of the charge; S4: After the charge is melted, gradually increase the voltage to 180-220V, stabilize the current at 35000-40000A, maintain the temperature in the furnace at 1700K-1800K, and the reaction time is 2-3h. The high temperature range of 1700K-1800K is conducive to the full reaction of carbon in coal and chromium oxide in chromium ore, accelerating the reduction process. During this period, the electrode insertion depth needs to be adjusted in time through the electrode lifting system to keep the three-phase electrode buried in the charge at a depth of 1.2-1.5 times the electrode diameter to ensure arc stability and uniform heat distribution. S5: After smelting, add slag-making agent into the ore-fired furnace and continue stirring for refining. The refining time is 0.5 to 1 hour. Then the furnace is taken out and the slag is removed. Among them, SiO 2 The content is controlled at 24% to 30%; S6: The molten steel is transferred into the converter, argon gas is blown into the converter for deoxidation, and the furnace temperature is fine-tuned to stabilize the temperature of the molten steel in the converter at 1550K to 1650K; S7: Pour the molten steel into the mold, control the casting speed at 2-3 t / h, maintain the casting temperature at 1450K-1550K, cool naturally, and obtain the high carbon ferrochrome product after demoulding.

[0006] In a preferred embodiment, as described in S1, the chromium ore contains Cr 2 O 3 The content is 42% to 48%, and the chromium raw material includes chromium powder and chromium block. The particle size of the chromium powder is less than 10 mm, the particle size of the chromium block is 10 to 100 mm, and the weight ratio of the chromium powder to the chromium block is 1:1 to 3.5.

[0007] In a preferred embodiment, as described in S1, the weight ratio of lime to silica in the solvent is 1:1.2-1.5.

[0008] In a preferred embodiment, as described in S2, the particle size of the silica is 5 to 20 mm, the particle size of the lime is 3 to 15 mm, and the SiO2 The content is greater than 98%, and the purity of the lime is greater than 90%.

[0009] In a preferred embodiment, as described in S2, the P content and S content in the extra-low sulfur coal and anthracite are both less than 0.005%, and the particle sizes of the metallurgical coke, extra-low sulfur coal and anthracite are all less than 5 mm.

[0010] In a preferred embodiment, as described in S5, the slag-making agent includes lime and fluorite, wherein CaF 2 The content is greater than 80%, and the particle size is 2 to 8 mm. The weight ratio of lime to fluorite is 3 to 5:1 to 2, wherein fluorite can adjust the fluidity of the slag and promote the separation of impurities.

[0011] In a preferred embodiment, as described in S5, the amount of slag-forming agent added is 4% to 7% of the total weight of the charge.

[0012] In a preferred embodiment, as described in S5, the SiO in the slag 2 The content of is controlled at 24% to 30%, comprising the following steps: St1: Take slag samples from the slag mouth every 20 minutes to test CaO and SiO 2 Content; St2: If the slag contains SiO 2 If the content of SiO is lower than 24%, silica is added to the furnace. 2 The content of silica is 98%, and the amount of silica added is calculated by the following formula: , where M represents the amount of silica added, M 1 represents the total mass of the charge, Cm represents the SiO in the slag 2 The target value of the content of SiO in the slag is represented by Dm. 2 The actual content percentage value, 98% means that SiO 2 Content; St3: If SiO 2 If the content exceeds 30%, lime is added to the submerged arc furnace, wherein the particle size of the lime is less than 1 mm, the purity of the lime is 90%, and the amount of lime added is calculated by the following formula: , where M 2 Indicates the amount of lime added, M 1 represents the total mass of the charge, Cm represents the SiO in the slag 2 The target value of the content of SiO in the slag is represented by Dm. 2 The actual content percentage value is 90%, which indicates the purity of lime, 56 indicates the molar mass of CaO, and 60 indicates the molar mass of SiO 2The molar mass of St2 and St3, wherein the value range of Cm is 24% to 30%, and the specific value is determined according to actual production requirements.

[0013] In a preferred embodiment, as described in S6, the argon gas flow rate is 10-15 Nm 3 / h, lasting for 10 to 15 minutes.

[0014] The technical effects achieved by the present invention are: The present invention adopts a high proportion of low-phosphorus and low-sulfur carbonaceous components to prepare a reducing agent, and controls the smelting temperature and the SiO2 content in the slag. 2 The content can be regulated and controlled. When producing high-carbon ferrochrome, the Cr content and C content in the high-carbon ferrochrome can be effectively increased, and the use of coke-based reducing agents is greatly reduced. The advantages of abundant coal reserves, low cost and high reaction activity are fully utilized, and the problems of high cost and low reducibility of coke-based reducing agents in the prior art are solved. The problem of large amounts of pollutants generated by coke-based reducing agents during use and deep processing is also avoided. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0016] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0017] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in a preferred embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0018] Preparation Example 1: Preparation of chromium raw materials The chromium ore is processed into blocks, and after screening, the chromium blocks with a particle size of 10 to 100 mm and the chromium powder with a particle size of less than 10 mm are mixed to obtain the chromium raw material. 2 O 3 The content is 45%.

[0019] Preparation Example 2: Preparation of solvent Silica and lime are uniformly mixed at a ratio of 1:1.5 to obtain a solvent, wherein the particle size of the silica is 5 to 20 mm, the particle size of the lime is 3 to 15 mm, and the SiO2 The content is greater than 98%, and the purity of the lime is greater than 90%.

[0020] Preparation Example 3: Preparation of reducing agent Metallurgical coke, extra-low sulfur coal and anthracite are screened and dried respectively so that the particle sizes of the metallurgical coke, extra-low sulfur coal and anthracite are all 3-5 mm, and then the metallurgical coke, extra-low sulfur coal and anthracite are mixed in a weight ratio of 1:3:6 to obtain a reducing agent, wherein the P content and S content in the extra-low sulfur coal and anthracite are both less than 0.005%, and the fixed carbon content in the metallurgical coke, extra-low sulfur coal and anthracite is greater than 85%.

[0021] Preparation Example 4: Preparation of slag-forming agent Lime and fluorite are uniformly mixed at a ratio of 4:1.5 to obtain a slag-making agent, wherein CaF 2 The content is greater than 80%, the particle size is 2-8 mm, and the purity of the lime is greater than 90%.

[0022] Embodiment 1 Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 190V and the secondary working current is 38000A. Maintain the temperature in the submerged arc furnace at 1600-1700K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 35%.

[0023] It should be noted that K is Kelvin temperature.

[0024] Embodiment 2 Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 200V and the secondary working current is 40000A. Maintain the temperature in the submerged arc furnace at 1700-1800K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag.2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 27%.

[0025] Embodiment 3 Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 220V and the secondary working current is 43000A. Maintain the temperature in the submerged arc furnace at 1800-1900K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 22%.

[0026] Embodiment 4 In this embodiment, based on the first embodiment, SiO in the slag is removed. 2 The content is adjusted to 30%, specifically, Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 190V and the secondary working current is 38000A. Maintain the temperature in the submerged arc furnace at 1600-1700K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace and stir continuously. After stirring for 20 minutes, take out the slag sample from the tapping hole for testing. The SiO in the slag sample is 2 The content is 35%. Add 23.25 kg of lime with a purity of 90% to the submerged arc furnace, continue stirring for 20 minutes, remove from the furnace, slag and detect the SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 30%.

[0027] Embodiment 5 In this embodiment, based on the second embodiment, SiO in the slag is removed. 2 The content is adjusted to 24%, specifically, Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 200V and the secondary working current is 40000A. Maintain the temperature in the submerged arc furnace at 1700-1800K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace and stir continuously. After stirring for 20 minutes, take out the slag sample from the tapping hole for testing. The SiO in the slag sample is 2 The content is 27%. Add 32.55 kg of lime with a purity of 90% to the submerged arc furnace, continue stirring for 20 minutes, remove from the furnace, slag and detect the SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 24%.

[0028] Embodiment 6 In this embodiment, based on the third embodiment, SiO in the slag is removed. 2 The content is adjusted to 25%, specifically, Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 220V and the secondary working current is 43000A. Maintain the temperature in the submerged arc furnace at 1800-1900K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace and stir continuously. After stirring for 20 minutes, take out the slag sample from the tapping hole for testing. The SiO in the slag sample is 2 The content is 27%. Add 13.78 kg of silica to the ore-fired furnace, continue stirring for 20 minutes, remove from the furnace, slag and detect the SiO in the slag. 2The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 25%.

[0029] Comparative Example 1 In this comparative example, on the basis of Example 1, the ultra-low sulfur coal in the reducing agent is replaced with metallurgical coke, and other conditions remain unchanged. Specifically, The metallurgical coke and anthracite are screened and dried respectively, so that the particle sizes of the metallurgical coke and anthracite are 3-5 mm, and then the metallurgical coke and anthracite are mixed in a weight ratio of 4:6 to obtain a reducing agent, wherein the P content and S content in the anthracite are both less than 0.005%, the fixed carbon content in the metallurgical coke and anthracite is greater than 85%, and the carbonaceous component in the reducing agent accounts for 60%; Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 190V and the secondary working current is 38000A. Maintain the temperature in the submerged arc furnace at 1600-1700K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 31%.

[0030] Comparative Example 2 In this comparative example, based on Example 2, the anthracite in the reducing agent is replaced with metallurgical coke, and other conditions remain unchanged. Specifically, The metallurgical coke and the ultra-low sulfur coal are screened and dried respectively, so that the particle sizes of the metallurgical coke and the ultra-low sulfur coal are 3-5 mm, and then the metallurgical coke and the ultra-low sulfur coal are mixed in a weight ratio of 7:3 to obtain a reducing agent, wherein the P content and the S content in the ultra-low sulfur coal are both less than 0.005%, and the fixed carbon content in the metallurgical coke and the ultra-low sulfur coal is greater than 85%, and the carbonaceous component in the reducing agent accounts for 30%; Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 200V and the secondary working current is 40000A. Maintain the temperature in the submerged arc furnace at 1700-1800K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 28%.

[0031] Comparative Example 3 In this comparative example, on the basis of Example 3, the extra-low sulfur coal and anthracite in the reducing agent are replaced with metallurgical coke, and other conditions remain unchanged. The fixed carbon content in the metallurgical coke is greater than 85%, and the carbonaceous component in the reducing agent accounts for 0%. Specifically, Take 300KG of chromium raw material, 105KG of reducing agent and 45KG of solvent and mix them to obtain the charge. Load the charge into the submerged arc furnace layer by layer. The thickness of each layer does not exceed 100mm. Start the furnace with 120V voltage and 25000A current. The secondary working voltage is 220V and the secondary working current is 43000A. Maintain the temperature in the submerged arc furnace at 1800-1900K for smelting. Add 22.5KG of slag-making agent into the submerged arc furnace, stir continuously for 40 minutes, take out the furnace, slag and detect SiO in the slag. 2 The molten steel in the submerged arc furnace is transferred to the converter, and argon is blown into the furnace for deoxidation. The argon flow rate is 10-15Nm 3 / h, lasting for 15min, and at the same time fine-tuning the furnace temperature to stabilize the temperature of the molten steel in the furnace at 1550-1650K, pouring the molten steel into the mold, controlling the casting speed at 2-3t / h, cooling naturally, and demolding to obtain the high-carbon ferrochrome product. Among them, SiO in the slag 2 The content is 21%.

[0032] Test Case The high carbon ferrochrome products obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to composition analysis tests. The results are shown in Table 1 below (the balance is Fe and other unavoidable impurities): Table 1

[0033] Combined with the data in Comparative Examples 1 to 3, it can be seen that as the proportion of low-phosphorus and low-sulfur carbonaceous components in the reducing agent gradually decreases, the P content and S content in the product gradually increase, indicating that the use of low-phosphorus and low-sulfur carbonaceous components to replace coke components can effectively reduce the P content and S content in the product; at the same time, combined with the data in Examples 1 to 3 and Comparative Examples 1 to 3, it can be seen that due to the use of a high proportion of low-phosphorus and low-sulfur carbonaceous components in the reducing agent in Examples 1 to 3, the P content and S content of the products in Examples 1 to 3 are greatly reduced, and the Cr content and C content are greatly increased. By increasing the Cr content and C content in the product, the strength, toughness, ductility, wear resistance and other properties of high-carbon ferrochrome can be correspondingly improved; Combining the data in Examples 1 to 6, it can be seen that, when other process parameters remain unchanged, in Examples 2 and 4, the P content and S content in the product are relatively low, and the Cr content and C content are relatively high, indicating that when the temperature is maintained at 1700-1800K during the melting stage of the charge, it is beneficial to increase the Cr content and C content in the product. Specifically, chromium oxide (such as Cr 2 O 3 ) needs to be reduced to metallic chromium at high temperatures. The temperature range of 1700-1800K ensures that the carbonaceous reducing agent (C) and Cr 2 O 3 Fully reacted (reaction formula: Cr 2 O 3 +3C→2Cr+3CO), accelerate the reduction process, and avoid excessive temperature leading to energy waste or excessive loss of lining materials. If the temperature is too high, the reducing agent may excessively reduce the SiO in the slag. 2 , resulting in an increase in the Si content in the alloy, while the proportion of Cr and C is relatively reduced. By controlling the temperature, the reduction efficiency of chromium can be prioritized to reduce the consumption of carbon in side reactions; The data in Example 1 and Example 4, Example 2 and Example 5, and Example 3 and Example 6 are compared. Since the data in Examples 1 to 3 are not analyzed for SiO in the slag, 2 The content of SiO in the slag can be adjusted by combining the above data. It can be seen that when other process parameters remain unchanged, the content of SiO in the slag 2 Controlling the content is beneficial to increasing the C content in the product; Among them, in Example 2 and Example 4, since the smelting temperature is maintained at 1700-1800K and the SiO 2 The content is controlled at 24% to 30%, and the comprehensive performance of the product is better than that of the products in other embodiments. Specifically, SiO 2It is an acidic oxide, and its content directly affects the basicity of the slag (usually expressed as CaO / SiO 2 Ratio measurement), when SiO 2 When the slag is controlled at 24% to 30%, the viscosity and melting point of the slag are in an appropriate range, which not only ensures the effective separation of the metal droplets and the slag (reducing the mechanical entrainment loss of Cr in the slag), but also avoids the slag being too viscous to hinder the escape of CO gas. 2 If the content is too high, the reducing agent will preferentially reduce SiO 2 Rather than Cr 2 O 3 (SiO 2 The reduction Gibbs free energy is low), by regulating the SiO 2 The content can be increased to 24% to 30%, and the slag composition can be adjusted by combining an appropriate amount of alkaline flux (such as CaO) to reduce SiO 2 activity, inhibiting its reduction to Si, thereby concentrating carbon on the reduction of chromium oxides and reducing the total carbon consumption; In summary, the reducing agent is prepared by using a high proportion of low-phosphorus and low-sulfur carbonaceous components, and at the same time, the smelting temperature and the SiO2 content in the slag are controlled in a coordinated manner. 2 When producing high carbon ferrochrome, it can effectively increase the Cr and C contents in high carbon ferrochrome. Carbon is used to reduce Cr first. 2 O 3 Rather than SiO 2 or other impurity oxides, which greatly reduces the use of coke-based reducing agents, gives full play to the advantages of abundant coal reserves, low cost and high reaction activity, solves the problems of high cost and low reducing power of coke-based reducing agents in the prior art, and avoids the problem of coke-based reducing agents generating a large amount of pollutants during use and deep processing.

[0034] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. A method for producing high carbon ferrochrome by using coal in an ultra-high proportion instead of a conventional reducing agent, characterized in that: The following steps are involved: S1: pre-treating chromium ore to obtain chromium raw materials, mixing silica and lime to obtain solvent; S2: Mixing a chromium raw material, a reducing agent and a solvent to obtain a furnace charge, wherein the weight ratio of the chromium raw material, the reducing agent and the solvent is 0.35-0.45:1:0.15-0.25, and the reducing agent includes the following components in weight ratio: 30%-60% of extra-low sulfur coal, 30%-65% of anthracite, and 5%-10% of metallurgical coke, and the fixed carbon content of the extra-low sulfur coal and the anthracite is greater than 85%; S3: Load the charge into the ore-fired furnace, start the furnace with an arc-starting electrode, the starting voltage is 100-120V, the current is 25000-35000A, and the arc is started quickly to raise the temperature, so as to promote the initial melting of the charge; S4: After the charge is melted, gradually increase the voltage to 180-220V, stabilize the current at 35000-40000A, maintain the temperature in the furnace at 1700K-1800K, and the reaction time is 2-3h; S5: After smelting, add slag-making agent into the ore-fired furnace and continue stirring for refining. The refining time is 0.5 to 1 hour, then remove from the furnace and remove the slag. The content of SiO2 in the slag is controlled at 24% to 30%. S6: The molten steel is transferred into the converter, argon gas is blown into the converter for deoxidation, and the furnace temperature is fine-tuned to stabilize the temperature of the molten steel in the converter at 1550K to 1650K; S7: Pour the molten steel into the mold, cool it naturally, and demould to obtain the high carbon ferrochrome product.

2. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S1, the Cr2O3 content in the chromium ore is 42% to 48%, and the chromium raw material includes chromium powder and chromium blocks. The particle size of the chromium powder is less than 10 mm, the particle size of the chromium block is 10 to 100 mm, and the weight ratio of the chromium powder to the chromium block is 1:1 to 3.

5.

3. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S1, the weight ratio of lime to silica in the solvent is 1:1.2-1.

5.

4. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S1, the particle size of the silica is 5 to 20 mm, the particle size of the lime is 3 to 15 mm, the SiO2 content in the silica is greater than 98%, and the purity of the lime is greater than 90%.

5. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S2, the P content and S content in the extra-low sulfur coal and anthracite are both less than 0.005%, and the particle sizes of the metallurgical coke, extra-low sulfur coal and anthracite are all less than 5 mm.

6. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S5, the slag-making agent includes lime and fluorite, the CaF2 content in the fluorite is greater than 80%, and the particle size is 2-8 mm, wherein the weight ratio of lime to fluorite is 3-5:1-2.

7. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S5, the amount of slag-forming agent added is 4% to 7% of the total weight of the charge.

8. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S5, the content of SiO2 in the slag is controlled at 24% to 30%, comprising the following steps: St1: Take slag samples from the slag mouth every 20 minutes to detect the SiO2 content in the slag; St2: If the SiO2 content in the slag is lower than 24%, silica is added into the ore-fired furnace, wherein the SiO2 content in the silica is 98%; St3: If the SiO2 content exceeds 30%, lime is added into the ore-fired furnace, wherein the particle size of the lime is less than 1 mm.

9. The method for producing high carbon ferrochrome by using coal in a super high proportion instead of a conventional reducing agent according to claim 1, characterized in that: As described in S6, the argon gas flow rate is 10-15 Nm 3 / h, lasting for 10 to 15 minutes.

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