A method for producing high-carbon ferrochrome by using coal to replace traditional reducing agents with an extremely high proportion

Abstract

The present invention belongs to the technical field of alloy smelting, and particularly relates to a method for producing high-carbon ferrochrome by using coal to replace traditional reducing agents in an ultra-high proportion. The method for producing high-carbon ferrochrome comprises the following steps: pretreating chromite ore to obtain chromium raw materials, mixing silica and lime to obtain a flux; mixing the chromium raw materials, reducing agents, and flux to obtain furnace charge; loading the furnace charge into a submerged arc furnace, starting the furnace with an arc ignition electrode, quickly raising the arc to increase the temperature, and promoting the preliminary melting of the furnace charge; after the furnace charge melts, maintaining the temperature in the furnace at 1700K - 1800K for a reaction time of 2 - 3h. By using a carbonaceous component with a high proportion of low phosphorus and low sulfur to prepare a reducing agent and controlling the smelting temperature and the SiO2 content in the slag, the present invention can effectively increase the Cr content and C content in high-carbon ferrochrome, greatly reduce the usage amount of coke-based reducing agents, and solve the problems of high cost and low reducibility of coke-based reducing agents in the prior art.

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.

[0004] 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

[0005] 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 adopting a high proportion of low-phosphorus and low-sulfur carbonaceous components to prepare the reducing agent, and regulating the smelting temperature and the SiO2 content in the slag, 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, giving full play to the advantages of abundant coal reserves, low cost and high reaction activity, and solving the problems of high cost and low reducibility of coke-based reducing agents in the prior art.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for producing high carbon ferrochrome by replacing traditional reducing agents with coal in an ultra-high proportion, comprising the following steps:

[0008] S1: Pretreat the chromite ore to obtain chromium raw materials, mix silica and lime to obtain a flux;

[0009] S2: Mix the chromium raw materials, reducing agent, and flux to obtain furnace burden. Among them, the weight ratio of the chromium raw materials, reducing agent, and flux is 0.35 - 0.45:1:0.15 - 0.25. The reducing agent includes the following components by weight ratio: 30% - 60% of extra-low sulfur coal, 30% - 65% of anthracite, and 5% - 10% of metallurgical coke. The fixed carbon content in both the extra-low sulfur coal and anthracite is greater than 85%;

[0010] S3: Charge the furnace burden into the submerged arc furnace, start the furnace with an arc-starting electrode. The starting voltage is 100 - 120V, and the current is 25000 - 35000A. Rapidly start the arc to increase the temperature, and promote the initial melting of the furnace burden;

[0011] S4: After the furnace burden melts, gradually increase the voltage to 180 - 220V, keep the current stable at 35000 - 40000A, maintain the temperature in the furnace at 1700K - 1800K, and the reaction time is 2 - 3h. Among them, the high-temperature range of 1700K - 1800K is conducive to the full reaction of carbon in the coal with chromium oxide in the chromite ore, accelerating the reduction process; During this period, it is necessary to adjust the electrode insertion depth in a timely manner through the electrode lifting system to keep the depth of the three-phase electrodes buried in the furnace burden at 1.2 - 1.5 times the electrode diameter, ensuring stable arc and uniform heat distribution;

[0012] S5: After the smelting is completed, add a slag-forming agent to the submerged arc furnace and continuously stir for refining. The refining time is 0.5 - 1h, then tap the furnace and skim the slag. Among them, the content of SiO2 in the slag is controlled at 24% - 30%;

[0013] S6: Transfer the molten steel into a converter, blow argon into the furnace for deoxidation operation, and at the same time slightly adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550K - 1650K;

[0014] S7: Pour the molten steel into a mold, control the casting speed at 2 - 3t / h, maintain the casting temperature at 1450K - 1550K, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained.

[0015] In a preferred embodiment, as described in S1, the content of Cr2O3 in the chromite ore is 42% - 48%. The chromium raw materials include chromium powder and chromium lumps. The particle size of the chromium powder is less than 10mm, the particle size of the chromium lumps is 10 - 100mm, and the weight ratio of the chromium powder to the chromium lumps is 1:1 - 3.5.

[0016] In a preferred embodiment, as described in S1, the weight ratio of lime to silica in the flux is 1:1.2 - 1.5.

[0017] In a preferred embodiment, as described in S2, the particle size of the silica is 5 - 20 mm, the particle size of the lime is 3 - 15 mm, the SiO2 content in the silica is greater than 98%, and the purity of the lime is greater than 90%.

[0018] In a preferred embodiment, as described in S2, the P content and the 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.

[0019] In a preferred embodiment, as described in S5, the slag former includes lime and fluorite. The CaF2 content in the fluorite is greater than 80%, and the particle size is 2 - 8 mm. Among them, the weight ratio of lime to fluorite is 3 - 5:1 - 2. Among them, the fluorite can adjust the fluidity of the slag and promote the separation of impurities.

[0020] In a preferred embodiment, as described in S5, the addition amount of the slag former is 4% - 7% of the total weight of the burden.

[0021] In a preferred embodiment, as described in S5, the SiO2 content in the slag is controlled at 24% - 30%, including the following steps:

[0022] St1: Take a slag sample from the slag notch every 20 minutes to detect the contents of CaO and SiO2;

[0023] St2: If the SiO2 content in the slag is lower than 24%, add silica into the submerged arc furnace. Among them, the SiO2 content in the silica is 98%, and the addition amount of the silica is calculated by the following formula:

[0024] ,

[0025] In the formula, M represents the addition amount of the silica, M1 represents the total mass of the burden, Cm represents the target value of the SiO2 content in the slag, Dm represents the percentage value of the actual content of SiO2 in the slag, and 98% represents the SiO2 content in the silica;

[0026] St3: If the SiO2 content exceeds 30%, add lime into the submerged arc furnace. Among them, the particle size of the lime is less than 1 mm, the purity of the lime is 90%, and the addition amount of the lime is calculated by the following formula:

[0027] ,

[0028] In the formula, M2 represents the addition amount of lime, M1 represents the total mass of the burden, Cm represents the target value of the content of SiO2 in the slag, Dm represents the actual content percentage value of SiO2 in the slag, 90% represents the purity of lime, 56 represents the molar mass of CaO, and 60 represents the molar mass of SiO2. Among them, in St2 and St3, the value range of Cm is 24% - 30%, and its specific value is determined according to actual production requirements.

[0029] In a preferred embodiment, as described in S6, the argon flow rate is 10 - 15 Nm 3 / h, and the duration is 10 - 15 min.

[0030] The technical effects achieved by the present invention are as follows:

[0031] By using a carbonaceous component with a high proportion of low - phosphorus and low - sulfur to prepare a reducing agent, and regulating the smelting temperature and the content of SiO2 in the slag, when producing high - carbon ferrochrome, the present invention can effectively increase the Cr content and C content in high - carbon ferrochrome, greatly reduce the usage amount of coke - type reducing agents, give full play to the advantages of rich coal reserves, low cost, and high reaction activity, solve the problems of high cost and low reducibility of coke - type reducing agents in the prior art, and also avoid the problem of generating a large amount of pollutants during the use process and deep - processing process of coke - type reducing agents. Specific Embodiments

[0032] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] Secondly, the so - called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present invention. The "in a preferred embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0035] Preparation Example 1: Preparation of Chromium Raw Materials

[0036] The chromium ore is pelletized, and after screening, chromium lumps with a particle size of 10 - 100 mm and chromium powder with a particle size less than 10 mm are mixed to obtain chromium raw materials, among which the content of Cr2O3 in the chromium ore is 45%.

[0037] Preparation Example 2: Preparation of Flux

[0038] Silica and lime are uniformly mixed at a ratio of 1:1.5 to obtain a flux. Among them, the particle size of the silica is 5 - 20 mm, the particle size of the lime is 3 - 15 mm, the SiO2 content in the silica is greater than 98%, and the purity of the lime is greater than 90%.

[0039] Preparation Example 3: Preparation of Reducing Agent

[0040] The metallurgical coke, extra-low sulfur coal, and anthracite are respectively screened and dried so that the particle sizes of the metallurgical coke, extra-low sulfur coal, and anthracite are all 3 - 5 mm. Then, the metallurgical coke, extra-low sulfur coal, and anthracite are mixed at a weight ratio of 1:3:6 to obtain a reducing agent. Among them, 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%.

[0041] Preparation Example 4: Preparation of Slag-forming Agent

[0042] Lime and fluorite are uniformly mixed at a ratio of 4:1.5 to obtain a slag-forming agent. Among them, the CaF2 content in the fluorite is greater than 80%, the particle size is 2 - 8 mm, and the purity of the lime is greater than 90%.

[0043] Example 1

[0044] Take 300 KG of chromium raw materials, 105 KG of reducing agent, and 45 KG of flux and mix them to obtain furnace charge. The furnace charge is loaded layer by layer into the submerged arc furnace, and the thickness of each layer does not exceed 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 190 V, and the secondary working current is 38000 A. Maintain the temperature in the submerged arc furnace at 1600 - 1700 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace, stir continuously for 40 minutes, then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, and the duration is 15 min. At the same time, slightly adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the high-carbon ferrochrome product is obtained. Among them, the SiO2 content in the slag is 35%.

[0045] It should be noted that K is the Kelvin temperature.

[0046] Example 2

[0047] Take 300 KG of chromium raw materials, 105 KG of reducing agents, and 45 KG of fluxes and mix them to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 200 V, and the secondary working current is 40000 A. Maintain the temperature in the submerged arc furnace at 1700 - 1800 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace, stir continuously for 40 minutes, then tap the furnace, skim the slag, and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation, with the argon flow rate being 10 - 15 Nm 3 / h, for a duration of 15 min. At the same time, finely adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome product is obtained. Among them, the SiO2 content in the slag is 27%.

[0048] Example 3

[0049] Take 300 KG of chromium raw materials, 105 KG of reducing agents, and 45 KG of fluxes and mix them to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 220 V, and the secondary working current is 43000 A. Maintain the temperature in the submerged arc furnace at 1800 - 1900 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace, stir continuously for 40 minutes, then tap the furnace, skim the slag, and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation, with the argon flow rate being 10 - 15 Nm 3 / h, for a duration of 15 min. At the same time, finely adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome product is obtained. Among them, the SiO2 content in the slag is 22%.

[0050] Example 4

[0051] In this example, based on Example 1, the SiO2 content in the slag is adjusted to 30%. Specifically,

[0052] Take 300 KG of chromium raw materials, 105 KG of reducing agent, and 45 KG of flux and mix them to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 190 V, and the secondary working current is 38000 A. Maintain the temperature in the submerged arc furnace at 1600 - 1700 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace and continuously stir. After stirring for 20 minutes, take out the slag sample from the taphole for detection. The SiO2 content in the slag sample is 35%. Add 23.25 KG of lime with a purity of 90% into the submerged arc furnace and continue to stir for 20 minutes. Then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, with a duration of 15 min. At the same time, slightly adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained, where the SiO2 content in the slag is 30%.

[0053] Example 5

[0054] In this example, based on Example 2, the SiO2 content in the slag is adjusted to 24%. Specifically,

[0055] Take 300 KG of chromium raw materials, 105 KG of reducing agent, and 45 KG of flux and mix them to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 200 V, and the secondary working current is 40000 A. Maintain the temperature in the submerged arc furnace at 1700 - 1800 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace and continuously stir. After stirring for 20 minutes, take out the slag sample from the taphole for detection. The SiO2 content in the slag sample is 27%. Add 32.55 KG of lime with a purity of 90% into the submerged arc furnace and continue to stir for 20 minutes. Then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, with a duration of 15 min. At the same time, slightly adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained, where the SiO2 content in the slag is 24%.

[0056] Example 6

[0057] In this example, based on Example 3, the SiO2 content in the slag is adjusted to 25%. Specifically,

[0058] Take 300 kg of chromium raw materials, 105 kg of reducing agent and 45 kg of flux for mixing to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25,000 A. The secondary working voltage is 220 V and the secondary working current is 43,000 A. Maintain the temperature in the submerged arc furnace at 1800 - 1900 K for smelting. Add 22.5 kg of slag-forming agent into the submerged arc furnace and continuously stir. After stirring for 20 minutes, take out the slag sample from the tapping hole for detection. The SiO2 content in the slag sample is 27%. Add 13.78 kg of silica to the submerged arc furnace and continue to stir for 20 minutes. Then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, and blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, with a duration of 15 min. At the same time, slightly adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained. Among them, the SiO2 content in the slag is 25%.

[0059] Comparative Example 1

[0060] On the basis of Example 1, in this comparative example, the extra-low sulfur coal in the reducing agent is replaced by metallurgical coke, and other conditions remain unchanged. Specifically,

[0061] Screen and dry the metallurgical coke and anthracite respectively to make the particle sizes of the metallurgical coke and anthracite both 3 - 5 mm. Then mix the metallurgical coke and anthracite according to the weight ratio of 4:6 to obtain the reducing agent. Among them, the P content and S content in the anthracite are both less than 0.005%, the fixed carbon content in both the metallurgical coke and anthracite is greater than 85%, and the carbonaceous component proportion in the reducing agent is 60%;

[0062] Take 300 kg of chromium raw materials, 105 kg of reducing agent and 45 kg of flux for mixing to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25,000 A. The secondary working voltage is 190 V and the secondary working current is 38,000 A. Maintain the temperature in the submerged arc furnace at 1600 - 1700 K for smelting. Add 22.5 kg of slag-forming agent into the submerged arc furnace and continuously stir for 40 minutes. Then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, and blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, with a duration of 15 min. Meanwhile, finely adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into a mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained. Among them, the SiO₂ content in the slag is 31%.

[0063] Comparative Example 2

[0064] Based on Example 2, in this comparative example, anthracite in the reducing agent is replaced with metallurgical coke, and other conditions remain unchanged. Specifically,

[0065] Screen and dry metallurgical coke and extra-low sulfur coal respectively, so that the particle sizes of both metallurgical coke and extra-low sulfur coal are 3 - 5 mm. Then mix metallurgical coke and extra-low sulfur coal in a weight ratio of 7:3 to obtain a reducing agent. Among them, the P content and S content in the extra-low sulfur coal are both less than 0.005%, and the fixed carbon content in both metallurgical coke and extra-low sulfur coal is greater than 85%. The carbonaceous component in the reducing agent accounts for 30%.

[0066] Take 300 KG of chromium raw materials, 105 KG of reducing agent, and 45 KG of flux for mixing to obtain furnace charge. Layer by layer load the furnace charge into a submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A, with a secondary working voltage of 200 V and a secondary working current of 40000 A. Maintain the temperature in the submerged arc furnace at 1700 - 1800 K for smelting. Add 22.5 KG of slag-forming agent into the submerged arc furnace, stir continuously for 40 minutes, tap the furnace, remove the slag and detect the SiO₂ content in the slag. Transfer the molten steel in the submerged arc furnace into a converter, and blow argon into the furnace for deoxidation operation. The argon flow rate is 10 - 15 Nm 3 / h, with a duration of 15 min. Meanwhile, finely adjust the furnace temperature to keep the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into a mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained. Among them, the SiO₂ content in the slag is 28%.

[0067] Comparative Example 3

[0068] Based on Example 3, in this comparative example, both extra-low sulfur coal and anthracite in the reducing agent are replaced with metallurgical coke, and other conditions remain unchanged. And the fixed carbon content in the metallurgical coke is greater than 85%, and the carbonaceous component in the reducing agent accounts for 0%. Specifically,

[0069] Take 300 kg of chromium raw materials, 105 kg of reducing agent and 45 kg of flux for mixing to obtain the furnace charge. Load the furnace charge layer by layer into the submerged arc furnace, with the thickness of each layer not exceeding 100 mm. Start the furnace with a voltage of 120 V and a current of 25000 A. The secondary working voltage is 220 V and the secondary working current is 43000 A. Maintain the temperature in the submerged arc furnace at 1800 - 1900 K for smelting. Add 22.5 kg of slag-forming agent into the submerged arc furnace, stir continuously for 40 minutes, then tap the furnace, skim the slag and detect the SiO2 content in the slag. Transfer the molten steel in the submerged arc furnace into the converter, blow argon into the furnace for deoxidation operation, with the argon flow rate of 10 - 15 Nm 3 / h, and the duration is 15 min. At the same time, slightly adjust the furnace temperature to make the temperature of the molten steel in the furnace stable at 1550 - 1650 K. Pour the molten steel into the mold, control the casting speed at 2 - 3 t / h, and let it cool naturally. After demolding, the finished high-carbon ferrochrome is obtained. Among them, the SiO2 content in the slag is 21%.

[0070] Test Example

[0071] Conduct component analysis tests on the high-carbon ferrochrome products obtained in Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1 below (the balance is Fe and other inevitable impurities):

[0072] Table 1

[0073] ;

[0074] 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. This shows that using low-phosphorus and low-sulfur carbonaceous components to replace the coke component 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 high proportion of low-phosphorus and low-sulfur carbonaceous components in the reducing agents in Examples 1 to 3, the P content and S content in 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 properties such as strength, toughness, ductility, and wear resistance of high-carbon ferrochrome can be correspondingly improved;

[0075] It can be seen from the data in Examples 1 to 6 that, while keeping other process parameters 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. This shows that when melting the furnace charge, when the temperature is maintained at 1700 - 1800K, it is beneficial to increase the Cr content and C content in the product. Specifically, the reduction of chromium oxides (such as Cr2O3) to metallic chromium needs to be carried out at high temperatures. The temperature range of 1700 - 1800K ensures that the carbonaceous reducing agent (C) reacts fully with Cr2O3 (reaction formula: Cr2O3 + 3C → 2Cr + 3CO), accelerating the reduction process, and at the same time avoiding excessive energy waste or excessive loss of furnace lining materials due to too high temperature. If the temperature is too high, the reducing agent may reduce SiO2 in the slag excessively, resulting in an increase in the Si content in the alloy, while the proportion of Cr and C decreases relatively. By controlling the temperature, the reduction efficiency of chromium can be guaranteed preferentially, and the consumption of carbon in side reactions can be reduced;

[0076] Comparing the data in Examples 1 and 4, Examples 2 and 5, and Examples 3 and 6, since the SiO2 content in the slag was not regulated in Examples 1 to 3, it can be seen from the above data that, while keeping other process parameters unchanged, regulating the SiO2 content in the slag is beneficial to increasing the C content in the product;

[0077] Among them, in Examples 2 and 4, since the melting temperature is maintained at 1700 - 1800K and the SiO2 content in the slag is controlled at 24% - 30%, the comprehensive performance of their products is better than that of the products in other examples. Specifically, SiO2 is an acidic oxide, and its content directly affects the basicity of the slag (usually measured by the CaO / SiO2 ratio). When SiO2 is controlled at 24% - 30%, the viscosity and melting point of the slag are in an appropriate range, which not only ensures the effective separation of metal droplets from the slag (reducing the mechanical entrainment loss of Cr in the slag), but also avoids hindering the escape of CO gas due to overly viscous slag. If the SiO2 content in the slag is too high, the reducing agent will preferentially reduce SiO2 rather than Cr2O3 (because the reduction Gibbs free energy of SiO2 is lower). By regulating the SiO2 content to 24% - 30% and adjusting the slag composition with an appropriate amount of basic flux (such as CaO), the activity of SiO2 can be reduced, inhibiting its reduction to Si, so as to concentrate carbon on the reduction of chromium oxides and reduce the total consumption of carbon;

[0078] In summary, by using a carbonaceous component with a high proportion of low-phosphorus and low-sulfur to prepare a reducing agent, and at the same time, by synergistically controlling the smelting temperature and the SiO2 content in the slag, when producing high-carbon ferrochrome, it is possible to effectively increase the Cr content and C content in the high-carbon ferrochrome. Carbon is preferentially used to reduce Cr2O3 rather than SiO2 or other impurity oxides, significantly reducing the usage amount of coke-based reducing agents, giving full play to the advantages of abundant coal reserves, low cost, and high reaction activity, solving the problems of high cost and low reducibility of coke-based reducing agents in the prior art, and also avoiding the problem of generating a large amount of pollutants during the use and deep processing of coke-based reducing agents.

[0079] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention are implemented according to the conventional means in the art without special description and limitation.

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 flux; S2: Mixing a chromium raw material, a reducing agent and a flux to obtain a furnace charge, wherein the weight ratio of the chromium raw material, the reducing agent and the flux is 0.35-0.45:1:0.15-0.25, and the reducing agent comprises 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, and then the slag is removed from the furnace and slag is removed. The content of SiO2 in the slag is controlled at 24% to 30%. Specifically, the content of SiO2 in the slag is controlled at 24% to 30%, which includes 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 content of SiO2 exceeds 30%, lime is added into the submerged arc furnace, wherein the particle size of the lime is less than 1 mm; 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 flux 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 S6, the argon gas flow rate is 10-15 Nm 3 / h, lasting for 10 to 15 minutes.