Optimization method for smelting process parameters of high-carbon ferrochrome based on physical and chemical properties of anthracite

Abstract

The present application relates to the field of ferroalloy smelting and high-carbon chromite hot stove smelting process optimization, and particularly relates to a high-carbon chromite smelting process parameter optimization method based on the physical and chemical properties of anthracite. The content includes: obtaining the basic parameters of the furnace, and calculating the anthracite smelting adaptation index and the theoretical carbon demand; based on the anthracite smelting adaptation index, the theoretical carbon demand is corrected to obtain the actual amount of anthracite added; based on the basic parameters of the furnace and the actual amount of anthracite added, the slag-iron separation burden value is calculated, and the corrected smelting setting temperature is further calculated; based on the anthracite smelting adaptation index and the corrected smelting setting temperature, the reduction completion degree is calculated, and whether the high-carbon chromite tapping condition is reached is judged. The problems of incomplete reduction of chromium oxide, increase of chromium oxide content in slag, increase of unit power consumption and difficulty in realizing stable optimization of the high-carbon chromite smelting process under the condition of anthracite in the existing high-carbon chromite hot stove production process are solved.

Description

Technical Field

[0001] This invention relates to the field of ferroalloy smelting and process optimization of high-carbon ferrochrome submerged arc furnace smelting, and particularly to a method for optimizing process parameters of high-carbon ferrochrome smelting based on the physicochemical properties of anthracite. Background Technology

[0002] High-carbon ferrochrome is an important ferroalloy raw material for the production of stainless steel, heat-resistant steel, and high-strength alloy steel. Currently, it is mainly produced using a carbothermal reduction process in an electric arc furnace. In the smelting of high-carbon ferrochrome, the reducing agent not only plays a role in reducing chromium oxide and ferrous oxide, but also directly affects the heat distribution within the furnace, the permeability of the furnace charge, the slag formation state, and the slag-iron separation effect. Therefore, the type and physicochemical properties of the reducing agent have a significant impact on the smelting process of high-carbon ferrochrome. With the increasing utilization of anthracite resources, using anthracite to partially or completely replace coke, or combining anthracite with other reducing agents such as semi-coke and metallurgical coke in the reduction process, has become an important development direction for high-carbon ferrochrome smelting.

[0003] However, anthracite differs significantly from traditional reducing agents such as coke and semi-coke in terms of physicochemical properties, including fixed carbon content, reactivity, particle size distribution, ash content, moisture content, and volatile matter. Especially in complex systems involving multiple reducing agents, existing high-carbon ferrochrome smelting processes typically determine the amount of anthracite added based on empirical carbon blending or fixed proportions. This makes it difficult to accurately reflect the actual reducing capacity of different batches of anthracite, easily leading to problems such as insufficient reducing agent resulting in incomplete chromium oxide reduction, or excessive reducing agent causing increased residual carbon, higher power consumption, and fluctuating furnace conditions. Furthermore, the ash from anthracite entering the furnace increases slag volume and alters slag viscosity. Existing processes lack dynamic evaluation and adjustment mechanisms to address the impact of ash on slag formation, easily leading to problems such as deteriorated slag-iron separation, metal inclusions, and decreased chromium recovery.

[0004] Furthermore, in existing high-carbon ferrochrome submerged arc furnace production processes, the timing of tapping largely relies on fixed holding times or operator experience, lacking a method to evaluate the degree of reduction by incorporating operating parameters such as furnace gas conditions, electrical heat input, and smelting temperature. This makes it difficult to accurately reflect the actual progress of the reduction reaction within the furnace. Insufficient holding time can easily lead to incomplete chromium oxide reduction, while excessive holding time increases unit power consumption and furnace lining load, thus affecting the stability and economy of the high-carbon ferrochrome smelting process. Therefore, a high-carbon ferrochrome smelting process optimization method is needed that can dynamically optimize smelting process parameters by combining the physicochemical properties of anthracite with furnace condition parameters. Summary of the Invention

[0005] This invention provides a method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite. This addresses the problems of existing high-carbon ferrochrome submerged arc furnaces, which mostly use coke or semi-coke as the main reducing agent. This often leads to a mismatch between theoretical carbon content and actual effective reduction capacity, resulting in incomplete chromium oxide reduction, increased chromium oxide content in the slag, and increased unit power consumption. Furthermore, existing high-carbon ferrochrome smelting processes lack a dynamic correction mechanism for slag volume increases, slag viscosity changes, and slag-iron separation deterioration caused by anthracite ash content, easily leading to metal inclusions, unstable tapping, and decreased chromium recovery. Finally, existing high-carbon ferrochrome smelting processes largely rely on fixed holding times or manual experience to determine tapping timing, lacking analysis of reduction completion based on furnace gas conditions, electrical and thermal input, and smelting temperature. This results in significant furnace condition fluctuations, making it difficult to achieve stable optimization of the high-carbon ferrochrome smelting process under anthracite conditions.

[0006] The present invention provides a method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite, comprising the following:

[0007] Obtain the basic parameters for the furnace feed, and calculate the anthracite smelting compatibility index, which characterizes the comprehensive reducing capacity of anthracite, and the theoretical carbon requirement for high-carbon ferrochrome smelting based on the basic parameters for the furnace feed; correct the theoretical carbon requirement for high-carbon ferrochrome smelting based on the anthracite smelting compatibility index and the basic parameters for the furnace feed, and obtain the actual amount of anthracite added.

[0008] Based on the basic parameters of the furnace feed and the actual amount of anthracite added, the slag-iron separation burden value is calculated; based on the slag-iron separation burden value and the basic parameters of the furnace feed, the smelting set temperature is dynamically adjusted to obtain the corrected smelting set temperature; based on the anthracite smelting compatibility index and the corrected smelting set temperature, the reduction completion degree is calculated, and based on the set reduction completion degree threshold, it is determined whether the conditions for tapping high-carbon ferrochrome are met.

[0009] Preferably, the basic parameters for furnace feed include: fixed carbon mass fraction, ash mass fraction, volatile matter mass fraction, moisture mass fraction, carbon dioxide reactivity index, median particle size, chromium oxide mass fraction and ferrous oxide mass fraction, chromite mass fed into the furnace, furnace temperature, slag flow temperature, theoretical slag mass, electrode current, and carbon monoxide volume fraction.

[0010] Preferably, a particle size fit term is constructed by performing an index calculation on the median particle size; an impurity and disturbance burden term is constructed based on the mass fraction of ash, moisture, and volatile matter in anthracite; and an anthracite smelting fit index is calculated based on the particle size fit term and the impurity and disturbance burden term, combined with the carbon dioxide reactivity index.

[0011] Preferably, a correction for in-furnace carbon loss is introduced, and the theoretical carbon requirement for high-carbon ferrochrome smelting is calculated by combining the mass of chromite ore fed into the furnace, the mass fraction of chromium oxide, and the mass fraction of ferrous oxide.

[0012] Preferably, a slag viscosity burden term is constructed based on the slag viscosity and the set target slag viscosity; an ash slag expansion term is constructed based on the theoretical slag quality, the actual amount of anthracite added, and the ash mass fraction of anthracite; a slag flow temperature approximation term is constructed based on the furnace temperature and the slag flow temperature; and the slag viscosity burden term, the ash slag expansion term, and the slag flow temperature approximation term are multiplied together to obtain the slag-iron separation burden value.

[0013] Preferably, a slag-iron separation burden value less than 1 indicates that the current slag-iron separation state is better than the target slag-iron separation state; a slag-iron separation burden value equal to 1 indicates that the current slag-iron separation state has reached the target slag-iron separation state; when the slag-iron separation burden value is less than or equal to 1, the current furnace temperature is maintained; a slag-iron separation burden value greater than 1 indicates that the current slag-iron separation state is lower than the target slag-iron separation state, and furnace temperature correction is required.

[0014] Preferably, the reduction completion rate is generated based on the anthracite smelting compatibility index, carbon monoxide volume fraction, electrode current, and the corrected smelting set temperature, combined with an exponential function and integral.

[0015] Preferably, when the reduction completion rate is greater than or equal to the reduction completion rate threshold and the slag-iron separation burden value is less than or equal to the set maximum allowable slag-iron separation burden value, it is determined that the conditions for tapping high-carbon ferrochrome have been met; when the reduction completion rate is greater than or equal to the reduction completion rate threshold, but the slag-iron separation burden value is greater than the maximum allowable slag-iron separation burden value, it indicates that the reduction process of chromium oxide and ferrous oxide has reached the tapping conditions, but the slag fluidity is insufficient and the slag-iron separation burden is too high, so short-term heating is prioritized; when the reduction completion rate is less than the reduction completion rate threshold, the heat preservation continues and the current electric heat input state is maintained.

[0016] The beneficial effects of the technical solution of the present invention are:

[0017] 1. By incorporating fixed carbon mass fraction, ash mass fraction, volatile matter mass fraction, and moisture mass fraction into the process of determining high-carbon ferrochrome smelting parameters, the amount of anthracite added is determined without relying solely on fixed carbon content or empirical ratios, thus improving the accuracy of carbon blending when anthracite replaces coke. By calculating the theoretical carbon consumption based on the actual reduction requirements of chromium oxide and ferrous oxide in chromite ore and combining it with the anthracite smelting compatibility index to determine the actual addition amount, the residual chromium oxide caused by insufficient reducing agent can be reduced, improving the utilization efficiency of the reducing agent. It can also reduce the increase in residual carbon, furnace condition fluctuations, and increased power consumption caused by excessive carbon blending.

[0018] 2. By converting the additional slag, slag viscosity, and furnace temperature conditions caused by anthracite ash into the burden of slag-iron separation, the adverse effects of anthracite ash on slag-iron separation can be judged in a timely manner. Slag fluidity can be improved by smelting temperature correction, reducing the risk of metal inclusions and chromium loss. By combining furnace gas reducibility, electrode current, smelting temperature, and anthracite smelting compatibility index to judge the degree of reduction completion, the degree of reduction can be avoided due to insufficient holding time, and the degree of reduction due to excessive holding time can also be avoided. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite, as described in this invention. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] The following description, in conjunction with the accompanying drawings, details the specific scheme of the method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite provided by this invention.

[0023] See attached document Figure 1 The diagram illustrates a flowchart of a method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite, according to an embodiment of the present invention. The method includes the following steps:

[0024] S1. Obtain the basic parameters for the furnace feed, and calculate the anthracite smelting compatibility index, which characterizes the comprehensive reducing capacity of anthracite, and the theoretical carbon requirement for high-carbon ferrochrome smelting based on the basic parameters for the furnace feed; correct the theoretical carbon requirement for high-carbon ferrochrome smelting based on the anthracite smelting compatibility index and the basic parameters for the furnace feed, and obtain the actual amount of anthracite added.

[0025] Before the smelting of high-carbon chromite ore in a furnace begins, basic parameters for the incoming coal are obtained. Specifically, anthracite samples are first taken, and industrial analysis methods are used to obtain fixed carbon mass fraction, ash mass fraction, volatile matter mass fraction, and moisture mass fraction. The anthracite samples are then crushed, sieved, and pre-treated by dry distillation (or removal of moisture and volatile matter) to prepare char samples. A certain mass of the char sample is weighed using an analytical balance and placed in the high-temperature reaction tube of a carbon dioxide reactivity testing device. Under a set reference high-temperature condition, such as 1000°C, a constant flow rate of carbon dioxide gas is introduced, and the reaction is carried out for a specified time. After the test, the parameters are analyzed using... The carbon dioxide reactivity index was obtained. Standard sieving methods, such as GB / T 477-2008 "Coal Sieving Test Methods", were used to statistically analyze the particle size distribution of anthracite and calculate the median particle size. Subsequently, the composition of the chromite ore fed into the furnace was analyzed. The mass fractions of chromium oxide and ferrous oxide were obtained using chemical composition analysis methods, such as volumetric methods. The mass of the chromite ore fed into the furnace was obtained through a weighing device. Simultaneously, the current furnace temperature was obtained using a submerged arc furnace temperature measuring device. The slag viscosity was measured at different temperatures using a high-temperature rotary viscometer, obtaining corresponding data points for "temperature-viscosity" and plotting a viscosity-temperature curve. The slag flow temperature was determined using the constant slope method. The theoretical slag mass was obtained by multiplying the mass of the chromite ore fed into the furnace by the sum of the mass fractions of chromium oxide and ferrous oxide, and then subtracting this from the total ore mass. The electrode current was obtained using an electrode detection device. The volume fraction of carbon monoxide in the furnace gas was obtained by installing an online gas analyzer in the submerged arc furnace flue or gas outlet pipeline. All the parameters mentioned above are records from the same furnace batch, and all the methods mentioned above are methods that have been publicly used in the fields of metallurgy, coal chemical industry and mineral processing for a long time.

[0026] After replacing coke with anthracite in high-carbon ferrochrome submerged arc furnaces, the carbothermic reduction capacity within the furnace is no longer solely determined by the fixed carbon content. The fixed carbon mass fraction of anthracite directly affects the theoretically effective reduced carbon amount that a unit mass of anthracite can provide; the carbon dioxide reactivity index directly affects the ability of anthracite to participate in gasification and indirect reduction reactions under high-temperature conditions; the median particle size directly affects the pore structure of the furnace charge and the stability of the gas flow channels within the furnace; the ash mass fraction directly affects the amount of ineffective minerals entering the slag system; the moisture mass fraction directly affects the additional heat consumption during smelting; and the volatile matter mass fraction directly affects the intensity of gas evolution within the furnace and the degree of furnace gas fluctuation. All of these parameters collectively influence the comprehensive reduction capacity of anthracite during high-carbon ferrochrome smelting.

[0027] Because the collected parameters have different physical meanings and varying numerical ranges, a single parameter cannot be directly used to determine the amount of anthracite added; otherwise, the permeability of the furnace charge will deteriorate when the particle size deviates from the target range. Therefore, all parameters are first uniformly converted into anthracite smelting compatibility index, which characterizes the comprehensive reducing capacity of anthracite. This ensures that subsequent calculations of anthracite addition, slag-iron separation burden, and reduction endpoint determination are all based on the same anthracite smelting compatibility result. The formula for calculating the anthracite smelting compatibility index is as follows: , in, The anthracite smelting suitability index is a dimensionless value used to characterize the overall suitability of the current batch of anthracite as a reducing agent in high-carbon ferrochrome smelting. The carbon dioxide reactivity index of anthracite is expressed as a percentage and is calculated as a decimal. The carbon dioxide reactivity index of the benchmark anthracite is the average value of the carbon dioxide reactivity index of historical anthracite in the furnace database, expressed as a percentage and calculated as a decimal. This indicates the median particle size of anthracite, in millimeters. The target feed particle size is the pre-defined standard feed particle size, selected from the median particle size corresponding to the optimal overall effect of chromium recovery rate and power consumption in the furnace database, in millimeters. First, the total amount of chromium fed into the furnace is calculated based on the mass of chromite ore and the mass fraction of chromium oxide. Then, the actual amount of metallic chromium recovered is calculated based on the mass of high-carbon ferrochrome after tapping and the mass fraction of chromium oxide obtained by the weighing device. Finally, the actual amount of metallic chromium recovered is divided by the total amount of chromium fed into the furnace to obtain the chromium recovery rate, which is a conventional indicator in this field. This represents the mass fraction of ash in anthracite coal, expressed as a percentage, and calculated using decimal form. The moisture content of anthracite coal is expressed as a percentage (%) and is calculated as a decimal. This represents the volatile matter mass fraction of anthracite, expressed as a percentage, and calculated using decimal form. This indicates the particle size matching item, which characterizes the degree of consistency between the current median particle size of anthracite and the target feed particle size. This indicates the effective high-temperature reduction capacity that anthracite can form under the current particle size conditions; This represents the burden of impurities and disturbances. The value of 1 indicates the basic state of anthracite itself, while the value of +1 avoids division by zero errors in the denominator.

[0028] After calculating the anthracite smelting compatibility index, it is necessary to further determine the theoretical carbon requirement for the current furnace batch to complete the reduction of chromium oxide and ferrous oxide. In the high-carbon ferrochrome smelting process, chromium oxide and ferrous oxide are the main carbon-consuming components. If the calculated theoretical carbon requirement is insufficient, it will lead to incomplete chromium oxide reduction and an increase in the chromium oxide content in the slag; if the calculated theoretical carbon requirement is too high, it will lead to an increase in residual carbon in the furnace, increased power consumption, and an increase in slag volume. Therefore, before calculating the actual amount of anthracite added, it is necessary to determine the theoretical carbon requirement based on the composition of the chromite ore. The formula for calculating the theoretical carbon requirement is as follows: , in, This indicates the theoretical carbon requirement for the current batch of high-carbon ferrochrome smelting, expressed in kilograms. This indicates the mass of chromite ore fed into the furnace, expressed in kilograms. It represents the molar mass of carbon, with units of kilograms per kilomolar or grams per molar; The molar mass of chromium oxide is expressed in kilograms per kilomol or grams per mole. This indicates the molar mass of ferrous oxide, expressed in kilograms per kilomolar or grams per molar. This indicates the mass fraction of chromium oxide in chromite, expressed in %, and calculated using decimal form. This represents the mass fraction of ferrous oxide in chromite, expressed as a percentage, and calculated using decimal form. This represents the correction amount for carbon loss in the furnace. It is dimensionless and is used to compensate for carbon loss caused by carbon carried out by the furnace gas, unreacted residual carbon, carbon consumption from side reactions, and insufficient local contact of the furnace charge. It is determined by calculating the average loss ratio after statistically analyzing the differences between the theoretical carbon consumption and the actual effective carbon consumption under the same furnace type, similar chromite composition, and similar anthracite batches. Among them, chromite with an absolute value of chromium oxide mass fraction difference not exceeding 2% and ferrous oxide mass fraction difference not exceeding 1% is considered similar chromite composition. Anthracite with an absolute value of fixed carbon mass fraction difference not exceeding 2% and carbon dioxide reactivity index difference not exceeding 5% is considered similar anthracite batch. This indicates the mass ratio of carbon required for the complete reduction of chromium oxide in a unit mass of chromite ore; This indicates the mass ratio of carbon required for the complete reduction of ferrous oxide in a unit mass of chromite. This represents the theoretical carbon mass required for the chromite ore fed into the furnace in the current batch under ideal stoichiometric conditions; This indicates the correction factor for actual carbon loss inside the furnace.

[0029] After calculating the theoretical carbon requirement, it is necessary to further determine the actual amount of anthracite added to meet the requirements of the current high-carbon ferrochrome smelting batch. Since the anthracite smelting compatibility index already comprehensively reflects the influence of carbon dioxide reactivity index, median particle size, ash content, moisture content, and volatile matter content on the overall reducing capacity, the theoretical carbon requirement cannot be directly used as the anthracite addition amount. It is necessary to correct the theoretical carbon requirement based on the anthracite smelting compatibility index and a fixed carbon content to obtain the actual anthracite addition amount. The mathematical formula is: , The unit is kilogram; This represents a fixed carbon mass fraction, expressed as a percentage, and calculated using decimal form.

[0030] S2. Based on the basic parameters of the furnace feed and the actual amount of anthracite added, calculate the slag-iron separation burden value; based on the slag-iron separation burden value and the basic parameters of the furnace feed, dynamically adjust the smelting set temperature to obtain the corrected smelting set temperature; based on the anthracite smelting compatibility index and the corrected smelting set temperature, calculate the reduction completion degree, and based on the set reduction completion degree threshold, determine whether the conditions for high-carbon ferrochrome tapping have been met.

[0031] After calculating the actual amount of anthracite added, it is necessary to further evaluate the impact of anthracite ash entering the slag system on the slag-iron separation process. In the high-carbon ferrochrome smelting process, anthracite ash entering the furnace will form new slag; this new slag will change the total slag mass, slag viscosity, and slag flowability. When the slag viscosity increases or the furnace temperature approaches the slag flow temperature, the resistance to the settling of molten metal droplets increases, easily leading to insufficient slag-iron separation and increasing the chromium oxide content in the slag. Therefore, before adjusting the furnace temperature, it is necessary to calculate the slag-iron separation burden value. The formula for calculating the slag-iron separation burden value is as follows: , in, This represents the slag-iron separation load value, used to characterize the degree of deviation of the current slag-iron separation state from the target slag-iron separation state. This indicates that the current slag-iron separation state is better than the target slag-iron separation state. This indicates that the current slag-iron separation state has reached the target slag-iron separation state. Therefore, when At the same time, maintain the current furnace temperature. This indicates that the current slag-iron separation state is lower than the target slag-iron separation state, and furnace temperature correction is required. This indicates the current slag viscosity, expressed in Pa·s. The target slag viscosity is expressed in Pa·s. Multiple production runs of the same submerged arc furnace are selected consecutively, and the chromium recovery rate, slag-iron separation time, and chromium oxide mass fraction in the slag are calculated for each run. All runs are sorted from high to low based on the chromium recovery rate, and the top 50% of runs are selected as candidate runs. Runs with slag-iron separation times higher than the average of all candidate runs are then removed from the candidate runs. Finally, runs with chromium oxide mass fraction in the slag higher than the average of all remaining runs are removed from the remaining runs. The slag viscosity corresponding to the final retained runs is sorted by numerical value, and the median is taken as the target slag viscosity. The slag mass is expressed as the theoretical basis, in kilograms. This indicates the Kelvin temperature corresponding to the slag flow temperature. This indicates the Kelvin temperature corresponding to the current furnace temperature; This represents the slag viscosity burden term, used to measure the degree of deviation of the current slag flow resistance from the target slag flow resistance; This indicates the expansion of ash content into slag. This represents the total mass of slag after including the mass fraction of anthracite ash. This indicates the slag flow temperature approximation term, used to measure the margin of the current furnace temperature relative to the slag flow temperature.

[0032] After calculating the slag-iron separation load value, the smelting temperature needs to be adjusted based on the current slag condition. During high-carbon ferrochrome smelting, an increase in the slag-iron separation load value indicates increased slag flow resistance, difficulty in molten metal droplet settling, and decreased slag fluidity. Maintaining the original furnace temperature can easily lead to metal inclusions and chromium oxide loss. Therefore, the smelting setpoint temperature needs to be dynamically adjusted based on the slag-iron separation load value. The formula for adjusting the smelting setpoint temperature is as follows: , in, This indicates the corrected smelting set temperature, in °C. The upper limit is the highest safe smelting temperature allowed by the electric arc furnace. As a specific example, it is taken as 1750 °C. This indicates the current furnace temperature, in °C. This represents the single-stage furnace temperature correction range, in °C. We select furnace temperature adjustment records corresponding to different slag-iron separation load values, and statistically analyze the temperature rise range under the condition that it does not cause furnace lining overheating, does not significantly increase unit power consumption, and can improve slag-iron separation effect. We take its stable and effective range as the value range. As a specific example, it can be taken as 30 °C to 80 °C. This represents the logarithmic correction term for the slag-iron separation burden.

[0033] When the slag-iron separation burden value is greater than 1, it indicates that the current slag fluidity is below the target state. Therefore, a positive temperature correction is generated after performing a logarithmic calculation on the slag-iron separation burden value. When the slag-iron separation burden value is equal to 1, the logarithmic result is 0, and no furnace temperature correction is performed. When the slag-iron separation burden value is less than 1, due to the adoption of... The system is designed to limit temperature fluctuations, thus preventing negative temperature corrections and avoiding frequent cooling of the high-carbon ferrochrome submerged arc furnace. The logarithmic form ensures a rapid initial increase in the slag-iron separation load value, followed by a gradual slowdown in the rate of temperature increase, preventing the furnace temperature from rising indefinitely.

[0034] After adjusting the smelting set temperature, it is necessary to further determine whether the current furnace batch meets the tapping conditions for high-carbon ferrochrome. During the smelting of high-carbon ferrochrome, chromium oxide reduction is not an instantaneous process, but rather progresses gradually with changes in furnace gas reducing properties, electrical heat input, and smelting temperature. Insufficient holding time will result in incomplete chromium oxide reduction; excessive holding time will increase unit power consumption and exacerbate the furnace lining load. Therefore, the degree of reduction completion needs to be calculated based on the anthracite smelting compatibility index, furnace gas conditions, electrical heat input conditions, and the corrected smelting set temperature. The formula for calculating the degree of reduction completion is as follows: , in, Indicates time The reduction completion rate is denoted by a value ranging from 0 to 1. The closer the value is to 1, the closer the carbothermic reduction process of chromium oxide and ferrous oxide in the current furnace is to completion. The reference smelting time, expressed in hours, is calculated by selecting multiple production runs of the same submerged arc furnace under conditions of stable charge composition, normal iron tapping, chromium recovery rate meeting standards, and qualified chromium oxide content in the slag. The average actual duration from the furnace temperature reaching the reference smelting temperature to the iron tapping standard is recorded for each run. The iron tapping standard is determined based on the current process standards at the production site. The reference smelting temperature is the average furnace temperature from the start of stable chromium oxide reduction to the point of reaching the iron tapping standard, with a reference value of 1700℃. This is a time variable, with the unit being hours; Indicates time The volume fraction of carbon monoxide in the furnace gas; The target carbon monoxide volume fraction is the average of the total carbon monoxide volume fraction of the furnace gas from the time the furnace temperature reaches the reference smelting temperature to the time the iron tapping standard is reached. Indicates time Electrode current, in amperes; The reference electrode current, in amperes, is the average value of all electrode currents from the time the furnace temperature reaches the reference smelting temperature until the iron tapping standard is reached. This indicates the Kelvin temperature corresponding to the corrected smelting set temperature; This represents the Kelvin temperature corresponding to the average furnace temperature from the time the furnace temperature reaches the reference smelting temperature to the time the iron tapping standard is reached. This represents the unit-time reduction propulsion coefficient after anthracite adaptation correction; Indicates time The cumulative effective reduction driving force; Represents the exponentially decaying term The dimensionless reduction propulsion intensity in the middle.

[0035] All basic parameters for furnace input, including but not limited to fixed carbon mass fraction, ash mass fraction, volatile matter mass fraction, and moisture mass fraction, as well as parameters obtained from the basic parameters for furnace input, including but not limited to anthracite smelting compatibility index, theoretical carbon requirement, slag-iron separation burden value, corrected smelting set temperature, and reduction completion rate, are stored in the furnace database.

[0036] When the restoration is complete And the slag-iron separation burden value When the conditions for tapping high-carbon ferrochrome are met, it is determined that the conditions for tapping are met; if but This indicates that the reduction process of chromium oxide and ferrous oxide has reached the conditions for tapping iron, but the slag fluidity is insufficient and the slag-iron separation burden is too high. Therefore, short-term heating is prioritized. If the temperature is maintained, the current electrical heating input will continue. The reduction completion threshold is used to determine whether the current high-carbon ferrochrome smelting process has reached the minimum reduction level that allows for iron tapping. The reduction completion level corresponding to iron tapping of each heat in the target heat set is statistically analyzed, and the lower limit of the statistical results is taken as the reduction completion threshold. All heats are sorted from high to low according to chromium recovery rate, and the top 50% of heats are selected as candidate heats. Heats with chromium oxide mass fraction in slag higher than the average chromium oxide mass fraction of candidate heats are then removed from the candidate heats. Finally, heats with chromium oxide mass fraction in high-carbon ferrochrome lower than the average chromium oxide mass fraction of the remaining heats or with fixed carbon mass fraction deviating from the average fixed carbon mass fraction of the remaining heats by more than 10% are removed from the remaining heats. The heats that are finally retained are the target heat set. This represents the maximum allowable slag-iron separation load value. The slag-iron separation load value corresponding to the tapping of each furnace in the target furnace set is statistically analyzed, and the upper limit of the statistical results is taken as the maximum allowable slag-iron separation load value.

[0037] In summary, a method for optimizing the process parameters of high-carbon ferrochrome smelting based on the physicochemical properties of anthracite was completed.

[0038] The order of the embodiments is for illustrative purposes only and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0039] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite, characterized in that, Includes the following: The basic parameters for smelting were obtained, and based on these parameters, the anthracite smelting suitability index, which characterizes the comprehensive reducing capacity of anthracite, and the theoretical carbon requirement for high-carbon ferrochrome smelting were calculated. A particle size suitability term was constructed by performing an index calculation on the median particle size in the basic parameters. An impurity and disturbance burden term was constructed based on the anthracite ash mass fraction, moisture mass fraction, and volatile matter mass fraction in the basic parameters. Based on the particle size suitability term and the impurity and disturbance burden term, combined with the carbon dioxide reactivity index in the basic parameters, the anthracite smelting suitability index was calculated. The theoretical carbon requirement for high-carbon ferrochrome smelting was corrected based on the anthracite smelting suitability index and the basic parameters to obtain the actual amount of anthracite added. Based on the slag viscosity and the set target slag viscosity, a slag viscosity burden term is constructed; Based on the theoretical slag mass, anthracite ash mass fraction, and actual anthracite addition amount in the basic parameters of the furnace feed, an ash content slag expansion term is constructed; based on the furnace temperature and slag flow temperature in the basic parameters of the furnace feed, a slag flow temperature approximation term is constructed. Multiply the slag viscosity burden term, the ash slag expansion term, and the slag flow temperature proximity term to obtain the slag-iron separation burden value. Based on the slag-iron separation burden value and the basic parameters of the furnace feed, the smelting set temperature is dynamically adjusted to obtain the corrected smelting set temperature. Based on the anthracite smelting compatibility index and the corrected smelting set temperature, the reduction completion degree is calculated, and based on the set reduction completion degree threshold, it is determined whether the conditions for tapping high-carbon ferrochrome have been met.

2. The method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite as described in claim 1, characterized in that, The basic parameters for the furnace feed include: fixed carbon mass fraction, ash mass fraction, volatile matter mass fraction, moisture mass fraction, carbon dioxide reactivity index, median particle size, chromium oxide mass fraction and ferrous oxide mass fraction, chromite mass feed, furnace temperature, slag flow temperature, theoretical slag mass, electrode current, and carbon monoxide volume fraction.

3. The method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite as described in claim 2, characterized in that, By introducing the correction for in-furnace carbon loss and combining it with the mass of chromite ore fed into the furnace, the mass fraction of chromium oxide, and the mass fraction of ferrous oxide, the theoretical carbon requirement for high-carbon ferrochrome smelting is calculated.

4. The method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite as described in claim 1, characterized in that, A slag-iron separation burden value less than 1 indicates that the current slag-iron separation state is better than the target slag-iron separation state; a slag-iron separation burden value equal to 1 indicates that the current slag-iron separation state has reached the target slag-iron separation state; when the slag-iron separation burden value is less than or equal to 1, the current furnace temperature is maintained; a slag-iron separation burden value greater than 1 indicates that the current slag-iron separation state is lower than the target slag-iron separation state, and furnace temperature correction is required.

5. The method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite as described in claim 2, characterized in that, Based on the anthracite smelting compatibility index, carbon monoxide volume fraction, electrode current, and the corrected smelting set temperature, the reduction completion degree is generated by combining exponential functions and integrals.

6. The method for optimizing high-carbon ferrochrome smelting process parameters based on the physicochemical properties of anthracite as described in claim 5, characterized in that, When the reduction completion rate is greater than or equal to the reduction completion rate threshold and the slag-iron separation burden value is less than or equal to the set maximum allowable slag-iron separation burden value, the conditions for tapping high-carbon ferrochrome are determined to be met. When the reduction completion rate is greater than or equal to the reduction completion rate threshold, but the slag-iron separation burden value is greater than the maximum allowable slag-iron separation burden value, it indicates that the reduction process of chromium oxide and ferrous oxide has reached the tapping conditions, but the slag fluidity is insufficient and the slag-iron separation burden is too high, so short-term heating is prioritized. When the reduction completion rate is less than the reduction completion rate threshold, the heat preservation continues and the current electric heat input state is maintained.

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