Method for evaluating harmfulness of coal ash behavior

Abstract

This invention relates to the field of iron and steel metallurgical process optimization technology, and in particular to a method for evaluating the harmfulness of coal ash behavior. The method uses a coal ash behavior harmfulness index to evaluate the degree of harm of coal ash to blast furnace smelting. The harmfulness of coal ash behavior is defined as HICA = [w1 × (K2O + Na2O) + w2 × Fe2O3] × f(ST); where HICA is the coal ash harmfulness index, K2O is the mass percentage of K2O in the coal ash, Na2O is the mass percentage of Na2O in the coal ash, Fe2O3 is the mass percentage of Fe2O3 in the coal ash, w1 and w2 are weighting coefficients, satisfying w1 + w2 = 1 and w1 > w2, ST is the softening temperature of the coal ash, and f(ST) is a temperature correction function. This invention provides a comprehensive and accurate method for quantifying the harmfulness of coal ash to blast furnace smelting, forming a comprehensive indicator that can directly and comprehensively warn of the operational risks of coal ash to blast furnaces.

Description

Technical Field

[0001] This invention relates to the field of steel metallurgical process optimization technology, and in particular to a method for evaluating the harmfulness of coal ash behavior. Background Technology

[0002] Blast furnace ironmaking is the most critical process in modern steel production, and its stable, efficient, and low-cost operation is of paramount importance. Pulverized coal, as the main fuel injected into the blast furnace from the tuyeres to replace expensive coke, has always been a focus of industry attention in terms of quality evaluation. However, traditional coal quality evaluation systems have significant limitations. Currently, the industry mainly relies on industrial analysis (fixed carbon, volatile matter), elemental analysis, and indicators such as ash fusion temperature to evaluate pulverized coal. These methods have two core flaws: static isolation and disconnect from dynamic operating conditions: traditional indicators are measured under standard experimental conditions and cannot accurately reflect the true behavior of pulverized coal in the blast furnace tuyeres, where temperatures reach as high as 2000℃ and residence time is extremely short. Ignoring the synergistic hazards of coal ash components: traditional ash fusion only reflects slagging tendency from a physical perspective, seriously ignoring the fatal hazards of coal ash chemical components (especially alkali metals K2O, Na2O, and Fe2O3) to blast furnace smelting. These components are "invisible killers" that lead to deterioration of coke strength, fluctuations in slag performance, and unsatisfactory furnace conditions.

[0003] Some existing patents focus on evaluating the slagging tendency of coal ash, but their application scenarios are mostly limited to boilers rather than blast furnaces; some construct indices to evaluate the catalytic effect of coal ash on coke dissolution, but do not cover the impact on slag fluidity; others fail to provide a unified index that can simultaneously quantify the comprehensive harm of coal ash to both coke dissolution and slag performance in blast furnaces. This makes it difficult for steel companies to quickly and accurately determine the overall operational risks that a type of pulverized coal may bring when blending and purchasing coal.

[0004] Therefore, there is an urgent need in this field for an innovative evaluation method that can break through the limitations of traditional indicators and deeply integrate and quantify the physical properties (fusibility) of coal ash with the chemical hazards of key chemical components, forming a comprehensive indicator that can directly and comprehensively predict blast furnace operation risks. This is the core technical problem that the "Coal Ash Hazard Index" invention patent aims to solve, and its purpose is to fill the gap in the existing technology for comprehensive and forward-looking evaluation of coal ash hazards. Summary of the Invention

[0005] This invention provides a method for evaluating the harmfulness of coal ash behavior. It is an evaluation method that can comprehensively and accurately quantify the degree of harm of coal ash to blast furnace smelting. It breaks through the limitations of traditional indicators and deeply integrates and quantifies the physical properties (fusibility) of coal ash with the chemical hazards of key chemical components, forming a comprehensive indicator that can directly and comprehensively warn of the risks of coal ash to blast furnace operation.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for evaluating the harmfulness of coal ash behavior uses a coal ash behavior harmfulness index to evaluate the degree of harm of coal ash to blast furnace smelting. The calculation model for the harmfulness of coal ash behavior is as follows: HICA=[w1×(K2O+Na2O)+w2×Fe2O3]×f(ST); Wherein, HICA is the toxicity index of coal ash, K2O is the mass percentage of K2O component in coal ash, Na2O is the mass percentage of Na2O component in coal ash, Fe2O3 is the mass percentage of Fe2O3 component in coal ash, w1 and w2 are both weighting coefficients, and w1+w2=1, and w1>w2, ST is the softening temperature of coal ash, and f(ST) is the temperature correction function.

[0007] Furthermore, the weighting coefficient w1 ranges from 0.5 to 0.8, and the weighting coefficient w2 ranges from 0.2 to 0.5.

[0008] Furthermore, the weighting coefficient w1 ranges from 0.6 to 0.7, and the weighting coefficient w2 ranges from 0.3 to 0.4.

[0009] Furthermore, the temperature correction function is: f(ST) = A / ST; Where A is a constant of the temperature correction function, with a value ranging from 1000 to 1500.

[0010] Furthermore, the temperature correction function is: f(ST) = 1300 / ST.

[0011] Furthermore, when the HICA (Hazard Index of Coal Ash) is less than 0.5, the degree of harm of coal ash to blast furnace smelting is determined to be low risk. When 0.5 ≤ Hazard Index of Coal Ash ≤ 1.0, the degree of hazard of coal ash to blast furnace smelting is judged as medium risk; When the Hazard Index of Coal Ash (HICA) is greater than 1.0, the degree of hazard of coal ash to blast furnace smelting is judged to be high risk.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1) Breaking through the limitations of traditional indicators, the physical properties (fusibility) of coal ash are deeply integrated and quantified with the chemical hazards of key chemical components to form a comprehensive indicator that can directly and comprehensively warn of blast furnace operation risks; 2) The index described in this invention can quantify the complex characteristics of coal ash into an intuitive basis for decision-making, guiding enterprises to accurately purchase low-hazard coal types and optimize coal blending structure, thereby effectively stabilizing blast furnace conditions, reducing operational difficulties caused by slagging and coke melting loss, significantly reducing costs, and improving economic efficiency. 3) The index described in this invention can serve as a key input for core procurement standards and coal blending models. By accurately quantifying the comprehensive harm of alkali metals and Fe2O3 in coal ash to blast furnace slagging and coke melting loss, it can directly guide the optimization of coal preparation structure. It is expected to effectively reduce fuel ratio and production costs and achieve rapid internal conversion. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below: This invention provides a method for evaluating the harmfulness of coal ash behavior, offering a comprehensive and accurate method for quantifying the harmfulness of coal ash behavior. The harmfulness of coal ash behavior refers to the degree of harm that coal ash poses to blast furnace smelting. The formula for calculating the harmfulness index of coal ash behavior is as follows: HICA = [w1× (K2O + Na2O) + w2 × Fe2O3] × f(ST); Wherein, HICA is the toxicity index of coal ash; K2O is the mass percentage of K2O component in coal ash, %; Na2O is the mass percentage of Na2O component in coal ash, %; Fe2O3 is the mass percentage of Fe2O3 component in coal ash, %; w1 and w2 are both weighting coefficients, and satisfy w1+w2=1, and w1>w2; ST is the softening temperature of coal ash; and f(ST) is the temperature correction function.

[0014] The weighting coefficient w1 ranges from 0.5 to 0.8, and the weighting coefficient w2 ranges from 0.2 to 0.5. The preferred weighting coefficients w1 are in the range of 0.5 to 0.8, and w2 is in the range of 0.2 to 0.5. The temperature correction function is: f(ST) = A / ST; Where A is a constant of the temperature correction function, with a value ranging from 1000 to 1500, and A preferably has a value of 1300.

[0015] The harmfulness index of coal ash behavior is divided into three risk levels: When the Hazard Index of Coal Ash < 0.5, the degree of hazard of coal ash to blast furnace smelting is judged to be low risk. When 0.5 ≤ Hazard Index of Coal Ash ≤ 1.0, the degree of hazard of coal ash to blast furnace smelting is judged as medium risk; When the Hazard Index of Coal Ash (HICA) is greater than 1.0, the degree of hazard of coal ash to blast furnace smelting is judged to be high risk.

[0016] The procurement, blending, and operational adjustments of pulverized coal for blast furnace injection are guided according to the risk level.

[0017] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0018] Example 1 A sample of commonly used pulverized coal from a steel plant was taken, and its ash composition was determined as follows: K2O = 1.2%, Na2O = 0.8%, Fe2O3 = 8.5%, ST = 1250℃. We set w1 = 0.6, w2 = 0.4, and f(ST) = 1300 / ST.

[0019] The calculated value is: HICA = [0.6 × (1.2 + 0.8) + 0.4 × 8.5] × (1300 / 1250) =[0.6×2.0+3.4]×1.04 =[1.2+3.4]×1.04 =4.78 The coal sample has an HICA of 4.78, which is greater than 1.0. It is classified as a high-risk coal and its use is recommended to be restricted or blended with other low-risk coal types.

[0020] Example 2 Take another coal sample with the following ash composition: K2O=0.5%, Na2O=0.3%, Fe2O3=5.2%, ST=1350℃. Take w1=0.6, w2=0.4, and f(ST)=1300 / ST.

[0021] The calculated value is: HICA = [0.6 × (0.5 + 0.3) + 0.4 × 5.2] × (1300 / 1350) =[0.6×0.8+2.08]×0.96 =[0.48+2.08]×0.96 =2.46 The coal sample has an HICA of 2.46, which is classified as a medium-risk level. It can be used in appropriate quantities under monitoring.

[0022] Example 3 A sample of high-quality pulverized coal was taken, and its ash composition was determined: K₂O = 0.15%, Na₂O = 0.08%, Fe₂O₃ = 2.2%, ST = 1495℃. The same calculation parameters were used: w₁ = 0.6, w₂ = 0.4, f(ST) = 1300 / ST.

[0023] The calculated value is: HICA = [0.6 × (0.15 + 0.08) + 0.4 × 2.2] × (1300 / 1495) = [0.6×0.23+0.88]×0.87 = [0.138+0.88]×0.87 = 1.018 × 0.87 = 0.89 The coal sample has an HICA of 0.89, which indicates a medium-risk level, and it can be used in appropriate quantities.

Claims

1. A method for evaluating the harmfulness of coal ash behavior, characterized in that, The hazard index of coal ash behavior is used to evaluate the degree of harm of coal ash to blast furnace smelting. The calculation model of the hazard index of coal ash behavior is as follows: HICA = [w1× (K2O + Na2O) + w2 × Fe2O3] × f(ST); Wherein, HICA is the toxicity index of coal ash, K2O is the mass percentage of K2O component in coal ash, Na2O is the mass percentage of Na2O component in coal ash, Fe2O3 is the mass percentage of Fe2O3 component in coal ash, w1 and w2 are both weighting coefficients, and satisfy w1+w2=1 and w1>w2, ST is the softening temperature of coal ash, and f(ST) is the temperature correction function.

2. The method for evaluating the harmfulness of coal ash behavior according to claim 1, characterized in that, The weighting coefficient w1 ranges from 0.5 to 0.8, and the weighting coefficient w2 ranges from 0.2 to 0.

5.

3. The method for evaluating the harmfulness of coal ash behavior according to claim 2, characterized in that, The weighting coefficient w1 ranges from 0.6 to 0.7, and the weighting coefficient w2 ranges from 0.3 to 0.

4.

4. The method for evaluating the harmfulness of coal ash behavior according to claim 1, characterized in that, The temperature correction function is: f(ST) = A / ST; Where A is a constant of the temperature correction function, with a value ranging from 1000 to 1500.

5. The method for evaluating the harmfulness of coal ash behavior according to claim 4, characterized in that, The temperature correction function is: f(ST) = 1300 / ST.

6. The method for evaluating the harmfulness of coal ash behavior according to claim 1, characterized in that, When the Hazard Index of Coal Ash < 0.5, the degree of hazard of coal ash to blast furnace smelting is judged to be low risk. When the Hazard Index of Coal Ash (HICA) is 0.5 ≤ 1.0, the degree of hazard of coal ash to blast furnace smelting is judged as medium risk. When the Hazard Index of Coal Ash (HICA) is greater than 1.0, the degree of hazard of coal ash to blast furnace smelting is judged to be high risk.