RU2190667C1 - Blast smelting method - Google Patents

Abstract

FIELD: ferrous metallurgy. SUBSTANCE: method involves periodically charging ore material and coke into furnace; providing continuous controlling of composition and amount of ore material and coke; controlling chemical composition of furnace top gas and rate of additional fuel blown through tuyeres into furnace hearth, blast furnace air, process oxygen; controlling blast furnace air temperature and moisture content; setting coke rate by ratio: C= 1/Cc. 1/qc . [qob. Mob-z(qb. Vb+qaf. Vaf)], where C is coke rate kg(dry)/t of cast iron; Mob is rate of ore burden, kg/t of cast iron; Cc is content of carbon in coke, parts; qc is heat equivalent of coke carbon, mJ/kg; qob is heat equivalent of ore burden, mJ/kg; qb is heat equivalent of blast furnace air, mJ/cu. m; qaf is heat equivalent of additional fuel, mJ/cu. m (kg); Vb is rate of blast furnace air, cu.m/t of cast iron; Vaf is rate of additional fuel, cu.m (kg)/t of cast iron; z is coefficient equal to 0.70-1.20. Method may be used for regulating blast furnace heat mode by optimized rate of coke depending on quality of burden materials. EFFECT: increased efficiency of furnace and improved quality of cast iron. 1 tbl, 1 ex

Description

 The invention relates to ferrous metallurgy, in particular to blast furnace production, and can be used to regulate the thermal regime of blast furnace smelting by optimizing the consumption of coke depending on the quality of the charge materials.

где ΔK - величина коррекции массы кокса в подаче, кг;
∑Fe - содержание Fe в шихтовых материалах, кг/подачу;
Z - заданное соотношение ∑Fe/∑C;
∑C - количество углерода, поступающего в печь с коксом и замененного топливной добавкой, кг/подачу;
С_к - содержание углерода в коксе с коррекцией по влаге, доли массы;
m_с - масса углерода, замененного топливной добавкой, кг/подачу;
m_к - количество кокса в подачу, которое загружается в доменную печь в данный момент, кг.The closest in technical essence and the achieved result to the claimed method is the method [RU 2017826, C 21 V 5/00, 08/15/94. Bull. fifteen] . The essence of the method lies in the fact that when using fuel additives (natural gas, solid or liquid fuel), the mass of carbon replaced by the fuel additive is additionally taken into account, the actual Fe / C ratio is determined and compared with a predetermined value, the value of which is assumed to be 1.6-2 3 kg / kg. If the difference between them ΔZ exceeds the indicator K, which is in the range | 0.005 | - | 0.015 |, the coke mass in the feed is adjusted, the change in which is determined from the following ratio:

where ΔK is the correction value of the coke mass in the feed, kg;
∑Fe - Fe content in charge materials, kg / feed;
Z is the given ratio ∑Fe / ∑C;
∑C - the amount of carbon entering the furnace with coke and replaced by a fuel additive, kg / feed;
With _to - the carbon content in the coke with moisture correction, mass fraction;
m _s - mass of carbon replaced by a fuel additive, kg / feed;
m _to - the amount of coke in the feed, which is loaded into the blast furnace at the moment, kg

 The disadvantage of this method is that the consumption of coke (correction of the mass of coke in the feed) is changed, not taking into account the amount of heat that is required to melt the mixture with a given heat demand. The iron content in the mixture does not fully reflect the heat consumption for the production of pig iron. In addition, the consumption of coke and fuel additives are taken into account through mass quantities and their calorific values are not taken into account. The method does not take into account the amount of heat supplied with the heated blast, as well as the cost of heat for decomposition of moisture contained in the blast. Analysis of the thermal balances of the operation of blast furnaces using fuel additives shows that with heated blast heat in the amount of 1500-2000 mJ / t of pig iron is supplied, which is about 20% of the total amount of heat consumed. As a result of this, this method does not achieve a technical effect.

 The technical effect when using the invention is to increase the productivity of the blast furnace with a minimum specific consumption of coke and to improve the quality of cast iron by reducing the sulfur and silicon contents and increasing the stability in chemical composition and heating.

где К - расход кокса, кг (сухого)/т чугуна;
М_р.ш - расход рудной части шихты, кг/т чугуна;
С_к - содержание углерода в коксе, доли;
q_с - тепловой эквивалент углерода кокса, мДж/кг;
q_р.ш - тепловой эквивалент рудной части шихты, мДж/кг;
q_д - тепловой эквивалент дутья, мДж/м³;
q_д.т - тепловой эквивалент дополнительного топлива, мДж/м³ (кг);
V_д - расход дутья, м³/т чугуна;
V_д.т - расход дополнительного топлива, м³ (кг)/т чугуна;
z - коэффициент, равный 0,70-1,20.The technical result is achieved by the fact that the method of blast furnace smelting includes periodic loading of charge materials and coke into the furnace, continuous monitoring of the composition and quantity of charge materials and coke, control of the chemical composition of blast furnace gas, additional fuel consumption, blasting, process oxygen, temperature and humidity control of blasting . Coke consumption is set by the ratio

where K is the consumption of coke, kg (dry) / t of pig iron;
M _r.sh - the consumption of the ore part of the charge, kg / t of pig iron;
C _to - carbon content in coke, fraction;
q _s - thermal equivalent of carbon coke, mJ / kg;
q _r.sh - thermal equivalent of the ore part of the charge, mJ / kg;
q _d is the thermal equivalent of the blast, mJ / m ³ ;
q _d.t - thermal equivalent of additional fuel, mJ / m ³ (kg);
V _d - blast consumption, m ³ / t of pig iron;
V _d.t - additional fuel consumption, m ³ (kg) / t of pig iron;
z is a coefficient equal to 0.70-1.20.

The thermal equivalents of the ore part of the charge (q _r ), blast (q _d ), additional fuel (q _d ) and carbon coke (q _s ) are calculated by the ratios:
q _r.sh = 32.0 • (M _r.sh ) ² -101.5 • (M _r.sh ) +86.235, (3)
where (M _r.sh ) is the flow rate of the ore part of the charge, t / t;
32.0; 101.5 and 86.235 are coefficients.

q _d = 1 • c _d • t _d -10.802φ, (4)
where 1 is the amount of blast, m ³ ;
c _d - heat capacity of the blast (diatomic gases), mJ / (m ³ deg.);
t _d - blast temperature, ^o С;
10,802 - thermal effect of the decomposition of H ₂ O, mJ / m ³ ;
φ is the humidity of the blast, m ³ N ₂ O / m ³ dry blast.

q _d.t = Q _d.t + 12.648 • γ • η _co + 10.802 • μ • η _n , (5)
where Q _d.t - thermal effect of combustion of additional fuel to CO and H ₂ , mJ / m ³ (kg);
12,648 and 10,802 - thermal effects of the formation of CO ₂ and H ₂ O, mJ / m ³ ;
γ and μ are coefficients reflecting the amount of СО and Н ₂ , respectively, formed in the furnace hearth from 1 m ³ (kg) of additional fuel, m ³ / m ³ ;
η _co and η _n - the degree of use, respectively, of CO and H ₂ , the share of units.

q _c = 1.8667 (5.250 + 12.648 • η _co ), (6)
where 5,250 is the thermal effect of the formation of CO, mJ / m ³ ;
1.8667 - the amount of CO formed during the combustion of 1 kg of carbon, m ³ .

 An increase in the productivity of the blast furnace and a decrease in the specific consumption of coke will occur due to the correspondence of the heat demand of the blast furnace process, taken into account using the heat equivalent of the ore part of the charge, with the heat from the combustion of coke, additional fuel and hot blast, taking into account the heat consumption for decomposition of the moisture of the blast.

 Conducting blast-furnace smelting with coke consumption calculated according to relation (3) ensures a stable and optimal thermal regime, which will reduce stochastic fluctuations in the temperature regime both in the furnace hearth and over the entire height. A stable thermal regime favors blast furnace smelting with the minimum allowable coke consumption, while at the same time ensuring sufficiently effective desulphurization of cast iron with a minimum silicon content. The optimal thermal regime favors the intensification of the process while maintaining a high level of quality of cast iron, including its chemical composition, temperature and stability according to these parameters.

 The following is an example embodiment of the invention, not excluding other options within the claims.

 EXAMPLE.

 In the process of blast furnace smelting, charge materials and coke are periodically loaded into the blast furnace, continuous monitoring of the composition and quantity of charge materials and coke, control of the chemical composition of blast furnace gas, consumption of additional fuel injected through the tuyeres in the furnace hearth, blasting, process oxygen, temperature control and humidity of the blast.

The method of blast furnace smelting is carried out on a blast furnace with a useful volume of 3200 m ³ . In a blast furnace, pig iron of the following chemical composition is smelted, wt.%: Si 0.45-0.62; Mn 0.11-0.20; S 0.013; P 0.08; Fe 94.63.

The ore part of the mixture consists of fluxed agglomerate of the following composition, wt.%: Fe 58.93; FeO 9.32; SiO ₂ 6.21; CaO 6.56; MgO 2.37; Al ₂ O ₃ 1.78. Scrap metal is not used.

Technical analysis of coke, wt.%: C _to 87.50; A 12.21; V 1.10, S 0.48.

The parameters of the combined blast: blast consumption (V _d ) 1000 m ³ / t of cast iron; blast temperature (t _d ) 1170 ^o C; humidity blast φ 0,015 m ³ / m ³ . As additional fuel injected through the tuyeres into the furnace hearth, natural gas is used with characteristics: Q _d.t = 1,958 mJ / m ³ ; the yield of CO (γ) is 1.077 m ³ / m ³ and the output of H ₂ (μ) is 2.06 m ³ / m ³ . The consumption of additional fuel is (V _dt ) 80 m ³ / t of cast iron. The consumption of process oxygen provides its content in the blast equal to 28.2%.

где К - расход кокса, кг (сухого)/т чугуна;
М_p.ш - расход рудной части шихты, кг/т чугуна;
С_к - содержание углерода в коксе, доли;
q_с - тепловой эквивалент углерода кокса, мДж/кг;
q_р.ш - тепловой эквивалент рудной части шихты, мДж/кг;
q_д - тепловой эквивалент дутья, мДж/м³;
q_д.т - тепловой эквивалент дополнительного топлива, мДж/м³ (кг);
V_д - расход дутья, м³/т чугуна;
V_д.т - расход дополнительного топлива, м³ (кг)/т чугуна;
z - коэффициент, равный 0,70-1,20.The degree of use of CO and H ₂ respectively are: η _co = 0.4; η _n = 0.4.
Coke consumption is set by the ratio

where K is the consumption of coke, kg (dry) / t of pig iron;
M _p.sh - ore charge charge, kg / t pig iron;
C _to - carbon content in coke, fraction;
q _s - thermal equivalent of carbon coke, mJ / kg;
q _r.sh - thermal equivalent of the ore part of the charge, mJ / kg;
q _d is the thermal equivalent of the blast, mJ / m ³ ;
q _d.t - thermal equivalent of additional fuel, mJ / m ³ (kg);
V _d - blast consumption, m ³ / t of pig iron;
V _d.t - additional fuel consumption, m ³ (kg) / t of pig iron;
z is a coefficient equal to 0.70-1.20.

 The iron content in iron is 94.63%; the coefficient of transition of Fe to slag ξ = 0.002 (fraction).

где [Fe] - содержание Fe в чугуне, мас.%;
ξ - коэффициент, отражающий количество Fe, переходящее в шлак, доли единицы;
Fe_р.ш - содержание Fe в рудной части шихты, % (масс.);
(М_Fe)_м.д - количество Fe, поступающее в шихту в виде металлолома, кг/т чугуна;
1000 - коэффициент пересчета расхода рудной части шихты (офлюсованного агломерата) на тонну чугуна.The degree of use of CO and H ₂ respectively are: η _co = 0.4; η _n = 0.4.
The consumption of fluxed sinter is calculated by the formula

where [Fe] is the Fe content in cast iron, wt.%;
ξ is a coefficient reflecting the amount of Fe passing into slag, fractions of a unit;
Fe _r.sh - Fe content in the ore part of the charge,% (mass.);
(M _Fe ) _ppm - the amount of Fe entering the charge in the form of scrap metal, kg / t of pig iron;
1000 - conversion factor of the ore part of the charge (fluxed sinter) per ton of cast iron.

 Calculation example.

2) q_р.ш = 32,15(1,609)² - 101,5(1,609) + 86,235 = 6,153 мДж/кг;
3) q_с = 1,8667(5,250 + 12,648•0,40) = 19,2442 мДж/кг С_K;
4) q_д = 1•0,00143•1170 - 10,802•0,015 = 1,511 мДж/м³;
5) q_т.д = 1,958 + 12,648•1,077•0,40 + 10,802•2,06•0,40 = 16,3076 мДж/м³.

2) q _r.s. = 32.15 (1.609) ² - 101.5 (1.609) + 86.235 = 6.153 mJ / kg;
3) q _s = 1.8667 (5.250 + 12.648 • 0.40) = 19.2442 mJ / kg C _K ;
4) q _d = 1 • 0.00143 • 1170 - 10.802 • 0.015 = 1.511 mJ / m ³ ;
5) q _etc = 1.958 + 12.648 • 1.077 • 0.40 + 10.802 • 2.06 • 0.40 = 16.3076 mJ / m ³ .

В таблице приведены примеры осуществления способа при различных значениях коэффициента z.To conduct blast furnace smelting, the coke consumption is set by the ratio (we will illustrate the calculation for the technology variant at z = 0.95)

The table below shows examples of the method for various values of the coefficient z.

 In the first example (z = 0.6), coke consumption for these blast parameters is excessive (K = 487 kg / t) for smelting pig iron (Si≤1.25%). As a result of this, the Si content in cast iron increases to 0.90%, which does not meet the requirements of converter steel production. The increased heating associated with the excessive consumption of coke reduces the intensity of smelting and, as a result, the daily production of pig iron decreases sharply and amounts to 7850 tons.

 In the fifth example (z = 1.30), the thermal regime of blast furnace smelting is lower than that required by the heat demand of the process. Coke consumption (K = 371 kg / t) is clearly less than the minimum possible value - 421 kg / t (example 4). For this reason, cast iron production per day decreased by 850 tons. Cast iron quality deteriorated: the sulfur content increased from 0.013% (examples 3 and 4) to 0.030%, the variability of cast iron in S, Si and temperature increased. In all respects, this technology example does not meet the technical and economic requirements of blast furnace production.

In the optimal examples (z = 0.70-1.20), due to the establishment of the required coke consumption, the thermal regime that is optimal from the point of view of the heat demand of the melting process is ensured and, due to this, the best performance is achieved for the productivity of the blast furnace - 8300-8350 t / day and for the quality of cast iron . Content S = 0.013%; Si = 0.45-0.62%, t _h = 1505-1550 ^o C, while achieving minimal stochastic fluctuations in the chemical composition and temperature of cast iron.

Claims (1)

A method for blast furnace smelting, including periodic loading of ore materials and coke into a blast furnace, continuous monitoring of the composition and quantity of ore materials and coke, monitoring of the chemical composition of blast furnace gas, consumption of additional fuel blown through the tuyeres in the furnace, blasting, process oxygen, temperature control and humidity of the blast, characterized in that the coke consumption is set by the ratio

where K is the coke consumption, kg (dry) / t of pig iron;
M _r.sh - consumption of the ore part of the charge, kg / t of pig iron;
С _К - carbon content in coke, shares;
q _c - thermal equivalent of carbon coke, mJ / kg;
q _r.sh - thermal equivalent of the ore part of the charge, mJ / kg;
q _d is the thermal equivalent of the blast, mJ / m ³ ;
q _d.t - thermal equivalent of additional fuel, mJ / m ³ (kg);
V _D - blast consumption, m ³ / t of pig iron;
V _d.t - additional fuel consumption, m ³ (kg) / t of pig iron;
z is a coefficient equal to 0.70-1.20;
wherein the thermal equivalent of the ore part of the charge is established by the ratio
q _r.sh = 32.0 • (M _r.sh ) ² -101.5 • (M _r.sh ) +86.235,
where 32.0; 101.5 and 86.235 are coefficients. M _r.sh - ore charge charge per 1 ton of pig iron, t / t.

Images