RU2228375C1 - Method of sintering sinter burden - Google Patents

Abstract

FIELD: metallurgy; sintering processes; sintering process automatic control systems. SUBSTANCE: proposed method includes preparation of burden from magnetite fine- grain concentrates at high content of Fe≥63%, oxidized ores, iron-containing wastes in form of blast-furnace dust, sintering slag, converter slag and blast- furnace slag, scale, wet fluxes in form of lime and dolomite, burnt lime, solid fuel in form of coke breeze and/or coals of various grades and handling returns; burden is mixed, pelletized and loaded to sintering machine in one or two layers at different ratio by mass and different content of carbon in each of them; then sinter is ignited, sintered and subjected to mechanical treatment. Granulometric composition of pelletized burden and content of wet fluxes are determined; content of fuel in burden is preset depending on required ratio. EFFECT: increased specific productivity of sintering machine; enhanced strength of sinter; reduced specific consumption of fuel; reduced usage of metal burden due to optimization and stabilization of burden sintering mode. 3 tbl, 1 ex

Description

The invention relates to metallurgy, and more particularly to sinter production, and can be used in an automatic control system for sintering process.

The closest in technical essence is the method of calculating specific fuel consumption, described in the Methodological guidelines for determining the fuel consumption standards for the production of iron ore sinter ("Methodical instructions for determining the fuel consumption standards for the production of iron ore sinter ...". Industry standard. RD 14-25 -230-88. - M .: MFM USSR, 1988). According to the specified method, specific fuel consumption ("standard") is determined by the formula

where b _n - standard specific fuel consumption, kg / t sinter; b _exp - solid fuel consumption determined experimentally on an agglomerate, kg / t sinter; b _i - saving (overspending) of solid fuel when changing the i-th component of the charge or i-th technological parameter, kg / t of sinter.

The disadvantages of this method are as follows.

1. The method allows to determine the specific fuel consumption in the form of a deviation from the base value and does not allow to determine the absolute value of this value.

2. The determination of the base value of the specific fuel consumption on an sintering cup contains a certain error due to insufficiently developed criteria for the similarity of laboratory sintering with sintering on a sintering machine.

The technical result of the claimed invention is to increase the specific productivity of the sinter machine, the strength of the sinter and to reduce the specific consumption of fuel and metal due to the optimization and stabilization of the thermal regime of sintering of the mixture.

The specified technical effect is achieved by the fact that the sintering method involves the preparation of a mixture of magnetite fine-grained concentrates with a high content of Fe≥63%, oxidized ores, iron-containing waste in the form of blast furnace dust, blast furnace and converter sludge, scale, crude fluxes in the form of limestone, dolomitized limestone and dolomite, burnt lime, solid fuel in the form of coke and / or different grades of coal, return, mixing, pelletizing and loading onto the sinter machine with one or two layers with different charge ratio mass and various contents each including carbon fuel, a subsequent ignition, sintering and machining the sinter by crushing, screening and cooling.

The fuel content in the charge is set based on the ratio

where C _t is the carbon content of the fuel in the charge, which is the total amount of carbon introduced into the charge by fuel in the form of coke and / or various types of coal, as well as with Fe-containing wastes in the form of blast furnace dust and sludge (sinter, blast furnace and converter production ), wt.%:

M _fl - the content of crude fluxes in the mixture, wt.%;

FeO — FeO content in the agglomerate, wt.%;

d _equiv - the average diameter of the granules pelletized mixture, calculated as the average harmonic value according to the results of sieve analysis:

where P is the mass of the sample pelletized mixture, kg; p _i , p _{i + 1} , ..., p _{i + n} - mass of the charge of classes i, i + 1, ..., i + n, kg; d _i , d _{i + 1} , ..., d _{i + n} are the average diameters of the granules of the classes respectively i, i + 1, ..., i + n, mm; n is the number of classes (n≥5);

0,0321 - coefficient, mm ^-1 ;

15,837 - coefficient,%;

0,144, 0,147 - coefficients (dimensionless);

k is an empirical coefficient equal to (0.5-2.0)%.

With a two-layer loading of the charge, the fuel content in the charge of each layer is calculated by the formulas:

where (C _t ) ⁱⁿ , (C _t ) ⁿ is the carbon content of the fuel in the charge, respectively, of the upper layer and in the charge of the lower layer, wt.%; ρ - coefficient reflecting the amount of charge loaded into the top layer, expressed in fractions with respect to the entire charge, dimensionless; z - coefficient (dimensionless), reflecting the weighted average ratio of carbon fuel distributed over the layers of the mixture, calculated by the formula:

where 1.9 is a coefficient, dimensionless;

β - coefficient equal to 0.15-0.35, dimensionless.

The invention consists in the following.

Agglomeration charge is composed of fine-grained magnetite concentrates with a content of Fe≥63%, oxidized ores, iron waste in the form of blast furnace dust, sinter, blast furnace and converter sludge, scale, raw fluxes in the form of limestone, dolomitic limestone and dolomite, calcined lime, solid fuel in the form of coke and / or different grades of coal and return.

The compiled charge is mixed, moistened and pelletized at specified parameters according to the moisture content of the charge, the rotation speed of the drum pelletizer and charge load. A pelletized charge is loaded onto a belt type sinter machine in one or two layers at different mass ratios of the charge and different fuel contents in the charge of each layer. The sintering of the mixture is carried out by sucking air through the layer of the mixture by creating a vacuum under the grates of the sintering carts. The sintered batch mixture is subjected to crushing and screening. Agglomerate (oversize product +5 mm) is cooled and sent to the blast furnace.

Sieve analysis pelletized charge is carried out periodically when changing, for example, the composition of the charge. Sieving is performed on sieves with a scale module of 1.44-2: the minimum size of the class allocated is <(0.74-0.44) mm, the number of classes is n≥5. The average diameter of the granules pelletized mixture - d _equiv calculated as the harmonic mean value by the formula (3).

Table 1 shows 3 examples of the results of the sieve analysis of the pelletized charge and the calculated values of d _equiv (sinter factory of NLMK OJSC, drum pelletizer 3.2 × 12.5 m).

An example of calculating the required carbon content of fuel in a charge.

Initial (given) conditions: M _fl = 8.00%; FeO = 10.00%; k = 0.75%. Substituting the corresponding values in relation (2), we obtain:

Experience No. 1:

With _t = 0.14410.00 + 0.0321 (10.00 + 15.837) 2.53 + 0.147.8.00-0.75 = 3.96%.

Experience No. 2:

With _t = 0.14410.00 + 0.0321 (10.00 + 15.837) 3.08 + 0.147.8.00-0.75 = 4.43%.

Experience No. 3:

C _t = 0.14410.00 + 0.0321 (10.00 + 15.837) 3.50 + 0.147.8.00-0.75 = 4.77%.

When loading the mixture in two layers, the required carbon content of fuel in the charge of each layer is additionally determined.

An example of calculating the carbon content of fuel in the charge by the layers of loading on the sinter machine

Initial (predetermined) conditions: carbon content of fuel in the total charge With _t = 3.96% (experiment No. 1); the proportion of the charge of the upper layer is ρ = 0.45; β = 0.20.

z = 1.9 ρ + β = 1.9 0.45 + 0.20 = 1.055.

Checking the total amount of carbon in the charge:

With _t = 0.45 · 4.52 + 0.55 · 3.505 = 2.034 + 1.927 = 3.962 = 3.96%,

where 0.45 and 0.55 are the proportion of the charge loaded onto the sinter machine by the upper layer and the lower layer, respectively; 2,034 and 1,925 - the average weighted amount of carbon fuel contained in the charge, respectively, of the upper layer and lower,%. The coefficient z reflects the ratio of these quantities

z = 2.034 / 1.927 = 1.055.

According to the technical analysis of the fuel used, the fuel consumption for sintering the charge is calculated (T = 100 C _t / C ^d , where T is the fuel content, for example, coke, in the charge,%; C ^d is the dry carbon content of the fuel,%). The value of C _t represents the total amount of carbon in the charge, regardless of the type of source of input, for example, carbon coke and / or various grades of coal, as well as carbon that entered the charge with Fe-containing waste in the form of blast furnace dust, blast furnace and other sludges.

The content of crude fluxes in the charge is set based on the conditions for obtaining the agglomerate of the required basicity, determined by the ratio of CaO / SiO ₂ , (CaO + MgO) / SiO ₂ at a given MgO content, taking into account the flow of lime. The content of FeO in the agglomerate is set by the technical conditions for the production of agglomerate from a mixture of this composition: in the production of fluxed agglomerate from fine-grained magnetite concentrates FeO = 9.00-15.00%.

The analysis of scientific, technical and patent literature shows the lack of coincidence of the distinguishing features of the proposed method with the signs of known technical solutions, on the basis of which it is concluded that the proposed technical solution meets the criterion of "inventive step".

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

Example. The ore part of the charge consists of the following components, wt.%:

Concentrates:

Lebedinsky 22.3

stoilensky 36.5

gubkinsky 21.7

ore stolenskaya 11.4

iron waste

sinter sludge 4.3 8

blast furnace dust 1.20

blast furnace slurry 1.78

scale 0.74

total 100.0

The chemical composition of the ore mixture, wt.%:

As raw fluxes, a mixture of Studen limestone and Dankovsky dolomitic limestone is used in a ratio of 2: 1, respectively. The fuel is coke: C ^d - 80.00%; V ^d - 1.50%; S $\genfrac{}{}{0ex}{}{\text{d}}{\text{i}}$ - 0.50%; And ^d is 18.00%.

The flow rate of raw fluxes is set based on the conditions for obtaining the agglomerate of a given basicity: CaO / SiO ₂ = 1.15 and a given MgO content = 1.60%.

The compiled charge is mixed, moistened and pelletized at specified parameters according to the moisture content of the charge, the rotation speed of the drum pelletizer and charge load. By means of a sieve analysis, the granulometric composition of the pelletized charge is determined, according to the results of which the average diameter of the pelletized pellet mixture is calculated, d _equiv .

A pelletized charge is loaded onto the sinter machine in one or two layers at different mass ratios of the charge and different fuel contents in the charge of each layer. The sintering of the charge is carried out on a belt-type sinter machine by sucking air through the charge layer by creating a vacuum under the grates of the sintering trolleys. The sintered batch mixture is subjected to crushing and screening. Agglomerate (oversize product +5 mm) is cooled and sent to the blast furnace.

The fuel content in the charge is set based on the ratio:

С _t = 0.144FeO + 0.0321 (FeO + 15.837) d _equiv + 0.147 M _fl - k,%,

where C _t is the carbon content of the fuel in the charge, which is the total amount of carbon introduced into the charge by fuel in the form of coke and / or various types of coal, as well as the carbon contained in Fe-containing wastes (in blast furnace dust, in sinter and blast furnace sludge), wt.%; M _fl - the content of crude fluxes in the mixture, wt.%; FeO — FeO content in the agglomerate, wt.%; 0,0321 - coefficient, mm ^-1 ; 15,837 - coefficient,%; 0,144, 0,147 - coefficients (dimensionless); k is an empirical coefficient equal to (0.5-2.0)%; d _equiv - the average diameter of the granules pelletized mixture, calculated as the average harmonic value according to the results of sieve analysis, mm

The formula for calculating d _equiv has the following form:

where P is the mass of the sample pelletized mixture, kg; p _i , p _{i + 1} , ..., p _{i + n} is the mass of the charge of classes i, i + 1, ..., i + n, kg; d _i , d _{i + 1} , ..., d _{i + n} are the average diameters of the granules of the classes respectively i, i + 1, ..., i + n, mm; n is the number of classes (n≥5).

The example illustrates two ways of loading the mixture onto an sinter machine: single-layer and two-layer.

With a two-layer loading of the charge, the carbon content of the fuel in the charge of each layer is calculated by the formulas:

where (C _t ) ⁱⁿ , (C _t ) ⁿ is the carbon content of the fuel in the mixture, respectively, of the upper layer and in the mixture of the lower layer, wt.%; ρ is a coefficient reflecting the amount of charge loaded into the top layer, expressed in fractions with respect to the entire charge, dimensionless; z - coefficient (dimensionless), reflecting the weighted average ratio of fuel distributed over the layers of the mixture, calculated by the formula

z = 1.9 ρ + β,

where 1.9 is a coefficient, dimensionless; β - coefficient equal to 0.15-0.35, dimensionless.

Table 2 shows examples of the implementation of the proposed method with a single-layer loading of the charge on the sinter machine, in table 3 - with a two-layer.

In examples No. 1 and No. 5 (table 2), the carbon content of the fuel in the mixture does not satisfy the requirement of the optimal thermal regime of sintering the mixture with the given parameters by size (d _equiv = 3 mm), the number of raw fluxes in the mixture (M _fl = 8.5 %) and FeO content in the agglomerate. In example No. 1, C _t exceeds the amount of fuel carbon in the charge regulated by the method: C _t >(4.68-3.18)%; in example No. 5, on the contrary, C _t <(4.68-3.18)%. In the first case, the carbon content of the fuel was determined at a coefficient value of k <0.50, in the second case, at k> 2.00. Due to the fact that the carbon content of the fuel in the charge does not correspond to the optimal values regulated by the claimed method, the technical and economic indicators of the sintering process in these examples are inferior in all compared parameters - in specific productivity, specific fuel consumption, in strength and stability of the thermal sintering regime - with examples of technologies No. 2, 3 and 4.

As in Table 2, in Table 3, examples No. 1 and No. 5 illustrate options for the sintering technology of the charge, when the carbon content of the fuel in the charge of the upper layer is (C _t ) ⁱⁿ and in the charge of the lower layer is (C _t ) ⁿ do not correspond to the optimal values: in example No. 1, the coefficient β <(0.15-0.35), in example No. 5, β> (0.15-0.35). As a result of this, in these examples the technical and economic indicators (specific productivity, specific fuel consumption and agglomerate strength) are inferior to the values of these indicators in technology examples No. 2, 3 and 4. The reason for this is stabilization and optimization of the thermal sintering regime due to the rational distribution of fuel carbon over charge layers. The higher level of stabilization of the thermal sintering regime in examples No. 2, 3 and 4 is indicated by the standard deviations of the FeO content: 0.891% and 1.155%, 1.136% in examples No. 1, 5, respectively.

Claims (1)

A method for sintering an agglomeration charge, including the preparation of a charge from magnetite fine-grained concentrates with a high content of Fe≥63%, oxidized ores, iron-containing waste in the form of blast furnace dust, agglomeration, blast furnace and converter sludge, scale, crude fluxes in the form of limestone, dolomitic limestone and dolomite burnt lime, solid fuel in the form of coke and / or different grades of coal, return, mixing, pelletizing and loading on the sinter machine in one or two layers with different mix ratio for ma sce and different content of fuel carbon in each of them, subsequent ignition, sintering and machining of the cake by crushing, cooling and screening, characterized in that the granulometric composition of the pelletized charge is determined, the content of raw fluxes in the charge, and the fuel content in the charge is set based on from the ratio: With _t = 0.144 FeO + 0.0321 (FeO + 15.837) d _equiv. +0.147 M _fl. -k,%, where C _t is the carbon content of the fuel in the charge, which is the total amount of carbon introduced into the charge by fuel in the form of coke and / or various types of coal, as well as with Fe-containing waste in the form of blast furnace dust and sludge from sintering, blast furnace and converter production, wt.%; M _fl. - the content of crude fluxes in the mixture, wt.%; FeO — FeO content in the agglomerate, wt.%; d _equiv - the average diameter of the granules pelletized mixture, calculated as the average harmonic value according to the results of sieve analysis: the number of classes n≥5, the sieving scale module 1.44-2, mm; 0,0321 - coefficient, mm ^-1 ; 15,837 - coefficient,%; 0,144, 0,147 - dimensionless coefficients; k is an empirical coefficient equal to 0.5-2.0,%, and the carbon content of the fuel in the charge of each layer is calculated by the formulas:

where (C _t ) ⁱⁿ , (St) ⁿ is the carbon content of the fuel in the mixture, respectively, of the upper layer and in the mixture of the lower layer, wt.%; ρ - coefficient reflecting the amount of charge loaded into the top layer, expressed in fractions with respect to the entire charge, dimensionless; z - dimensionless coefficient, reflecting the weighted average ratio of carbon fuel distributed over the layers of the mixture, calculated by the formula z = 1.9 ρ + β, where 1.9 is a coefficient, dimensionless; β is an empirical coefficient equal to 0.15-0.35, dimensionless.