RU2281976C2 - Burden for production of agglomerate - Google Patents

Abstract

FIELD: ferrous metallurgy; production of agglomerate and preparation of iron ore raw material for metallurgical process stage.

SUBSTANCE: proposed burden contains iron ore concentrate, iron-containing material, lime stone, solid fuel and vanadium-containing metal product of processing metallurgical slag dumps. Ratio of ingredients in burden is as follows, mass-%: iron-containing material, 15-40; limestone, 3-8; solid fuel, 4-7; vanadium-containing metal product of processing slag dumps, 4-12; the remainder being iron ore concentrate. Size of vanadium-containing metal product is up 10 mm. Used as iron-containing material are metallurgical dust and agglomeration and blast furnace returns.

EFFECT: reduced content of expensive iron ore concentrates in agglomerate burden; reduced consumption of solid fuel at retained strength characteristics.

3 cl, 2 tbl, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to the production of sinter, and can be used in the preparation of iron ore for metallurgical processing.

Known mixture for the manufacture of pellets (briquettes), consisting of iron-containing waste (blast furnace dust, converter, open-hearth) with additives of lime, concrete [1]. The specified charge plays a certain positive role. However, all these additives to the charge are mineral natural raw materials that must be extracted from the bowels, dried, crushed, grinded, and in some cases fired, i.e. to carry out a number of expensive technological operations. In addition, lime adversely affects the behavior of the pellets upon heating, causing them to crack, i.e. strength reduction.

A known mixture for the production of iron flux and a method for learning it [2], containing slag from steelmaking and iron-containing additives, in addition, for the purpose of recycling metallurgical waste and increasing the strength of granules as iron-containing additives, it contains scale and screening of sinter and pellets in the following ratio of components, the weight.%:

steelmaking slag 30-50 scale 10-20 screening of sinter and pellets fractions of 0.1-3.5 mm rest

Known mixture for sintering iron-containing materials containing dust and scale, and also additionally contains steel smelting sludge and lime in the following ratio of ingredients [3], wt.%:

steel sludge 10-30 blast furnace slurry 20-40 dust 20-40 scale 5-15 steelmaking slag 5-15 lime 5-20

The disadvantage of these blends is the low strength characteristics of the agglomerates. The agglomerate shipped from the sintering plant is subsequently subjected to predominantly abrasive loads upon delivery to the blast furnace during the interaction of the pieces during transportation and lowering in the bunkers of the blast furnace. In this case, mainly dusty fractions are formed and break off and pass into the fines cantilever sections of the lumpy product.

The closest technical solution to the proposed one is a mixture for the production of sinter, including chemical waste, scale, blast furnace dust, sludge from blast furnace production, limestone, coke breeze, characterized in that, in order to increase the strength of the sinter, it additionally contains vanadium-containing sludge from thermal power plants (TPPs) with a CaO content of 10% in the following ratio of ingredients [4], wt.%:

chemical waste 8-15 scale 35-55 blast furnace dust 10-15 blast furnace slurries 8-15 limestone 3,5-9,0 TPP vanadium sludge 2-25

In addition, 40-60% of the vanadium-containing sludge of TPPs has a particle size of less than 0.1 mm.

The disadvantage of the prototype is the lack of strength of the agglomerate, which leads to a deterioration in the gas permeability of the charge column due to the early destruction of pieces in the upper horizons of the blast furnace.

An object of the invention is to reduce the content of high-cost iron ore concentrates in the sinter mixture, to reduce the consumption of solid fuel, and also to increase the strength characteristics of the sinter.

The technical result is achieved due to the fact that the metal product is additionally introduced into the mixture of the sinter, in the following ratio of the ingredients of the mixture, wt.%:

iron material 15-40 limestone 3-8 solid fuel 4-7 metal product processing slag dumps 4-12 iron ore concentrate rest,

moreover, the vanadium-containing metal product obtained by processing dump steelmaking and blast furnace slag is crushed to a particle size of 10-0 mm, and metallurgical waste is used as iron-containing material: dust, blast furnace and steelmaking sludge, sinter and blast furnace returns.

The invention consists in the following.

Many metallurgical enterprises formed huge man-made landfills from metallurgical waste.

Waste recycling at the factory site does not always allow to utilize all iron-containing components due to the impossibility of direct involvement in the smelting due to the small particle size and low iron content in the feed.

These circumstances require the involvement of these wastes as additives in the sintering process. After a set of operations for the processing of slag receive a metal product having the following chemical. composition,%: Fe - up to 54.5; FeO - 31.2; CaO - up to 12.5; SiO ₂ - 13.0; S 0.19; C is 1.3; MgO - 5.0; V ₂ O ₅ - 2.5.

The increased proportion of slag-forming components of the mixture for the formation of sinter requires a high degree of preparation of the components of the mixture and high energy consumption.

In addition, the increased proportion of slag-forming materials with high basicity leads to blocking of iron ore grains from contact with gas and low reducibility in a blast furnace.

The vanadium-containing metal product used for the sintering charge contains compounds of the ferrite type (MgO FeO SiO ₂ ), (MgO FeO V ₂ O ₅ ).

Under the agglomeration process, when the heating and high-temperature processing of materials lasts for a very short time, the presence of ready-made compounds that do not require time for solid-phase processes contributes to their rapid melting and the formation of slag bundles uniformly distributed over the structure of the agglomerate.

Such agglomerates are durable both in the initial state and during reduction.

The improvement of the physicomechanical properties of the agglomerates is facilitated by the uniform distribution of ferrite and other ligaments preformed at the stage of firing enrichment. For a uniform distribution of the metal product of the processing of slag dumps, the size of its pieces should be comparable with the other components of the charge, for which it is crushed to size according to the class of 10-0 mm. The chemical composition of the charge materials is shown in table 1.

Improving the process of forming the ligament helps to reduce fuel consumption for the production of sinter, increase its quality as a whole.

The limits of the content of solid fuel in the mixture are determined by the strength and reducibility of the sinter.

With less than 4% solid fuel content in the charge, the strength of the sinter decreases sharply.

With a greater than 7% solid fuel content in the charge, the reducibility of the agglomerate sharply decreases.

The limits of the content of limestone in the mixture due to the basicity of the sinter, equal to 1.1-1.3.

With less than 3% limestone content, the basicity of the agglomerate will be less than 1.1%, and with a greater than 8% limestone content, the basicity of the CaO / SiO ₂ agglomerate exceeds 1.3.

The indicated limits of the values of the charge components correspond to the need to concentrate the binder compositions in the crystallization regions of ferrite solid solutions corresponding to equilibrium systems of the CaO - FeO - MgO - V ₂ O ₅ - SiO _{2 type} .

The optimum content of slag dump processing in the metal product mixture was experimentally established. The best results on the strength of the agglomerate and its reducibility were obtained with a metal product content of 4-12%.

EXAMPLE

Iron ore concentrate, metal-containing material, limestone, solid fuel (coke breeze) and metal product obtained from dump metallurgical slags were mixed, moistened, pelletized and sintered on an agglomeration machine. The height of the charge layer was 300 mm. The amount of limestone and solid fuel in the charge was 3-8.0 and 4.0-7.0%, respectively. To improve the strength characteristics of the sinter, a metal-containing product of processing slag dumps in a quantity of 4-12% with a grain size of up to 10 mm was added to the mixture. The moisture content of the metal product is 5-7%. The charge was ignited by the combustion products of a propane-butane mixture in air with a temperature of 1100-1200 ° С. After cooling, the sinter was subjected to drum tests to determine mechanical strength. After processing in a drum, the material was dispersed on sieves to determine the number of fractions +5.0 and -0.5 mm. The strength of the agglomerate was evaluated by the yield of fractions of more than 5 mm, which characterizes the indicator of abrasion resistance.

The test results are shown in table 2.

Analysis of the results of agglomerate tests shows that the use of a metal product increases the yield from 63.5 to 66.7%, the strength in the drum from 64.2 to 68.1%, the sulfur content does not exceed 0.072%, the consumption of solid fuel decreases from 9, 5 to 4-7%. In addition, experimental testing of the sinter with the addition of vanadium-containing metal product was carried out on blast furnace No. 3 of the Nizhny Tagil Metallurgical Combine. Agglomerate contributed to the improvement of the process of varnish formation in the furnace and lowering the viscosity of the final blast furnace slag, due to which an improvement in the separation of smelting products at the outlet from the furnace was achieved and losses of cast iron with slag were significantly reduced.

The decrease in the viscosity of blast furnace slag occurred due to the lesser formation of titanium carbonitrides in the furnace and granulated, due to the favorable chemical composition of the metal product from dump slag, its low melting point (12050-1300 ° C), and good fluid mobility in the molten state.

Slag viscosity decreased from 0.29 to 0.22-0.24 Pa · s, which ensured a decrease in metal concentration in slag at the outlet from the furnace by 11-23%.

When comparing the claimed technical solution and the method taken as a prototype, it is seen that due to the inclusion of the above components in the sinter charge according to the developed technology, it was possible to achieve:

1) reduce the consumption of scarce components of MMS in the mixture, and therefore, increase the production of sinter;

2) to reduce the consumption of solid fuel in the charge, since in these components there is a certain content of combustible carbon;

3) to reduce the presence of small classes in the sinter charge (CL - 1 mm) by reducing the consumption of MMS concentrate, to increase gas permeability, and hence the strength characteristics of the sinter.

Thus, the proposed technical solution meets the criterion of "novelty." The analysis of patents and scientific and technical information did not reveal the use of new significant features used in the proposed invention, according to their functional purpose. Therefore, the present invention meets the criterion of "inventive step".

Information sources

1. The effect of lime and bentonite on the process of producing iron ore pellets, "Metallurgy and coke chemistry." Res. interagency. scientific and technical. collection, 1974, issue 38, pp. 23-26.

2. A.S. 713919, C 22 V 1/24, publ. in the bull. No. 5, 1980

3. A.S. 630301, C 22 V 1/14, publ. in bull. No. 40, 1978

4. A.S. 1529738, C 22 V 1/16, publ. in the bull. No. 27, 1995 (p. 310).

Table number 1
The chemical composition of the charge materials Ingredient Content, wt.% Fe Cao SiO ₂ S FROM V ₂ O ₅ Ore concentrate 63,20 1.78 5.54 0.282 - - Blast furnace dust 38,0 8.02 8.00 0.29 13.5 0.53 Sludge 53.8 5.82 3.92 0.2 4.3 0.70 Scale 65.0 1.49 2.00 0,03 0.41 0.15 Return sinter 63,20 1.78 5.57 0.280 - 0.40 Metal product (steelmaking and blast furnace) 55,4 12.82 13.7 0.19 2,3 2,50 Limestone 0.00 53.00 1,50 0.05 - -

Table number 2 EXAMPLE The composition of the mixture,% Agglomerate Strength Indicators Sulfur content,% Ore concentrate Limestone Solid fuel Metal-containing material V-containing metal product (steelmaking, blast furnace) Impact resistance, fraction output +5 mm,% Abrasion resistance, fraction yield -0.5 mm,% Famous (prototype) 52,5 8.0 9.5 30,0 - 64,2 9,4 0,078 one. 46.3 8.5 5.8 35.5 3.9 64.3 7.5 0,076 2. 48.0 7.5 6.3 33.7 4,5 65,2 8.7 0,072 3. 48.5 7.0 6.5 31,4 6.6 67.2 8.8 0,069 four. 49.8 6.8 5.5 31,0 6.9 68.1 8.1 0,070 5. 43.0 3.4 4,5 38.3 10.8 66.5 7.9 0,072 6. 32,4 7.8 7.2 40.1 12.5 64.3 9.6 0,076 7. 38.5 8.2 9.0 30.3 14.0 62,4 9.7 0,079 8. 42.0 7.4 9.6 26.5 14.5 62.0 9.9 0,078

Claims (3)

1. The mixture for the production of sinter, including iron ore concentrate, iron-containing material, limestone and solid fuel, characterized in that it further comprises a vanadium-containing metal product for processing slag dumps in the following ratio of ingredients, wt.%: Iron material 15-40 Limestone 3-8 Solid fuel 4-7 Vanadium-containing metal product slag processing 4-12 Iron ore concentrate Rest moreover, a vanadium-containing metal product with a particle size of up to 10 mm is used. 2. The mixture according to claim 1, characterized in that metallurgical dust, blast furnace slurry, sinter and blast furnace returns are used as the iron-containing material. 3. The mixture according to claim 1, characterized in that they use a vanadium-containing metal product obtained by processing dump steelmaking and blast furnace slag.