RU2412258C1 - Briquette for metallurgical production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: briquette consists of iron containing waste from production of direct reduction of iron in form of iron containing slime - 40-60 %, metallised breakage 25-55 %, carbon containing material 3-10 %, binding including water solution of liquid glass 1-2 % and water dispersion on base of polyvinyl-acetate 2-3 %.

EFFECT: utilisation of production waste from direct reduction of iron; production of briquettes for metallurgical production with level of harmful impurities below allowed levels and possessing sufficient durability for transporting, melting and at moistening.

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Description

The invention relates to metallurgy, namely to the production of cast iron and steel with the preparation of the charge material in the form of briquettes.

A known briquette for metallurgical production, including iron-containing fine waste, carbon-containing material and a binder, and steel-making waste is used as iron-containing waste, and oily scale and lime are used as iron waste (RF patent No. 2317341, IPC С22В 1/245, publ. 02.20.2008 ) The mixture is pressed and the briquettes are kept in a humid environment.

The known solution is quite expensive, and it is impossible to apply it to obtain briquettes from waste products for the direct reduction of iron.

The closest technical solution adopted for the prototype is a briquette for metallurgical production, including iron-containing waste, a carbon-containing material, a binder with liquid glass, and a mixture of loam, clay or feldspar and sodium carbonate is used as a binder. The composition of the briquette is known from the method of preparing the charge material (RF patent No. 2154680, IPC С22В 1/243, publ. 08/20/2000).

The disadvantage of the prototype is that the resulting briquettes have insufficient strength (especially impact), as well as low moisture resistance.

The objective of the invention is the use of waste products for the direct reduction of iron as raw materials for blast furnace and steelmaking by manufacturing briquettes with sufficient strength and recoverability of iron.

This object is achieved in that in a briquette for metallurgical production, including iron-containing waste, carbon-containing material, a binder with liquid glass, iron-containing waste is used as waste from the production of direct reduction of iron in the form of iron-containing sludge and metallized fines, the binder contains an aqueous dispersion based on polyvinyl acetate in the following ratio of components, wt.%:

iron sludge 40-60 metallized trifle 25-55 carbon material 3-10 aqueous solution of water glass 1-2 polyvinyl acetate-based aqueous dispersion 2-3

The solution to this problem is possible based on the conditions of interaction of the polymer and silicate components of the binder with other components of the briquette. With increasing pressure, the polymer component of the binder undergoes a transition to the ultra-high elastic state of reversible deformation. Under such conditions, the pressure on a superfluid polymer, according to the Griffitz-Irwin theory of adhesive strength, significantly increases its adhesive properties due to the formation of a polymer matrix with simultaneous shrinkage of the polymer on the solid surface of the briquette due to the difference in the volume expansion coefficients of the contacting bodies, which causes an internal stress, while the rheological effect of repulsion does not have a significant effect on the composition, because the relatively low viscosity of the superfluid polymer contributes to the most complete wetting of the rough surface. This effect finally manifests itself after removal of the solvent and drying of the composition. In addition, according to the mechanical theory of adhesion, with an increase in the surface roughness, the adhesive strength increases, which is due to both an increase in the surface area and the formation of mechanical links between the polymer and the substrate due to the flowing of the polymer in the roughness, which is the greater, the lower the viscosity of the polymer.

Liquid glass in a binder increases the rigidity and strength of briquettes. The pressed composition with liquid glass retains its strength in further heat treatment at the stage of steel or cast iron smelting at temperatures above 800 ° C.

The composition of the briquettes was selected as a result of the experiments.

Briquettes were made as follows.

The initial components were:

iron-containing sludge generated in the production of direct reduction of iron in hot iron briquetting plants, fractions less than 1 mm;

metallized fines formed in the production of direct reduction of iron in hot briquetting plants of iron, fractions less than 5 mm;

carbon-containing material as a reducing agent and carburizing agent in the form of coke breeze, fractions less than 1 mm;

50% aqueous solution of water glass, part of a binder;

50% aqueous dispersion based on polyvinyl acetate, in particular an aqueous dispersion of a low molecular weight medium viscosity varnish vinyl ester lacquer

acetic acid with vinyl propionate, plasticized with butylbenzylphthalate, part of the binder.

A dry mixture was prepared by mixing iron-containing sludge and metallized fines. The binder parts were mixed. The dry mixture and binder were mixed for 10 seconds. The composition and coke breeze were mixed for 1 min. The molds were filled and pressed at a pressure of 20 MPa. Briquettes of cylindrical shape with a diameter of 50 mm and a height of 20 mm.

The composition of the briquettes, wt.%:

Composition No. 1: ЖШ - 30, УМ - 2, ВРЖС - 0.5, ВДП - 1.5, ММ - 66.

Composition No. 2: ЖШ - 39, УМ - 3, ВРЖС - 1, ВДП - 2 ММ - 55.

Composition No. 3: ЖШ - 50, УМ - 7, ВРЖС - 1,5, ВДП - 2,5 ММ - 39.

Composition No. 4: ЖШ - 60, УМ - 10, ВРЖС - 2 ВДП - 3 ММ - 25.

Composition No. 5: ЖШ - 70, УМ - 12, ВРЖС - 2.5, ВДП - 3.5, ММ - 12,

where ZhSh - iron-containing sludge; UM - carbon-containing material at 100% carbon; ВРЖС - an aqueous solution of water glass; VDP - aqueous dispersion of polyvinyl acetate; MM is a metallized trifle.

The chemical composition of the briquettes,%: Fe total. - 78-80, Fe met. - 56-61, FeO - 23-29, SiO ₂ -3.6-3.9, CaO - 1.5-1.6, S - 0.05-0.06, P is 0.01.

The test results of the briquettes are shown in the table.

Options Briquette Compositions one 2 3 four 5 The strength of the briquettes in compression, kgf / cm ² Press 10 sec after pressing 4.4 6.9 7.7 8.0 5.1 after 2 hours exposure 6.2 8.0 8.6 10,2 7.3 after 24 hours exposure 6.6 8.3 9.1 10.6 7.9 Pressing 3 min after pressing 7.3 10.9 11.6 13,2 6.2 after 2 hours exposure 9.3 11.9 13.8 13,4 8.2 after 24 hours exposure 9.6 12,4 13.9 14.6 8.4 Impact strength (number of drops from a height of 1.5 m onto a steel plate) After pressing 10 sec one 3 3 four 2 After pressing 3 min 2 four 5 5 2

The use of briquettes makes it possible to utilize waste from the direct reduction of iron as a raw material for blast furnace and steelmaking.

The resulting briquettes do not contain, in excess of the permissible level, impurities harmful to the metallurgical process, have sufficient strength for transportation and smelting, and retain strength when wetted.

Claims (1)

A briquette for metallurgical production containing iron-containing waste, a carbon-containing material, a binder, including an aqueous solution of liquid glass, characterized in that the iron-containing waste uses waste from the direct reduction of iron in the form of iron-containing sludge and metallized fines, and the binder further includes an aqueous dispersion of based on polyvinyl acetate, in the following ratio, wt.%:
iron sludge 40-60 metallized trifle 25-55 carbon material 3-10 aqueous solution of water glass 1-2 polyvinyl acetate-based aqueous dispersion 2-3