RU2330898C2 - Preform for steel production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy industry. Particularly it concerns preparing of charge material for steelmaking. Preform contains oil calx 25-35%; dust from scrubbing of Martin furnace and utility "Furnace - scoop " 4.7-10.0%; fine magnetic output 40-60%; activated sludge 10-15%; slaked lime from 10 till 0%; cement from 10 till 0%.

EFFECT: usage of performs which contain activated sludge - sediment of biological treatment facilities from local and manufacturing effluents, will allow to receive steel with minimal cost for carbonaceous part of charge and simultaneously will be implemented utilisation of contaminating environment material and with reduced content of sulphur, phosphorus and carbon.

Description

The invention relates to metallurgical production, namely to the preparation of charge materials for steelmaking.

Known briquette for smelting ferrous metals [1]. The briquette contains crushed steel scrap, coke breeze, binders and slag-forming additives.

The disadvantage of the briquette is the use of coke breeze as a carbon-containing component, leading to saturation of the metal with sulfur, which requires an increased amount of slag-forming materials. In addition, the low carbon content and high cost of coke breeze reduces the use of briquettes in the production of ferrous metals.

Closest to the claimed composition of the charge briquette for the smelting of ferrous metals is a briquette in which coke breeze as a carbon-containing material is replaced by an electrode battle of graphite electrodes [2].

The disadvantages of these briquettes is that to use the battle of graphite electrodes in the composition of the briquette requires a special installation for crushing and grinding of graphite electrodes, and the high cost of battle of graphite electrodes significantly increases the cost of the briquette.

An object of the invention is the creation of a briquette of sufficient mechanical strength for the production of steel with the efficient use of environmental waste from urban and industrial enterprises.

The technical result is achieved by adding to the composition of the briquette as a carbon-containing material of activated sludge - sediment of biological treatment facilities of urban and industrial wastewater in the amount of 10-15%. These sediments contain both combustible mass up to 70-75%, and ash particles up to 20-30%. The carbon content in the sludge is 56-61% [3]. The presence in the briquette of activated sludge as a carbon-containing component in an amount of 10-15% is due primarily to the composition of the sludge. It is within these limits that the optimal conditions for the occurrence of chemical reactions in the briquette upon heating in the furnace and in the melt of charge materials are ensured. Less than 10% of activated sludge in the briquette as a carbon-containing material will lead to increased consumption of cast iron, and more than 15% due to the relatively high content of silt particles in the silt will lead to an increase in heat consumption for heating the metal charge.

As iron-containing material, oily scale is used - waste from rolling production in an amount of 25-35%. Dross is a mixture of metal oxides with waste oil containing 85% carbon. A scale content of less than 25% is not enough for the iron recovery process in the briquette, and more than 35% leads to a loss in the mechanical strength of the briquette.

A small magnetic product - products of a crushing and screening complex for processing waste open-hearth slag, is used in a briquette in an amount of 40-60% with a grain size of not more than 5 mm with a metallic iron content of at least 30%. The content of a small magnetic product of less than 40% in the briquette impairs the quality of the metal-containing material, and more than 60% reduces the possibility of utilizing other iron-containing production wastes (scale, dust).

Sufficient mechanical strength of the briquette is ensured by the introduction of binding dust, cement and lime.

Dusts from gas cleaning of open-hearth furnaces and steel after-treatment plants are supplied for briquettes with a grain size of not more than 2.5 mm and a moisture content of not more than 1.5%. The total percentage of dust should be in the range from 4.7 to 10.0%, because this is due to the need to dispose of industrial waste. The use of dusts below 4.7% does not provide a binding effect and an increase in the strength of the briquette, and more than 10.0% cannot be used because of the need to ensure the required porosity and gas permeability in the briquette, which leads to a decrease in the process of iron reduction.

If necessary, partially dust can be supplemented with cement or lime. The use of lime or cement in the composition of the briquette depends on the technological features of the production of various grades of steel.

An increase in lime content of more than 10% leads to a decrease in the quality of smelted steel due to the release of hydrogen from lime-fluff.

The use of cement of more than 10% no longer leads to a noticeable binding effect and an increase in the strength of briquettes, and also significantly increases the cost of manufacturing briquettes due to the high price of cement.

Thus, the mixture for the production of briquettes, in addition to sludge, contains oily scale, dust from gas cleaning of open-hearth furnaces and an out-of-furnace steel processing unit, a small magnetic product (metal metal in slag) and, depending on the grade of smelted steel, may contain lime and cement in the following ratio of components, wt. %:

Scale oily 25-35% Dust gas open-hearth furnaces and installation "Furnace - ladle" 4.7-10.0% Small magnetic product 40-60% Active sludge 10-15% Cannon Lime from 10 to 0% Cement from 10 to 0%

The manufacture of briquettes is as follows.

All components of the briquettes are mixed until a molding material is homogeneous in color and composition.

The mass of material per batch is determined by calculation.

The duration of mixing materials from 3 to 12 minutes (depending on the moisture content of the components of the briquette).

To provide the necessary "raw" strength of the briquette, water is added to the mechanical mixture. An excess of moisture of more than 15% (in excess of 100% of the mass of the mixture) leads to gas evolution and high porosity of the briquette. A decrease in the moisture content of the mixture before briquetting can lead to a decrease in the strength of the briquette.

The process of mixing and forming the mixture should be continuous. After mixing, the mass enters the press. Pressing pressure of at least 10 MPa.

Finished pressed briquettes are stacked on pallets and in this position are kept in the air until a set of technological strength.

The use of briquettes, which include activated sludge, will make it possible to obtain steel with minimal costs for the carbon-containing part of the charge with the simultaneous utilization of nature-contaminating material and with a reduced content of sulfur, phosphorus and carbon.

Information sources

1. A.S. USSR No. 855039, 1981.

2. Patent RU No. 2083681.

3. P.S. Turovsky "Sewage treatment". - M .: Stroyizdat, 1988, 256 p.

Claims (1)

Briquette for the production of steel, including iron and carbon materials and binders, characterized in that the activated sludge is used as the carbon containing material - sludge from biological treatment facilities of urban and industrial wastewater in the following ratio of components, wt.%: oily scale 25-35 dust of gas open-hearth furnace and ladle furnace 4.7-10.0 small magnetic product 40-60 activated sludge 10-15 canned lime from 10 to 0 cement from 10 to 0