RU2366740C2 - Multi-component reducing mixture for melting of ferrosilicium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to iron and steel industry, particularly to production of ferroalloys by carbothermic reduction. Reducing mixture contains coke nut, brown coal of B grade with the lower heat of working fuel combustion equal to 3200 kcal/kg and working moisture contents up to 40 %; as loosening substance the reducing mixture contains cannel coal and wood chips at following ratio, % (for carbon): cannel coal 25-50, brown coal of B grade 14-20, wood chips 2-5, coke nut - the rest.

EFFECT: possibility to develop multi-component reducing mixture of lowered caloric value.

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Description

The invention relates to the field of ferrous metallurgy, and in particular to the production of ferroalloys by carbon thermal reduction.

As a carbon reducing agent, mainly coke nut is used.

Known reducing agent for the carbon thermal process, consisting of coke nut and hard coal, for example, lean, slightly sintering or long flame [1, 2, 3].

However, not all types of coal are suitable for effective use as a reducing agent due to the difference in their material compositions and physicochemical properties.

The disadvantage of using coal in the reducing mixture is the high level of lower heat of combustion of the working fuel, which for all types of coal (A, T, SS and D) is in the range of 5200-6500 kcal / kg. The high calorific value of coal reduces the resistance of the furnace equipment, adversely affects the coking mode of self-sintering electrodes. This leads to an increase in hot downtime and loss of productivity.

The objective of the invention is to develop a reducing mixture with reduced calorie content.

The problem is solved in that in the proposed recovery mixture, consisting of coke nut and hard coal, grade B brown coal with a lower heat of combustion of working fuel of 3200 kcal / kg and a working moisture content of up to 40% is introduced as a low-calorific component, and as a charge cultivator introduced long-flame coal and wood chips in the following mass ratio of components,% (carbon):

- long flame coal - 25-50;

- brown coal - 14-20;

- wood chips - 2-5;

- coke nut - the rest.

The essence of the invention lies in the use of brown coal grade B with reduced heat of combustion, which reduces the calorific value of blast furnace gas. In its original form, brand B coals have up to 40% moisture in their composition, which is easily removed by heating, cooling the top surface and lowering the temperature of the resulting top gases. The resistance of the furnace equipment increases, the overhaul period increases. The coking zone of the electrodes moves to the optimal level - in the middle of the contact cheeks.

The reducing mixture consisting of coke nut (25-70%), grade D coal (25-50%), grade B coal (14-20%) and wood chips (2-5%) was tested for carbon in the production of high-silicon brand ferrosilicon FS75 on industrial furnaces with a capacity of 20 MVA.

The use of the proposed reducing mixture allows to increase the productivity of furnaces by 3.2-5.5%, reduce specific energy consumption by 3.5-5.7%, increase the extraction of silicon in the alloy by 1.2-1.6%

The proposed recovery mixture is tested under industrial conditions and proposed for implementation in ferroalloy plants in the smelting of ferrosilicon.

The main results of FS75 grade ferrosilicon heats are presented in the table.

Table INDICATORS OPTIONS BASE SUGGESTED The productivity of the furnace at 1 MW of used power, bases. t / MW

Specific energy consumption, kW · h / t

Extraction of silicon. % 93.7 95.3

Information sources

1. A.S. USSR No. 530909, M. cl. ² C2C 7/00, Bull. No. 37, publ. 10/05/76 g.

2. A.S. USSR No. 755875, M. cl. ³ C22V 5/10, Bull. No. 30, publ. 08/15/80

3. RF patent No. 2236481, IPC ⁷ C22C 33/04, Bull. No. 26, publ. 04/20/04

Claims (1)

A multicomponent reducing mixture for smelting ferrosilicon containing coke nut, grade B brown coal with a lower heat of combustion of working fuel equal to 3200 kcal / kg and a working moisture content of up to 40%, and long-flame coal and wood chips in the following mass ratio of components as a ripper ,% (carbon):
long flame coal 25-50 brown coal grade B 14-20 wood chips 2-5 coke nut rest