SU1571089A1 - Method of heating furnace for step-fluidized bed for magnetizing roasting of iron ores - Google Patents

Abstract

This invention relates to the production of iron ore in ferrous metallurgy. The aim of the invention is to reduce fuel consumption and improve the quality of the finished product. The continuous control of the height of the layer of raw pellets is carried out by the magnitude of the gas permeability of the layer across the width of the kiln carts and the monitoring of this gas permeability by the temperature difference of the heat carrier at the exit from the adjacent elements of the layer that are 40-80 times the average size of the piece. For example, in the first section of the drying zone, the temperature of the heat transfer fluid is measured at a distance of 100 mm from the surface of a layer of chromel-copel thermocouples, the distance between which is 60 medium gauge pieces. By their readings, the temperature difference between the elements of the layer is determined and when this difference reaches 10 degrees. correcting the gas permeability of the layer by changing its height in the corresponding area by 2 medium caliber pieces. The adjustment is repeated until the temperature difference approaches zero.

Description

The invention relates to the production of iron ore raw materials in the ferrous metallurgy, namely to the magnetising roasting of iron ores.

The purpose of the invention is to reduce fuel consumption and improve product quality.

The heating of the SHS furnace is carried out by co-burning solid and gaseous fuels directly in the volume of the working chamber. Solid fuel is intended to be fed into the re-reduction chamber of an SHS furnace and heated with the highest possible content of a reducing agent (carbon, volatile) and to replace a part of natural gas as a heat source. Partial recovery of ore particles occurs through the creation in the chamber of a weakly reducing medium and direct contact of solid iron oxides with carbon. Volatile solid fuels work well as a substitute for natural gas and as a source of reducing components in a gaseous environment.

The relatively low volatile content in solid fuels (up to 6.0%) requires an increased content of SLF

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native gas in total-fuel consumption (heat) for the process. With a lower volatile content in solid fuels (less than 6.0%), the volatile fraction in the total balance is small and the adjustment of natural gas consumption, without yielding a tangible effect, only complicates the process automation. When the content in the solid fuel is volatile in the amount of up to 6.0%, the heat consumption of the solid fuel must be 0.50-0.70 of the total fuel consumption per process. With a lower consumption of solid fuel (less than 0.50 of the total consumption), an insufficient amount of solid reducing agent gets into the re-reduction chamber and the quality (degree of reduction) of the burnt ore does not meet the requirements of this raw material. With a large consumption of solid fuel (more than 0.70 of the total consumption), the total amount of combustible gases combusted in a gas suspension is not enough to evenly heat the entire mass of the charge and the quality of the finished product also deteriorates.

The invention is as follows.

The raw mixture (ore and coal) is loaded into the SHS furnace and successively moved from stage to stage under the influence of high-speed gas-air jets in the direction of the re-recovery chamber. The gas-air mixture (natural gas, coal and air) is burned directly in the furnace volume and a coolant is formed with the required temperature potential. The mixture successively passes through the zones of drying, heating, and partial recovery, and is loaded onto the charge batch of the secondary recovery chamber. The heat transfer medium transfers heat to the iron ore charge, when turning over the re-reduction chamber, it gives up particles of material falling out of the gas suspension and is discharged from the furnace head. The degree of ore reduction on the charge batch of the secondary recovery chamber is 10-30%. The completion of the restoration takes place in the descending dense layer (in the re-recovery chamber).

The increase in volatile content in solid fuel is over 6.0% for every

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4% is accompanied by an increase in solid fuel consumption in the overall balance, starting from 0.70 from the total heat, by 0.20-0.04 from the total fuel consumption. The consumption of natural gas at the same time reduced accordingly. by the same amount, i.e. the total heat consumption for the process is left unchanged. With a smaller increment in the consumption of solid fuel (less than 0.02 of the total fuel consumption), the heating efficiency of the charge and the quality of the burnt ore no longer increase, the consumption of scarce natural gas remains unreasonably high. With a larger increment in the consumption of solid fuel (by more than 0.04 of the total consumption), an excess amount of carbon gets into the re-reduction chamber, its irretrievable losses with tails increase during restoration, the burnt ore is overestimated and the degree of iron 5 drawn from the ore falls.

The use of the invention will provide an increase in the uniformity of burning of iron ore, a stable recovery of the entire volume of material required for complete iron extraction with subsequent ore dressing, and a 3-4 times reduction in carbon losses with tails during enrichment.

Claims (1)

Invention Formula A method of heating a staggered layer furnace for magnetizing the burning of iron ores, including co-burning of gaseous fuel supplied through tuyeres and solid fuel supplied to the mixture, characterized in that, in order to reduce fuel consumption and improve product quality, solid fuel consumption in heat at in it, volatile amounts of less than 6% are set to 0.50-0.70 of the total fuel consumption for heat, and with an increase in volatile content from 6% for every 4% increase in consumption of solid fuels a, starting from 0.70 of the total, increases, and the consumption of gaseous fuel, respectively, is reduced by 0.02-0.04 of the total fuel consumption for heat “