RU2333265C2 - Method of metallurgical charge material preparation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns ferrous metallurgy. Particularly, it concerns preparation of flux ingredients burning wastes for feeding in metallurgical charge by means of manufacturing iron-containing slag-forming briquettes which are used as lime substitute while cast steel and steel making process. Small-fractional limestone burning wastes at a shape of aspiration lime are captured from removed from aggregate gase burning, combined with water and blended until full liming, and then it is introduced iron-containing wastes of metallurgy, blended, implemented briquettes forming and its hardening.

EFFECT: it is provided aspiration lime utilisation directly at the place of its forming, reducing of operating costs while receiving cast iron or steel and costs reducing for wastes utilisation.

1 dwg

Description

The invention relates to ferrous metallurgy, in particular to the preparation of waste products for calcining fluxing components for feeding into a metallurgical charge by production of iron-containing slag-forming briquettes used as a substitute for lime in the production of iron and steel.

A known method of dedusting exhaust gas from a rotary kiln designed for calcining limestone (see AS No. 1649227 A1, MKI 5 F27B 7/20, publ. 05.15.91, Bull. 18), which includes collecting a fine fraction of limestone calcining waste from gas exhaust gas flow of a rotary kiln.

The essential features that coincide with the essential features of the proposed technical solution are the capture of a fine fraction of limestone calcining waste from the exhaust gases from the calcining unit.

The disadvantage is the inability to dispose of a significant amount of aspiration limestone calcining dust at the place of its formation. Therefore, lime dust collected by suction plants is accumulated in the hopper, and then transported by truck or other means of transport to the sinter preparation section of the sinter plant, and in enterprises where there is no sinter plant, it is dumped or transferred to construction organizations.

Taking into account the physical properties of dust (fineness, increased activity in the open air, dust emission during overloads, etc.), its transfer and use away from the place of formation causes additional difficulties (use of special vehicles, aspiration of loading and unloading places, limited storage time, etc.).

The disadvantage of this method is the formation of a significant amount of recyclable small-fraction waste, which increases the cost of finished products and pollutes the surrounding atmosphere.

A known method of preparation and supply of material of a metallurgical charge (see Ukrainian patent for invention No. 6439, MKI 5 C21B 1/00, Bull. No. 8-1, 12/29/94), including crushing, drying, separation of the technological fraction, feeding into the unit for roasting with preliminary passing it through a counterflow of exhaust combustion products passing through cyclones - multi-stage loading heaters, collecting the finished product, collecting fine-grained waste of the finished product and collecting dust collected in the hopper.

The essential features of the prototype, which coincide with the essential features of the proposed technical solution, are: trapping a fine fraction of limestone calcining waste in the form of suction lime from the exhaust gases from the calcining unit.

The disadvantage of the prototype is the limited consumption in the sinter charge of the required amount of lime due to emissions of a proportionally increasing amount of toxic pulverulent fractions formed during the extinguishing of lime at the moment of contact with wet concentrate and water, large losses of lime (up to 5%) as a result of the entrainment of its small classes with steam, which is intensively formed during the quenching of lime, incomplete use of the intensifying ability of lime due to insufficient contact of lime with the concentrate. Therefore, the process of extinguishing individual particles of lime does not have time to end and proceeds when pelletizing the charge and laying it on an agglomerate. Since the process of slaking lime is accompanied by an increase in its volume, this leads to the destruction of the already formed granules of the mixture.

The basis of the invention is the task to improve the method of preparation and supply of material of the metallurgical charge by introducing operations that provide for the joint processing of fine-grained waste material (e.g. limestone) and iron-containing waste from metallurgical industries for the production of iron-containing slag-forming briquettes used as a substitute for calcined lime in the production of iron and steel .

The problem is solved in that in the method of preparing the material of the metallurgical charge, including the capture of a fine fraction of limestone firing waste in the form of suction lime from the exhaust gases from the firing unit, according to the invention, the lime is combined with water and mixed until the lime is completely extinguished, and then iron-containing waste is introduced metallurgical industries, mix, produce the formation of briquettes and their curing.

A causal relationship between the essential features of the invention and the achieved technical result is as follows.

The combination of a fine fraction of the product of firing the material (lime dust trapped by suction plants) with water and mixing it until the lime is completely "extinguished" and its further connection with iron-containing waste from metallurgical production makes it possible to obtain a charge for the production of a product with new consumer properties - iron-containing, slag-forming briquettes, used in the metallurgical process as a substitute for calcined lime.

The method is implemented using the line for the preparation of the material of the metallurgical charge shown in the drawing.

The line for preparing the material of the metallurgical charge comprises a device 1 for collecting fine-grained limestone calcining waste in the form of suction lime from the exhaust gases from the calcining unit 2 and a lime collecting tank 3, as well as a briquette forming system 7 consisting of feeding mechanisms 10 and briquetting 11. The line equipped with two reactors 4, made in the form of mixers and equipped with a water dispenser 5, a capacity of 6 for receiving iron-containing waste from metallurgical production and contains hardening posts, and reactors 4 are connected with a capacity 6 for receiving iron-containing waste and a capacity 3 for collecting lime by means of dosing 9 and transporting 12 lime and iron-containing waste, and with a system 7 for forming briquettes by means of 8 supplying a mixture of slaked lime and iron-containing waste obtained in reactors 4.

A vibrating press is installed as a briquetting mechanism.

The line works as follows.

The crushed material (limestone) is sent to the firing unit 2. After firing, the material enters (not shown) into precipitators and is cooled, and a gas stream containing fine-fractioned suction lime is sent to a device 1 for collecting small-fractional waste from firing material and cleaned. The purified gas is discharged into the atmosphere by means of a fan and a pipe, and the aspiration lime trapped in the device 1 is sent to a container 3 for collecting lime, and then it is fed by means of dosing 9 and transportation 12 to reactors 4, which use gravity or forced-action mixers water is dispensed there by dispenser 5 and mixed until the lime is completely "quenched". In order to ensure the continuity of the cycle and to ensure the mode of "blanking" in the line, it is planned to install two reactors 4, which use gravity or forced-action mixers that work in cycles - during operation of the first mixer, the second is loaded and vice versa.

Reception of iron-containing waste from metallurgical production is carried out in a container 6 for receiving iron-containing waste from metallurgical production, from which, by means of dosing 9 and transportation 12, it is transferred to reactors 4 in a predetermined ratio, taking into account the preparation of a mixture with a moisture content of 8-10%.

The total preparation time of the batch is 5-6 minutes.

The prepared semi-dry mixture by the feeding mechanism 8, for example, by a conveyor belt, is fed into the briquette forming system 7, which consists of the feeding mechanisms 10 and briquetting 11 of the material.

After forming, raw briquettes on technological pallets are placed in containers and transferred to hardening stations for their curing. After 12-14 hours, the briquettes are unloaded into the hopper and from the hopper as they accumulate in the dump truck and transported to the consumer (blast furnace or steel shop).

The use of the invention provides the disposal of aspiration lime directly at the place of its formation, which eliminates the negative impact of dust on the environment, reduces the cost of transporting dust, eliminates the use of special delivery vehicles, and also allows you to get a product with new consumer properties - iron-containing slag-forming briquettes used in metallurgical process as a substitute for burnt lime. This allows to reduce production costs in the production of cast iron or steel by replacing some of the components with waste-based briquettes, and provides a reduction in waste disposal costs.

Claims (1)

A method of preparing a material of a metallurgical charge, including trapping a fine fraction of limestone calcining waste in the form of suction lime from exhaust gases from a calcining unit, characterized in that the lime is combined with water and mixed until the lime is completely extinguished, and then iron-containing metallurgical waste is introduced, mixed, produced formation of briquettes and their curing.