RU2094480C1 - Method of producing charge stock for smelting steel - Google Patents

Abstract

FIELD: ferrous metallurgy. SUBSTANCE: invention aims at producing charge stock in the form of standard-shape block with uniformly distributed therein solid oxidants and iron-carbon alloy for steelmaking. To that end, in a method including preliminarily charging solid oxidants into boxes of casting machine and subsequently filling boxes with liquid cast iron, solid oxidants, prior to be charged into boxes, are submitted to drying to relative moisture content in their layer no more than 2%, solid oxidants being charged in the form of 5-25-mm fraction with 5-mm fraction content no more than 5% and liquid cast iron being poured in at temperature 1250-1300 C. EFFECT: standardized quality of final product. 1 tbl

Description

 The invention relates to ferrous metallurgy, in particular, to the production of charge billets used in steelmaking.

 A known method of producing a billet of billets used for steelmaking on a casting machine in cast iron, in which a solid oxidizing agent, in particular, iron ore material (pellets, sinter and the like) is pre-filled in the molds mounted on the conveyor, and then molten iron is poured into the molds . The formed charge stock is cooled by a filling machine, and then ingots are removed from the prototype [1] molds.

The disadvantage of the above method is the fact that the solid oxidizing agent is not subjected to preliminary preparation before being fed into the molds. As shown by the practice of producing a billet stock under industrial conditions, loading into the molds of a filling machine an unprepared solid oxidizer causes difficulties during operation:
the presence of a fine fraction of a solid oxidizing agent does not allow stable production of ingots of a billet of a predetermined constant composition due to difficulties in the uniform distribution of molten iron throughout the volume of ingots;
the supply of a solid oxidizer to molds with a moisture content of more than 2% sometimes leads to popping and emissions of molten iron and solid oxidizer from molds.

 A study of the moisture distribution in a solid oxidizer showed that the bulk of the moisture (70-75%) is contained in fine fractions, i.e. in pieces smaller than 5 mm. Separation of small fractions of a solid oxidizing agent from the bulk of it in the wet (initial) state on the screen is not feasible. Wet trifle on the screen does not separate from the bulk of the solid oxidizer and does not lead to the desired results. A trifle accumulating on the dispenser tray holds back (slows down) the flow of larger pieces. As a result of such an uneven loading of the solid oxidizer, the ingot billets contain a different amount of solid oxidizer, i.e., a substandard charge preparation is obtained.

 In addition, loading wet material onto which molten iron is fed leads to pops (microexplosions) and emissions from molds and of filler and cast iron are a serious safety violation.

 Thus, the presence in the solid filler of fines, in an amount of more than 5 wt. leads to a violation of the production technology of the billet stock and safety. Separation of fines from the bulk of the solid oxidizing agent in the wet (initial) state is not feasible, since the surface tension of moisture-containing fines is larger than the force generated by the vibrating screen.

 The technological result of the invention is achieved by the fact that in the method of producing a billet of billets for steelmaking, which includes pre-loading solid oxidizing agents into the molds of the casting machine and their subsequent pouring with molten iron, the solid oxidizing agents are dried to relative humidity in their layer not more than 2% before being loaded into the molds and then fractions of less than 5 mm and more than 25 mm are separated from their flow, while a fraction of less than 5 mm is allowed to contain no more than 5 wt.

The solid oxidizer is pre-dried, i.e. heating to a temperature above 100 ^o C, usually 110-115 ^o C, and incubated at a given temperature for a certain time, that is, until the relative humidity is not more than 2% (obtained experimentally).

Liquid cast iron is poured with a temperature of 1250-1380 ^o C. This temperature is established experimentally, i.e. when passing iron trucks from the release of pig iron from the blast furnace to their supply to the casting section in about 2-4 hours

Concrete example
On a casting machine of cast iron, a dryer was installed in the flow of solid oxidizer, which provides drying of the solid oxidizer of pellets with a size of 5-25 mm to a relative humidity of not more than 2%. A fraction of less than 5 mm by weight of the pellets should not exceed 5%
The dried solid oxidizer was fed into the molds of the casting machine, and then filled with liquid cast iron with a temperature of 1350 ^o C.

 The amount of the obtained billet billets met the factory specifications (see table).

 Analysis of the tests showed that according to the invention, stable pigs are obtained in terms of the solid oxidizer content and, consequently, by weight.

Claims (1)

A method of manufacturing a billet of billets for steelmaking, comprising preloading solid oxidizing agents in the molds of the casting machine and then pouring them with molten iron, characterized in that the solid oxidizing agents are dried to a relative humidity in their layer of not more than 2%, while in the molds solid oxidants are loaded with a fraction of 5 25 mm with a content of fractions of less than 5 mm of not more than 5 wt. and molten iron is poured onto them with a temperature of 1250 1380 ^o C.

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