The method of preparation of pig iron

 

The invention relates to ferrous metallurgy and can be used to produce castings of pig iron. The method includes entering into a ladle with liquid cast iron solid charge similar chemical composition with subsequent forced mixing. Before pouring of cast iron, the temperature of which 1390-1460oWith that in bucket introducing pre-heated to 300-600oWith a solid charge in the amount of 4-12% by weight of liquid iron and stand 1,0-2,5 hours the Invention allows to increase the yield of liquid iron and to improve its quality. table 1.

The invention relates to ferrous metallurgy, namely to foundry, and can be used to produce castings of pig iron.

There is a method of remelting chips and other disperse waste metals and alloys in the environment of solid metal, in which the input method mechanical dipping or mixing the waste is pre-heated with heat of the liquid metal in the furnace in the range from the liquidus temperature of the liquid metal to the temperature of the liquidus 200o(Patent of the Russian Federation 2135613, 22, 7/00, 1999).

However, the known method allows to melt scrap, mainly chips or di what about the cast iron way bad is applicable because of the presence on the surface of pig iron a large number of sang, and slag.

Closest to the proposed technical solution is the way secondary remelting scrap, comprising the following operations: scrap generated in the process of making castings of cast iron, is mixed with liquid cast iron having a temperature of1470oWith a ratio of30 kg/ton liquid iron and forcibly stirred obtained tub (application 63-20882, Japan, 2002).

The disadvantage of this method is that heat liquid iron is only enough to melt no more than 30 kg/t of solid charge and had little impact on improving the quality of cast iron. In addition, when using pig iron it is difficult to provide a temperature above 1470oWith because of the large heat loss during transportation.

The objective of the invention is to increase the yield of liquid iron and its quality improved.

This object is achieved in that in the method of preparation of pig iron, including input into the ladle with molten cast iron solid charge similar chemical composition with subsequent forced mixing, before pouring of cast iron, the temperature of which 1390-1460oWith that in bucket introducing preheated to a temperature of 300-6th result, achieved by using the proposed method consists in the following: - an increase in the yield of liquid iron on 4-12%; - improving the quality of cast iron due to the modifying effect.

We offer pre-heating solid charge to a temperature of 300-600oWith optimal, because of the heat less than 300oDoes not allow to create conditions for its complete dissolution, which leads to heterogeneity of structure of iron and mechanical properties of the casting body, falling damping properties of cast iron and, as consequence, to decrease in the quality of cast iron.

Heating of the solid charge more than 600oWith impractical due to excessive heat loss to heat.

The amount of solid charge less than 4% leads to a decrease in the number of processed iron charge, insufficient inoculum effect and, as consequence, to decrease in the quality of cast iron.

The amount of solid charge more than 12% excessively Zoological cast iron, not enough dissolved solids, which leads to heterogeneity of structure of iron and mechanical properties of the casting body, falling damping properties of cast iron and, as consequence, to decrease its quality.

The dwell time of the melt after entering the solid metal h leads to excessive cooling down of the iron.

The temperature of the molten cast iron is less 1390oInsufficient to dissolve the solid charge and can lead to excessive cooling down, and lower quality cast iron.

The temperature of the molten cast iron is more 1460oSince it is impossible to provide for production of castings from the blast furnace pig iron because of the large heat losses during its transportation in foundries.

Example. Cast iron for the proposed and known methods of preparing iron was smelted in blast furnaces JSC "ZSMK" in volume 3000 m2and was put in the shop of the molds 100-ton domain hot-metal ladles. On the stand for drying ladles gas burner heated to a temperature of 400oWith the part of retired moulds weighing 8 tons At the end of heating placed it on the bottom of the intermediate 100-ton ladle. From the blast of the bucket cast iron with temperature 1410oWith poured into the tundish and has stood the iron 1.5 h to dissolve the solid charge (moulds). Then the iron was poured into 60-ton bottling bucket and purged with nitrogen. This cast iron poured through moulds which have undergone the operation in Converter plants JSC "ZSMK". The following table shows the parameters for the processing of iron in the proposed method, the results from the second method of preparation of pig iron is industrially applicable in foundries steel plants to produce castings of pig iron.

Claims

The method of preparation of pig iron, including input into the ladle with molten cast iron solid charge similar chemical composition with subsequent forced mixing, characterized in that before pouring of cast iron, the temperature of which 1390-1460oWith that in bucket introducing pre-heated to 300-600oWith a solid charge in the amount of 4-12% by weight of liquid iron and stand 1,0-2,5 hours

 

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Blow - through plug // 2243847

FIELD: metallurgy, namely agitation of melt in casting ladle, modifying melt and blowing gas under high pressure through melt.

SUBSTANCE: plug includes ceramic housing having at least one through gap between end surfaces of body and envelope embracing housing; unit for supplying gas to outer end surface of housing for passing gas under preset pressure through gap to inner end surface of housing and into melt. Ceramic housing includes outer part in the form of sleeve and inner part in the form of truncated cone; gap is formed between said parts. Inner part of housing may be moved relative to outer part and it may be forced by means of elastic bottom member towards melt for closing gap. Tube for supplying gas is communicated with cavity arranged under outer end surface for opening gap.

EFFECT: improved design, namely reliable concave plug with controlled gap whose width depends upon pressure of supplied gas, prevention of metal leakage out of ladle.

10 cl, 7 dwg

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