RU2243465C1 - Refractory coke bed - Google Patents

Abstract

FIELD: metallurgy, in particular, composition of refractory coke bed for cupolas.

SUBSTANCE: refractory coke bed is composed of layers arranged in alternation, with one layer being mixture of crushed refractory and carbonaceous articles and other layer being composed only of crushed carbonaceous articles. Height of lower layer composed of mixture of crushed refractory and carbonaceous articles is equal to distance from hearth to lower cut of burner tunnels. Height of middle layer composed only of crushed carbonaceous articles is 400-700 mm. Upper layer is composed of mixture of refractory and carbonaceous articles. Total height of refractory coke bed is 1.5-1.7 equivalent diameters of cupola hearth.

EFFECT: increased content of carbon in cast iron.

2 dwg, 1 tbl

Description

The invention relates to the field of ferrous metallurgy, and more specifically to the composition of idle refractory heads for gas cupolas.

Known idle refractory spike of a shaft-reflective furnace, consisting of refractory material covered with coke from above (see B.A. Noskov, V.F. Pelikh. Cast iron melting in cupola furnaces and furnaces using natural gas .: M., 1969, p. 91). The porous bed is located on a water-cooled grate and is divided into two parts, as it were: a single spike from refractory material and a single coke spike that do not affect each other. However, a single spike, consisting of one refractory, has insufficient resistance, since the pieces of the refractory interacting with the slag, form refractory eutectics. Pieces of ears were soldered, and the melting process was upset.

Closest to the proposed invention, a single refractory spike containing high-alumina and chamotte refractories and carbon-containing material that are layered, the carbon-containing material in the lower part of the hearth from its bottom to the level of the gas burner tunnels, and the refractories on the said layer of carbon-containing material to the upper cut of the hearth ( Patent RU No. 2194932 C1, F 27, 1/08, 12/20/2002).

However, this idle refractory spike does not exclude the possibility of sintering of its refractory component during long-term melting, since the temperature of the use of fireclay refractory according to GOST 390-96 is 1350 ° C, and the working bodies of the blank spike are heated to a temperature of 1650-1700 ° C. In addition, the maximum degree of carburization of cast iron is not achieved, since the carbon-containing component of the blank spike is located in the lower part of the hearth, where the temperature of the blank spike is lower than in the overheating zone located above the burner tunnels, where the maximum temperature is observed, which contributes to an increase in the degree of dissolution of carbon in the metal .

The invention is directed to increasing the carbon content in melted iron.

This is achieved by the fact that a single refractory spike containing alternately alternating layers is loaded onto the bottom of the gas cupola mine shaft, made with mountain and burner tunnels, the lower and upper layers of which are composed of a mixture of refractory and carbon products, and the middle layer is of pure carbon products, while the height of the lower layer is equal to the distance from the bottom of the shaft to the lower cut of the burner tunnels, the height of the middle layer is 400-700 mm, and the total height of the idle refractory spike is 1.5-1.7 equivalent diameters g ornament of gas cupola.

Loading into the mine cupola of this composition a blank refractory spike creates the necessary conditions for the carburization process to occur.

In figure 1. the location of the idle refractory spike over the section of the cupola shaft is shown; in FIG. 2 - temperature change of the spike and metal along the height of the shaft (1 - temperature of the idle refractory spike; 2 - temperature of the metal).

The use of a blank refractory spike as a material for the lower and upper layers of the battle of purely carbon products is not economically feasible due to their high cost, since in these areas the carburization process is not intensive due to the low temperature of the spike, and a mixture of refractory and carbon products allows melting in stable mode.

A decrease in the height of the middle layer of less than 400 mm leads to a decrease in the carbon content in cast iron, because the contact time of the metal with the carbon products of the head decreases, and an increase of more than 700 mm does not give a positive effect due to the low temperature of the metal, which slows down the process of dissolution of carbon.

The decrease in the total height of the KHOK below 1.5 D _equiv. leads to a decrease in the temperature of the metal at the exit of the cupola and a decrease in the carbon content in cast iron, because the metal enters the low temperature carburization zone. Increase in total head height in excess of 1.7 D $\genfrac{}{}{0ex}{}{}{\text{eq}}$ economically impractical because The performance of the smelter is reduced.

Idle refractory spike works as follows.

After heating the cupola, the calculated amount of a uniformly mixed refractory spike, consisting of a mixture of carbon and refractory products so that its height was equal to the distance from the bottom to the bottom cut of the burner tunnels, was loaded onto the bottom of the shaft. Then, a layer of blank refractory ears consisting of a battle of purely carbon products with a thickness of 250-850 mm was loaded onto this layer. A uniformly mixed blank refractory spike, consisting of a mixture of carbon and refractory products, was loaded onto this layer so that the total height of the CWC was 1.4-1.8 D _{equiv of the} cupola furnace.

After 20-30 minutes a metal charge was loaded onto a single refractory spike. Combustion products, passing through a single refractory spike, warmed it up, and the maximum heating temperature of the CFC was observed in a layer 400–700 mm high above the burner tunnels, consisting of a battle of purely carbon products. The molten metal, flowing down into pieces of the CFC, fell into this layer where it was intensively carburized.

Further, the carbonized metal flowed down the idle refractory cone, consisting of a mixture of carbon and refractory products, where it overheated. The results of the studies are presented in the table.

As can be seen from the table, the use of such a blank refractory spike makes it possible to increase the carbon content in remelted cast iron.

Claims (1)

A single refractory spike containing a battle of carbon and refractory products loaded onto the bottom of a gas cupola shaft made with mining and burner tunnels, characterized in that the spike contains alternately alternating layers, the lower and upper of which consist of a mixture of the battle of refractory and carbon products, and the middle layer is from the battle of purely carbon products, while the height of the lower layer is equal to the distance from the bottom of the shaft to the lower cut of the burner tunnels, the height of the middle layer is 400-700 mm, and the total height is idle the refractory spike is equal to 1.5-1.7 equivalent diameters of the hearth of the gas cupola.

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