SU789669A1 - Exothermic briquette for cupola melting - Google Patents

Description

one

The invention relates to foundry, in particular, to the composition of an exothermic briquette for smelting iron.

A known exothermic briquette U based on silicon carbide, which intensifies the cupola process and is a substitute for ferrosilicon in the following ratio of components, wt.%:

Silicon dioxide 15-25 Aluminum oxide 7-30 Calcium oxide 12-15 Silicon carbide Else

In this briquette, silica, alumina and calcium oxide are slag-forming constituents. They must prevent silicon carbide from premature interaction with the gas phase before entering the cupola into the melting zone, where they must melt and release silicon carbide to interact with liquid iron, so that carbon and silicon from silicon carbide should go into iron with simultaneous heat release with an eco-thermal effect.

However, in the known briquette, the slag-forming components have a melting point of .15001700 ° C. In connection with such a high melting temperature, the slag-forming components cannot melt in the cupola in the melting zone, where the gas phase temperature is 1340-1380 s. Therefore, the known briquette begins to collapse only in the zone of maximum temperatures (in the oxygen zone of the cupola), where the temperature of the gas phase reaches 150 ° C to 1700 ° C. In this case, the destruction of the briquette does not have time to pass completely, since the briquette is in the oxygen zone of the cupola for a very short time. Basically briquette destruction and interaction

The 20 silicon carbide contained in the cast iron occurs in the hearth of the cupola, where also the metal is held for a short time. But since silicon carbide, unlike

If 25 other silicon carriers dissolve in liquid iron slowly, then this dissolution process does not have enough time to complete in the hearth of the cupola. At the same time, a significant part of silicon carbide, which did not have time to dissolve in the iron, floats into the slag and is carried away from the cupola. This leads to a significant loss of silicon carbide, therefore, the degree of its absorption by the pig iron decreases. But since the exothermic effect of silicon carbide dissolution is directly dependent on the degree of its absorption by the iron, the exothermic effect from the use of silicon carbide is not fully utilized.

The purpose of the invention is the creation of exothermic silicon carbide-based briquettes, which make it possible to increase the degree of absorption of silicon carbide by the pig iron and increase the exothermic effect.

To achieve this goal, a well-known briquette was used, in which the ratio of components was changed.

The proposed exothermic briquette has the following composition of components, wt.%:

Silicon Dioxide 26-35 Aluminum Oxide 2-6

Calcium oxide 16-25 Silicon carbide Else In the proposed briquette, the slag-forming constituents (silica, alumina and calcium oxide) are taken in such a proportion that their melting temperature does not exceed 1340-1380 ° C.

Thus, at a temperature of 1340-138 (the slag-forming components in the briquette are melted, the briquette is destroyed, silicon carbide is released for its subsequent interaction with liquid iron with an exothermic effect. The temperature of 1340-1380 ° C is reached in the cupola already in the melting zone, therefore the briquette already in this zone begins to break down, freeing silicon carbide and practically the destruction of the briquette takes place completely at the end of the melting zone. The freed silicon carbide interacts with liquid iron. Thus, the reactions Procedure silicon carbide with molten iron offered when applying briquettes are started much earlier than with the known preform, which requires for its destruction a temperature of about 1500-1700 ° C. Therefore, when applying briquettes in a cupola proposed process silicon carbide dissolving in the molten iron occurs

almost completely. The iron and carbon carbide silicon saturation reactions of the silicon. The silicon passes most completely, the degree of absorption of silicon carbide by the iron increases, and, as a consequence of J, the maximum exothermic effect is obtained.

In tab. 1 shows the compositions proposed and known briquettes in table. 2 - data on the absorption of silicon and carbon from silicon carbide contained in briquettes; in tab. 3 - the destruction of the proposed and known briquettes, depending on the heating temperature. The absorption coefficient of silicon varies from 0.81-0.87 (briquettes 1 and t 3) to 0.94-0.96 briquette No. 2).

The carbon uptake factor is in the range of 0.81-0.88 (briquettes nos. 1 and 3) and 0.92-0.95 (briquette no. 2).

The absorption coefficient of silicon from a known briquette is 0.650, 71.

In briquettes # 1 and # 3, the absorption of silicon carbide is almost within the same limits. The best results were obtained when using briquettes No. 2. Slag-forming components in briquette No. 2 melt at 13401350s, therefore, the destruction of the briquette occurs in the melting zone of silicon carbide from the briquette manages to fully dissolve in the liquid metal with the maximum exothermic effect.

From tab. 3, it can be seen that the proposed briquettes are destroyed much earlier than the known briquette, which leads to an increase in the degree of absorption of silicon carbide by the pig iron and, accordingly, to obtaining the maximum exothermic effect.

Thus, the absorption rate of the silicon carbide silicon contained in the briquette by the cast iron is 0.94-0.96; The absorption rate of carbon iron from silicon carbide contained in the briquette is 0.92-0.95; the temperature of the cast iron rises by 60-80 ° C with the addition of 4% briquettes to the charge.

The good absorption of silicon carbide by cast iron allows the proposed briquettes to be widely used as an effective carrier of silicon with additional overheating of cast iron at 6080 ° C.

T a G5 l and t e

Suggested briquettes

Suggested briquettes

The formation of the liquid phase of slag-forming and spreading

table 2

1340-1380

1500-1520

Claims (1)

Invention Formula Exothermic briquette for cupola melting containing silicon carbide, silicon dioxide, aluminum oxide to calcium oxide, characterized in that, in order to increase the degree of absorption of silicon carbide by the pig iron and increase the exothermic effect, it contains components in the following amounts weight,%: . . Silicon Dioxide 26-35 Alkimine Oxide 2-6 Calcium Oxide 16-25 Silicon carbide Rest Information sources, taken into account in the examination 1. The patent of Germany 1583262, CL.18 B 1/08, published 1977,