Study of aluminosilicate refractories after operation in the presence of fluorine-containing wastes

Abstract

Samples of aluminosilicate refractory after operation in the shaft and in the hearth of a coke-gas cupola were investigated; this cupola was used for smelting of cast iron with spheroidal graphite using carbon wastes from aluminium electrolysis production as a reducing agent. Use of only fluorine-containing carbon wastes as a solid fuel in cast iron production allows to utilize hazardous man-caused wastes, improves the economic performance of production and has influence on resistance of fireclay refractories. It was established that the products acquire a distinct zone features during the service, due to penetration of the components of gas and liquid phases and the effect of low-boiling components of carbon-containing wastes. Upon that, changes in the structure along the distance from the working space are complex ones in lining thickness and in concentration of volatile components in the "cold" parts of the lining. Permanent character of the mullite content in different zones of fireclay products can be traced, as well as a slight increase in the less altered zone, despite the different service conditions. Absence of alkaline and fluoride phases in the zones of refractory products in the pores and structure of the fireclay refractory was established, due to migration of these gaseous phases into the working space of the cupola with their subsequent removal with furnace gases. Additional development of mullite in certain zones of refractory was revealed, resulting by its synthesis from alumina that did not react during fireclay refractories manufacture under the mineralizing action of a fluorine compound. Use of fluorine-containing carbonaceous wastes as a solid fuel in cast iron production makes it possible to utilize hazardous man-caused wastes, improves the economic performance of production and has slight effect on resistance of aluminosilicate refractories in the conditions of a coke-gas cupola.