A combined lining of the sintering zone of rotary kilns for firing of magnesite

Abstract

Increased wear resistance of a combined lining consisting of acid and basic parts in the sintering zone of rotary kilns for firing of magnesite was established on the basis of chemical and petrographic investigations and visual observations. The wear of ShB aluminosilicate parts is by fusion and of PKhTs refractories primarily by spalling. The ShB parts have a lower wear rate. The positive effect from the combination of PKhTs and ShB parts in a combined lining is obtained both between them and with the material being fired in the kiln. The products of chemical interaction of ShB and PKhTs parts are refractory minerals (spinel and forsterite) and low-melting compounds (glassy phase and cordierite). The increase in wear resistance of the combined lining is caused by contact burning together (welding together) of the high-temperature layers of the parts with formation of a monolith. The use of a combined lining of the sintering zone is recommended for introduction into rotary kilns of the cement and other industries for the purpose of economy in basic refractories. It should be noted that at present unfired chromite-periclase parts with 35.1 wt.% R2O3, 55.4 wt.% MgO+CaO, and 0.8 wt.% P2O5 are being successfully used as the basic refractories in a combined lining to decrease fuel and raw material consumption. Their compressive strength is 45.3–53.9 N/mm2 and their open porosity 10.8–15.1%.