Effects of Raw Material Characteristics and Sintering Aids on Properties of Silica^-based Ramming Mixes

Silica-based ramming mixes are widely used as lining materials in coreless induction furnaces, which serve as the main equipment for iron and steel in foundry industry. The service life of linings made from silica-based ramming mixes depends on the properties of quartzite raw materials. In this paper, quartzites from three regions were selected as raw materials, with boron oxide and boron phosphate as sintering aids. By comparing and testing performance such as the phase composition, permanent linear change, bulk density, apparent porosity, and slag resistance, the effects of raw material characteristics and sintering aids on the performance of the silica-based ramming mixes were investigated. The results showed that boron oxide-containing ramming mixes prepared from quartzite with a fast phase transition showed lower strength and greater expansion as well as lower slag penetration index. For boron phosphate as a sintering aid, ramming mixes made from quartzites with medium and slow phase transition rates had an approaching slag penetration index comparable to those containing boron oxide, although their strength was lower than the latter. According to the melting requirements of stainless steel, boron phosphate can replace boron oxide as a sintering aid for silica-based ramming mixes. Regarding practical applications for linings of coreless induction furnaces, the selection of quartzite as the raw material for silica-based ramming mixes shall be comprehensively considered from multiple aspects.