Refractory Grade Bauxite: An Overview about the Effects of different Bauxite Sources and Forming Processes on the Quality of the Material

Abstract

Refractories have been very important for humankind development enabling the manufacturing of a wide range of materials. Primary industries demanding refractories include the manufacturing of steel, non-ferrous metals, glass, lime, cement, ceramics, petrochemicals and incineration. Refractory grade bauxites (RGBs) are high-alumina materials used as aggregates in shaped and unshaped refractory linings suitable to withstand high temperature heating and a corrosive environment. Despite the wide availability of bauxite ores in the world, few countries can supply a bauxite with refractory grades. Guyana, China and Brazil have emerged as suppliers for the refractory industry and the peculiarities of each bauxite from these countries impact directly on the refractory and how the manufacturing process can impact the refractory properties. The Guyanese RGB presented the highest alumina content (~90% Al2O3). However, a Brazilian RGB with lower alumina content (~85% Al2O3) presented the highest hot modulus of rupture value (HMoR at 1200°C/5h = 5.12 MPa). As for the Chinese RGBs, these presented a higher heterogeneity, evidenced in variation on chemical composition resulting in worse thermo mechanical performance (HMoR< 4.10 MPa). Two different forming process for Brazilian RGBs showed that the briquetting operation produces angularshaped grains (sphericity = 0.7), whereas the extrusion mechanism produces rounded grains (sphericity = 0.9) which