Physical and Mechanical Properties of Fired Bricks from Amazon Bauxite Tailings with Granite Powder

In the Amazon region, bauxite processing generates significant quantities of clay mineral-rich tailings, which pose a major challenge for bauxite mining operations. This study explores the use of bauxite tailings to produce fired bricks and evaluates their properties. Using a Box–Behnken experimental design, nine specimens were prepared with varying granite content (0%, 5%, 10%, 20%, and 30%) and fired at three different temperatures: 800 °C, 900 °C, and 1000 °C. The bauxite tailings contain gibbsite, kaolinite, Al-goethite, and hematite, while the granite powder comprises quartz, potassium feldspar, sodium plagioclase, muscovite, and occasionally kaolinite. Linear shrinkage values remained within recommended limits, below 8%. Apparent porosity (AP) results ranged from 60.2% to 72%, with maximum water absorption reaching 23.6%. The compressive strength of bricks without granite addition was 11.9 MPa at 900 °C, with the highest value recorded at 14.9 MPa at 800 °C when granite was added. These findings indicate that bauxite tailings, when supplemented with pulverized granite, exhibit promising potential for fired brick production.