China Nonferrous Metallurgy

Chinas annual red mud emissions are as high as 100 million tons, and the main treatment methods are landfill or storage, and there is a shortage of clay raw materials needed for the preparation of ceramics. The new CaO-MgO(10%)-SiO₂-Al₂O₃ system ceramic material has superior mechanical properties and optimistic market prospects. In this paper, the baking test of new ceramic preparation raw materials with different red mud mixing amount was designed. The microstructure and phase composition of different baked products were tested, and the physical and mechanical properties and heavy metal leaching of the products were investigated. The main phases of the samples are pyroxene phase and anorthite phase. The formation of pyroxene phase is beneficial to improve the flexural strength of the samples, and the formation of anorthite phase is beneficial to solidify sodium element and promote the densification process. The performance of the samples is similar, and they all show superior mechanical properties at 1140℃. Under the temperate, the linear shrinkage rate and bulk density are the largest, the water absorption rate is the smallest, and the flexural strength is the highest. At 30 % red mud mixing amount, the water absorption and flexural strength indexes exceeded the GB/T 4100—2015 standard. The leaching test showed that the solidification rate of each sample was as high as 99.91%, and the leaching values of seven typical heavy metals were lower than the limits of drinking water standards. This study provides a new way for the reuse of red mud in the ceramic industry. It not only solves the problem of red mud disposal, but also saves a lot of ceramic clay resources.