Sintering and Heavy Metal Solidification Mechanism of Anorthite Building Sintered Brick from Stone Coal Tailings After Vanadium Extraction

This is an article in the field of ceramics and composites. Vanadium extraction tailing from stone coal is a dangerous industrial waste. Comprehensive utilization of vanadium extraction tailings from stone coal has important environmental and economic significance. The fired bricks for building were prepared from the vanadium extraction tailings of stone coal. The effects of firing temperature on microstructure and properties were studied, and the leaching activity passivation mechanism of Cu, V, and Zn heavy metal was explored. The results showed that sintering temperature significantly affected the phase composition, microstructure and performances of sintered bricks. Properly increasing the firing temperature was not only in favour of silicon-rich liquid phase generation to increase the density of samples by the reaction between quartz and alkaline element in raw materials, but also contributed to anorthite transformation from melilite and the mullite formation. These crystalline phases bond with glass, endowing the product with high density and compressive strength. In addition, an increase in firing temperature improved the Cu, V, and Zn residual content in the product, reduced the pore size and volume, thus achieving the solidification of Cu, V, and Zn. With the 1 150 ℃ firing temperature and 3 h holding time, the properties of the sintered building bricks can meet the requirements of standard Mu25 in 《fired common bricks》(GB/T5101-2003). Cu, V, and Zn leaching concentrations in the product were below the standard values. This study provides a new insight for the efficient utilization of vanadium tailings from stone coal.