Zpravodaj Hnědé uhlí 2023, 63(1)
Extraction of Ti and Ga from Coal Combustion by-products by combined chlorination-cement method
Globally, around 1 200 Mt of coal combustion by-products (CCBs) are produced by burning coal each year. They are currently considered as waste materials and are often landfilled, leading to many environmental problems. In addition to the dominant alumo-silicate matrix, they contain relatively high amounts of rare earth elements (REE) and other valuable metals, which is why they are increasingly thought of as a material for use in construction industry and as a source of valuable metals. A potentially waste-free combined roasting method, consisting of heat treatment of a mixture of CCBs, CaCO3 and CaCl2, provides a potential link between the two directions of CCBs processing. In one step, this method produces valuable elements in the form of the respective chlorides, and a cement product is obtained from the residual material. In this article, the dependence of the most important roasting parameters on the degree of extraction of Ti and Ga in the form of chlorides is described. Optimising the roasting conditions has achieved the degree of extraction of Ti nearly 56 % and Ga around 100 %.
Keywords: fly ash, CCBs, chlorination, titanium, germanium
Published: March 1, 2023 Show citation