However, issues such as mercury release during calcining need to be resolved. Zirconia is produced by calcining zirconium compounds, exploiting its high thermal stability. Beneficiation of phosphate ore is a process which includes washing, flotation and calcining. The origins of Calix began in 2005, with work on flash calcining. Crystalline tricalcium phosphate can be obtained by calcining the precipitate. Chamotte is made by calcining fire clay (AlO-SiO) above . Calcined petroleum coke (CPC) is the product from calcining petroleum coke. Pyrometallurgical processes that involve gases and solids are typified by calcining and roasting operations. Typically these materials are prepared by calcining intimate mixtures of oxides and carbonates. Calcining at different temperatures produces magnesium oxide of different reactivity. This again produces a long, relatively cool calcining zone. The primary use of magnesium carbonate is the production of magnesium oxide by calcining. Brick-built calcining kilns were used for reducing iron ore before transport to the Corby Steelworks.