Energy contribution of coal waste recycled with limestone to produce a Portland clinker

Analysis has revealed that Moroccan coal gangue consists of silica, clays, and coal, making it a viable substitute for clay in clinker production. Our previous study demonstrated that the clinkering of a cement raw mix with 18.5% (wt) coal gangue and limestone produced a good Portland clinker. This clinker was close to that given by a cement raw mix of a cement plant, and which was taken as a reference-raw RR. The coal gangue contains around 8.8-11.8% coal, exhibits a calorific value of 3.77 MJ/kg and displays an exothermic effect of 67.3 J/g as determined by DSC analysis. This exothermic release is also observed in the LG cement mix. The objective of this study is to estimate the energy contribution of coal gangue in clinker production by comparing the thermochemical energy balances during clinkering up to 1450°C for the two clinker raw materials, LG and RR; our calculations indicate an energy gain of approximately 2.13%.