Synthesis and characterization of belite clinker by sustainable utilization of alumina sludge and natural fluorite (CaF2)

Abstract

Certain reservations regarding the high energy costs needed for Portland cement production and eco-friendliness of the cement synthesis process are pointed out. Belite clinker synthesis offers an effective alternative approach capable of addressing these reservations by producing cements at reduced temperatures/CO2 emission. The present study suggests a new method to synthesize belite clinkers at even lower temperatures by incorporating the natural fluorite (CaF2) into a mixture of limestone and alumina sludge originated from the water purification plants. The obtained clinkers and their respective cements are characterized by free lime contents, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, refusal, Blaine fineness and mechanical resistance analyses. The obtained results reveal that the synthesized belite cement possesses mechanical strength similar to that of ordinary belite cement. In addition, the introduction of CaF2 into the clinkers not only lowers their preparation temperatures but also facilitates the formation of crystalline phases which eventually leads to inproved hydraulic properties of the cement.