The Effect of Addition Basalt Stone and Coal as Substitution Material for Producing Cement Clinker

Abstract

National infrastructure development in Indonesia requires supporting materials, one of which is cement. This increases cement clinker production. The composition of limestone as the main raw material required in the manufacture of clinker is 81%. Basalt is used as an alternative raw material because it contains SiO2, Al2O3, and Fe2O3 with a total of >70%. It meets the chemical requirements of ASTM C618 as a substitute material for cement making. This study aims to determine the effect of adding 10% basalt rock and coal variations as a limestone substitution in cement clinker manufacture. Coal is obtained from the Tanggamus district with the variations used, namely 5, 10, 15, and 20% outside the total mass. Raw materials such as limestone, silica stone, clay, basalt stone, coal, and iron sand are ground with a ball mill and formed into pellets followed by burning at sintering temperatures of 1100, 1200, and 1300 oC with a holding time of 2 h. The clinker was analyzed using XRF (X-Ray Fluorescence), XRD (X-Ray Diffraction), and OM (Optical Microscope). This study aims to know the effect of coal on the cement clinker. The results showed that the manufacture of cement clinker at 15% substitution of coal at 1300 oC obtained a CaO compound of 66.384% and SiO2 of 22.747% with sample results close to ASTM requirements (C150-99). The phases formed are alite, belite, aluminate, and ferrite. From microanalysis with a 100 µm magnification, it can be seen that the phases alite and belite.