We have problem of hard clinker used in cement grinding. This clinker is produced by using 100 per cent pet coke in firing. Although chemical composition of clinker is correct. It has 50 per cent C3S, 5.5 per cent C3A, & liquid approx 28.5 per cent & SO3 in clinker 1.6 per cent. But minerology observed under microscopy reveals following: Mineralogical composition and Granulometry of - 6 mm clinker: Phases present Quantity (per cent) Granulometry (size in micron) Min. Max. Average required size Alite (C3S) 46.5 8 82.69 42.14 20 Belite (C2S) 34.5 3.5 93.00 38.26 15 Liquid phase (C3A+C4AF) 18.6 Porosity Low porous 22 120 65 (more data attached) Photomicrographs are given in attachment. Kindly suggest How to reduce Alite grain size & increase porousity of clinker. Our kiln is already running in full RPM. Is it possible to make softer clinker by changing chemical composition.