- limestone flour feed grade Composition: Caco3 98% Mgco3 1% Fe2o3 0.2% Ca content 40, 9 % Hcl insoluble 1.5% Density 2.7 g / cm3 Bond index 14.5 kwh / t Hard 3 Particle size 0-0.4 mm 100% - limestone grid Composition: caco3 98% Mgco3 1% Fe2o3 0.2% Ca content 40, 9 % Hcl insoluble 1.5% Density 2.7 g / cm3 Bond index 14.5 kwh / t Hard 3 Particle size 0-2.0 mm 100%