Clinker is a solid material produced in the manufacture of Portland cement as an intermediary product. The Portland clinker essentially consists of four mineral phases: two calcium silicates, alite (Ca3Si) and belite (Ca2Si), along with tricalcium aluminate (Ca3Al) and calcium aluminoferrite (Ca4AlFe). These main mineral phases are produced by heating at high-temperature clays and limestone. Portland cement clinker is made by heating a homogeneous mixture of raw materials in a rotary kiln at high temperatures. The products of the chemical reaction aggregate together at their sintering temperature, about 1450 °C.
The content of the major oxides is controlled by using modulus calculations to maintain the required proportions of CaO, SIO2, AL2O3, and Fe2O3. The modules are calculated as follows:

Parameter Formula typical range
92 - 98
2,3 - 2,7
1,4 - 1,8

Lime Saturation Factor (LSF) is the ratio of the actual amount of lime to the theoretical lime required by the major oxides in the raw mix of clinker.
Silica Ratio (MS) or SR is the amount of melt phase in the burning zone as a function of MS. When MS is high, the amount of melt is low and vice versa.
Alumina Ratio (MA) or AR is the temperature by which the melt forms depending on the MA.