Formulation of optimization model of raw material composition to achieve clinker quality standards (Case study PT Semen Padang Plant IV)

Cement making process required four main raw materials, Lime Stone as a source of CaCO3, Silica Stone as a source of SiO2, Clay as a source of Al2O3 and Iron Sand as a source of Fe2O3. Proportion of raw materials approximately 80% CaCO3, 15% SiO2, 3% Al2O3 and the remaining 2% for Fe2O3. Due to operational constraints in the mine area, Indarung IV plant is experiencing a shortage of SiO2 source material that is Silica Stone, to anticipate this condition selected Pozzolan as alternative raw material because the SiO2 content in Pozzolan is above 60%. This research uses Linear Programming to get formulation model of optimization of raw material composition with Pozzolan as a substitute of Silica stone by minimizing cost. Ash composition factors and calories of fuel are not made into consideration. The results of this study obtained the most optimal raw material composition with minimal cost and meet the standard strength three days clinker min. 200 kg/cm2, by inputting the oxide composition of each raw material and the minimum and maximum constraint into the model formulation. The use of Pozzolan as a substitute raw material for Silica increases raw material costs 265.74 rp/ton.