Green Practice in Cement Industry: Energy and Economic Analysis on The Substitution of Limestone by Cement Kiln Dust

Abstract

The cement industry is one type of industry that is highly consuming energy. Cement production generally involves several stages: mining, raw milling, burning, finishing mill, and packaging. The finish mill is the stage where the clinker (output of burning stage) is mixed with other materials such as gypsum, limestone, and additives (trass or fly ash). This study is aimed to examine the substitution of limestone in the finish mill by cement kiln dust (CKD) that is generated from raw mill. The approach of study was simulations to calculate the mass and energy balance and economic aspects (production cost and profit) based on the varied percent of CKD that substitute the limestone. Simulation results show that energy requirements are reduced by 469,730 kJ/ton for each addition of %CKD thanks to lower water content of CKD than limestone. Less energy requirements means less fuel requirements thus lowering production costs by IDR 66,500 /ton of raw meal /%CKD. In addition, CKD substitution to limestone can reduce waste and pollution from the cement industry so that it can increase profit by IDR 312,000 /ton of product /%CKD.