Optimization of HPGR-Based Clinker Grinding Circuit at Abyek Cement Plant Using Steady-State Process Simulations

Abstract

Abyek cement plant is equipped with four clinker grinding lines; every grinding line consists of a two-compartment tube ball mill. Recently, in a retrofit project, two high pressure grinding rolls (HPGR) units were installed in two grinding lines before the tube ball mills to grind clinker feed. The efficiency of these HPGR units is reported to be under design specification. In this study, an approach based on population balance modelling of grinding process and circuit simulations was used to optimize HPGR milling operation. Representative samples were taken from HPGR units’ feed and product streams to obtain HPGR model parameters, namely, breakage distribution function and selection function or specific rate of breakage. Screen analysis tests were carried out to determine Particle Size Distribution (PSD) of every powder sample and its d80 as powder size index. Tumbling grinding tests with laboratory ball mills were also done using collected samples to determine breakage distribution function of feed to HPGR units. Selection function was estimated based on PSDs of HPGR feed and product samples using NGOTC program. A comparison between HPGR measured and predicted product PSDs proved validity of modelling and simulation approach. Several simulation trials were performed to find the best settings of main input variables including applied roll pressure, roll gap and rolls rotational speed which showed that their optimal values are 180 bar, 0.01300 m and 2 m/s, respectively. Plant implementation of these settings for one of the HPGR units showed a 22% decrease in d80 of product. The optimization study indicates that production capacity can be increased from 150 t/h to 180 t/h with a Blain fineness of 3000 cm 2 /g.