Thermal Energy Storage System Using Silica Sand as Heat Storage Medium: Simulation of Geita Gold Mine

Currently, Geita Gold Mine (GGM) relies on electrical energy from the national grid and diesel power generators to generate electricity for various industrial applications.The plant currently spends a large amount of money on generating power from diesel generators.The total annual cost of power generation from diesel generators including lubricants is USD 56,057,990.The total annual fuel cost is USD 53,531,805 for a total of 54,985,473 liters per year.Most of the power generated by the generators is consumed in the industrial thermal processes.Thermal energy applications at the plant are thermal drying of the extracted ores to remove moisture content before further processes, thermal treatment of minerals and in gold refining and smelting which require over 1000 temperatures.However, this thermal energy can be obtained from thermal energy storage system.This study was initiated to investigate the potential of silica sand as thermal energy storage medium for GGM.In the assessment of the potential of silica sand, three (3) different samples were collected at the GGM site from three different locations and the samples were analyzed to determine their chemical compositions using energy-dispersive x-ray fluorescence (EDXRF) and later purified using coke to obtain the 95% desired purity.Thereafter, silica sand thermal energy storage model was developed using the chemical compositions and thermal properties of the analysed silica sand.The model performance assessment used heat transfer in the solids interface in COMSOL Multiphysics.The silica content of the three samples were 87.32%, 78.25%, and 75.59% silica content.The model results show capacity to be charged for two hours and discharging for twelve hours.