© IEOM Society Design of a crushing system that improves the crushing efficiency of gold ore at a local mine: case of Zimbabwe Tawanda Mushiri D.Eng. Student; University of Johannesburg, Department of Mechanical Engineering, P. O. Box 524, Auckland Park 2006, South Africa. tawanda.mushiri@gmail.com Lecturer; University of Zimbabwe, Department of Mechanical Engineering, P.O Box MP167, Mt Pleasant, Harare Charles Mbohwa Professor and Supervisor; University of Johannesburg, Auckland Park Bunting Road Campus, P. O. Box 524, Auckland Park 2006, Room C Green 5, Department of Quality and Operations Management, Johannesburg, South Africa. cmbohwa@uj.ac.za Abstract Mining involves a number of processes which are useful in gold extraction. The processes involved are gravity concentrations, flotation, etc. are available for the extraction of gold metal from its ores. The common processes for recovery of gold solution includes: (I) Carbon adsorption, Merrill-Crowe process, (II) electro winning and (III) ion- exchange / solvent extraction. All these processes require the particles involved to be in certain sizes. Hence crushing and grinding are used to attain the required sizes. This leads the mine plant to be set in a way which let the gold extraction process to be attained economically and at a high rate.The local mine, a gold mine in Zimbabwe has been growing for the past years and production of gold ore from the ground has increased. The current crushing setup is operating at 15 tonnes per hour which is low compared to their production rate such that ore from the ground is piling up. This paper addresses the critical design parameters that will increase the crushing capacity of the plant to 35 tonnes per hour.There are three main steps in designing a good crushing plant: process design, equipment selection, and layout. The paper analyses all of these steps Keywords Gold mining, crushing, Zimbabwe, jaw crusher, cone crusher 1.0 Introduction Gold mining is the process of mining gold ores from the ground up till the stage where pure gold is extracted(Richiewiki, 2010). The gold ores are usually big and have to be crushed to reduce them to a size of about 12mm diameter before pure gold can be extracted from them. The ore usually has to pass various crushing stages, each reducing the ore to a certain size. Crushing plant layout is of vital importance. Gold-containing rocks are crushed for several reasons. Crushing reduces the physical size of large rocks, exposing more surface area of rock, thus exposing any gold that may be in the rock and increasing the probability of obtaining the gold from the rock by gravity concentration or by leaching with cyanide. There may be several sizes and shapes of gold grains in the rock--round, flat, coarse or tiny. Because of this, several stages of crushing or grinding can be required(WebElements, 2015). Secondary factors to consider when crushing are the desired size of the crushed material and quantity of material to be crushed (“feed rate”). The desired particle size of determines the number of stages of crushing (primary, secondary and tertiary) and the type of machine to be used. The quantity of material entering the crusher determines Proceedings of the 2015 International Conference on Operations Excellence and Service Engineering Orlando, Florida, USA, September 10-11, 2015