The Extractive Metallurgy Industry

Abstract

Several minerals are extracted from the earth, namely, base metals, precious metals and materials such as coal, limestone, salt etc. In this chapter, the mining and processing methods of gold, a precious mineral and bauxite, which is a valuable mineral, are covered in detail. Several processes are involved in mining and extraction of these minerals from the earth’s crust. There are similarities in the processing methods, but there are also key differences concerning the processing of the ores. Two methods used to mine gold, which are surface and subsurface mining, are discussed. The later involves digging tunnels or shafts into the earth buried deposits of ore, while surface mining consists of removing surface foliage, dirt and if required layers of bedrock from the land to reach buried deposits. Processing for gold involves a number of unit operations including crushing/grinding of the ore, gravity concentration, amalgamation, retorting, floatation and agglomeration, roasting, leaching/extraction of gold from the ore; these have comprehensively been covered. Gold mining could pose serious risks to personal and the environment, if not handled properly. The impact of mining on the environment and methods of reclaiming the degraded environment are presented in this chapter. The extraction of alumina from the earth crust and the methods and technologies employed in the processing bauxite into alumina have also been covered. Finally, the nature of the mining industry in Ghana, especially, the mining of ore-bearing rock, the extraction of gold from the ore-bearing rocks and the economics of the industry in the country have been discussed.