The water problem in relation to mining at konkola division, Nchanga consolidated copper mines limited

Abstract

Nchanga Consolidated Copper Mines Limited, Konkola Division (formerly Bancroft Mines Limited) is the wettest mine on the Zambian Copperbelt and probably the second wettest in the world. The stratigraphic position of the orebody, between the Hangingwall and Footwall Aquifers, results in large quantities of controllable and uncontrollable water flowing into the workings during mining operations. In 1970 an average of 340 000 cubic metres (75 million gallons) pet day were pumped to surface, equivalent to 64 tonnes of water per tonne of ore hoisted. Sufficient pumping capacity has to be installed to lower the water table in the various aquifers in time to meet production commitments. The sustained capacity for 1972 wiII be in the region of600 000 cubic metres (130 million gallons) per day. The mining method of sub-level open stoping requires dewatering of the Footwall Aquifer during development operations and dewatering of the Hangingwall Aquifers prior to stoping. Water is, therefore, a major consideration in mine planning. A clear understanding of the geological features of the Konkola mining area is essential to develop a successful and efficient dewatering scheme. Dewatering of the various aquifers is achieved by drilling boreholes and by driving mining headings into the aquifers. The problem of recharge is not yet solved and research in this field is in progress, including colour and infrared aerial photographic surveys, chemical and neutron activation analyses of waters, regional water balance studies, and age determinations of waters by natural isotope analysis.