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Water quality in an abandoned gold mining belt, Beatrice, Sanyati Valley, Zimbabwe

2005; Elsevier BV; Volume: 30; Issue: 11-16 Linguagem: Inglês

10.1016/j.pce.2005.08.026

1873-5193

S. Ravengai, David Love, Maideyi Mabvira-Meck, Kudzai Musiwa, William Moyce,

Tailings Management and Properties

The Beatrice Gold Belt, located 65 km south of Harare, lies astride the Mupfure River, a tributary of the Sanyati River, Zambezi Basin. The belt has been mined for gold since 1900, but was abandoned towards the year 2000. The Mupfure River provides water for commercial agriculture in the local farming areas and smallholder farming in Mhondoro Communal Lands, as well as other users downstream in Chegutu and Kadoma Districts. There were four mines in the belt: Beatrice, Joyce, Argyle and Roma. They are all closed, and rehabilitation has only taken place at Beatrice mine. Each mine is located under 5 km from the Mupfure River, and so run-off from the mines and their dumps can easily reach the main river system. The dominant sulphides are arsenopyrite (FeAsS), pyrite (FeS2), galena (PbS) and stibnite (Sb2S3). Gold is generally locked up in sulphides or occurs in close contact to the sulphides, so processing is associated with release of acid, arsenic and metals into streams that flow into the Mupfure River. This study was thus carried out to assess the potential impact of these abandoned mines on the water quality of the Mupfure river and its tributaries. Water samples were collected along the tributaries that drain the mining area, as well as from the mine-shafts. Parameters tested include pH, iron, copper, nickel, lead, zinc, antimony, and arsenic. Chemical results obtained show that the surface water is slightly contaminated with respect to Pb, Zn and Ni. Such contamination is attributed to the mine dumps. However, the near-neutral pH and only slight contamination show that the impact on water quality of the Beatrice mines is largely localised probably due to likely low run-off volumes from the mining sites compared to the rest of the catchment. The slight contamination could also indicate that acid mine drainage is proceeding at a slow rate or the fact that it is in its initial stages. Long term environmental management should therefore focus on controlling the localised impact of the old mines as well as controlling the acid drainage.