The balancing act of sustainable mining--New research into the role of sulphate balances in assessing and mitigating mining's impact on lakes and rivers

摘要

Acid mine drainage (AMD) has plagued the sulphide mining industry since Roman times. The German scientist, Georg Agricola, mentioned it as far back as the late medieval era. Concerns about AMD pertain to the generation of acid by sulphide oxidation and the mobilization of iron and base metals by acid reactions. Nowadays, mine discharge, process effluents, seepage from tailings and contaminated site run-off are channelled through one or two treatment plants. There, the acid is neutralized and soluble iron and base metals are precipitated with lime. Excess alkalinity is then neutralized with carbon dioxide before discharge to a water body. Traditionally, this was considered sufficient protection from adverse ecological impact. Now, however, the significance of sulphate ions in downstream systems is gradually receiving more attention as the supplies of fresh water become constrained.