Forecasting prospective development of acid mine drainage composition in two active open pit mines in Saxony (Germany)

摘要

MIBRAG mbH runs the two open pit mines Schleenhain and Profen in the south ofLeipzig. Various mine drainage waters are pumped in more than 200 wells and arecombined in one central drainage station in the respective open pit. The various maindrainage waters show different qualities which result from the interaction of groundwaterwith the geologic units in the different recharge areas around the open pit mines. Thecomposition of the mixed water is of importance with regard to its discharge into riversas well as with regard to its utilisation as pit lakes flooding water. The estimation andforecast of the mixed water quality is based on the time dependant groundwater fluxesand their spatial qualities. The motivation for this work is a current debasement of thepumped mine drainage water w. r. t. iron- and sulphate-concentration as well as acidity.The groundwater flow into the two open pit mines is modelled with a non-reactive hydro-geological model. With the predicted groundwater flow it is possible to make a forecastof the mixed water quality assuming constant qualities of the various groundwaters in therecharge areas around the open pit. A box model was used which mixes the separatefluxes with their respective water qualities.