Mine cost control through effective mine drainage at Bogala mines - phase 1

Abstract

The Bogala Graphite Mines in Sri Lanka is experiencing a considerable water flow problem for more than two decades which has resulted in increasing total production cost due to high dewatering cost. This case study was basically carried out to optimize the mine dewatering cost by preventing water inflow where possible. This paper describes only the phase 1 of the study, which is "The identification of water recharge sources in to the mine". Major water seepage takes place above 72 fathom (fm) levels and a significant inflow is at 52 fathoms level which discharges water at a rate of 8.5 liters/s. Initially, major joints/fractures above 72 fathom were measured and the fracture network in the problematic area of the mine was developed. Interpretation of the fracture model provided valuable data on water recharge locations. Simultaneously environmental isotopes (2H and lsO) analysis on surface, subsurface water bodies and underground seepage locations were carried out to identify the exact water recharge locations. The 2H and 180 contents were plotted in graphs in various suspected combinations with local meteoric water lineto identify interconnections. Even though, some solutions were presented to reduce the mine dewatering cost, further analysis is needed with continuous sampling of data to confirm the tentative conclusions.