Reconfiguring deep-level mine dewatering systems for increased water volumes

Abstract

Deep-level mines are faced with a host of challenges that can pose a threat to the safety of underground mine employees. Significant among these threats is the risk of underground floods as a result of fissure water flowing into mine shafts. Neighbouring mine shafts are frequently connected at certain underground levels, allowing flood water to overflow from one shaft to another. Damage of equipment and loss of production are also risk factors to be considered if a mine is to flood. As mining depth increases the initially installed water reticulation system becomes outdated and ineffective at distributing and removing water from a mine. Inevitably the reconfiguration of older mine water reticulation systems becomes a necessity for the effective and efficient management of water within mines. Previous studies have investigated the reconfiguration of mine water reticulation systems. These studies mainly focused on reconfiguration for the purpose of energy cost saving, decreased water wastage and improved cooling system operation. The identified studies did not, however, focus on reconfiguration of a mine water reticulation system for the management of excessive water volumes. The primary objective of this study is to focus on possible solutions for the reconfiguration of a deep-level mine water reticulation system to compensate for excess water. The secondary objective is to improve the water reticulation system after reconfiguration occurred. System improvements after reconfiguration can consist of water demand optimisation, energy cost optimisation and pump automation. A five-step method was developed to reconfigure a deep-level mine water reticulation system for excess water management. The five steps within the developed methodology can be listed as: 1. Data acquisition of mine WRS and problem identification 2. Solution development 3. Validate the proposed reconfiguration solution 4. Implementation and system improvement 5. Results quantification. The five-step method developed for this study was successfully tested on two case studies that involved four different mine shafts. Completion of the first case study proved that the involved mine could remove an additional volume of 0.7 ML (29%) of excess water per day. In the second case study the amount of water that had to be pumped to surface by the involved mine was reduced by 1.74 ML (31.4%) per day. This allowed better performance of the mine’s water reticulation system. Implementation of proposed system improvements made to two mines, in the form of system automation and load shift projects, realised a total cost saving of R1.28-million within the first year. Results attained from applying the developed methodology proved that mine water reticulation functionality was improved, excess water volumes could be removed, and solved the identified problems unique to each of the two case studies. These aforementioned results proved that the study objective had been successfully met because possible solutions for the reconfiguration of a deep-level mine water reticulation system, to compensate for excess water, had been attained.