Mining processes generate two kinds of specific waste, overburden/waste rock and tailings. The overburden or waste rock is typically non-toxic; however, it may generate acid-mine water if it contains a Potential Acid Forming material (PAF) and contaminates the environment. Therefore, an efficient mineral waste management is another key focus of the Company.
The Company carries out the preliminary risk assessment for all business units to identify whether there are any risks regarding the mineral waste. The waste management standard specific to the mineral waste has been developed and deployed across operations, covering the pre-mining until the post-mining stages. The following activities are associated with the mineral waste:
|Coal extraction||Overburden/waste rock|
The Company integrates an overburden management plan with the mine plan for each specific mine. Since the pre-mining stage, the geological survey has been performed to determine the geochemistry of overburden and to create a geological model with aims to minimize amount of overburden removal and maximize in-pit backfilling.
Tailings management plan is developed for each operation by applying a risk-based approach, throughout their entire life, from the location selection in pre-mining stage to the reclamation in mine closure stage. In Australia, the Reject Emplacement Area (REA) Oversight Committee has been appointed to carry out the standard and audit process. All tailings storage facilities are designed and inspected regularly by external experts, as well as the tailings management plans that are periodically reviewed especially when there are significant changes in the mining plans.
Acid Mine Drainage Management
The acid mine drainage management procedure has been developed and used as a Company’s framework with several preventive measures. The acid mine drainage is one of the key issues discussed in the mine planning review meeting to ensure its efficiency. Where acid mine water exists, water quality must be well treated prior to discharge to the environment or the mine closed.