We prefer, therefore, to develop a waste management plan that takes such considerations into account to allow the mine operator as many options for recovery and recycling as possible, thereby extending his potential for profit.
We also recommend including in the plan the fact that, when waste rock is clearly uneconomical, even for future mining, it must be prevented from contributing to acid mine drainage.
Other factors to take into consideration are the overburden, slags, water treatment sludge, tailings, and gaseous waste. The overburden, usually piled on site for cost-effectiveness, should ideally be used for recontouring and revegetation when the mine is closed. Rather than being discarded, slags can be profitably repurposed as aggregate in concrete and road construction where suitable.
When water treatment sludge contains arsenic or cadmium, it is hazardous and must be disposed of by specialists such as EnviroServ.
The days of depositing tailings directly into rivers or wetlands, introducing sediment and contaminants and adversely affecting aquatic life, are long gone. But the design, management, rehabilitation and closure of tailings storage facilities and, indeed, the hydraulic remining of tailings still all call for highly specialised skills.