Waste

Mining produces hazardous and non-hazardous wastes, which can be a threat to the environment unless they are disposed of properly. Costs of disposal in landfill sites can be high too. So we aim to reduce the quantity and toxicity of the waste we produce through a waste management plan for every one of our mines. Plans are tailored to each mine but they all aim to reduce the amount of waste sent to landfill by producing less waste in the first place, then by reusing and recycling more.

The different wastes from our operations are:

waste rock, where we have removed strata to expose ores or coal
tailings and slag from processing ores
hazardous wastes from smelting, such as heavy metal contaminated sludge or high iron content waste from producing zinc

Mineral waste

We are committed to reducing the quantity and toxicity of the mineral waste we produce, and to managing this waste safely and effectively.

Waste rock is reused as back fill, in landscaping or stockpiled in waste rock storage areas. Certain types of waste rock can react with air and water to produce sulphuric acid. This strong acid has the potential to leach heavy metals from the waste rock, which can then leak into the surrounding soil or water. We carefully monitor for leaching, and manage it either by treating or by containing and evaporating the solution.

Disposing of mine tailings is a significant environmental issue, affecting the safety of our employees, local communities and the quality of the local environment. We regularly check the structural capacity of our tailing dams and monitor groundwater for leaching.

We use slag as a by-product or sell it for use in road construction or brickmaking. Because it is used as a raw material, we do not classify slag as a waste material or include it in our waste generation data.

The hazardous waste we produce includes jarosite (a high iron sulphate content waste from zinc production). We have developed a process to convert jarosite into jarofix, a stable and inert material that can be safely disposed in landfills.

Non-mineral waste

Hazardous and non-mineral waste consists mainly of hydrocarbon-related waste and small quantities of refractory block. The majority of waste oil is sent off-site for recycling at licensed facilities.

Our non-hazardous waste consists of glass, paper, packaging and scrap metal, which is either: