Tailings and other mining waste and how it is handled
Waste management is often one of the most important parts of a mining operations’ environmental work. Proper waste management can significantly limit the environmental impact of mining operations.
Mining waste occurs in all mining operations. Mining waste can be divided into several different parts, the most significant of which are:
- Mining drainage water
All mining activities give rise to waste rock (gangue), tailings and mining drainage water. The quantity and volume can vary greatly between different activities, in particular depending upon which material is being mined and in what concentration, as well as whether it is mined in open pits or underground.
Gangue is the rock that is mined to access the ore (the mineable part of the rock that is financially viable). Gangue is present in both open pits and underground mines. The Gangue is deposited in close proximity to the mine and is generally covered by moraine or redeposited in the open pit or underground mine upon completion of the operations, referred to as remediation or land reclamation. In several cases, this occurs continuously during the operations, referred to as successive land reclamation and remediation.
Tailings arise after the ore is crushed and processed into a mineral concentrate that is often sold on to smelters. What remains is referred to as tailings and is a waste. This material, like the mineral concentrate, is very fine-grained. The amount of tailings that arises relates to the content of valuable substances taken from the ore. A low content of valuable substances causes more tailings to occur, while a higher level, for example, as in several iron ore mines (where the iron content may exceed 40 percent), leads to less tailings per tonne of processed ore.
The most common is that the tailings are deposited in enrichment warehouses, which are facilities designed to hold the sand. In some cases, tailings can be used for filling rock rooms.
Mining drainage water
Mining drainage water is water used by mining operations in various processes, or rain, surface or groundwater affected by the mine or the waste from the mine. When the mining drainage water leaves the mining operations, for example via run-off from a tailings pond, it can be regarded as a kind of waste. For example, the environmental permit contains information on the concentration of metals or other substances that the water may contain when it leaves mining operations. If necessary, the mining operations may need to construct a water treatment plant that remains in operation until the land reclamation related to the mine has been done or it achieves stable conditions so that the environment is not at risk of harm. Mining drainage water is often recirculated several times in the operations, for the purpose of minimising the use of water.
Last reviewed 2022-06-17