Characteristics, Management And Reuse Of Wastewater In Mining

Coal mine water treatment is essential, since most coal mines produce significant environmental pollution. There is a growing concern about the quality of life on mining sites. This calls for innovative efforts to protect the environment. The mining firms are required to reduce the number of pollutants discharged into the environment. The environmental management is regarded as an essential of the overall management plan of an organisation as opposed to the sideline and stand-alone issues in the past. Quality wastewater treatment is required on mine sites to counter the above shortcomings.

Characteristics and sources of wastewater

In any waste management application, it is important to identify the source and features of the waste. The same applies to wastewater management and treatment. The main source of wastewater from coal mine sites can be classified into mine water, domestic wastewater, process wastewater and surface run-off.

The most probable contaminants in the produced wastewater by a typical coal mining plant can be classified into five categories: chemical organic, physical, biological, radiological and chemical inorganic. Physical contaminants include colour, suspended solids, turbidity, taste and order and temperature. Chemical organic contaminants include coal, soap and detergents, oil and grease, rubber and dyes.

Chemical inorganic include heavy metals, acids, alkalis, dissolved salts, cyanide and so on. Biological contaminants include viruses, bacteria, and small organisms while radiological contaminants include tritium, uranium and other radioactive substances.

The chemical and physical type of pollutants are the most crucial in most mining industries and they need special mine water treatment technologies.

Mine water

Mine water is generated in mines that involve underground mining. The source of mine water is from seepage of the excavated area of the mine. Mine water is typically collected in underground sumps and involve a nominal retention time. Mining companies have an opportunity to recycle mine water in the areas of underground dust suppression and firefighting within the mining operation.

The mine water quantity depends on the ground conditions and the level of the groundwater table. The quality of the water varies from mine to mine and depends upon the local conditions. The most common pollutants of mine water are minerals from aquiferous rock strata that get dissolved in the water. Suspended solids levels of the stream are typically very low. Mine water contains a considerable amount of dissolved minerals and the minerals give high hardness to mine water. In the case of acid mine drainage, the mine water pH can be as low as 2. This is mainly due to sulphides oxidation.

Toxic metals

Mine water may contain toxic metals such as zinc, aluminium and barium. The concentrations of these toxic metals are usually small in the coal industry. However, in the metalliferous industry, depending on the process being used, mine effluents may contain cadmium, arsenic, copper, chromium, lead, mercury, gold, and in case of uranium mining, other types of radioactive substances may be present. Before using any coal mine water treatment methods, experts should test the water and know the types of contaminants present and come up with the best treatment methods.

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