Clean Mining For Purify Highly Contaminated Wastewater And Soils
It has only been in the last 25 years that regulators have understood the devastating impact of Acid Rock Drainage (also referred to as Acid Mine Drainage or AMD). It is considered to be the principal threat posed by mining activity, past, present and in the future. Typical sources of Acid Rock Drainage (ARD) at mine sites are underground workings where ground water percolates through a honeycomb of tunnels and shafts, piles of waste rock, mining overburden and exposed tailings. Mines may be a source of Acid Rock Drainage for thousands of years.
ARD pollution can poison drinking water, contaminate ground water and destroy aquatic life. Many of the contaminants, such as arsenic, cadmium, copper and lead, are highly toxic, and can produce devastating effects on the environment.
It is estimated that some 13 billion tonnes of stone, 10 billion tonnes of sand and gravel, and 500 million tonnes of clay are used annually in the construction of tailings dams. Accordingly, there are tens of thousands of tailings dams worldwide containing billions of tonnes of mineral processing wastes.
Due to their vast quantities, liquid nature and very high content of toxic metal contaminants, their containment and control are an ongoing management concern at virtually all mine sites. The impact of seepage is a constant concern.
The most serious issue relates to the potential of tailings dams to fail or collapse, claiming lives and causing considerable environmental damage. The damage caused by these failures in terms of human casualties, destruction of property, disruption of communications, pollution of the environment and economic loss to the mining industry is enormous. There has been a reported failure of a tailings dam almost every year for the past two decades, each with widespread and devastating results.
When reagents are applied to ARD they purify the contaminated water to stringent environmental standards. Tailings dams and exposed waste rock can be treated both effectively and economically. This remarkable technology can be applied to economically treat AMD, tailings dam water, sulphidic mine tailings, acid sulphate soils and waste rock dumps to:
- Permanently neutralize acid.
- Trap trace metals and prevent leaching.
- Enhance nutrient retention capacity and promote
- vigorous plant growth.
The application of these reagents can prevent the formation of acid rock drainage in the first place by stabilizing exposed waste rock, mining overburden and tailings. In most cases treated soils and wastes can be used to create a rich substrate for plant growth.