Ore Mining Techniques
Mining is the process of extracting mineral ores and other materials from mines. Mining activities includes exploration, extraction and the processing of minerals up to the refined product (coal, metal, cement, oil shale, oil sands, etc). During this process, ore and waste rock are brought to the surface. Mining techniques can be divided into two common types: surface mining and underground mining. Surface mining usually occurs where mineral deposits are close to the surface. It is done by stripping surface vegetation and layers of bedrock in order to reach buried ore deposits. Underground mining also referred to as sub-surface mining consists of digging tunnels or shafts from the earth surface into the mineral seam, which can be hundreds of meters below the surface. 

Environmental Effects 
Mining activities may have in many ways significant impacts in the environment. Those adverse impacts include soil erosion, forest loss, ecosystem disruption, loss of biodiversity, air pollution, surface water and groundwater contamination by leakage of chemicals from mining processes resulting in public health effects if not properly controlled and managed. Besides generating environmental damage, changes in the in the landscapes as a result of crust rocks dumps are also very disturbing for local communities living in the vicinity of mining areas. Exposure to harmful gases, dust and highly toxic chemicals causes illness, injury and fatality. In coal mining, coal fires remain a serious health and safety hazard affecting the environment by releasing toxic fumes, reigniting grass, causing forest fires and destroying buildings and infrastructures. Metal mining generate large amounts of waste rocks, known as tailings, which usually are dumped into ponds made in some countries of naturally existing valleys. Extraction of minerals and excavation reduce groundwater depth and decrease natural filtration, leading to groundwater contamination. 

Green Mining
In recent years, new approaches have emerged to foster the development of mining methods that minimize the negative impacts of mining activities in the environment and their subsequent public health effects. These so-called green mining or sustainable mining methods are tentative environmental solutions and strategies defined by a set of principles, technologies, best practices that have the potential to reduce the ecological footprint, through energy efficiency and water efficiency improvement, substantive reduction in greenhouse gas emission, chemical use and waste generation. In many countries, mining companies are required to follow stringent environmental regulations that increase accountability and liabilities for environmental stewardship during and after mining operations. At the end of the operations, mine areas are required to be properly rehabilitated to ensure they returned close to their original state. Reducing the environmental impacts of mining activities is one of the most significant challenges for the sector.


Related Links 
http://www.mining.com/web/at-mining-sites-renewable-energy-systems-are-up-to-70-percent-less-expensive-than-diesel-power/