The nature of mining processes creates a potential negative impact on the environment both during the mining operations and for years after the mine is closed. This impact has led to most of the world’s nations adopting regulations to moderate the negative effects of mining operations. Safety has long been a concern as well, though modern practices have improved safety in mines significantly.
Mining methods are constantly changing and improving as companies forge new technologies to enhance rates of extraction and minimise impacts such as noise, dust and land and water disturbance. There are numerous mining methods utilised around the world including open-cut mining (truck-and-shovel, strip mining, quarrying and dragline), underground mining (stoping methods, bord-and-pillar, longwall, caving methods, cut-and-fill and retreat benching) and highwall mining hammer crusher.
The primary opening into an underground mine can either be a shaft, a ramp (which can also be called a decline) is driven downinto the earth, or an audit which is a horizontal opening that is driven into the side of a mountain or hill. They all have the same purpose – to provide access for people, equipment and materials and to supply a way of making ore to be brought to the surface. Most of the time, shafts are vertical, but they can also be inclined, they are equipped with headframes and hoists, the headfames are the structures at the top of the hoist which enclose it.
On the other hand, ramps, most of the time spiral downward at a gradient of about 15% to permit access into the mine by mobile equipment which are rubber-tired. In few cases, the ramps are driven in straight lines to accommodate conveyor belts, or they have straight runs with switch back points. Ramps are in most cases cheaper than shafts when it comes to developing. But the total cost might be higher than the cost of developing a shaft to reach the depth desired when it is dependent on the angle of the decline, the size of the opening and the encountered ground conditions.
These factors among others are what will influence the selection of a mining method and the overall plan for developing the orebody. Operating mines vary in size from small underground operations (some of these operations have only a few levels of production and may produce less than 100 tonnes of ore per day) to the large open pits (some of which move thousands of tonnes or ore and waste rock per day).
- quarry: http://www.hxjq-mill.com/news/quarry_machine.html
- hammer crusher: http://www.hx-crusher.com/n123.html
- cement making machinery: http://www.hx-crusher.com/n266.html
- coal crusher: http://www.hx-crusher.com/n273.html