Updating uncertainties in friction angles of clean sands
For lower value materials (e.g., sand, gravel and clay)which account for the bulk of the material minedthe amount of waste material that can be tolerated is minimal.It is safe to assume, however, that the worlds mines must produce at least twice the final amount required (excluding the removal of surface overburden, which is subsequently replaced and therefore handled twice).Finding the balance between the desire of mining companies to cut costs and those of workers to safeguard their jobs has been a key issue throughout the world of mining.
For example, each ounce of gold is the result of dealing with about 12 tonnes of ore; each tonne of copper comes from about 30 tonnes of ore.
Some work in an atmosphere without natural light or ventilation, creating voids in the earth by removing material and trying to ensure that there will be no immediate reaction from the surrounding strata.
Despite the considerable efforts in many countries, the toll of death, injury and disease among the worlds mineworkers means that, in most countries, mining remains the most hazardous occupation when the number of people exposed to risk is taken into account.
The environmental effect of the use of minerals is becoming an important issue for the industry and its workforce.
The debate on global warming, for example, could affect the use of coal in some areas; recycling lessens the amount of new material required; and the increasing use of non-mineral materials, such as plastics, affects the intensity of use of metals and minerals per unit of GDP.
Minerals and mineral products are the backbone of most industries.