Natural resources are the foundation for our lives and lifestyles.
What would our lives be like without mining? Imagine a world without transportation such as jet planes or railroads, without communications such as cell phones or radar, without decorative items such as art or jewelry, without buildings such as skyscrapers or parking garages, without defense systems items such as missiles or submarines, without medical care items such as X-rays or surgical tools. We wouldn’t have any of these things without mining and minerals.
Limestone is a sedimentary rock composed mostly of the mineral calcite and comprising about 15% of the Earth's sedimentary crust. It is a basic building block of the construction industry (dimension stone) and the chief materials from which aggregate, cement, lime, and building stone are made. 71% of all crushed stone produced in the U.S. is either limestone or dolomite. As a source for lime, it is used to make paper, plastics, glass, paint, steel, cement, carpets, used in water treatment and purification plants, in the processing of various foods and household items (including medicines).
Rock Classification: sedimentary
Most limestone and dolomite are mined from open quarries, although in many areas economic and environmental considerations favor large-scale production by underground mining. The only carbonate materials not consistently recovered by surface or underground mining are shell products that are dredged from parts of U.S. coastal waterways.
Surface Limestone Mining:
The basic elements of surface mining are overburden removal, drilling, blasting and hauling ore to the crushing and processing plant. The selection of surface mining equipment varies with the particular requirements at each operation, including production capacity required, size and shape of the deposit, haul distances, estimated life of the operation, location relative to urban centers, and other social and economic factors. Other factors that must be considered in surface mining are the value of the products produced, location of competitive operations, and environmental and safety requirements associated with a particular deposit.
Underground Limestone Mining:
The basic operations in underground mining are drilling, blasting, loading and hauling, scaling, and roof bolting. Drilling equipment includes horizontal drills and down hole track drills. This equipment is generally quite different from that used for surface mining and results in much smaller blast holes and a lower volume of rock produced with each blast. Other equipment required in the underground mine includes powder loaders, which are used to blow ammonium nitrate–fuel oil mixtures into the blast holes. Scaling rigs, which are used to remove loose rocks from the ribs and roof of the mine, and roof-bolting equipment may also be required in an underground mine.
Most underground limestone and dolomite mines are room-and-pillar-type operations, and many recover rock from both headings and benches. It is not uncommon for an underground limestone mine to have several benches and an overall mine height up to 30 m. Whereas the thickness of the deposit being mined is directly controlled by the thickness of the rock and related roof conditions, it is not uncommon for an individual heading to be 7.5 to 10.5 m high, and in some instances to reach as high as 15 m. Rooms are generally 13.5 to 15 m wide, which, depending on the type of drilling jumbo used, normally can be mined with one- or two-drill setups.
A V-type drill pattern is commonly used to maximize the amount of rock produced with each shot to reduce the amount of unbroken rock in the shot face. Roof scaling is normally required as a safety measure; roof bolting may or may not be required, depending on roof conditions at the individual mine. Loading and hauling equipment may include standard 22 to 45 ton haul trucks and correspondingly sized front-end loaders. In some mines, the loading equipment may be more typical of underground hard-rock operations, and may include load-haul-dump units or other types of tramming equipment.