Quarry

A quarry is used for extraction of solid rock from a rock deposit. When one speaks of loose rock sand or gravel pit.

The rock excavation can be operated in the depth and breadth or on a mountain in the horizontal direction. The majority are open pit quarries, also referred to as open quarries. In special cases the rock is mined in underground quarries.

Most quarries are the reduction of bulk and mass of raw materials for industry. Quantitatively, even later come quarries for building stone ( paths coverings, interior decoration, facades, grave stones, garden design, etc.).

History

The Egyptians broke mainly soft rock, such as limestone and sandstone quarries, which were located in the immediate vicinity of the structures. Limestone was used for all the great pyramids of the Old Kingdom, as the Cheops Pyramid, the Pyramid of Khafre and the Pyramid of Menkaure in Giza. Quarries for hard rock were at Mons and Mons Claudianus Porphyrites in Egypt. A most notable example of an ancient Egyptian quarry forms the Unfinished Obelisk of Aswan. The Great Temple of Ramses II at Abu Simbel was wrapped in sandstone.

The Greeks broke in antiquity from mainly marbles and rare sand or limestone. For example, they built the Acropolis with Pentelinischem marble, whose quarry was located not far from Athens. However, they also transported large single pieces like the Kouroi on ships.

The Romans broke mainly soft rock, such as Roman travertine from Tivoli and volcanic tuffs from the room Orvieto; to the 2nd century they referred mainly marble from the Greek island of Paros and used later for more valuable work Carrara marble. However, they also began, marble and limestone for the purpose of lime ( lime burning ) degrade.

Quarries on German territory were operated on a larger scale only since the Roman times. Important Roman quarries were about the sea rocks in the Odenwald, the Kriemhildenstuhl in the Palatinate. It was not until the Romanesque period began in Germany a quarry to build the church buildings of sandstone and limestone in a larger scale.

Process Description

With a deposit approved to reduce the process chain consists initially of the elimination of any existing overburden, thereafter the collection, mostly by blasting. Then, the usable rock is transported to the processing plant, in which the feed material crushed by means of crusher or mill and is classified, if necessary wires or classifier. A modern quarry is a capital intensive and highly automated operation. The end products are some exceptions building materials, which are divided according to their grain size: crushed stone, gravel, gravel, ballast and water blocks. As chippings repeatedly broken chippings are called, which are used in particular in the qualified asphalt road, but also in concrete production.

A special form of the quarry are enterprises that produce market-driven shaped natural stones such as disks or paving stones. In this type of the quarry are the most famous rocks of marble, limestone, granite, basalt and slate. Ideally, it involves deposits whose strata are already structured according to the desired shape. Otherwise, the desired shapes must be made by sawing or splitting.

Natural stones used in Germany are increasingly no longer local or regional near quarries, as well as local extraction costs far higher than those for example in Asia. The operation of a quarry is subject to very extensive regulatory approval procedures and extensive conditions. The reclamation after completion of the rock degradation is regulated in detail. In Indian and Chinese quarries for example, the costs are kept low by other working conditions, safety precautions, general inhumane forms of accommodation and child labor.

Rock criteria

The nature of the mined rock is very diverse. They differ primarily according to their geological origin. Examples are limestone, dolomite, granite, basalt or greywacke. The determining quality is mainly the strength and the wear behavior. In the final product to be marketed, these criteria are also essential. There are also criteria that result from the process technology of preparation, these are mainly the purity of the classified fractions and the cubicity of particle shape.

Transport

The salable materials produced in a quarry are mostly solids with a relatively low tonnage value. When marketing therefore transport costs are often very competitive determinative; they largely define the regional marketing limits to competition. Is predominant in trucking, mainly in Switzerland and the rail transport is widespread, major supply areas can be economically realized only when appropriate conditions on marine transportation.

Business numbers in Germany

In Germany, 144 million tonnes were mined natural stone in 2004. The peak was in 1994 with 189 million tonnes ( source:. Federal Statistical Office). The number of quarries in Germany is according to the association, at around 2000, where approximately 25,000 people are employed. In particular, quarries, where rocks can be for recovery win as natural stone, report for years declining number of farms, mainly because rocks from India and China will be imported as a commodity and cheap products.