Deposit is a term from applied geology and mining for certain areas of the earth's crust in which there are natural concentrations of solid, liquid or gaseous raw materials , the mining of which is economically worthwhile ( buildable deposit) or could be worthwhile in the future (usable deposit) ) . Natural accumulations of usable ores , minerals and rocks , the extraction of which is uneconomical, are called deposits . In the legal context one speaks ofNatural resources .
The Lagerstättenkunde is both a science , the geological explored processes that lead to the accumulation of raw materials in the earth's crust, on the other hand, the term deposit purely market-economy or technically defined. Commodity markets are usually viewed as world markets .
In the English-speaking world, the German word deposit is used as a foreign word, but there it describes a particularly rich fossil deposit . The correct translation of deposit into English is instead: mineral deposit (although this term is sometimes limited to ore deposits). The economically interesting part of a deposit is a resource (or storage resource hereinafter). More precisely, however, would be: non renewable resource ( non-renewable resources ).
General evaluation factors
As is customary in most world markets, the price of raw materials results from the interplay between supply and demand . The demand for a certain raw material is determined by its possible uses. If there are inexpensive methods of producing the desired end products, the demand will increase. However, if the raw material can easily be replaced by other materials or recycled from waste , it will decrease. The raw material resources that are available can be shown in the McKelvey diagram : Here, the profitability of an occurrence is plotted against its degree of geological security. This security is assessed according to certain storage categories; see below .
The minimum content ( cut-off grade ) at which mining a deposit is still worthwhile depends not only on the quality of the raw materials, but also on many economic, technical and even political factors.
- The development costs can increase significantly, for example, due to the remote location of the deposit, extreme climatic conditions or inadequate infrastructure .
- The mining costs depend, among other things, on the depth of the earth's crust ( depth ), the amount of mountain and groundwater , the energy required for production and the technical properties of the raw materials. At times, unfavorable metallurgy can even prevent mining entirely. The McArthur River polymetallic deposit in Australia, discovered in 1956, has not been exploited to this day despite its high metal content, because the minerals cannot be metallurgically processed due to their extremely small grain size .
- The marketing costs of a deposit are particularly determined by the length of the transport routes to the customers .
- In densely built-up and industrially developed areas, the competing interests of the neighboring residents ( building land , water rights, nature conservation , etc.) are often decisive for the official refusal to dismantle.
- In some countries, the state levies taxes on the extraction of raw materials so high that economic extraction is no longer possible. Even in countries with political unrest or that are known for their expropriation policies, there is seldom a significant mining industry. However, other countries try to encourage mining with tax incentives. In the 1960s, for example, the Republic of Ireland granted foreign investors complete tax exemption for the first few years of operation. In some cases this led to intensive overexploitation and extremely short operating times for the new mines before investors withdrew from the country again.
- Since mining is a particularly capital-intensive industry, the operators are dependent on extensive investments . In 1997, for example, the scandal surrounding the Canadian exploration company Bre-X Minerals led to an enormous loss of confidence among investors in the raw materials industry. As a result, there has been a wave of bankruptcies among smaller exploration and mining companies around the world.
All of these factors must be put in relation to the achievable market price. On the other hand, technical innovations can unexpectedly turn unprofitable deposits into deposits. The Nchaga Consolidated copper mines in Zambia were able to extract 80,000 tonnes of copper from nine million tonnes of overburden after the introduction of a metal extraction process .
Raw material categories
Deposits are usually divided into three groups according to their economically most important component:
Element raw materials :
- Ores for the metallurgy (metallurgy): accumulations of metal -containing minerals such as iron ore ( magnetite , hematite and siderite ), copper gravel ( chalcopyrite ), lead gloss ( galena ), zinc blende ( sphalerite ), tin stone ( cassiterite ), silver gloss ( Akanthit ), manganese oxide ( manganese dioxide ), cinnabar ( mercury sulfide ), as well accumulations of solid occurring elements such as gold , silver or sulfur . A subgroup are spar deposits ( fluorspar and barium ) from which fluorine and barium can be extracted .
- Salts for ( agricultural ) chemistry: e.g. B. potassium chloride , magnesium sulfate , saltpetre ( nitrates ), borates , rock salt ( halite ) etc. and de-icing salt
- Hydrocarbons such as crude oil and natural gas for the production of fossil energy . These are often associated with sedimentary rocks containing kerogen ( oil shale ) and other raw materials such as asphalt , earth wax ( ozokerite ) and bitumen .
- Fossil fuels from combustible biogenic sediments and sedimentary rocks (Kausto biolithe , from Greek καύσης , combustion): z. B. Brown and bituminous coal ( anthracite coal ) and peat
- A special case is uranium mining for the extraction of uranium ores as a starting material for the production of fuel elements for nuclear power plants or fissile material for nuclear weapons
- In the broadest sense, geothermal energy also belongs to this group as a natural resource.
Property raw materials
- Industrial minerals : e.g. B. kaolin (clay), feldspar and bitter spar ( magnesite ), quartz , graphite , talc , asbestos , mica , alums , vitriols as well as corundum and diamonds of inferior quality for abrasives production
- so-called "stones and earth": usable rock such as granite , limestone , gypsum , clay , kieselguhr , bentonite , dolomite , trass , colored earth , phosphates and bulk raw materials for the production of building materials, such as As the gravel surface mining for the extraction of gravel , sand and gravel - overlaps with the previous group occur.
- Gemstones : z. B. Diamond, emerald , ruby / sapphire , garnet , amber etc.
The sum of all deposits and deposits in a particular region forms the reserves or resources there. The basis for the calculation of resources, both for entire countries and for individual deposits, is a scheme of stock categories that describes the approximate level of knowledge about the respective stocks. The key figures are the error limit (FG) and the reliability of information (AS). For example, so that a resource can be designated as safe, so much data must be available that the error limit is not more than about 10% and there is a confidence level of more than 80%. This means that if you have calculated a supply of 100,000 tons of ore in a deposit, for example from sampling, drilling, mapping, etc., then the amount actually available should be between 110,000 and 90,000 tons, and the probability that these amounts will exceed or exceed should be less than 20%. The more sparse the available data, the higher the margin of error and the lower the reliability of the information.
The usual classification describes the supplies as:
- Safe ( proven ): (FG: about 10%; AS:> 80%) The extent and shape of the resource ( e.g. an ore or an oil field ) are known.
- Likely ( probable ): (FG: about 20%; AS: 60 to 80%) The size of the resource is only incompletely known, but it is a connection to a secure resource.
- Possible, as indicated ( possible , Indicated ): (FG: about 40%; AS: 40 to 60%) The resource is through outcrops known at a distance, explored by reliable geophysical measurements or by test drilling.
- Assumed ( inferred ): (FG: approx. 60%; AS: 20 to 40%) The resource has only been explored through a few outcrops, or its existence is assumed based on geophysical or geochemical data .
- Prognostic ( undiscovered ). These are the as yet undiscovered deposits, but their discovery can be expected in the future by comparing them with the geology of other, well-known areas. The prognostic stocks can still be divided into hypothetical (AS: 10 to 20%) and speculative (AS: <10%).
North American model, the stock categories are safe and probably as measured ( Measured ) summarized. Together with the possible resources, they form the identified ( demonstrated ) resources. If you add the assumed resources, you get all the identified resources. The resources discovered thus include all reserves, the location, content, quality and quantity of which are known or can be estimated from specific geological findings . This contrasts with the prognostic stocks.
In addition, there are numerous other classifications of resources, both in the different countries and for the different types of deposits, as well as by the individual mineral explorers. Sometimes the reserves are distinguished from the resources. The meaning of the two terms is so different in the various languages that a consistent use of the term reserve is almost impossible. In German, it usually refers to the part of a resource that can be economically extracted at the time of the valuation. The term resource is then often equated with unbuildable supplies. With falling world market prices, deposits worth building with reserves can turn into deposits with resources that are not worth building, and vice versa.
The United States Geological Survey provides the following definition:
- Stock base ( reserve base ): That part of an identified resource that satisfies the specific physical and chemical minimum criteria for the current mining and production practices, including those for content, quality, thickness and depth. The reserve base includes both current economic reserves as well as reserves that can possibly be economically reduced within a certain planning period.
- Reserves ( reserves ): That part of the reserve base which could be economically extracted or produced at the time of determination. The term does not have to mean that extraction systems are installed and working. Reserves only contain extractable amounts of substance.
Exploration and investigation of deposits
After preparatory literature research and the first reconnaissance in the area, the prospecting phase begins . If the signs suggest a deposit, special mapping is carried out, the surface is digged , or the first shallow exploratory drilling is carried out.
After an area of interest has been located, the demarcation follows. The detailed investigations ( geological mapping , sampling in pits and boreholes, geochemical and mineralogical - petrographic analyzes) are systematically continued and expanded. In this phase, geophysical methods such as gravimetry , seismics , magnetics , electrical and radar methods are increasingly used.
At the end of this phase of exploration, it should be possible to estimate the dimensions of the deposit and to calculate the reserves for the first time.
In the best case, the actual development follows. The exploration work will be complemented by technical experiments and find the feasibility (English: study feasability-study ) their preliminary statements. Then the actual mining can begin.
Conflict Potential and Mining Law
The development and exploitation of deposits is very time-consuming and cost-intensive, leads to extraordinarily high yields, but also costs in aftercare and has considerable effects and after-effects on the environment and the surrounding area. It can thus lead to considerable conflicts at regional, national and international level. For global mining companies and their employees, the security of contracts and investments is of great importance, state institutions are interested in the highest possible taxes and duties from the mining business, customers and recipient countries want security of supply and low prices.
There are two basic legal concepts and conflict resolution mechanisms with regard to local ownership of natural resources.
- the principle of mountain freedom : that is, the state has the right to dispose of the mineral resources . This legal tradition is particularly prevalent in German mining law and in many countries whose economies are largely based on the export of raw materials.
- the principle of owner mining. In principle, the landowner is the owner of the mineral resources. On public land, the finder acquires rights to his find. This view comes from the English common law . The French Civil Code and the legal systems based on it represent a mediating point of view. The above-ground deposits belong to the landowner and the underground deposits to the state, which can issue mining licenses to the relevant companies. In the Federal Republic of Germany, a distinction was made between the excavation law and the federal mining law, whereby the mining supervision remains a state matter. The GDR, on the other hand, had a central supreme mining authority .
Depending on the location, course and development of deposits and deposits, this also results in conflicts between different legal traditions, regional authorities and contractual regulations. The discovery or possible development of extensive raw material deposits can exacerbate existing territorial conflicts and problematic border-drawing issues as well as contribute to new legal instruments such as the 200-mile zone for coastal states. Conversely, successful cross-border conflict settlement - such as with the ECSC as the forerunner organization of the EU , the North Sea Oil or the Spitsbergen Treaty - are a stable basis for international cooperation.
- F. Neukirchen, G. Ries: The world of raw materials: Deposits, extraction and economic aspects , Springer Spectrum, Berlin 2014, ISBN 978-3-642-37738-9 .
- WL Pohl: Mineral and energy raw materials: An introduction to the formation and sustainable use of deposits , 5th edition, Schweitzerbartsche Verlagbuchhandlung, Stuttgart 2005, ISBN 3-510-65212-6 .
- FW Prokop, W. Streck, M. Sagher, RW Tschoepke, HW Walther, H. Pietzner, G. Stadler, H. Vogler, H. Werner: Investigation and evaluation of deposits of ores, usable minerals and rocks (Vademecum 1) , 2nd edition, Geological State Office North Rhine-Westphalia, Krefeld 1981.
- Schrätze, Helmut (1984) Geotectonics and Formation of Deposits. Geosciences in our time; 2, 3; 82-89; doi: 10.2312 / geosciences . 1984.2.82 .
- Geological portrait of deposits in the Mineralienatlas Wiki
- Lecture Electricity Economics TU Clausthal (PDF; 250 kB)
- Mineral Commodity Summaries , on usgs.gov