kaolin
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Kaolin , also known as china clay , porcelain clay , white clay , china clay or in the pharmacy as bolus alba or pipe earth , is a fine, iron-free, white rock that contains kaolinite , a weathered product of feldspar , as its main component . Other components are various other clay minerals and undecomposed feldspar particles.
Kaolin is mainly in the production of paper and for the preparation of porcelain used . In addition, Bolus alba is used, among other things, as a component of some powder bases and also added to food (see use ).
The price for one tonne of kaolin was between 137 and 190 US dollars from 2006 to 2012 . In 2003 a consumption of 45 million tons was covered by a production volume of 45.6 million tons.
In 2013, kaolin was the first unconsolidated rock of the year .
etymology
The word kaolin ( Chinese 高嶺土 / 高岭土 , Pinyin gāolǐngtǔ - "earth from Gaoling") is derived from the Chinese place name Gaoling ( 高嶺 / 高岭 , gāolǐng - "high mountain range"). This is the name of a village in the People's Republic of China in the northwest of Jiangxi Province , in Fuliang County in the district-free city of Jingdezhen . There the “white earth”, the Germanized kaolin , was found. The word came to Europe in the 18th century through a French Jesuit priest, where it replaced the previously common terms “white clay” or “Passau earth”.
Occurrence and mining
A deposit on the Aeolian Islands (Italy) was already exploited 2000 years ago .
Deposits
Two types of kaolin deposits can be distinguished:
- Primary occurrence
A distinction is made between hydrothermal deposits and residual deposits. Granites or rhyolites are chemically weathered on site, i.e. in situ by surface water, flowing groundwater or hydrothermal fluids.
- Secondary occurrences
Secondary kaolins are mostly rearranged primary kaolins. They were eroded at the point of origin, then transported and deposited together with other material in the form of lenses. Some secondary kaolinites were formed by hydrothermal alteration , i.e. chemical weathering by groundwater, of arkoses . A sediment with a feldspar content of more than 25% is called arkosis.
Worldwide occurrence
Kaolin occurs comparatively rarely in nature; there are notable deposits in Brazil, the USA, Germany , France, England , the Czech Republic , Japan , China , India and the Philippines. The worldwide assured and probable reserves are calculated at 14.2 billion tons, the worldwide annual production in 2003 was 45.6 million tons. Based on these data, the global kaolin reserves theoretically reach until 2300.
Dismantling
The main mining countries for kaolin clay in 2014 were after Brazil (7.7%), the USA (20.9%), China (11.5%) and Germany (17.6%).
The largest mining companies worldwide are Imerys (F), CADAM / PPSA (Bra), Thiele (USA), BASF (USA), Huber (USA) and Amberger Kaolinwerke (Germany), which now operate under the umbrella of the Quarzwerke Group .
Germany, Poland, Czech Republic, Ukraine
The main mining areas for kaolin in Germany are near Hirschau in the Upper Palatinate. One of the most important continental kaolin, quartz sand and feldspar deposits in Europe is located in the kaolin area in the Hirschau-Schnaittenbacher Senke . The Amberger Kaolinwerke (founded in 1901), the largest manufacturer of the industrial mineral kaolin in Germany, and the traditional Dorfner group of companies mine the raw earth there in open-cast mines; it is processed into porcelain primarily in the companies Seltmann Weiden and Bauscher .
In Lohrheim im Taunus and also in the Westerwald , kaolin is occasionally mined.
Another mining area is located in the central Saxon hill country near Seilitz and Kemmlitz ( "Börtewitz Basin" ). Kaolin, which was formed by kaolinitic weathering of granites , is extracted from the deposits there for Meissen porcelain . From 1901 to 1965 kaolin was also mined for this purpose near Hohburg in the Leipziger Land (Hohburg village book by Manfred Müller).
Kaolin and white-burning clay are mined by Kaolin- und Tonwerke Salzmünde GmbH from pits in the Halle (Saale) area near Salzmünde / Möderau, Etzdorf, Spergau and Rossbach.
Small deposits were or still exist in the Rheingau in the former Geisenheim kaolin quarry and in Rheinhessen .
In addition to the plant in Hirschau-Schnaittenbach, Quarzwerke GmbH (Amberger Kaolinwerke) operates mining in Kemmlitz (Kemmlitzer kaolin works) and in Caminau ( Caminau kaolin works ) in Upper Lusatia in Saxony .
Kaolin is mined in Poland in Nowogrodziec (Naumburg am Queis, east of Görlitz ) and in Gluhivzi in the Ukraine (a location of Quarzwerke GmbH).
Czech mining areas are located near Pilsen and Karlsbad . Other - mostly closed - kaolin pits are located around Lieskau and Röblingen am See in Saxony-Anhalt and in the Ore Mountains near Aue .
Dismantling in Austria
Austria is the sixth largest producer in the world. The main deposits and operations in Austria are in Kriechbaum-Weinzierl (municipalities of Allerheiligen im Mühlkreis , Perg ( Weinzierl ), Schwertberg , Tragwein , pit and opencast mining) and Aspang / Zöbern .
In Austria, Kamig (Österreichische Kaolin- und Montanindustrie Aktiengesellschaft) in Tragwein is the largest of the three existing mining companies. In 2004, 80 people were employed at two mining sites in Lower Austria and one in Upper Austria, and 104,986 tons of raw kaolin were mined in open-cast mining, in Upper Austria also in mining. This resulted in 16,345 tons of pure kaolin in tragacanth and 5,832 tons of muscovite mica in the Lower Austrian mining sites.
Varieties
Varieties of kaolin have names from Anglo-Saxon mining that have been adopted by the processing industry:
- Ball clays
contain only small amounts of other minerals or organic material. Firing creates white products such as sanitary ware, but also tiles and tiles.
- Fireclay
is found directly under coal seams and - apart from higher temperature resistance - has properties similar to ball clay.
Depending on the deposition environment, volcanic ash can be converted into minerals or remains as such. Water is necessary for the ashes to alter. If the sedimentation environment is acidic, for example in coal swamps where organic acids are found from the decay of plants, the ashes are converted to kaolinite. This rock is known as "claystone". Old "claystones" that have undergone a precipitation reaction are "fireclays".
- Underclays
may or may not contain kaolinite. The "underclay" is the area directly under a coal seam and was the ground on which the plants that make up coal today grew. When "underclay" is referred to as "fireclay", it is rich in kaolinite. Refractory bricks and cements, for example for molding sand in foundries, are made from “underclay”, “fireclay” or “flint clay”.
- Flint clay
is hard, smooth and breaks like a shell. It does not develop plasticity (malleability) when it is mixed with water and cannot be extinguished. "Flint clay" crystallizes from a gel with a kaolinite composition on the bottom of lakes, possibly karst lakes.
properties
| Oxidic composition in% | ||
| oxide | theoretically | typical analysis |
|---|---|---|
| Al 2 O 3 | 39.50 | 38.5 |
| SiO 2 | 46.54 | 45.5 |
| Na 2 O | - | 0.1 |
| TiO 2 | - | 1.4 |
| Fe 2 O 3 | - | 0.3 |
| H 2 O | 13.96 | 13.7 (unfired) |
Kaolinite, the main component of kaolin, is a hydrated aluminum silicate. From a chemical point of view, kaolinite is thus an aluminum salt of silica. Kaolinite is synthetically produced from polysilicic acid and aluminum hydroxide under hydrothermal conditions. The theoretical formula is Al 2 O 3 · 2SiO 2 · 2H 2 O or, as a sum formula, Al 2 Si 2 O 5 (OH) 4 . In the Color Index it is listed under PigmentWeiß19 and with its chemical structure under CI 77005. It is a natural, fine-grained and well crystallized clay mineral with a “book” -like structure - a sheet silicate . In each of these “book pages” the same layering of octahedral aluminate and tetrahedral silicate layers is repeated, which are connected by layers of oxygen atoms. Due to this layering, the plasticity (deformability) is low, but the chemical structure provides a high level of fire resistance and a solid, dense body is formed when burning . In addition, this structure leads to small particle sizes.
Kaolin is a white powder with a density of 2.58 g / cm³ and the only white, technically available mineral pigment that occurs naturally with a particle size of less than 2 µm. The melting point of kaolin is around 1450 ° C. The whiteness of the dry reflection is 82% for a coarse kaolin and up to 87% for fine kaolin, an anhydrous calcined kaolin can also reach over 91%. The refractive index is 1.56. Its Mohs hardness is 2.5. A fine kaolin has a spherical equivalent particle diameter of 0.5 µm and a proportion of 90% particles under two micrometers, for a 325-mesh sieve the residue is less than 0.01%. Simpler, coarse kaolins have an equivalent diameter of 3.5 µm and form 0.1% residue on the 325 sieve, but even this has 40% of the particles below 2 µm.
The oil requirement as a measure of the relative surface area is 32 g / 100 g for a coarse kaolin, 45 g for 100 g fine kaolin and 55 g for 100 g calcined kaolin.
use
| Industry / use | Share of total use |
|---|---|
| Paper coating | 49.7% |
| Filler in the paper | 22.8% |
| Rubber industry | 13.2% |
| Paint and plastics industry | 4.5% |
| Ceramic industry other "non-filler" |
6.2% |
| Food and fertilizer industry | 3.2% |
| Insecticides / fungicides | 0.4% |
In addition to being used as china clay, kaolin is mainly used as a filler. Its pigment properties depend on the type of substrate.
Ceramics
Thanks to its high melting point of 1450 ° C, kaolin is mainly used in the ceramics industry as a basis for the production of white porcelain and for light-burning clay masses. Well-known end product is the Meissen porcelain . An additive in the production of floor and wall tiles promotes the quality; the higher the kaolin content, the larger the tile can be, as its mechanical properties are improved after firing.
Pigment and filler
- As a white pigment , it is used in the manufacture of coating colors and paints .
- In papermaking it has a double role as a filler in the pulp and as a coating pigment for coatings.
- In polyethylene (HDPE), kaolin can be used as a filler to improve the modulus of elasticity .
- Soft kaolin is used in tire production.
- In cosmetics it serves as the basis for the manufacture of powder and is often used in deodorant creams.
- As a raw material in the “lead” and colored pencil production (“lead” and colored lead).
Food
Kaolin is added in the food industry as a carrier , separating agent and bleaching agent. This is what the name bleaching earth is based on, because due to its structure it absorbs secondary substances that are easy to absorb. Kaolin is not absorbed by the human intestine, but excreted unchanged. The quantities used are also very small and the substance is considered harmless. In the EU it was approved as a food additive with the number E 559 for certain foods and as a carrier for colorings until January 31, 2014 . Kaolin is also used for animal feed. Furthermore, kaolin is used in the production of fine fruit as a sunscreen for the sensitive apple peel in aqueous suspension in the plantations.
Pesticides
Kaolin as an active ingredient in pesticides is permitted at least in the EU and Switzerland. Be fought about the pests Birnblattsauger , walnut fruit , cherry fruit fly and pollen beetle .
Others
- As a coagulant in blood collection tubes (for calculating the PTT , a coagulation parameter).
- As bedding material in the gasification of solid fuels in fluidized bed gasifiers .
Like other absorbent powders, kaolin can be used as a cleaner for grease stains on fabric or paper. It is applied thickly, and over a longer period of time the fat from the tissue is distributed in the larger amount of kaolin. It is cleaned by tapping it.
In cosmetics as a face pack (see also white clay). Effect: Cleansing and fat-absorbing effect on skin impurities.
In combination with cayenne pepper ( capsaicin or capsicinoids are the active ingredient), mustard oil and water , kaolin is used in the form of Munari packs (Italian pack) as heat therapy for pain and tension in the musculoskeletal system, individually or in combination with massage .
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy . 7th edition. Springer, Berlin 2005, ISBN 3-540-23812-3 .
Web links
- Geodidactic short film "From volcano to porcelain" - report by Lutz Geißler on "Network for geoscientific public relations", requested on August 6, 2009
Individual evidence
- ↑ https://de.statista.com/statistik/daten/studie/246402/umfrage/preisentwicklung-von-kaolin/ Information from Statista GmbH: Price development of kaolin from 2006 to 2012 , accessed on May 15, 2020
- ↑ a b Kaolin - Rock of the Year 2013 ( Memento from March 12, 2016 in the Internet Archive ) Hessian State Office for Nature Conservation, Environment and Geology
- ↑ F. Machatschki: Reserves and distribution of mineral raw materials , Springer-Verlag 2013, 191 pages, page 754
- ↑ https://www.bgr.bund.de/DE/Themen/Min_rohstoffe/Downloads/studie_rohstoffwirtschaftliche_einordnung_2014.pdf?__blob=publicationFile&v=4 Federal Institute for Geosciences and Raw Materials / M. Drobe, F. Killiches: Occurrence and production of mineral raw materials - a country comparison , page 18, accessed on May 15, 2020
- ↑ Kaolin- und Tonwerke Salzmünde GmbH (Ed.): 190 Years of Kaolin- and Tonwerke Salzmünde, Verlag Störr, Usedom, 2008.
- ↑ https://www.quarzwerke.com/footer/news-detail/news/neue-nassklassierung-in-gluhivzi-ukraine/ Message from Quarzwerke GmbH on the Gluhivzi location, accessed on May 15, 2020
- ↑ a b c Temple C. Patton: Pigment Handbook Volume 1 Properties and Economics . John Wiley & Sons, London 1973. ISBN 0-471-67123-1 .
- ↑ Regulation (EU) No. 380/2012 of the Commission of May 3, 2012 amending Annex II of Regulation (EC) No. 1333/2008 of the European Parliament and of the Council with regard to the conditions and quantities of use for food additives containing aluminum . In: EUR-Lex .
- ↑ Food: Dioxin hazard from open-cast mining. In: Focus Online . November 8, 2004, accessed January 22, 2015 .
- ↑ mdr.de: Simply genial ( Memento from February 15, 2013 in the Internet Archive ), August 30, 2011.
- ↑ Glenn, D. E Prado, A. Erez, J. McFerson, G. Puterka. 2002. A reflective, processed-kaolin particle film affects fruit temperature, radiation reflection, and solar injury in apple. J. Amer. Soc. Hoard. Sci. 127 (2): 188-193.
- ↑ General Directorate Health and Food Safety of the European Commission: Entry on aluminum silicates (aka kaolin) in the EU pesticide database ; Entry in the national directory of plant protection products in Switzerland ; accessed on May 25, 2019.
- ↑ Gerda Vacariu, Othmar Schuhfried, Marta Korpan: Physical therapy and rehabilitation for pain syndromes in the musculoskeletal system. In: Compendium of Physical Medicine and Rehabilitation. 3rd edition, 2013, p. 357 ISBN 978-3-7091-0467-5 .
