Oil shale in Estonia
Encyclopedia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
's oil shale
Oil shale
Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...
deposits account for just 17% of total deposits in the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
but the country generates 90% of its power from this source. The oil shale industry in Estonia employs 7,500 people—about one percent of the national work force—and accounts for four percent of its gross domestic product.
There are two kinds of oil shale in Estonia – Dictyonema
Basidiolichen
Basidiolichens are lichenized members of the Basidiomycota, a much smaller group of lichens than the far more common ascolichens in the Ascomycota. In arctic, alpine, and temperate forests, the most common basidiolichens are in the agaric genus Lichenomphalia and the clavarioid genus Multiclavula...
argillite
Argillite
An argillite is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillaceous rocks are basically lithified muds and oozes. They contain variable amounts of silt-sized particles. The argillites grade into shale when the fissile layering typical of shale is...
(claystone
Claystone
Claystone is a geological term used to describe a clastic sedimentary rock that is composed primarily of clay-sized particles ....
) and kukersite
Kukersite
Kukersite is a marine type oil shale of Ordovician age, found in the Baltic Oil Shale Basin in Estonia and North-West Russia. It was named after Kukruse settlement in Estonia in 1917 by Russian paleontologist Mikhail Zalessky....
. The first attempt to establish an open-cast oil shale pit and to start oil production was undertaken in 1838. Modern utilization of oil shale commenced in 1916. Production began in 1921 and the generation of power from oil shale in 1924.
In 2005 Estonia was the leading producer of shale oil
Shale oil
Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock into synthetic oil and gas...
in the world. Of all the power plants fired by oil shale, the largest was in this country.
As of 2007, six mines (open cast or underground) were extracting oil shale in Estonia.
Reserves
There are two oil shale types in Estonia–Dictyonema argillite (claystone) and kukersite.Dictyonema argillite
The marineMarine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
-type Estonian Dictyonema argillite (also known as Dictyonema oil shale, Dictyonema shale or alum shale) of an Early Ordovician age is a brown lithified claystone belonging to the formation of black shales of sapropel
Sapropel
Sapropel is a term used in marine geology to describe dark-coloured sediments that are rich in organic matter...
ic origin. It occurs in most of northern Estonia on an area of about 11000 square kilometres (4,247.1 sq mi). The thickness of the Dictyonema argillite layer varies from less than 0.5 metres (1.6 ft) to 8 metres (26.2 ft) and lays at a depth of 10 to 90 m (32.8 to 295.3 ft). Geological reserves of Dictyonema argillite in Estonia were estimated approximately to 70 billion tonnes. Although reserves of the Dictyonema argillite surpass those of kukersite, its quality is poor as a source for the energy production. The heating value of the Dictyonema argillite is 5–8 MJ/kg, and the Fischer Assay
Fischer Assay
The Fischer assay is a standardized laboratory test for determining the oil yield from oil shale to be expected from a conventional shale oil extraction. A 100 gram oil shale sample crushed to...
oil yield is 3–5%. The organic content of the Dictyonema argillite of north-western Estonia varies from 10 to 20%, and it contains up to 9% pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
. It also contains a small scale of heavy metals, such as uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
(up to 300 g/t), molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
(up to 600 g/t), and vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
up to 1200 g/t. The argillite of north-western Estonia has sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
content of 2–4 %; it contains fewer metals and up to 17% of organic matter.
Kukersite
Kukruse
Kukruse is a village in Kohtla Parish, Ida-Viru County in northeastern Estonia.Kukersite, a marine type oil shale of Ordovician age, is named after Kukruse.Eduard von Toll lived in Kuckers manor....
settlement in Estonia. Kukersite lies near the surface and dips to the south, so that deposits are found at depths from 7 to 170 m (23 to 557.7 ft). It occurs as an often calcareous layer of 2.5 to 3 m (8.2 to 9.8 ft) thickness. There are a total of 50 oil shale layers. Kukersite was deposited in a shallow marine basin, forming a part of the Baltic oil shale basin with a total area about 3000 square kilometres (1,158.3 sq mi) to 5000 square kilometres (1,930.5 sq mi). The main kukersite deposits in Estonia are the Estonian deposit and the Tapa deposit.
Estonian kukersite deposits are one of the world's highest-grade deposits with more than 40% organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
content and 66% conversion ratio into shale oil and oil shale gas
Oil shale gas
Oil shale gas is a synthetic gas mixture produced by oil shale pyrolysis. Although often referred to as shale gas, it differs from the natural gas produced from shale, which is also known as shale gas.-Process:...
. Fischer Assay oil yield is 30 to 47%. The principal organic component of kukersite is telalginite
Telalginite
Telalginite is a structured organic matter in sapropel, composed of large discretely occurring colonial or thick-walled unicellular algae such as Botryococcus, Tasmanites and Gloeocapsomorpha prisca. Telalginite is present in large algal bodies. It fluoresce brightly in shades of yellow under...
, derived from the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
green alga
Green algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
, Gloeocapsomorpha prisca, which has affinities with the modern cyanobacterium, Entophysalis major, an extant species that forms algal mat
Algal mat
An algal mat is a layer of usually filamentous algae on marine or fresh water soft bottoms. It may be considered one of many types of microbial mats. Algae and cyanobacteria are ubiquitous, often forming within the water column and settling to the bottom. In shallow environments, they are often...
s in inter-tidal to very shallow subtidal waters. Matrix
Matrix (geology)
The matrix or groundmass of rock is the finer grained mass of material in which larger grains, crystals or clasts are embedded.The matrix of an igneous rock consists of finer grained, often microscopic, crystals in which larger crystals are embedded. This porphyritic texture is indicative of...
mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s dominantly include low-magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
, and siliciclastic minerals
Siliciclastic
Siliciclastic rocks are clastic noncarbonate sedimentary rocks that are almost exclusively silica-bearing, either as forms of quartz or other silicate minerals. All siliciclastic rocks are formed by inorganic processes, or deposited through some mechanical process, such as stream deposits that are...
. They are not rich in heavy metals.
Early history
The first written information about oil shale in Estonia were made by August Wilhelm HupelAugust Wilhelm Hupel
August Wilhelm Hupel was a Baltic German publicist, estophile and linguist....
in 1777. According to Peter Simon Pallas
Peter Simon Pallas
Peter Simon Pallas was a German zoologist and botanist who worked in Russia.- Life and work :Pallas was born in Berlin, the son of Professor of Surgery Simon Pallas. He studied with private tutors and took an interest in natural history, later attending the University of Halle and the University...
, the occurrence of burning rock on the southern coast of the Gulf of Finland occurs in the travel notes of the 18th century naturalist and explorer Johann Anton Güldenstädt
Johann Anton Güldenstädt
Johann Anton Güldenstädt was a Baltic German naturalist and explorer in Russian service....
. According to Paul Kogerman
Paul Kogerman
In 1938–1939 Kogerman was ex officio member of the National Council . From October 1939 until the Soviet occupation of Estonia on 21 June 1940 Kogerman served as Minister of Public Education....
, Estonia's former Minister of Education and the founder of the oil shale chemistry, Estonian oil shale was discovered by a professor of University of Tartu
University of Tartu
The University of Tartu is a classical university in the city of Tartu, Estonia. University of Tartu is the national university of Estonia; it is the biggest and highest-ranked university in Estonia...
Otto Moritz Ludwig von Engelhardt.
The first scientific research on the oil yield of Estonian oil shale was carried out at the St. Petersburg Imperial Academy of Sciences
Russian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....
in 1791 by a German chemist Johann Gottlieb Georgi
Johann Gottlieb Georgi
Johann Gottlieb Georgi was a German geographer and chemist.Georgi was professor of chemistry at St Petersburg. He accompanied both Johann Peter Falck and Peter Simon Pallas on their respective journeys through Siberia. Gergi was particularly interested in Lake Baikal...
. The paper was based on the samples collected on the territory of Kohala Manor near Rakvere
Rakvere
Rakvere is a town in northern Estonia and the county seat of Lääne-Viru County, 20 km south of the Gulf of Finland.-History:The earliest signs of human settlement dating back to the 3rd-5th centuries AD have been found on the present theatre hill. Probably to protect that settlement, a wooden...
. In 1838—1839, a Baltic German geologist Gregor von Helmersen
Gregor von Helmersen
Gregor von Helmersen , was a Baltic German geologist, born at Kammeri manor , near Tartu , Estonia).He received an engineering training and became major-general in the corps of Mining Engineers...
described in detail the Vanamõisa oil shale deposit. In 1838, he undertook the first attempt to establish an open-cast pit in the vicinity of Rakvere and attempted to obtain oil from the Vanamõisa oil shale deposit by distillation. Although the attempt of shale oil distillation failed, oil shale was used as a low-grade fuel. In the nineteenth century, the geology and chemistry of oil shale were also studied in the University of Tartu
University of Tartu
The University of Tartu is a classical university in the city of Tartu, Estonia. University of Tartu is the national university of Estonia; it is the biggest and highest-ranked university in Estonia...
by Georg Paul Alexander Petzholdt, Alexander Gustav von Schrenk, Carl Ernst Heinrich Schmidt
Carl Schmidt (chemist)
Carl Ernst Heinrich Schmidt , also known in Russia as Karl Genrikhovich Schmidt was a Livonian chemist. He determined the typical crystallization patterns of many important biochemicals such as uric acid, oxalic acid and its salts, lactic acid, cholesterin, stearin, etc. He analyzed muscle fiber...
, Friedrich Schmidt
Friedrich Schmidt
Friedrich Schmidt was Baltic German geologist and botanist in Russian Empire. He won the Wollaston Medal in 1902.- External links :*...
, and others.
1900–1945
Studies of Estonian oil shale resources and mining possibilities intensified in the beginning of 20th century because of industrial development of Saint Petersburg and a shortage of fuel resources in the region. In 1910, there was a plan of construction of a large-scale shale oil plant in Estonia. The coming of World War IWorld War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, coupled with a serious fuel crisis, accelerated these studies and in 1916, a group of geologists led by Nikolay Pogrebov were sent to Estonia to organize the mining of oil shale and its transportation to St. Petersburg. In June 1916, the first tonnes of oil shale were mined in Pavandu and were delivered to the Saint Petersburg Polytechnical Institute
Saint Petersburg Polytechnical University
Saint Petersburg State Polytechnical University is a major Russian technical university situated in Saint Petersburg. Previously it was known as the Peter the Great Polytechnical Institute and Kalinin Polytechnical Institute .-Imperial Russia:...
for large-scale experiments. Oil shale was utilized at gasworks
Gasworks
A gasworks or gas house is a factory for the manufacture of gas. The use of natural gas has made many redundant in the developed world, however they are often still used for storage.- Early gasworks :...
and was also burned in boiler houses. For large-scale oil shale utilization, construction of oil shale-fired power plants and shale oil thermal processing factories was planned. However, Germany occupied Estonia and the following Estonian War of Independence caused their cancellation. At the same time, experiments on the uses of oil shale started in Estonia.
The year 1916 is considered the beginning of the Estonian oil shale industry. In 1917, Russian paleontologist Mikhail Zalessky named kukersite oil shale after the Kukruse settlement. Continuous mining activities started shortly after. In 1918, the state-owned company National Oil Shale Industry (predecessor of Viru Keemia Grupp
Viru Keemia Grupp
Viru Keemia Grupp is an Estonian holding group of oil shale industry, power generation, and public utility companies.-Operations:VKG's two main areas of operations are shale oil extraction, and electricity and heat production and distribution....
) opened an open-pit mine at Pavandu, followed by the open-pit mine at Vanamõisa in 1919 and underground mines at Kukruse and Käva in 1920 and 1924 respectively. At the same time, several foreign investors started their oil shale activities in Estonia. Underground mines were opened at Kiviõli
Kiviõli
Kiviõli is an industrial town in Ida-Viru County, Estonia with a population of 7000 . The main industry is oil shale mining, which gives the town its name...
(1922), Küttejõu (1925), Ubja (1926), Viivikonna (1936), and Kohtla
Kohtla Parish
Kohtla Parish is an Estonian municipality located in Ida-Viru County. It has a population of 1,491 and an area of 101 km².-Villages:Amula, Järve, Kaasikaia, Kaasikvälja, Kabelimetsa, Kohtla, Kukruse, Mõisamaa, Ontika, Paate, Peeri, Roodu, Saka, Servaääre, Täkumetsa, Valaste, Vitsiku.- External...
(1937). Initially, oil shale was used primarily in the cement industry, for firing in locomotive furnaces, and as a household fuel. The first large industrial consumer of oil shale was the Kunda cement factory (now Kunda Nordic Cement), which transferred its rotary kiln
Rotary kiln
A Rotary kiln is a pyroprocessing device used to raise materials to a high temperature in a continuous process. Materials produced using rotary kilns include:* Cement* Lime* Refractories* Metakaolin* Titanium dioxide* Alumina* Vermiculite...
s for cement production to oil shale firing in 1921.
Shale oil production started in Estonia in 1921, when the National Oil Shale Industry built the first experimental oil shale processing retort
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
s in Kohtla-Järve
Kohtla-Järve
Kohtla-Järve is a city and municipality in north-eastern Estonia, founded in 1924 and incorporated as a town in 1946. The city is highly industrial, and is both a processor of oil shales and is a large producer of various petroleum products. The city is also very diverse ethnically: it contains...
. These retorts used vertical retort technology, the forerunner of current Kiviter processing
Kiviter process
-History:The Kiviter process is based on the earlier vertical retort technology . This technology underwent a long process of development...
technology. In 1924, an oil plant using horizontal retort (fusion retort) technology was opened in Vanamõisa. The German-owned company Eesti Kiviõli (predecessor of Kiviõli Keemiatööstus) built four tunnel kilns between 1927 and 1938. Swedish owned Eestimaa Õlikontsortsium (Estonian Oil Consortium), founded in 1928 and operating in Sillamäe, used originally internally heated retorts, but switch to tunnel kilns in 1935.
In 1931, Consolidated Gold Fields of the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
built an oil factory at Kohtla-Nõmme
Kohtla-Nõmme
Kohtla-Nõmme is a borough in northeastern Estonia. Administratively it constitutes Kohtla-Nõmme Parish — a rural municipality within Ida-Viru County. It has a population of 1,047 and an area of 4.64 km².-External links:* *...
equipped with eight rotating retorts (Davidson's retorts). This facility was closed in 1961.
The oil shale-fired power industry started in 1924, when the Tallinn
Tallinn
Tallinn is the capital and largest city of Estonia. It occupies an area of with a population of 414,940. It is situated on the northern coast of the country, on the banks of the Gulf of Finland, south of Helsinki, east of Stockholm and west of Saint Petersburg. Tallinn's Old Town is in the list...
Power Plant switched to oil shale. Afterward oil shale-fired power plants were built in Püssi
Püssi
Püssi is an urban municipality in Ida-Viru County, Estonia, with a population of 1,838. A large brown heathland is located just to the south of the town, and the Tallinn-Narva railway runs right through the centre of the municipality, before disappearing into the dense forest typical of the...
, Kohtla, Kunda, and Kiviõli. At the beginning of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, the total capacity of oil shale power plants was 32.5 MW. These power plants used mainly furnaces with a movable-bar sloping grate (Krull-Lomshakov or Ilmarine-type).
Systematic research of oil shale and its products began in Estonia in 1925, initiated by professor Paul Kogerman.
Post World War II
After World War II, the shale oil industry was developed at Kohtla-Järve and Kiviõli. Between 1946 and 1951, 13 Kiviter-type retorts were built in Kohtla-Järve with an additional three retorts built between 1981 and 1987. In addition, between 1956 and 1968 two tunnel kilns were in operation. From 1953 to 1963, eight Kiviter-type retorts were in use at Kiviõli. The first GaloterGaloter process
The Galoter process is a shale oil extraction technology for a production of shale oil, a type of synthetic crude oil. In this process, the oil shale is decomposed into shale oil, oil shale gas, and spent residue...
-type retorts with a solid heat carrier were built at Kiviõli in 1953 and 1963 (closed in 1963 and 1981 respectively) and the Narva Oil Plant
Narva Oil Plant
Narva Oil Plant , a subsidiary of Eesti Energia, is a producer of shale oil from oil shale. It operates a commercial scale shale oil retorting plant, located in Narva, Estonia.-History:...
with two Galoter-type retorts was commissioned in 1980 near the Eesti Power Plant.
From 1948, Estonian-produced oil shale gas was used in Leningrad
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
and in northern Estonian cities as a substitute for natural gas. 276 gas generators were operational until 1987. During 1946–1952, Dictyonema argillite was used for uranium production in Sillamäe
Sillamäe
Sillamäe is a town in Ida-Viru County in the northern part of Estonia, on the southern coast of the Gulf of Finland. It has a population of 16,183 and covers an area of 10.54 km²...
.
In 1949, the Kohtla-Järve Power Plant – the first power plant in the world using pulverized oil shale at an industrial scale – was commissioned with capacity of 48 MW, followed by the Ahtme Power Plant in 1951 with capacity of 72.5 MW. The world's two largest oil shale-fired power stations – Balti Power Plant and Eesti Power Plant (known as the Narva Power Plants
Narva Power Plants
The Narva Power Plants are a power generation complex in Narva in Estonia, near the border with Leningrad Oblast, Russia. The complex consists of the world's two largest oil shale-fired thermal power plants, Eesti Power Plant and Balti Power Plant . In 2007, Narva Power Plants generated about...
) – were opened in 1965 and in 1973. Because of the success of oil shale-based power generation, Estonian oil shale production peaked in 1980 at 31.35 million tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s. In 2004, two power units with circulating fluidized bed combustion (CFBC) boilers were put into operation at Narva Power Plant.
In 1984, the scientific-technical journal Oil Shale was founded in Estonia.
Mining
As of May 2007, Estonia has been actively engaged in exploiting oil shale on a significant scale and accounts for 70% of the world's processed oil shale. In 2005, Estonia mined 14.8 million tonnes of oil shale. During the same period, mining permits were issued for almost 24 million tonnes, with applications for mining an additional 26 million tonnes. Estonia has adopted the "National Development Plan for the Use of Oil Shale 2008-2015", which limits the annual mining of oil shale to 20 million tonnes. Companies involved in oil shale mining are Eesti PõlevkiviEesti Põlevkivi
Eesti Energia Kaevandused is a subsidiary of Eesti Energia, an Estonian state-owned energy company. The core activity of Eesti Energia Kaevandused is oil-shale mining in the north-east of Estonia. The company has 3,150 employees...
, Viru Keemia Grupp
Viru Keemia Grupp
Viru Keemia Grupp is an Estonian holding group of oil shale industry, power generation, and public utility companies.-Operations:VKG's two main areas of operations are shale oil extraction, and electricity and heat production and distribution....
, Kiviõli Keemiatööstus and Kunda Nordic Cement.
Open-pit mining
Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow....
is approximately fifty-fifty, although it is tending to move away from open-cast production as bed depths increase.
The Aidu and Narva opencast mines, operated by Eesti Põlevkivi, uses surface mining
Surface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...
technology of stripping with relatively big bucket (10–35 cubic meters) excavator
Excavator
Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating platform . The house sits atop an undercarriage with tracks or wheels. A cable-operated excavator uses winches and steel ropes to accomplish the movements. They are a natural progression from the...
s. Both the overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
and the bed
Bed (geology)
In geology a bed is the smallest division of a geologic formation or stratigraphic rock series marked by well-defined divisional planes separating it from layers above and below. A bed is the smallest lithostratigraphic unit, usually ranging in thickness from a centimeter to several meters and...
are at first broken up by blasting
Rock blasting
Rock blasting is the controlled use of explosives to excavate, break down or remove rock. It is practised most often in mining, quarrying and civil engineering such as dam or road construction...
. Stripping is done with smaller excavators in opencasts with thin overburden using front end loaders
Loader (equipment)
A loader is a heavy equipment machine often used in construction, primarily used to load material into or onto another type of machinery .-Heavy equipment front loaders:A loader A loader is a heavy equipment machine often used in construction, primarily used to load material (such as asphalt,...
and hydraulic excavators. The Aidu opencast mine uses bulk extraction of all beds, while the Narva opencast mine and the Põhja-Kiviõli opencast mine, operated by Kiviõli keemiatööstus, use highly selective extraction in three layers of seams. Exhausted open-cast areas are gradually being regenerated through land recultivation and reforestation
Reforestation
Reforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation....
.
Underground mines exploit room and pillar
Room and pillar
Room and pillar is a mining system in which the mined material is extracted across a horizontal plane while leaving "pillars" of untouched material to support the roof overburden leaving open areas or "rooms" underground...
method. Longwall mining
Longwall mining
Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice . The longwall panel is typically 3–4 km long and 250–400 m wide....
, used earlier, was abandoned in 1990s. The largest oil shale mine in the world is the Estonia Mine, opened in 1972. It is operated by Eesti Energia Kaevandused.
Shale oil extraction
In 2005, Estonia was the largest shale oil producer in the world although it is expected that as of 2007, China has taken that position. In 2005, Estonia produced 345,000 tonnes of shale oil, of which 222,000 tonnes were exported, 8,000 tonnes were utilised for electricity generation and 98,000 tonnes for heat generation. There are three shale oil producers in Estonia: VKG Oil (a subsidiary of Viru Keemia Grupp), Narva Oil Plant (a subsidiary of Eesti EnergiaEesti Energia
Eesti Energia AS is a state-owned energy company in Estonia with its headquarters in Tallinn. The company operates in Estonia, Latvia, Lithuania, Finland and Jordan. In Estonia the company operates under the name Eesti Energia, while using the brand name Enefit for international operations...
) and Kiviõli Keemiatööstus.
Power generation
The Estonian energy company Eesti EnergiaEesti Energia
Eesti Energia AS is a state-owned energy company in Estonia with its headquarters in Tallinn. The company operates in Estonia, Latvia, Lithuania, Finland and Jordan. In Estonia the company operates under the name Eesti Energia, while using the brand name Enefit for international operations...
owns the largest oil shale-fuelled power plants (Narva Power Plants) in the world. In Estonia, more than 90% of power is generated from oil shale.
Cement production
The spent shale (semi-cokeCoke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...
) is used for portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
production at the Kunda Nordic Cement factory. In 2002, 10,013 tonnes of semi-coke were used for cement production. As well, the Viru Keemia Grupp is planning to construct a cement factory for utilizing spent oil.