COAL

Coal or coal is one of the fossil fuels. General sense is a sedimentary rock that can be burned, are formed from organic deposits, primarily remnants of plants and are formed through a process pembatubaraan. The main elements consist of carbon, hydrogen and oxygen. Coal is also an organic rock that has the properties of complex physical and chemical that can be encountered in various forms. Elemental analysis gave the empirical formula as C137H97O9NS formula for bituminous and anthracite C240H90O4NS for. Coal Age Coal formation requires certain conditions and only occur in certain eras in the history of geology. Carboniferous period, about 340 million years ago (Mya), is the formation of the most productive coal where almost all the deposits of coal (black coal) that is economical in the northern hemisphere is formed. In the Permian Period, about 270 Mya, also formed the coal deposits that are economical in the southern hemisphere, like Australia, and continuing until the Tertiary Period (70-13 Mya) in the range of the other hemisphere. artery coal-forming Nearly all the coal-forming plants come from. The types of coal-forming plants and age according to Diessel (1981) are as follows: Algae, from Pre-Cambrian Times to the Ordovician and single-celled. Very few coal deposits of this period. Silofita, from the Silurian to Devonian Middle Ages, is derived from algae. Little coal deposits of this period. Pteridofita, age of Upper Devonian to Upper Carboniferous. The main coal-forming material was carbon in Europe and North America. Plants without flowers and seeds, and reproduce by spores grow in warm climates. Gimnospermae, a period ranging from Permian to Cretaceous Middle Ages. Heterosexual plants, seeds encased in fruit, such as pine, contain high levels of sap (resin) high. Pteridospermae types like gangamopteris and Glossopteris is the main constituent Permian coal as Australia, India and Africa. Angiosperms, from the Upper Cretaceous period until now. Modern plants, fruit that covers the seed, the male and female in a single flower, is less sticky than gimnospermae so that, in general, less can be preserved. Class and type of coal Based on the formation process is controlled by pressure, heat and time, coal is generally divided into five classes: anthracite, bituminous, sub-bituminous, lignite and peat. Anthracite is the highest grade of coal, with black shiny (luster) metallic, containing between 86% - 98% elemental carbon (C) with a water content of less than 8%. Bituminous coal contains 68-86% elemental carbon (C) and water yield of 8-10% by weight. Class of the most coal mined in Australia. Sub-bituminous coal contains less carbon and more water, and therefore a source of heat is less efficient than the bituminous. Lignite or brown coal is very soft coal containing 35-75% water by weight. Peat, porous and has a moisture content above 75% and the lowest calorific value.