Iron is the fourth abundant element in the earth’s crust with an abundance rate of 5%, and serves as the tenth most abundant element in the world. Iron is a metal mainly in black and grey color with the symbol of Fe, atomic number 26, atomic weight of 55.84 (56 ~), gravity of 7.3-7.8 grams per cubic centimeter, inflexibility of 4 in the Mose scale, with metal shining of grayish shadow, boiling point of 2750 degrees centigrade and melting point of 1536 degrees. As the fourth abundant element and the first heavy metal, iron exists in almost all mineral ores.
Iron compounds at early stage are found as a crystal of melted material and at the main stage it is crystallized inside alkaline ores in the form of iron and magnesium silicates or subsidiary oxides and sulfurs or more than the amount of the main minerals, and eventually from thermal source in the form of carbonates, oxides and sulfurous of the main mineral or gang mineral in various mine strata.
Iron concentration in substitute metamorphic ores (meta-somatic) and/or sedimentary ores (left out sediments and chemical and organic sediments) is highly important too. In the latter form iron particularly emerges in the form of siderite, limonite or pyrite. Some of these masses have undergone changes due to proximal or regional metamorphosis. Almost three fourth of the world iron products and 6.7 percent of its deposits in the world are in the form of sedimentary and decomposed minerals. Due to the decomposition of the same ores or their primary masses iron is washed out and enters decomposition solutions.
Iron is a metal which is extracted from iron ore and is hardly found in solid (free) form. This element is mainly extracted from hematite iron ore (Fe2O3). In order to achieve iron its impurities should be removed through chemical reduction during which iron is separated by reduction with carbon (a more reactive element). This process occurs in high furnaces at the temperature of about 2000 degrees centigrade.
More than 300 iron minerals are found in the nature the most important of which are magnetite, hematite, martite, goethite, limonite, siderite and shamosite. Iron accumulation is generally the result of a magma process or skaren resulting from basaltic magma while the sedimentary types are accumulated next to the sedimentary ponds.
Different kinds of iron ores are: Sedimentary (stripe, aliti, siderite, spring, stratum) magmatic, metamorphic, analytical, thermal, exlasibon, submarine, metamorphic, igneous and skaren. The most important sources of iron in the world are sedimentary-stratum iron minerals, maffick and ultramaffick stratum ores and skarens containing iron. Some 90 percent of the global iron is yielded from sedimentary-stratum iron minerals however about 1-2 percent of the one billion tons of iron consumed in the world comes from internal magma minerals and slightly more from iron minerals.
Geophysical methods for exploration of minerals and proper exploration places are used for primary identification and complementary exploration of iron ore mines. At the first step abnormalities are found at the follow-up stage or primary steps of exploration by using aerial geophysical information gathered at a regional and small scale of a vast area. The other step is to use ground geophysical methods at the preliminary, semi-detailed and detailed phase of exploration in which geophysical information is used to locate the exact spot of the hidden deposit, its shape, scope and depth. Magnetometry is one of the geophysical methods which is used for iron exploration and discovery of magnetic ores of iron such as magnetite, hematite, …
Iron processing includes crushing, washing and sorting in a heavy environment. Magnetic separation can be used for magnetite ores. The synthetic iron oxide is produced through a variety of methods such as thermal collapse, direct sedimentation, aniline process or synthesis by means of steam method.
Iron ore is the main raw material in the global steel industries and iron is consumed most among other metals to the extent it accounts for 95% of the produced metal reserve throughout the world and forms the foundation of the present civilization. The reason is its abundance, easy achievement, cheap price and high tenacity.
Iron is used in manufacturing various types of light and heavy machinery, ships, railroad, bridges, dams, buildings, military equipments, home appliances, and factory construction. Some 99% of the total iron ore is consumed by steel and cast iron production industries. Other iron ore consumptions which are very slight include: Use of iron ore in concrete, production of cement, excavation mud, as a heavy catalysis in washing coal and as color pigments.
In steel mills the iron ore is mixed with coke and limestone and then melted. The limestone decreases the iron ore melting temperature and coke produces carbon dioxide by the oxygen of the ore. The melted iron which contains some 3 to 4 percent carbon is used for various applications.
99% of the total iron consumption goes to steel and cast iron industries. Steel is the best known alloy of iron that covers most types of ferrous forms.
According to the data released by the British Geology Society (BGS) production of iron ore in Iran rose from 12208437 tons in 2000 to 34500000 tons in 2010. The highest rate of production belongs to the years 2008 and 2009 and the lowest belongs to 2000. Production of raw iron in Iran has reached from 6679088 tons in 2000 to 10532000 tons in 2010. The highest amount of production relates to 2009 and the lowest amount relates to 2000. Meanwhile, production of raw steel in Iran went from 6614519 tons in 2000 to 11995000 tons in 2010, most of which was produced in 2010 and least of which was produced in 2000.