Iron Ore Beneficiation
Iron ore beneficiation is a multistage process that raw iron ore undergoes to purify it prior to the process of smelting, which involves melting the ore to remove the metal content. The process of iron ore beneficiation has two complementary goals and these define the methods used to refine it. The iron content of the ore needs to be increased and gangue, which is native rock and minerals of lesser value within the ore itself, must be separated out.
Methods such as screening, crushing, and grinding of iron ore are often used in various ways to purify it, along with several stages of magnetic separation. The iron ore industry classifies the material by the concentration of the metal that is present after iron ore beneficiation has been completed. High-grade iron ore must have a concentration of 65% iron or higher, and medium grade of 62% to 65%.
Low-grade iron ore includes all mixtures below 62% iron concentration, which are not considered to be viable types of ore for use in metallurgy. Many sources of iron ore are used in steelmaking, including remnants of primary production. Magnetite is a common form of iron ore and is frequently used in the production of steel. Ores containing very high quantities of hematite or magnetite are known as natural ore and they can be entered directly into the furnace for processing.
Iron ore can also be used in many industrial processes and products, including fertilizer, animal feed, detergents, and land conservation. Many plants use iron as a fertilizer to improve soil fertility. Fertilizers containing iron are important to plants because plants absorb iron from soil better than from any other modern form of iron.
The extraction of iron ore is generally performed through a blasting and removal process from large open pit mines, before it is crushed, screened and blended for export or local consumption. Once blended, iron ore is sintered with other minerals such as limestone and coke as a source of calcium and carbon. After sintering, the material is subjected to further processing to reduce completely any impurities that might be present.
The final product produced through beneficiation in the iron ore industry is a concentrate containing between 65% and 72% iron with low levels of impurities such as sulfur, phosphorus, and silica. These higher grade ores can then be sold as concentrate or further processed into pellets and other materials for use in steel production processes. While these processes are beneficial, it is important to remember that they also represent potential environmental risks to the region and its inhabitants due to the presence of chemicals used in the beneficiation process.
