Iron ore refers to ores containing iron elements or iron compounds that have useful value and are almost exclusively used as raw materials for iron and steel production. Iron and steel is the pillar industry of the national economy. Iron ore is the most important raw material for iron and steel production. It takes about 1.6 tons of iron ore to produce 1 ton of pig iron, and iron ore accounts for more than 60% of the cost of pig iron.
According to the composition of iron bearing minerals, iron ore can be divided into four main categories: magnetite, hematite, limonite and siderite. Due to their different chemical composition, crystal structure and geological conditions, all kinds of iron ores have different external morphology and physical characteristics.
Magnetite
The main iron-bearing minerals are magnetite, whose chemical formula is Fe3O4, in which FeO=31%, Fe2O3=69%, and the theoretical iron content is 72.4%. This ore sometimes contains TiO2 and V2O5 composite ore, called titanomagnetite or alum titanomagnetite respectively. Magnetite has strong magnetic properties. The crystals are often octahedral, and a few are rhomboid dodecahedron. Aggregate often into dense block, color stripe is iron black, semi-metallic luster, relative density 4.9 ~ 5.2, hardness 5.5 ~ 6, no cleavage, gangue is mainly quartz and silicate. Poor reducibility, generally contains higher harmful impurities sulfur and phosphorus.
Hematite
Hematite is anhydrous iron oxide ore, its chemical formula is Fe2O3, the theoretical iron content is 70%. This mineral often forms huge deposits in nature and is the main mineral in industrial production, both buried and mined. Iron content of hematite is generally 50% ~ 60%, containing less harmful impurities sulfur and phosphorus, reduction is better than magnetite, therefore, hematite is a better raw material for iron making.
Limonite
Limonite is a water-bearing iron oxide ore, which is generated after weathering from other ores. It is the most widely distributed in nature, but there are few deposi