Iron is the earliest discovered, the most widely used and the most used metal in the world, accounting for about 95% of the total metal consumption. Iron ore is a mineral aggregate containing iron elements or iron compounds, which can be used economically. It is an important raw material for steel production enterprises. In nature, it mainly exists in the form of various iron compounds, forming various types of iron ore. Now more than 300 kinds of iron ore have been found. However, under the current industrial technology conditions, there are mainly four kinds of ores with good industrial value, namely magnetite, hematite, siderite and limonite.
The main factors affecting the use value of iron ore are iron content of ore, gangue chemical composition, physical properties of ore, pyrometallurgical properties of ore and ore optionality. Generally speaking, iron content of ore is a key index to determine whether it can be smelted directly. Iron ore with a general grade (iron content) less than 50% can be smelted and utilized only after ore dressing.
The beneficial or harmful chemical composition in the ore is also an important factor determining the economic value of the ore. The common main impurities include sulfur, phosphorus, arsenic, zinc, lead, copper, fluorine, titanium and alkali metal, etc., among which the adverse effect of the harmful impurities in iron and steel smelting should be paid great attention to. The physical properties of ore mainly refer to ore porosity, mechanical strength, grain size, etc. Too large or too small of these elements is not conducive to smelting process.
Iron ore is abundant in nature and widely distributed all over the world. According to the proven iron ore reserves data, the world's iron ore reserves are mainly concentrated in Australia, Brazil, Russia and China, among which the top four countries account for 67.3% of the world's reserves. In particular, Australia, Brazil and India not only have far more reserves than other countries, but also have high grade iron ore, less impurities, with high economic value.