Study of the occurrence law of iron in different types of sorting tailings of Anshan-type low-grade hematite

Anshan-type low-grade hematite ore is one of the most important types of iron ore in China. It is usually separated by a combined process of gravity concentration-magnetic separation-reverse flotation. However, the tailings produced by different separation operations have different properties, and a large amount of the residual iron in the minerals cannot be recovered effectively; therefore, mixing these tailings is unscientific for most concentrators. Given this situation, this paper takes the iron tailings of the Qidashan iron ore dressing plant as an example to make a comparative analysis of the technological mineralogy of four types of tailings (i.e., gravity tailings, magnetic tailings, flotation tailings, and mixed tailings) and evaluate the recoverability of iron in these tailings. The results show that the main iron and gangue minerals are hematite and quartz, respectively. The content of harmful elements S and P is low in the tailings. In addition, the metal distribution rate of iron in the tailings varies with the size, showing a rule of high at both ends and low in the middle. It is also found that iron minerals are mainly wrapped in coarse gangue, and iron minerals in the flotation tailings are mainly contained in fine-grained conglomerates. Although the iron minerals in the magnetic separation tailings are extremely fine, mixed tailings have a wide range of particle sizes and extremely uneven distribution. Single gravity separation and magnetic separation methods are used to reconcentrate different types of tailings, and the best index is found to exist in flotation tailings, followed by gravity tailings, and that of mixed tailings is the worst. However, recovering iron from magnetic tailings is pointless. The mineralogical characteristics of Anshan-type hematite ore tailing underlies its recovery potential of iron and provides a reference for the retreatment of similar iron ore tailings.