Direct reduction of low grade chromite overburden for recovery of metals

Abstract

The management of huge volumes of overburden at chromite mines is a concern, and there is a need to make effective use of this material. Therefore, direct reduction of low grade chromite overburden from the Sukinda chromite mines was studied at high temperatures to recover Fe, Cr and Ni. The effect of process parameters, such as temperature, time, reductant and flux, on the recovery of these metals was studied. The bench scale results obtained were then used in laboratory rotary hearth furnace reduction experiments, where it was found that a cycle time of 25 min is required for maximum recovery of metal. It was observed that y90% of Fe and .90% of Ni were recovered and thus have the potential to reduce the volume of waste at chromite mines.

Aluminum Mineral Processing and Metallurgy: Iron-Rich Bauxite and Bayer Red Muds

“…However, the high-temperature reduction and smelting process exhibit a lot of advantages for ironmaking [27,28]. In this processes, carbon composite pellets are reduced and smelted to produce metallic iron, which is then separated from slag at a furnace temperature of 1573 K or higher.…”

Semi-Smelting Reduction and Magnetic Separation for the Recovery of Iron and Alumina Slag from Iron Rich Bauxite

“…In addition, DRI is an excellent feedstock for the electric furnaces or basic oxygen furnace, and can be used to produce higher grades of steel [17,18]. Thus, this method is considered to be an effective method for the treatment of complex iron ore and low-grade iron ore resources [19,20]. Chu et al [21] used the coal-based direct reduction and magnetic separation process to recover iron from red mud, the results showed that the iron recovery rate and total iron content in the magnetic product could be up to 98.37% and 82.52%, respectively.…”

“…The reaction equations and the Gibbs free energy that varies with the temperature are calculated using Factsage 7.0, and are presented in Figure 6. It can be seen that the diaspore (AlOOH) and gibbsite (Al(OH) 3 ) are easily decomposed into alumina (Al 2 O 3 ) and water (H 2 O) at low temperatures (Equations (16) and (17) (21), (22), and (23) are predominant at the indicated experimental temperature range, whereas the reactions of Equations (19) and (20) are negative. The standard free energies of Equations (18), (21), (22), and (23) are more negative than that of Equations (19) and (20).…”

Early stage hydration properties of calcium aluminosilicate slag

“…These high ferrous bauxite is mainly composed of gibbsite (Al(OH) 3 ), diaspore (AlOOH), goethite (FeOOH), hematite (Fe 2 O 3 ) and kaolinite (Al 2 Si 2 O 5 (OH)4· 2H 2 O), the content of Al 2 O 3 and Fe 2 O 3 is over 65wt%, the content of SiO 2 is about 7-12wt% & Zhang et al 2014). Current studies estimate that the coal-based direct reduction method can be used to produce a high quality pig iron from low grade iron ores, and thus it is an ideal technology for adding value to marginal iron ore reserves (Kapure et al 2011& Guo et al 2013). Valuable iron in high ferrous bauxite is preferentially recovered by coal-based direct reduction and melting method (Zhang et al 2015a).…”