Biomass waste as a clean reductant for iron recovery of iron tailings by magnetization roasting. (1st September 2022)

• Record Type: Journal Article
• Authors: Deng, Jinhuan; Ning, Xun-an; Shen, Junhua; Ou, Weixuan; Chen, Jiayi; Qiu, Guoqiang; Wang, Yi; He, Yao
• Is Part Of: Journal of environmental management. Volume 317(2022)
• Publication Date: 2022-09-01
• Subjects: Iron tailings -- Biomass-derived gas -- Magnetic separation -- Phase transformation -- Gaseous product; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115435
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: The magnetization roasting with coal as primary reductants adds cost and causes environmental pollution. Therefore, it is of great importance to investigate the biomass application as a reductant for magnetization roasting to recover iron from low-utilization iron tailings for emission mitigation and green utilization. This study systematically investigated the impact of biomass (pyrolysis gas from agricultural and forestry waste) as a reductant on the conversion of iron tailings to magnetite in magnetization roasting. Additionally, the thermal decomposition of biomass, phase transformation and microstructure evolution of iron tailings were analyzed by TG, XRD, BET, and other methods to elucidate the conversion mechanism for facilitating magnetized hematite in iron tailings with biomass-derived gas. The results showed that woody biomass was a more appropriate reductant for magnetization roasting; 650 °C was the optimal temperature for the complete transformation of hematite to magnetite by reduction roasting with biomass waste. Through magnetic separation, the concentrate with an iron grade of 62.04% and iron recovery of 95.29% was obtained, and the saturation magnetization was enhanced from 0.60 emu/g to 58.03 emu/g of iron tailings. During the magnetization roasting, CO and H2 generated from biomass reduced the hematite in tailings particles from interior to exterior, forming a loose structure with rich microfissures, facilitating the subsequent separation operations. This study offers a novel reference for applying biomass to exploit hematite minerals and shows the potential of biomass for energy savings and emission reduction in the utilization of iron tailing resources. Highlights: Biomass can effectively convert hematite to magnetite in iron tailings at 650 °C. Iron concentrates with a grade of 62.04% and a recovery of 95.29% are obtained. The woody biomass outperforms the straw biomass in iron recovery. Magnetite increases from 0.10% to 96.06% with an enhanced magnetism performance. Biomass could serve for the efficient treatment of hematite-bearing minerals.