Producing magnetite concentrate from iron tailings via suspension magnetization roasting: A pilot-scale study

• Published in: Separation science and technology Vol. 58; no. 7; pp. 1372 - 1382
• Main Authors: Cheng, Shaokai, Han, Yuexin, Tang, Zhidong, Li, Wenbo
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.05.2023; Taylor & Francis Ltd
• Subjects: Beneficiation; Feeding habits; Feeding rates; Flow rates; Flow velocity; Fluidizing; Food processing; Haematite; Hematite; Iron; Iron ores; Iron tailings; Magnetic properties; Magnetic separation; Magnetite; Magnetization; Magnetometers; Mine tailings; Minerals; Ores; phase transformation; Phase transitions; Pollution; pre-concentration; Recovery; Resource utilization; Roasting; Separation; Siderite; Solid wastes; suspension magnetization roasting; Tailings; Technology; Temperature
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1080/01496395.2023.2189055

In the process of iron ore beneficiation, a considerable amount of iron was lost to the tailings, resulting in the waste of resources and environmental pollution. In this study, an innovative technology of pre-concentration followed by suspension magnetization roasting and low-intensity magnetic separation (PSRM) was used to recover iron from iron tailings. The iron grade of the roasted feed ores was increased from 15.68% to 33.19% by pre-concentration process. Subsequently, the suspension magnetization roasting was performed to transform the weak magnetic minerals into magnetite, and magnetite concentrate was obtained via low-intensity magnetic separation. The effects of feeding rate, roasting temperature, reducing gas CO flow rate, and fluidizing gas N 2 flow rate during suspension magnetization roasting were investigated, and the pilot-scale equipment was conducted for 72 h continuously under the optimum roasting conditions. The phase transformation and magnetic property variations of the minerals before and after roasting were analyzed by X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM), respectively. The results showed that an iron concentrate with iron grade of 63.04% and total iron recovery of 48.40% was obtained under the optimum roasting conditions: feeding rate of 111.70 kg/h, roasting temperature of 550°C, CO flow rate of 4.0 m 3 /h, and N 2 flow rate of 2.0 m 3 /h. The hematite and siderite in tailings were transformed into magnetite with an average magnetic conversion rate of 86.46%. This innovative PSRM technology provides an important reference for the resource utilization of solid waste and the recovery of iron from iron tailings.