Enhanced iron extraction from high-phosphorus waste limonite ore via suspension magnetization roasting: A pilot-scale study

High-phosphorus limonite was unable to be efficiently utilized owing to the difficulty in Fe extraction and dephosphorization. The requirement for iron ore is increasing with the rapid development of industry. Therefore, it is necessary to develop a method for the high utilization of high-phosphorus limonite. Traditional processes can't treat low-grade iron ore and are unable to transform the phase of iron minerals, thus they are very inefficient. To solve these problems, a novel method was proposed in this work for enhancing iron extraction and dephosphorization from high phosphorus limonite by suspension magnetization roasting-two stages of grinding and magnetic separation-flotation. After being treated by the above joint processes, a flotation concentrate with an iron grade of 59.50% and a phosphorus of 0.317% was obtained. The iron recovery and flotation concentrate yield of the total process were 75.39% and 57.52%, respectively. Compared with traditional multi-stage griding-magnetic separation with a Fe grade of 50% concentrate, there were significant improvements in Fe grade and Fe recovery. During SMR, the limonite transformed into magnetite with strong magnetism, and structures of iron ore became loose and porous. These changes enhanced the effect of magnetic separation and separation of apatite from magnetite. In general, this work provides a fresh approach to the efficient utilization of high-phosphorus waste limonite.