Magnetite Beneficiation Process Research - Yunnan Luquan Over Lean Hematite Fines

The main iron ore resources are found in fifty countries of the world, and twelve countries account for the majority of the iron ore with large iron reserves. The characteristics of iron resources in different countries vary with different deposits, minerals, grade of raw ore and so on. For instance, the average grade of iron ores in Brail is higher than60%and iron ores assay more than50%Fe in Australia. However, the mean grade of iron ores in China is as low as32%Fe, which is regarded as lean iron ore. Moreover, iron minerals are finely disseminated in the lean ore. So it is necessary to study the beneficiation of the ores to meet the increasing demand of iron industries in China.In this research, three kinds of low grade and finely disseminated iron ore samples weighting800kg was obtained from Luquan county, Yunnan China. Through chemical analysis and mineralogical study on the samples, some conclusions about the raw ores were drawn. The valuable minerals in the ore are hematite and magnetite, and the main gangue mineral is quartz with small amount of impurity elements like S, P and As. The iron ore assays18.64%Fe, where hematite and magnetite are finely disseminated. According to above basic information, many tests on the composite iron ores were conducted.Dry magnetic separation was used for preconcentration to produce the tailings firstly, but it didn’t work. Flotation is one of the universal processes for iron ore processing, and flotation tests were employed in the preliminary study, including the investigation of the reagents and the grinding fineness by single-stage roughing and scavengering process. According to the results of the condition tests, optimized flowsheet was preliminarily determined but the marketable iron product could not be obtained. After that, tests to develop a combined flowsheet by "Stage Grinding-Magnetic Separation-Gravity Separation" were conducted. A low magnetic separator was used for roughing after primary grinding to-0.074mm85%and once cleaning after regrinding to-0.074mm95%. A high magnetic separator was used for tailings rejecting. A slime shaking table was used for reconcentration of the middings from low and high magnetic separators. The concentrates from the shaking table and the one from low magnetic separator can be merged into one as the final concentrate assaying above50% Fe with the recovery more than60%, and the other products were discarded as tailings. The whole process on the refractory iron ore is easy and economic, and provides technical basis for the further concentration of lean and finely disseminated iron ores.