Research On Pretreatment Of High Phosphorus Oolitic Hematite Ore By Leaching

The reserves of NingXiang high phosphorus oolitic hematite is huge, but it’s very difficult to separate, a lot of researchers have deeply studied in this kind of iron ore. Affected by the cost and the technology lever, up to present, it has not been qualitied used in production. On the basis of a lot of references, the alumina production techniques in the alkali solution are applied to pretreat the oolitic hematite in this thesis, it provides a new thinking for the development and utilization of oolitic hematite.The experiment use the means of optical microscope, electron microscope, X-ray diffraction, chemical analysis, EDS etc, amply analyzed the chemical composition, mineral composition, distribution and oolitic characteristics of NingXiang high phosphorus oolitic hematite ore. The results show that:the iron element exists mainly in hematite and limonite, the main gangue minerals are quartz, chamosite and collophane, aluminiferous minerals are diaspore and boehmite. The ore mineral composition structure is complex, hematite usually form oolitic structure which layers of annular wrapped with quartz, chamosite, phosphate rock and clay mineral. Oolitic can be divided into iron-rich oolite and lean-iron oolite, while the particle size were ranged from0.1to0.5mm.Alkali leaching high phosphorus oolitic hematite is a new method of pretreating oolitic hematite, this experiment have studied on four conditions such as leaching temperature, leaching time, leaching of alkali mass fraction and calcium oxide additives on the leaching process, then analyzed the effect of each condition. The test results of one stage of leaching and two stage of leaching showed that two stage of leaching can improve the leaching result more effectively.The experiment results is:adopting one stage of leaching pretreatment oolitic hematite is difficult to obtain the good leaching result; while with two stage of leaching pretreatment can, then use strong magnetic separation can achieve the qualified iron concentrate. Optimal conditions is:test sample10g, particle size-0.074mm accounted for99%, sodium hydroxide20g, water30g, calcium oxide1g, leaching temperature260℃, leaching time 60min, with hot water washing, filtering, drying, adding sodium hydroxide20g, water30g, calcium oxide1g, leaching again at260℃for60min, then use hot water washing, filtering, and adding36%acetic acid, lOmL acid stirring30min, finally use strong separation, magnetic filed strength1.0T. Finally got the iron concentrate with grade of56.29%, P2O5grade of0.20%, recovery rate of75.52%results.At the same time, the leaching mechanism analysis results show that the oolitic hematite structure has changed after leaching pretreatment, the grade of phosphorus grade decreased obviously, that indicate leaching is good for dephosphorization.The research results lay a technical foundation for pretreatment of oolitic hematite.