Characterization of a complex carbonate-silicate apatite ore and its concentration by a two-stage anionic flotation method

Abstract A carbonate-silicate low weathering phosphate ore from an igneous origin deposit in Southeastern Brazil presents a challenge mainly for apatite flotation from its gangue minerals, calcite and dolomite, plus the presence of phlogopite, diopside, magnetite, richterite, ilmenite, vermiculite, quartz and many other minor impurities. Recently, selectivity has been greatly enhanced by using CO2 instead of air, so in this study a variant process was used. In a first stage, carbonate minerals were floated with the use of CO2 as bubble gas; the collector was a saponified fatty acid, medium hydrocarbon chain. Then, the depressed minerals were floated using a sulfosuccinate collector and air as the froth gas. A significant improvement in the apatite concentration has been achieved: the initial 5.28% P2O5 tenor was raised to 21.58%. The overall P2O5 recovery was 61.8% and 12.0% of the global mass recovery. However, the amount of impurities was still significant with the presence of carbonates, phlogopite and minor magnetite. Therefore, the processing route presented herein is quite viable, but further research is necessary to improve the whole method.摘要 产自巴西东南部火成岩矿床的碳酸盐-硅酸盐弱风化磷矿石，其分选难点主要在于从方解石、白云石以及金云母、透辉石、磁铁矿、碱闪石、钛铁矿、蛭石、石英等多种次要杂质矿物中浮选分离磷灰石。此前已有研究证实，以二氧化碳（CO₂）替代空气作为气泡气体可显著提升分选选择性，本研究据此采用了改进的浮选工艺：第一阶段以二氧化碳作为气泡气体，采用中等烃链皂化脂肪酸作为捕收剂，浮选脱除碳酸盐矿物；随后以磺基琥珀酸盐类捕收剂、空气作为泡沫气体，浮选脱除经抑制的其余矿物。本工艺实现了磷灰石品位的显著提升：原矿初始五氧化二磷（P₂O₅）品位为5.28%，最终精矿品位提升至21.58%；五氧化二磷总回收率达61.8%，总质量回收率为12.0%。然而，精矿中仍残留碳酸盐、金云母及少量磁铁矿等杂质，杂质占比依然较高。综上，本研究所提出的选矿工艺具备较高可行性，但仍需开展进一步研究以优化整套分选流程。