辽宁某低品位菱镁矿提质降杂试验研究与工业实践

辽宁某菱镁矿选厂所处理矿石属高硅高钙型低品位菱镁矿矿石，生产现场采用反-正浮选工艺流程，存在反浮选捕收剂泡沫流动性差和选择性差，对有用矿物的夹带严重，流程运行不稳定且难以实现闭路循环，正浮选脱钙效果差，菱镁矿损失大、回收率低（MgO回收率仅35%）等问题。由于技术经济指标欠佳而处于停产状态。针对原流程存在的问题，提出采用等可浮反浮选-正浮选强化脱杂新工艺，其中，等可浮反浮选作业在弱酸性矿浆pH（6.0左右）环境中，以水玻璃为调整剂，BK-428（阳离子型捕收剂）为捕收剂，脱除含硅钙脉石；正浮选作业在弱碱性矿浆pH（9.0左右）环境中，以六偏磷酸钠为抑制剂，BK410B（阴离子型捕收剂）为捕收剂，强化脱除含钙硅脉石，从而实现低品位菱镁矿的提质降杂。在系统的实验室试验和选矿扩大连选试验研究的基础上，进行了新工艺的工业试验研究。工业试验最终从MgO品位为42.94%、SiO₂含量4.14%和CaO含量2.91%的低品位菱镁矿矿石中获得了MgO品位为47.14%、回收率为76.02%的菱镁矿精矿，精矿中SiO₂和CaO含量分别降至0.28%和0.53%。 

The Experimental Research and Industrial Practice on Improving Quality and Reducing Impurities by Flotation from a Low Grade Magnesite Ore in Liaoning

A magnesite ore treated in a mineral processing plant in Liaoning province belongs to low-grade ore bearing high silicon and calcium, and the reverse-direct flotation flowsheet was adopted, but there was in a state of shutdown due to the poor technical and economic indexes caused by the problems existing in the original flowsheet such as poor liquidity and selectivity of collector froth, severe entrainment of useful mineral, unstable flowsheet operation and the difficulty in implementation of closed-circuit production in the reverse flotation stage, poor effect of calcium removal in the direct flotation stage, big loss and low recovery of magnesite (only 35% of MgO recovery), etc. Based on the problems existing in the original flowsheet, it was proposed in this paper to treat the ore by the process of iso-flotability reverse-direct flotation, namely, iso-flotability reverse flotation with water glass as regulator and novel anionic collector BK-428 under condition of weak acidic pulp (pH 6.0) was adopted to remove silicate and dolomite, and direct flotation by sodium hexametaphosphate as regulator and cationic collector BK410B under condition of weak alkali pulp (pH 9.0) was used to further remove dolomite and silicate, and it could realize the quality improvement and impurities reduction of low-grade magnesite ore. By this new process, based on the systematic laboratory tests and continuous pilot tests, the industrial tests were carried out and the magnesite concentrate with a MgO grade of 47.14% and a recovery rate of 76.02% was obtained from the low grade magnesite ore with MgO 42.94%, while SiO₂ and CaO content in concentrate decreased from 4.14% and 2.91% to 0.28% and 0.53% respectively.