焙烧脱碳对含钒石煤相变及浮选行为的影响

Influence of Decarbonization by Roasting on Changes of Mineral Phases and Flotation Behavior of Vanadium-Bearing Stone Coal

湖北某高钙云母型含钒石煤中矿物被碳质深度浸染,浮选前需要焙烧脱碳。通过热重-差示扫描量热(TG-DSC)、傅里叶红外光谱(FTIR)、X射线衍射(XRD)等分析测试手段对原矿及不同温度焙烧脱碳样进行了表征分析,探讨了不同温度脱碳对浮选行为的影响。结果表明,该含钒石煤随着焙烧温度的升高,依次发生黄铁矿氧化、碳质的燃烧、方解石的分解等反应。600~700℃,碳质和黄铁矿基本消失,云母八面体结构未被破坏,方解石部分分解,固硫后剩余的CaO使浮选矿浆pH值升高,Ca^(2+)浓度增大。浮选试验结果表明,随焙烧温度的提高,碳质逐渐脱除,矿物表面性质差异扩大,脱碳样的浮选效果比原矿有明显改善。650℃脱碳样浮选,由于Ca^(2+)的活化作用,石英被油酸钠捕收,可得产率为21.10%,V_2O_5品位为0.36%的尾矿产品,钒损失率仅为10.05%,精矿的V_2O_5品位为0.95%。700℃脱碳时,矿浆过高的pH值和Ca^(2+)含量使微细颗粒发生无选择性聚沉,消耗大量的油酸钠,不利于浮选的进行。

The minerals in high-calcium and mica-type vanadium-bearing stone coal in Hubei province were severely contaminated by carbon,so roasting decarburization is necessary for the stone coal before flotation. Thermogravimetry-differential scanning calorimetry（ TG-DSC）,Fourier transform infrared spectroscopy（ FTIR）,X-ray diffraction（ XRD） analyses were measured for raw ore and decarburized samples for characterization,and the effects of decarbonization by roasting on flotation behavior at different temperatures were discussed. The results showed that reactions of oxidation of pyrite,combustion of carbon and calcite decomposition occurred successively in the vanadium-bearing stone coal with the increase of roasting temperature. At 600 ~ 700 ℃,carbon and pyrite disappeared,octahedral structure in mica was not damaged,some calcite decomposed,and the remained CaO after sulfur-fixation made the p H and concentration of Ca^（2＋）increase in flotation pulp. The flotation tests showed that with roasting temperature increasing,the gradual removal of carbon,the differences among mineral surfaces were enlarged,so decarburized samples got better results than the raw ore. At 650 ℃,the quartz was collected by sodium oleate due to the activation of Ca^（2＋）,which made the tailing＇s yield of 21. 10%,V_2O_5 grade of0. 36%,and loss rate of V_2O_5 was only 10. 05%,while grade of V2O5 for concentrate was the highest 0. 95%. At 700 ℃,the fine particles coagulated without selection,and much sodium oleate was consumed due to the high pulp p H and concentration of Ca^（2＋）,which was not conducive to the flotation.