阴离子捕收剂浮选分离一水硬铝石与高岭石的表面晶体化学

Surface Crystal Chemistry in Selective Flotation of Diaspore from Kaolinite Using Anionic Collector

铝土矿正浮选实践中,常采用脂肪酸阴离子捕收剂(如油酸)选择性分离一水硬铝石和高岭石等铝硅酸盐矿物。矿物表面晶体化学特性是产生选择性浮选分离的决定性因素。笔者研究了油酸钠(Na OL)浮选体系中一水硬铝石和高岭石的可浮性,发现一水硬铝石可浮性明显好于高岭石。红外光谱分析表明,矿物表面Al质点与油酸的羧酸基团发生化学吸附作用。借助Materials Studio软件分别计算了2种矿物常见晶面的单位面积断裂键数,并计算了矿物晶面/捕收剂的作用能。计算分析发现,矿物晶面单位面积断裂键数以及与油酸根离子相互作用能大小存在差异,具体为:一水硬铝石(100)>(001)>(010),而高岭石(010)>(110)>(001),而且油酸与一水硬铝石3个晶面的的作用皆强于高岭石。矿物晶体晶面的Al-O断裂键数不同导致油酸作用下高岭石和一水硬铝石的可浮性差异。

The practice of flotation on bauxite, often use a fatty acid（oleic acid） as an anionic collector for selective separation of diaspore from other aluminum silicate minerals such as kaolinite. Surface crystal chemistry of minerals is found to be the decisive factor for selective flotation separation. In the sodium oleate（Na OL） flotation system, the flotability of diaspore and kaolinite was studied. It was found that results for the flotation of diaspore are significantly better than that of kaolinite. The infrared spectral analysis show that Al sites on the surface of minerals react with carboxyl group of oleic acid by chemisorption. The surface broken bond densities and the interaction energy of planes to reagents were calculated using Materials Studio software. The results found that the sizes of the surface broken bond densities of the mineral crystal planes and interaction energy with oleate ions for diaspore are（100） （001） （010）, and（010） （110） （001） for kaolinite. As well, interaction energies between three planes of diaspore crystal and oleic acid are stronger than those for kaolinite. We conclude that the flotability difference between kaolinite and diaspore can attributed to the different numbers of broken bond Al-O on different mineral crystal planes.