Flotation separation of Xixia andalusite ore

The flotation behavior of Xixia andalusite was studied with different collectors. The tests were conducted with a pure andalusite sample in micro-flotation cell and then with an ore sample in a mechanical flotation cell. The surface charge was measured on pure andalusite sample and the isoelectric point (IEP) was found to be pH 5.2. Andalusite is floated with an amine collector above IEP where mineral surface is negatively charged. In contrast, an alkyl sulfonate collector (sodium dodecyl benzene sulfonate) is effective in the pH range where andalusite surface is positively charged. Furthermore, andalusite is floated with oleate in neutral and mildly alkaline pH values. 55.3% Al2O3 is produced with 75.6% andalusite recovery when using the alkyl benzene sulfonate collector. Starch is found to be an effective depressant for gangue minerals in alkyl benzene sulfonate flotation. Moreover, slimes are found to have an adverse effect on the flotation of andalusite. Therefore, pretreatment by desliming and pre-float (to remove carbonaceous species) prior to andalusite flotation is necessary.