Use of the QEM∗SEM analysis in flotation testwork on a phosphate ore containing monazite

Abstract

The flotation behaviour of monazite in Australian Mt Weld phosphate ore was studied by QEM∗SEM (Quantitative Evaluation of Materials by Scanning Electron Microscopy). The flotation products of two batch tests AF5 and AF27 were analysed. In both tests, fatty acid was used as collector and the flotation pH was adjusted to 9.8. Sodium silicate was used in test AF5 but not in test AF27. It was found that sodium silicate depressed the flotation of all the iron minerals to a greater extent than the phosphate minerals and remarkable differences in floatabilities between the iron and phosphate minerals resulted. In test AF5, apatite floated faster than monazite in the rougher stage while monazite floated faster than hematite in the scavenger stage. Apatite in the concentrates was mostly liberated from the other minerals. The degree of liberation of apatite in the tailing and the other minerals in all the flotation products was low. Monazite was mainly associated with the iron minerals especially ilmenite. On the basis of the QEM∗SEM analyses of the floatabilities and the intergrowth and association characteristics of the major minerals, a flotation flowsheet was suggested to recover monazite from the phosphate ore as a by-product.