Recovery of apatite as a by-product from carbonatite-pyrochlore ore

CIM Bulletin, Vol. 74, No. 836, 1981

GENNARD DELISLE, Project Engineer, Ministere de I'Energie et des Ressources du Quebec, Centre de Recherches Minerales, Quebec

Les Services TMG (Niobec) currently treat a niobium ore in the Chicoutimi area of Quebec. The mineral pyrochlore is present in a carbonatite deposit which assays 5% to 7% apatite.The ore is ground to minus 65 mesh and deslimed at 10 micrometres. Part of the carbonates are floated with a fatty acid emulsion and rejected to the tailings as a first step to ensure the proper conditions for the flotation of the pyrochlore concentrate. The carbonate concentrate is 65% minus 44 micrometres and is composed of dolomite, calcite, 22% apatite and a minor amount of silicates.A laboratory investigation was undertaken to determine the feasibility of extracting apatite from the carbonate concentrate. This led to the development of an economic flowsheet to produce high-grade apatite concentrate. The apatite is depressed with phosphoric acid, and the pH is adjusted at 4.8-5.0 with sulphuric acid. An additional amount of fatty acid is added to permit efficient flotation of the carbonates. In a second stage, the silicates left behind with the apatite concentrate can be removed by depressing the apatite with AIC13 while floating the silicates with a secondary amine.The results of the laboratory tests indicate the possibility of producing an apatite concentrate assaying 38.3% P2O5 (83.7% BPL) with a recovery of 66.2%. Pilot-plant tests undertaken at the concentrator yielded a concentrate of 34% P2O5 and recovery of 76%.
Keywords: Industrial minerals, Apatite, Carbonatite, Pyrochlore ore, Flotation, Reagents, Niobec mine.