Flotation of Feldspar with Amine

The role of hydrofluoric acid in the flotation separation of feldspare with dodecylammonium acetate as collector was studied. The results obtained were as follows : (1) The Hallimond tube tests showed that the floatability of feldspar with DAA reached to the maximum at pH 10 and was poor at pH less than 3 or more than 12,which was attributed to the adsorption properties of DAA on the mineral. The isoelectric point of feldspar in DAA solutions found by the Zeta potential studies was measured at pH 3.5 and electrostatic force contributed to the adsorption of DAA on the untreated samples. (2) Hydrofluoric acid or fluorides activates feldspare in acidic solution, increases the adsorption of DAA on the surface of the feldspar, and consequently most efficient flotation is observed. Potassium fluoride showed good activating properties among many fluorides. (3) Chemisorption of DAA on the feldspar prepared in hydrofluoric acid solution might play a predominant role in flotation of feldspar regardless of the Zeta potential in solutions. The formation of fluosilicates are predicted as the reaction products of feldspar surface with hydrofluoric acid. (4) The presense of hydrofluoric acid is requisite for coagulation of feldspar fines. Potassium fluosilicate showed a marked effect on the adsorption of DAA and the adhesive property to air bubble, thus the activation of feldspar by hydrofluoric acid was related to the formation of the alkali metal fluosilicates. (5) X-ray diffraction chart on the feldspar pre-treated with hydrofluoric acid solution showed the formation of fluosilicate on the feldspar surface, which was identified as poiassium fluosilicate. (6) Results of experimental work conducted to evaluate the mechanism of the activation by hdrofluoric acid or fluorides on feldspar present the formation of potassium fluosilicate on the surface of the mineral, selective chemisorption of DAA in acidic solution, and resultant increase in floatability.