| The surface and crystal chemistry of spodumene (LiAl SiO(,3) (,2)) and its flotation behavior were studied in the present research.;Considering the heterogeneity of the mineral surfaces, a new polyionic surface sites model that accounts for all cationic and anionic surface atomic sites was developed to explain the surface charge mechanism at the mineral-aqueous solution interface.;The industrial practice of the selective flotation of spodumene from other pegmatic aluminosilicates is successfully explained using the difference in the surface crystal chemistry of the minerals contained in the ore. The availability of proper aluminum sites on spodumene for the chemisorption of oleate collector is the key to the problems.;The wettability and point of zero charge for various silicate minerals is related to the crystal structure of the minerals.;A review of the surface properties of the minerals indicate that the mineral surface is very heterogeneous due to the omnipresent crystal defects of various kinds and/or due to the inherent anisotropic crystal structure for some minerals.;In Part Two of the present study, various surface chemical investigations were carried out on oleate-spodumene systems, since oleate is the major collector being used most effectively in industry.;The surface chemical investigations that were studied include the aqueous chemistry of oleate collector and spodumene-water systems, the effect of acidic and alkaline leaching of spodumene during various surface chemical investigations, X-ray photoelectron spectroscopy, electrophoretic mobility, oleate adsorption study, infrared spectroscopy, contact angle measurements and Hallimond flotation study. The results of these surface chemical investigations indicate that the oleate-spodumene system has a primary major peak and a secondary minor peak response at the solution pH of 8 and 4, respectively.;Based on the findings of the present study, it is recommended that spodumene should be conditioned in an alkaline solution at an elevated temperature prior to flotation to enhance flotation recovery. It is also recognized that further improvement in the flotation of spodumene might be possible if an impact comminution mechanism that favors the production of the 110 cleavage crystal plane of spodumene is used. Therefore it is recommended also that crushing should extend as far as possible and that steel grinding media should be used, whenever possible. (Abstract shortened with permission of author.)... |
