Solubility Theory and minerals Floatability - sulfide minerals

While the solubility theory is a useful working hypothesis, it is not applicable to all minerals are floatable with xanthates, but not iron xanthates have yet been identified on iron sulfide minerals. Regardless of whether the collector action is a simple chemical reaction or not, there is a general and positive correlation between the flotability of most minerals and the solubility of the collector-metal salt. This relationship is complicated by collector molecular size, crystal structure of the mineral, and other factors.

Use of the electron diffraction method of investigation offers a more direct study of collector attachment. One such investigation of the xanthates-galena system indicated that either xanthic acid is adsorbed or xanthates ion plus H+ are coadsorbed. However, since the collector film is unstable in air, the adsorption of xanthic acid appears to be more logical. Figura 3 illustrates a two-dimensional arrangement of butylxanthic acid on a galena surface.

An analysis of plant operating data furnished additional information on the multiple layer adsorption of xanthates. In general, xanthates appears to be adsorbed in an odd (2n-1) number of layers with the nonpolar end always oriented outward. Hence, an excess of xanthates is merely wasted rather than serving as a depressant as might be expected if even number 82n) layers were formed. Detailed discussions of various collector theories are available in the literature.