Differential and preferential flotation
The pressing problems in differential and preferential flotation of ores are (1) the separation of lead sulphide from zinc sulphide, and (2) the separation of zinc and copper bearing sulphides from sulphides of iron.
Methods seeking separation of one sulphide from another by flotation are of two classes, viz.: (1) those in which a difference in flotability of the two minerals is created or enhanced by conscious control of one or more of the activating phenomena of the process, and (2) those in which the chemical nature of one of the sulphides is changed, with a resulting change in the nature of the surface. Methods of the first class truly accomplish “differential flotation” and this denomination should be closely restricted to such methods. Methods of the second class, by preferential chemical action, so change one of the sulphide minerals that it never floats, leaving the unaltered mineral to float under proper conditions. Freeman (Min. and Sci. Press, June 5, 1920, abstract from Proc. Australasian Inst, of M. and M.) calls this “preferential flotation” and this terminology may profitably be adopted.
Differential flotation of galena in the presence of blende may be brought about, in pulp-body concentration, by proper control of gasification and of kind and quantity of “oil,” in the presence of fresh ….Read more