"The flotation of sulphide minerals from siliceous and calcareous gangue minerals always gives a concentrate that is contaminated to a greater or lesser degree with the gangue minerals, even though the collectors used do not show any appreciable collecting properties for the gangue minerals when they are treated alone. In an effort to reduce the amount of undesirable gangue mineral floated with the concentrate it is the practice to add arbitrary amounts of various reagents such as quebracho, alkali hydroxides, carbonates, silicates, sulphides, phosphates, fluorides, and sulphuric acid which have been found to be advantageous. The mechanism of depression is in general not clear, although a number of possibilities are recognised such as, (i) prevention of activation resurfacing by soluble salts present in the pulp, (ii) closure of surfaces against collector reactions, (iii) destruction or nullification of collector coatings, (iv) dispersion, (v) resurfacing to produce water avidity. In any given case one or more of these possible mechanisms may be operative.
The use of sodium silicate as a conditioning agent in flotation pulps for the depression of gangue is widespread, and it is desirable that the mechanism of the depressant action be elucidated to allow close control of the flotation process to be obtained.
Two probable mechanisms for sodium silicate depression of gangue have been postulated, viz. (i) surface closure of gangue mineral surfaces by silicate ions by mass action effect, and (ii) dispersion of gangue minerals by adsorption of either silicate ions or sodium ions on the surface of the gangue minerals. An effort has been made in the work to be described to determine which of the ions, silicate or sodium, is the effective ion in producing dispersion and hence depression of the gangue minerals in the flotation of sulphides from an artificial pyrite-quartz mixture"--Introduction, pages 1-2.
Schlechten, A. W.
Materials Science and Engineering
M.S. in Metallurgical Engineering
Missouri School of Mines and Metallurgy
iv, 37 pages
© 1951 William McMinn Billinghurst, All rights reserved.
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Billinghurst, William McMinn, "The depression of quartz in sulphide flotation" (1951). Masters Theses. 2990.