The mechanism of the depressant action of dextrin on pyrite

Bogusz, Edwina J.; Bogusz, Edwina J.

Thesis

The mechanism of the depressant action of dextrin on pyrite

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Creator

Bogusz, Edwina J.

Contributors

Finch, J. A. (advisor)

Abstract

English

The separation of minerals by flotation depends on the effectiveness of the reagents used. The performance of depressants is paramount in rejecting the undesirable minerals while maintaining acceptable recoveries of the desired mineral. Iron-bearing minerals are the main contaminants in many ores: their removal is critical. Several different types of depressants have been used for this purpose, many of which are toxic. A shift has been made toward more environmentally friendly reagents including starch and dextrin. The purpose of this thesis was to determine the depression mechanism of dextrin on pyrite. A number of techniques were applied to give insight into the mechanism, including adsorption studies, microflotation tests, and solution and surface analyses. It was revealed that dextrin only adsorbed on mineral surfaces that contained some metal ionic sites. The degree of adsorption depended on the nature of the metal species, with lead being more reactive than iron. Dextrin was able to depress pyrite, regardless of whether dextrin adsorbed or not; however, adsorbed dextrin was more effective. It appeared as if dextrin inhibited the formation of dixanthogen on the surface, which could lead to reduced floatability of pyrite. Finally, it was observed that over time, adsorbed dextrin underwent a conformational change on the surface of the mineral. This change permitted a greater amount of xanthate to adsorb on the mineral.

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