Date of Award

Fall 12-13-2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Metallurgical Engineering

Committee Chair

Courtney A Young

First Advisor

Larry Twidwell

Second Advisor

John Kirtley

Abstract

In traditional chalcopyrite-molybdenite (Cu-Mo) flotation separation systems, inorganic depressants such as NaSH and NaCN are used to selectively depress chalcopyrite making it more hydrophilic so molybdenite can be floated and recovered. NaSH and NaCN are highly toxic, have high explosion potential, strong odor, and readily oxidize in air resulting in a high consumption rates. To control oxidation, nitrogen gas, and Nokes reagent are both necessary, making the process even more expensive. In addressing these challenges, attention is fast shifting to disodium carboxymethyl trithiocarbonate (Orfom® D8), a novel organic depressant designed to replace conventional inorganic depressants because it does not easily undergo oxidation, making it more economical. Compared to conventional inorganic depressants, it is less toxic and expresses a relatively mild odor compared to inorganic depressants. Surface chemistry studies of Orfom® D8 with ethyl xanthate as collector established that, because Orfom® D8 co-adsorbs with xanthate and thereby masks xanthate-induced hydrophobicity, improves selectivity. This makes the chalcopyrite hydrophilic, depressing it. A variety of different analytical techniques are explored to not only confirm the depression mechanism but also identify if it applies to collectors other than xanthate.

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