Masters Theses

Keywords and Phrases

Activation; Activator; Critical elements; Flotation; Pyrite; Tellurium

Abstract

Copper sulfide tailings from past and present mining operations are important secondary sources of critical elements such as tellurium (Te), a key component in cadmium–telluride photovoltaic solar cells. Characterization of tailing streams from copper porphyry (CP) ore flotation revealed that Te-bearing minerals are predominantly hosted in pyrite, which is usually depressed and discarded. Enhancing pyrite recovery is therefore a critical first step toward concentrating Te minerals for downstream extraction. However, pyrite flotation is often hindered by hydrophilic surface complexes formed during prior processing. This research investigated selective flotation of Te-bearing pyrite from CP tailings using micro flotation and bench-scale flotation, supported by contact angle, zeta potential, X-ray Photoelectron Spectroscopy (XPS), and Total Organic Carbon (TOC) analyses. Among various activation strategies, the combined use of sodium hydrosulfide (NaHS) and sodium sulfide (Na₂S) at pH 9.0 was most effective, producing the highest xanthate adsorption (0.34 mg/g), a hydrophobic-to-hydrophilic sulfur ratio of 1.30 in XPS, and contact angles of ~88°, indicating enhanced hydrophobicity. Optimization via Box–Behnken response surface methodology determined that, under optimal conditions (NaHS 150 g/t; Na₂S 300 g/t; PAX 175 g/t; MIBC 125 g/t at pH 9.0), micro flotation achieved ~93% pyrite recovery. Bench-scale flotation with controlled potential activation (CPA) achieved ~90% pyrite and ~82% Te recovery. These findings demonstrate that NaHS–Na₂S synergy effectively restores pyrite floatability by altering surface chemistry to favor collector adsorption, offering a scalable approach for selective Te recovery from sulfide tailings.

Advisor(s)

Alagha, Lana Z.
Moats, Michael S.

Committee Member(s)

Kumar, Aditya
Nakhaei, Fardis

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2025

Pagination

xiii, 143 pages

Note about bibliography

Includes_bibliographical_references_(pages 125-141)

Rights

© 2026 Mulenga Mutema Chibesa , All Rights Reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12561

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Included in

Metallurgy Commons

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