Sulfide Flotation in Complexing Media and Bacterial Degradation of the CU(II)-TETA Complex in an Aqueous Environment
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Authors
Cushing, Alexander
Date
Type
thesis
Language
eng
Keyword
Mineral Flotation , Chloride , Seawater , Chalcopyrite , Pyrite , CuTETA Degradation , Contact Angles , Electrochemistry , Pyrrhotite
Alternative Title
Abstract
Production of flotation concentrates from ores require a variety of reagents that include
complexing agents such as cyanide and triethylenetetramine (TETA). These chemicals, while
being useful for the process, can cause environmental issues.
In this thesis, the batch flotation of selected ores was investigated together with the surface
chemical phenomena related to the use of three complexants, namely TETA, cyanide and
chloride. The ores consisted of Ni-Cu sulfides, rich in pyrrhotite and a galena-pyrite sample, both
of which involved the use of TETA and a pyrite-based sample. Investigations with the first group
indicated that the metabisulfite SMBS/TETA combination in synthetic seawater performed better
in comparison with tap water. The synergistic effect of SMBS/TETA was superior due to
enhanced complexing activity in chloride-rich medium. The pyrite sample that had been pre-
contacted with cyanide was successfully desulfurized to minimize acid production potential in the
environment. These investigations were coupled with fundamental investigations on
electrochemistry of pyrrhotite, pyrite and galena through cyclic voltammetry, electrical
impedance spectroscopy, contact angle measurements under applied electrochemical potential, as
well as Raman spectroscopy and UV studies.
The electrochemical studies provided evidence for the synergistic effect of the SMBS/TETA
combination. The contact angle measurements provided support for formation metastable sulfur
causing hydrophobicity in the absence of collector, which was largely masked on iron sulfides
due to dominance of their surfaces with ferric hydroxide/oxide. Raman spectroscopy of the
flotation concentrates provided clear evidence for the formation of metastable elemental sulfur/polysulfide on cyanide-contacted pyrite, which was a key factor explaining its unusual
floatability. UV spectroscopy of ethanol extracts from the flotation concentrates provided further
evidence of elemental sulfur forming on the mineral surfaces.
Overall, these results represent a unique linkage between surface chemical phenomena and
genuine flotation behaviour of several ore samples. Proper use of the SMBS/TETA combination
is demonstrated to be a potential solution to rectify poor flotation of sulfide ores in seawater. The
sulfurous acid-copper sulfate treatment is demonstrated to be a potential solution for
desulfurization of cyanide tailings. In the environmental area, the microorganism Paecilomyces
sp. (KC790497.1) demonstrated to biodegrade over 90% Cu-TETA complex in aqueous
solutions.
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivs 3.0 United States
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivs 3.0 United States