2369
Developing a New Sulfidization Process to Improve the Flotation
of Oxidized Pyritic Gold Ores
Yangyang Huai
School of Chemical Engineering, The University of Queensland
Jiangxi Copper Corporation
Yongjun Peng
School of Chemical Engineering, The University of Queensland
Ronel Kappes
Newmont Corporation
ABSTRACT: With the depletion of high-quality base metal sulfide ores and the increasing demand of base
metals by the society, metal oxides and oxidized sulfide ores have to be processed. Although controlled potential
sulfidization has been widely applied to float metal oxide and oxidized sulfide ores, it suffers from a number of
drawbacks such as low efficiency and challenges of sulfidizing electrochemically active minerals. The objective
of this work was to identify limitations in its application in the flotation of an oxidized pyritic gold ore and
then develop a new sulfidization process to improve the flotation of this ore. Flotation tests and electrochemical
studies indicated that conventional sulfidization at –300 mV (SHE) only improved the flotation of the oxidized
ore slightly due to “superficial sulfidization” which produced hydrophobic sulfur oxidation products on the
surface of oxidized pyrite without promoting collector-induced flotation. To promote collector-induced
flotation, Cu(II) ions were added during grinding, followed by sulfidization and flotation of the oxidized ore.
This combination further improved the flotation of the oxidized ore as a result of the formation of Cu(I)S on the
surface of oxidized pyrite, which activated the pyrite and enhanced collector adsorption on the surface. Replacing
Cu(II) ions with Cu(I) ions improved the flotation of the oxidized ore furthermore due to the formation of more
Cu(I)S on the surface of oxidized pyrite. This study recommends a new sulfidization process that may be used
to improve the flotation of oxidized pyritic ores, and provides new knowledge that may be used to improve the
flotation of metal oxides and other types of sulfide ores.
INTRODUCTION
Base metals are extracted predominantly from sulfide ore
deposits and the extraction process mainly involves mineral
flotation to separate base metal minerals from other gangue
minerals and extractive metallurgy to dissolve base met-
als from their minerals. To selectively separate base metal
sulfide and precious minerals from gangue minerals during
flotation, thiol collectors, in particular xanthates, are often
used. This is because thiol collectors can selectively adsorb
on the surfaces of base metal sulfide and precious miner-
als. It is well documented that the adsorption of xanthates
on the surfaces of base metal sulfide and precious minerals
involves (i) chemisorption of xanthate ions, (ii) formation
Developing a New Sulfidization Process to Improve the Flotation
of Oxidized Pyritic Gold Ores
Yangyang Huai
School of Chemical Engineering, The University of Queensland
Jiangxi Copper Corporation
Yongjun Peng
School of Chemical Engineering, The University of Queensland
Ronel Kappes
Newmont Corporation
ABSTRACT: With the depletion of high-quality base metal sulfide ores and the increasing demand of base
metals by the society, metal oxides and oxidized sulfide ores have to be processed. Although controlled potential
sulfidization has been widely applied to float metal oxide and oxidized sulfide ores, it suffers from a number of
drawbacks such as low efficiency and challenges of sulfidizing electrochemically active minerals. The objective
of this work was to identify limitations in its application in the flotation of an oxidized pyritic gold ore and
then develop a new sulfidization process to improve the flotation of this ore. Flotation tests and electrochemical
studies indicated that conventional sulfidization at –300 mV (SHE) only improved the flotation of the oxidized
ore slightly due to “superficial sulfidization” which produced hydrophobic sulfur oxidation products on the
surface of oxidized pyrite without promoting collector-induced flotation. To promote collector-induced
flotation, Cu(II) ions were added during grinding, followed by sulfidization and flotation of the oxidized ore.
This combination further improved the flotation of the oxidized ore as a result of the formation of Cu(I)S on the
surface of oxidized pyrite, which activated the pyrite and enhanced collector adsorption on the surface. Replacing
Cu(II) ions with Cu(I) ions improved the flotation of the oxidized ore furthermore due to the formation of more
Cu(I)S on the surface of oxidized pyrite. This study recommends a new sulfidization process that may be used
to improve the flotation of oxidized pyritic ores, and provides new knowledge that may be used to improve the
flotation of metal oxides and other types of sulfide ores.
INTRODUCTION
Base metals are extracted predominantly from sulfide ore
deposits and the extraction process mainly involves mineral
flotation to separate base metal minerals from other gangue
minerals and extractive metallurgy to dissolve base met-
als from their minerals. To selectively separate base metal
sulfide and precious minerals from gangue minerals during
flotation, thiol collectors, in particular xanthates, are often
used. This is because thiol collectors can selectively adsorb
on the surfaces of base metal sulfide and precious miner-
als. It is well documented that the adsorption of xanthates
on the surfaces of base metal sulfide and precious minerals
involves (i) chemisorption of xanthate ions, (ii) formation