3106
Lewis Acid-Base Interactions of Allyl Thionocarbamate with
Cu Metal and Cu Sulfides
Shiqi Guo, Irina Chernyshova, Behzad Vairi, Raymond S. Farinato, D. R. Nagaraj
Earth and Environmental Engineering Department, School of Engineering and Applied Sciences, Columbia University
ABSTRACT: N-Allyl O-isobutyl thionocarbamate (AIBTC) is an intriguing ligand and stands apart from its
closest alkyl analogs, N-alkyl O-isobutyl thionocarbamate (IBPTC) and N-alkyl O-isopropyl thionocarbamate
(IPETC), by the presence of the allylic double bond. Despite this seemingly subtle modification, limited past
studies have indicated that AIBTC exhibits significant differences in its molecular level interactions with base
metal sulfides and precious metals, translating into significant differences in flotation performance at the
macroscopic scale in ores systems. While the alkyl analogs have found industrial application predominantly in
the flotation of copper ores as a selective Cu sulfide collector, the allyl counterpart, AIBTC, has demonstrated
improved performance in a broader spectrum of applications. Notably, these applications extend beyond copper
ores and, more recently, to coarse and fine particle recovery in several energy-critical metal ore systems, e.g.,
PGM/Ni/Cu. We believe that the interaction of AIBTC—a charge-neutral, non-oxidizable ligand—with
metals and metal sulfides is via Lewis acid-base concepts, but the exact mechanism and the influence of the
double bond are not known. In this study, ore flotation experiments were conducted to generate the data that
serve as the macroscopic outcomes in real practical systems. Solution properties, such as solubility and surface
tension vs. concentration, were determined however, these did not reveal the role of the allylic double bond.
Fundamental studies involving electrochemistry were conducted to understand specific molecular level Lewis
acid-base interactions on selected minerals, which could shed light on the role of the allylic double bond in
enhancing the flotation performance of AIBTC.
INTRODUCTION
Recent work in our group has yielded promising results for
critical minerals recovery from low-grade sulfide and pre-
cious metal ores and tailings using certain non-traditional
ligands in both coarse and fine size ranges in traditional
mechanical cells and, more importantly, in the newer flota-
tion devices. Two ligands have shown consistently better
performance. One of them is N-allyl O-isobutyl thionocar-
bamates (AIBTC). Its unique performance is different from
that of its closest analogs, N-propyl O-isobutyl thionocar-
bamate (PIBTC) or N-ethyl O-isopropyl thionocarbamate
(EIPTC, commonly also written as IPETC). N-allyl
O-isobutyl thionocarbamate has demonstrated a broader
spectrum of applications beyond Cu ores, whereas N-ethyl
O-isopropyl thionocarbamate has found industrial applica-
tion predominantly in the flotation of Cu ores as a selec-
tive Cu sulfide collector. The functional group containing
the donor atoms N, O, and S is the same for both ligands.
The most important difference is the allylic double bond
in AIBTC. This seemingly minor change in the hydrocar-
bon group seems to change its molecular level interactions
with sulfide minerals and precious metals, which translate
Lewis Acid-Base Interactions of Allyl Thionocarbamate with
Cu Metal and Cu Sulfides
Shiqi Guo, Irina Chernyshova, Behzad Vairi, Raymond S. Farinato, D. R. Nagaraj
Earth and Environmental Engineering Department, School of Engineering and Applied Sciences, Columbia University
ABSTRACT: N-Allyl O-isobutyl thionocarbamate (AIBTC) is an intriguing ligand and stands apart from its
closest alkyl analogs, N-alkyl O-isobutyl thionocarbamate (IBPTC) and N-alkyl O-isopropyl thionocarbamate
(IPETC), by the presence of the allylic double bond. Despite this seemingly subtle modification, limited past
studies have indicated that AIBTC exhibits significant differences in its molecular level interactions with base
metal sulfides and precious metals, translating into significant differences in flotation performance at the
macroscopic scale in ores systems. While the alkyl analogs have found industrial application predominantly in
the flotation of copper ores as a selective Cu sulfide collector, the allyl counterpart, AIBTC, has demonstrated
improved performance in a broader spectrum of applications. Notably, these applications extend beyond copper
ores and, more recently, to coarse and fine particle recovery in several energy-critical metal ore systems, e.g.,
PGM/Ni/Cu. We believe that the interaction of AIBTC—a charge-neutral, non-oxidizable ligand—with
metals and metal sulfides is via Lewis acid-base concepts, but the exact mechanism and the influence of the
double bond are not known. In this study, ore flotation experiments were conducted to generate the data that
serve as the macroscopic outcomes in real practical systems. Solution properties, such as solubility and surface
tension vs. concentration, were determined however, these did not reveal the role of the allylic double bond.
Fundamental studies involving electrochemistry were conducted to understand specific molecular level Lewis
acid-base interactions on selected minerals, which could shed light on the role of the allylic double bond in
enhancing the flotation performance of AIBTC.
INTRODUCTION
Recent work in our group has yielded promising results for
critical minerals recovery from low-grade sulfide and pre-
cious metal ores and tailings using certain non-traditional
ligands in both coarse and fine size ranges in traditional
mechanical cells and, more importantly, in the newer flota-
tion devices. Two ligands have shown consistently better
performance. One of them is N-allyl O-isobutyl thionocar-
bamates (AIBTC). Its unique performance is different from
that of its closest analogs, N-propyl O-isobutyl thionocar-
bamate (PIBTC) or N-ethyl O-isopropyl thionocarbamate
(EIPTC, commonly also written as IPETC). N-allyl
O-isobutyl thionocarbamate has demonstrated a broader
spectrum of applications beyond Cu ores, whereas N-ethyl
O-isopropyl thionocarbamate has found industrial applica-
tion predominantly in the flotation of Cu ores as a selec-
tive Cu sulfide collector. The functional group containing
the donor atoms N, O, and S is the same for both ligands.
The most important difference is the allylic double bond
in AIBTC. This seemingly minor change in the hydrocar-
bon group seems to change its molecular level interactions
with sulfide minerals and precious metals, which translate