2993
Deciphering O-Isopropyl Ethyl Thionocarbamate Adsorption
Mechanisms for Improved Arsenopyrite Separation from Pyrite
Using Density Functional Theory Calculations
Dharmendr Kumar, Vinay Jain, Beena Rai
Physical Sciences Research Area, TCS Research, Tata Consultancy Services Ltd.,
Hinjawadi-Maan, Phase III Pune, Maharashtra
Kishore Kumar M
Department of Metallurgical and Materials Engineering,
Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
Sriram Goverapet Srinivasan
Physical Sciences Research Area, TCS Research, Tata Consultancy Services Ltd.,
Tharamani, Chennai, Tamil Nadu, India
ABSTRACT: Selective flotation of arsenopyrite (Asp) from the sulphide ore concentrate is crucial considering
the environmental impacts caused by arsenic species during the downstream metallurgical processes. In addition,
the gold fraction locked in the lattice of Asp is economically attractive given the higher gold content of Asp
compared to pyrite (Py) and chalcopyrite with which it is commonly associated. In this context, O-isopropyl
ethyl thionocarbamate (IPETC) or Z-200 (commercial name) is the currently established collector molecule
that has selectivity to Asp at alkaline pH. However, the underlying mechanism involving the interaction
between IPETC, and the Asp/Py surface is yet to be understood. In this work, Density Functional Theory
(DFT) calculations were carried out to understand the interaction between IPETC and Asp (001)/ Py (100)
surfaces. Adsorption of both the neutral and deprotonated molecules on pristine Py and Asp surfaces, as well
as in the presence of Cu ions were studied. Quantum chemical descriptors indicated that the deprotonated
form (IPETCdp) exhibits increased reactivity and a propensity for strong adsorption compared to the neutral
molecule, with S and N atoms being the predominant electron donating sites. Neutral IPETC bound stronger
with pristine Py as compared to pristine Asp surface, in line with experimental observations. However, for
IPETCdp in the presence of Cu ions, the trend reverses with stronger interactions with Asp as opposed to the Py
surface. The deprotonated IPETC resulted in strong N—As bond which was not observed in case of the neutral
molecule. Presumably, such differential binding is a key driver in selective separation of Asp from Py at alkaline
conditions in the presence of Cu ions.
Keywords: DFT IPETC Asp Py Adsorption energy, Mineral Recovery
Deciphering O-Isopropyl Ethyl Thionocarbamate Adsorption
Mechanisms for Improved Arsenopyrite Separation from Pyrite
Using Density Functional Theory Calculations
Dharmendr Kumar, Vinay Jain, Beena Rai
Physical Sciences Research Area, TCS Research, Tata Consultancy Services Ltd.,
Hinjawadi-Maan, Phase III Pune, Maharashtra
Kishore Kumar M
Department of Metallurgical and Materials Engineering,
Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
Sriram Goverapet Srinivasan
Physical Sciences Research Area, TCS Research, Tata Consultancy Services Ltd.,
Tharamani, Chennai, Tamil Nadu, India
ABSTRACT: Selective flotation of arsenopyrite (Asp) from the sulphide ore concentrate is crucial considering
the environmental impacts caused by arsenic species during the downstream metallurgical processes. In addition,
the gold fraction locked in the lattice of Asp is economically attractive given the higher gold content of Asp
compared to pyrite (Py) and chalcopyrite with which it is commonly associated. In this context, O-isopropyl
ethyl thionocarbamate (IPETC) or Z-200 (commercial name) is the currently established collector molecule
that has selectivity to Asp at alkaline pH. However, the underlying mechanism involving the interaction
between IPETC, and the Asp/Py surface is yet to be understood. In this work, Density Functional Theory
(DFT) calculations were carried out to understand the interaction between IPETC and Asp (001)/ Py (100)
surfaces. Adsorption of both the neutral and deprotonated molecules on pristine Py and Asp surfaces, as well
as in the presence of Cu ions were studied. Quantum chemical descriptors indicated that the deprotonated
form (IPETCdp) exhibits increased reactivity and a propensity for strong adsorption compared to the neutral
molecule, with S and N atoms being the predominant electron donating sites. Neutral IPETC bound stronger
with pristine Py as compared to pristine Asp surface, in line with experimental observations. However, for
IPETCdp in the presence of Cu ions, the trend reverses with stronger interactions with Asp as opposed to the Py
surface. The deprotonated IPETC resulted in strong N—As bond which was not observed in case of the neutral
molecule. Presumably, such differential binding is a key driver in selective separation of Asp from Py at alkaline
conditions in the presence of Cu ions.
Keywords: DFT IPETC Asp Py Adsorption energy, Mineral Recovery