3509
Removal of Pyrite from Mine Tailings by Cementation-Magnetic
Separation Method for AMD Prevention
Hyunjin Na, Bogale Tadesse, Laurence Dyer, Richard Diaz Alorro
Western Australian School of Mines: Minerals, Energy and Chemical Engineering, Curtin University
ABSTRACT: This study investigated a new approach to separate pyrite (FeS2) from mine tailings using the
cementation-magnetic separation method by imparting a magnetic metal deposition on the surface of FeS2.
This metal deposition employed the cementation method (galvanic displacement reaction) using Al powder
from Co or Ni sulfate solution. After the cementation reaction, the reacted particles were subjected to magnetic
separation using disc magnetic, and their properties were characterized using X-ray diffraction (XRD). Results
showed the successful metal deposition on the surface of FeS2 via a simple cementation reaction using Al from
Co or Ni sulfate solution.
Keywords: Pyrite Magnetic Metal Deposition Cementation Magnetic Separation Galvanic Interaction
INTRODUCTION
Pyrite (FeS2), commonly found in mine tailings, is the main
reason for the formation of acid mine drainage (AMD)
when exposed to air and water in the environment (Park
et al., 2019 Craig and Vokes, 1993). At the same time,
tailings associated with FeS2 are still considered secondary
resources for various metals (Lèbre et al., 2017 Sarker et al.,
2022), such as gold (Au) (Gee et al., 2005 Valderrama and
Rubio, 2008 Hoang et al., 2022), copper (Cu) (Owusu et
al., 2016), and nickel (Ni) (Sirkeci et al., 2006). Therefore,
the removal of FeS2 from mine tailings is important to de-
risk and reprocess valuable metals simultaneously (Newell
et al., 2006 Ozun et al., 2019 Santander and Valderrama,
2019).
Magnetic separation is a way to separate FeS2, applica-
ble to a wide particle size range, a simple process, and envi-
ronmentally friendly techniques with fewer or no chemical
reagents (Wills and Finch, 2015). Although FeS2 is a weak
paramagnetic mineral, a magnetic coating technique can
enhance the magnetic susceptibility (Hwang et al., 1982).
Magnetic coating techniques artificially make magnetic sus-
ceptibility by providing highly selective attachment to the
target minerals with various support magnetic materials,
usually occurring in the liquid media (Parsonage, 1988).
Cementation is an attractive approach to make a mag-
netic coating on FeS2 possible while taking advantage of
the semiconductor property of FeS2 for galvanic interac-
tion. Cementation is the electrochemical process according
to the difference in standard reduction potential without
an external power source, called galvanic displacement and
electroless deposition (Djokic, 2010). In the cementation
reaction, the reduction of metallic ions (M2+) takes place
by adding metal (R, reducing agent) with a lower standard
reduction potential as in the following equation (Djokic,
2010). Provided that the galvanic interaction of FeS2
between conductive material, the electrons generated from
the anodic reaction (Eq. (1) and (2)) are expected to trans-
fer to FeS2, and the metal deposition occurs on the surface
of FeS2 from the magnetic ions’ solution (Jeon et al., 2020
Jeon et al., 2022).