3009
Evolution of Dissolved Constituent in Pulp During
Marmatite‑Pyrite/Pyrrhotite Selective Flotation with
Redox Potential Regulation
Congren Yang*, Haodong Li, Wenqing Qin, Qian Wei and Fen Jiao
School of Minerals Processing and Bioengineering, Central South University, Changsha, China
ABSTRACT: Marmatite or sphalerite is often associated with pyrite and pyrrhotite in natural polymetallic
sulfide deposits. Therefore, how to well achieve the selective separation of marmatite or sphalerite from associated
pyrite and pyrrhotite is an important issue, because it is directly related to the efficient and sustainable utilization
of zinc-bearing sulfide mineral resources. The results of flotation confirmed that pulp redox potential as well as
dissolved oxygen dominated the selective separation of marmatite from associated pyrite and pyrrhotite, and
the Zn recovery and Zn grade of zinc concentrates could be greatly improved by controlling Eh. The Raman
spectra confirmed that calcium polysulfide (CaSn, n =2–8) was generated and maintained long-term stability in
the pulp regulated by lime without Eh regulation. However, under Eh regulation, CaSn only kept momentary
existence in the pulp. Polysulfide reacted quickly with the added copper sulfate and formed brown precipitates,
whose main component was CuS, leading to the ineffectiveness of copper-activation for Zn flotation.The
findings are expected to help scholars understand the marmatite-pyrite/pyrrhotite selective flotation better,
favor the beneficiation of high-sulfur polymetallic sulfide ores in study or practice, and provide important
inspirations for the theoretical research or practical utilization on other similar sulfide resources, especially those
containing pyrrhotite.
Keywords: High-sulfur polymetallic sulfide ore, Marmatite, Pyrite and pyrrhotite, Zn-S selective flotation,
Pulp redox potential regulation, Polysulfide
INTRODUCTION
Marmatite is an essential resource for zinc metal produc-
tion. However, when marmatite is associated with pyrite
and pyrrhotite, the recovery of Cu-activated sphalerite or
marmatite by flotation is vulnerable to the disturbance of
associated pyrite and pyrrhotite, which can be attributed to
the following possible reasons: pyrrhotite has variable float-
ability and is prone to oxidation and argillization, greatly
worsening the flotation environment (He et al., 2012).
Regarding the marmatite-pyrite/pyrrhotite (Zn-S) selective
flotation, it was reported that pulp aeration could be used
as a pretreatment process for depressing pyrite and/or pyr-
rhotite (Forson et al., 2022 Owusu et al., 2014, 2015), and
the beneficial effect of oxygen gas in separation of sphalerite
from pyrite at pH 11 with xanthate was also reported (Shen
et al., 1998). The micro-flotation results indicated that it
was feasible to well separate marmatite from pyrrhotite by
Eh regulation (maintaining a Eh range from –250 to 0 mV
(vs. SHE) with butyl xanthate collector in alkaline media
pH11) (Li, 2000), and it was reported that the recovery of
Evolution of Dissolved Constituent in Pulp During
Marmatite‑Pyrite/Pyrrhotite Selective Flotation with
Redox Potential Regulation
Congren Yang*, Haodong Li, Wenqing Qin, Qian Wei and Fen Jiao
School of Minerals Processing and Bioengineering, Central South University, Changsha, China
ABSTRACT: Marmatite or sphalerite is often associated with pyrite and pyrrhotite in natural polymetallic
sulfide deposits. Therefore, how to well achieve the selective separation of marmatite or sphalerite from associated
pyrite and pyrrhotite is an important issue, because it is directly related to the efficient and sustainable utilization
of zinc-bearing sulfide mineral resources. The results of flotation confirmed that pulp redox potential as well as
dissolved oxygen dominated the selective separation of marmatite from associated pyrite and pyrrhotite, and
the Zn recovery and Zn grade of zinc concentrates could be greatly improved by controlling Eh. The Raman
spectra confirmed that calcium polysulfide (CaSn, n =2–8) was generated and maintained long-term stability in
the pulp regulated by lime without Eh regulation. However, under Eh regulation, CaSn only kept momentary
existence in the pulp. Polysulfide reacted quickly with the added copper sulfate and formed brown precipitates,
whose main component was CuS, leading to the ineffectiveness of copper-activation for Zn flotation.The
findings are expected to help scholars understand the marmatite-pyrite/pyrrhotite selective flotation better,
favor the beneficiation of high-sulfur polymetallic sulfide ores in study or practice, and provide important
inspirations for the theoretical research or practical utilization on other similar sulfide resources, especially those
containing pyrrhotite.
Keywords: High-sulfur polymetallic sulfide ore, Marmatite, Pyrite and pyrrhotite, Zn-S selective flotation,
Pulp redox potential regulation, Polysulfide
INTRODUCTION
Marmatite is an essential resource for zinc metal produc-
tion. However, when marmatite is associated with pyrite
and pyrrhotite, the recovery of Cu-activated sphalerite or
marmatite by flotation is vulnerable to the disturbance of
associated pyrite and pyrrhotite, which can be attributed to
the following possible reasons: pyrrhotite has variable float-
ability and is prone to oxidation and argillization, greatly
worsening the flotation environment (He et al., 2012).
Regarding the marmatite-pyrite/pyrrhotite (Zn-S) selective
flotation, it was reported that pulp aeration could be used
as a pretreatment process for depressing pyrite and/or pyr-
rhotite (Forson et al., 2022 Owusu et al., 2014, 2015), and
the beneficial effect of oxygen gas in separation of sphalerite
from pyrite at pH 11 with xanthate was also reported (Shen
et al., 1998). The micro-flotation results indicated that it
was feasible to well separate marmatite from pyrrhotite by
Eh regulation (maintaining a Eh range from –250 to 0 mV
(vs. SHE) with butyl xanthate collector in alkaline media
pH11) (Li, 2000), and it was reported that the recovery of