2
pigment and catalyst, magnetic discs, and solar panel appli-
cations [21,22].
Furthermore, Te is only economically recoverable
from copper porphyry deposits using complex production
processes [14,23–25]. Statistical data from 2000 to 2020
shows that 90% of Te production occurs as a by-product of
copper porphyry deposit anode slimes reprocessed by refin-
ing [22,23].
Literature suggests other production routes for Te, such
as the copper porphyry flotation streams, where 60 – 90%
of tellurium in the system is deported to the tailings or
non-copper-producing streams [9]. A study of the flota-
tion streams of a large copper porphyry concentrator in the
U.S.A. suggested that 88% of Te available in the flotation
streams was deported to the tailings. This study also indi-
cated that Te deported to the tailings was locked in larger
pyrite grains and associated with Au-Ag minerals [26].
Therefore, this study investigated the potential of dif-
ferent enrichment practices to recover Te minerals lost/
deported to copper tailings from operating copper mines.
Additionally, the study examined the mineralogy and
deportment of telluride minerals in CT and post-pro-
cessing streams for enrichment and enhanced recovery of
Te. The methodologies used for the characterization of
CT for tellurides and composition were inductively cou-
pled plasma-mass spectrometry (ICP-MS), X-ray fluores-
cence (XRF), and TESCAN’s Integrated Mineral Analysis
(TIMA). The strategies proposed for the enrichment and
enhanced recovery of tellurides were baseline pyrite/sulfide
flotation experiments using carbamate (EXP300422) and
xanthate (SIPX) collectors, and glycol (OREPREP X-237),
methyl isobutyl carbinol (MIBC) and terpineol frothers.
Lastly, gravity separation and froth flotation experiments
were used as a combined approach that would produce a
higher-grade pyrite/sulfide concentrate.
MATERIALS
Tailing Samples and Reagents
The copper tailings (CT) samples consisted of rougher
tailings grab samples from a large copper producer in the
U.S.A. The samples were air-dried and further split into
representative portions for flotation and gravity separation
experiments.
Flotation Reagents
Reagents such as carbamate (EXP300422) and xanthate
(SIPX) collectors, and glycol (OREPREP X-237) frother
were obtained from Cytec Industries (Solvay), and stock
solutions were prepared at 1g/L. Frothers such as methyl
isobutyl carbinol (MIBC) and terpinoel were purchased
from Fisher Scientific, and a stock solution was prepared at
1 g/L. Sodium hydroxide (NaOH) and hydrochloric acid
(HCl) were purchased from Fisher Scientific and used for
pH modification from prepared stock solutions of 10 g/L
and 9.12 g/L solutions, respectively.
RESEARCH METHODS
Characterization of Copper Tailings
TESCAN’S Integrated Mineral Analysis Studies
TESCAN’s Integrated Mineral Analysis (TIMA) was
performed on CT to identify the mineral associations
and locking behavior for different REEbearing mineral
phases. TIMA was conducted at Montana Technological
University’s Center for Advanced Materials Processing
(CAMP) using a polished epoxy mount of the copper tail-
ings sample. The sample was prepared for automated phase
analysis by scanning electron microscopy-energy dispersive
Xray (SEM-EDS) using TIMA software [27].
Characterization of Flotation and Gravity
Separation Experiments
X-Ray Fluorescence Studies
The samples were prepared -38 µm by abrasion. Tests were
performed in an energy dispersive x-ray fluorescence (XRF)
device with a 5sample carrousel. XRF characterization
identified and quantified the elemental content based on
the resulting X-ray fluorescence. The XRF was performed
to identify iron, copper, and sulfur in the CT, flotation con-
centrates, flotation tailings, gravity separation (GS) tailings,
GS concentrates, and GS middling samples [28].
Inductively Coupled Plasma—Mass
Spectrometry Studies
The inductively coupled plasma mass spectrometry
(ICP-MS) was performed to identify tellurium and other
valuables in the CT (experimental feed), flotation con-
centrates, and flotation tailings samples. ICP-MS “total”
digestion process was used to test digested powdered min-
eral samples in a fourstep dilution process beginning with
hydrochloric acid, second nitric acid, third perchloric acid,
and lastly, hydrofluoric acid. The digestion produced a sta-
ble ionic solution used for ICP-MS analysis [29].
BASELINE FLOTATION EXPERIMENTS
Bulk sulfide flotation experiments were conducted to estab-
lish a baseline and feasibility of concentrating tellurium-
bearing minerals from the CT samples. The selected sulfide
collectors were EXP300422 and SIPX. Flotation experi-
ments were carried out in a Denver D12 flotation machine
pigment and catalyst, magnetic discs, and solar panel appli-
cations [21,22].
Furthermore, Te is only economically recoverable
from copper porphyry deposits using complex production
processes [14,23–25]. Statistical data from 2000 to 2020
shows that 90% of Te production occurs as a by-product of
copper porphyry deposit anode slimes reprocessed by refin-
ing [22,23].
Literature suggests other production routes for Te, such
as the copper porphyry flotation streams, where 60 – 90%
of tellurium in the system is deported to the tailings or
non-copper-producing streams [9]. A study of the flota-
tion streams of a large copper porphyry concentrator in the
U.S.A. suggested that 88% of Te available in the flotation
streams was deported to the tailings. This study also indi-
cated that Te deported to the tailings was locked in larger
pyrite grains and associated with Au-Ag minerals [26].
Therefore, this study investigated the potential of dif-
ferent enrichment practices to recover Te minerals lost/
deported to copper tailings from operating copper mines.
Additionally, the study examined the mineralogy and
deportment of telluride minerals in CT and post-pro-
cessing streams for enrichment and enhanced recovery of
Te. The methodologies used for the characterization of
CT for tellurides and composition were inductively cou-
pled plasma-mass spectrometry (ICP-MS), X-ray fluores-
cence (XRF), and TESCAN’s Integrated Mineral Analysis
(TIMA). The strategies proposed for the enrichment and
enhanced recovery of tellurides were baseline pyrite/sulfide
flotation experiments using carbamate (EXP300422) and
xanthate (SIPX) collectors, and glycol (OREPREP X-237),
methyl isobutyl carbinol (MIBC) and terpineol frothers.
Lastly, gravity separation and froth flotation experiments
were used as a combined approach that would produce a
higher-grade pyrite/sulfide concentrate.
MATERIALS
Tailing Samples and Reagents
The copper tailings (CT) samples consisted of rougher
tailings grab samples from a large copper producer in the
U.S.A. The samples were air-dried and further split into
representative portions for flotation and gravity separation
experiments.
Flotation Reagents
Reagents such as carbamate (EXP300422) and xanthate
(SIPX) collectors, and glycol (OREPREP X-237) frother
were obtained from Cytec Industries (Solvay), and stock
solutions were prepared at 1g/L. Frothers such as methyl
isobutyl carbinol (MIBC) and terpinoel were purchased
from Fisher Scientific, and a stock solution was prepared at
1 g/L. Sodium hydroxide (NaOH) and hydrochloric acid
(HCl) were purchased from Fisher Scientific and used for
pH modification from prepared stock solutions of 10 g/L
and 9.12 g/L solutions, respectively.
RESEARCH METHODS
Characterization of Copper Tailings
TESCAN’S Integrated Mineral Analysis Studies
TESCAN’s Integrated Mineral Analysis (TIMA) was
performed on CT to identify the mineral associations
and locking behavior for different REEbearing mineral
phases. TIMA was conducted at Montana Technological
University’s Center for Advanced Materials Processing
(CAMP) using a polished epoxy mount of the copper tail-
ings sample. The sample was prepared for automated phase
analysis by scanning electron microscopy-energy dispersive
Xray (SEM-EDS) using TIMA software [27].
Characterization of Flotation and Gravity
Separation Experiments
X-Ray Fluorescence Studies
The samples were prepared -38 µm by abrasion. Tests were
performed in an energy dispersive x-ray fluorescence (XRF)
device with a 5sample carrousel. XRF characterization
identified and quantified the elemental content based on
the resulting X-ray fluorescence. The XRF was performed
to identify iron, copper, and sulfur in the CT, flotation con-
centrates, flotation tailings, gravity separation (GS) tailings,
GS concentrates, and GS middling samples [28].
Inductively Coupled Plasma—Mass
Spectrometry Studies
The inductively coupled plasma mass spectrometry
(ICP-MS) was performed to identify tellurium and other
valuables in the CT (experimental feed), flotation con-
centrates, and flotation tailings samples. ICP-MS “total”
digestion process was used to test digested powdered min-
eral samples in a fourstep dilution process beginning with
hydrochloric acid, second nitric acid, third perchloric acid,
and lastly, hydrofluoric acid. The digestion produced a sta-
ble ionic solution used for ICP-MS analysis [29].
BASELINE FLOTATION EXPERIMENTS
Bulk sulfide flotation experiments were conducted to estab-
lish a baseline and feasibility of concentrating tellurium-
bearing minerals from the CT samples. The selected sulfide
collectors were EXP300422 and SIPX. Flotation experi-
ments were carried out in a Denver D12 flotation machine