XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3003
separation difficult (Aikawa 2021). Therefore, a proper way
of depressing ZnS floatability during flotation of complex
sulfide ores containing PbSO4 should be established.
To address these problems, Aikawa (2022) developed
a sustainable process for complex sulfide ores containing
anglesite by combining extraction, flotation, and cemen-
tation of Pb. Firstly, removal of PbSO4 from the ores is
conducted by extracting PbSO4 with ethylenediaminetet-
raacetic acid (EDTA) as a pretreatment of flotation. After
solid-liquid separation, residues containing valuable miner-
als are fed to flotation and the filtrate containing extracted
Pb2+ is treated using cementation to recover extracted Pb2+
as zero-valent Pb (Pb0). Secondly, in flotation, zinc sulfate
and sodium sulfite are used as depressants for sphalerite
and extraction of PbSO4 prior to flotation is effective to
enhance Cu/Zn separation by depressing sphalerite float-
ability. Cementation is one of the effective methods to
recover metal ions as zero-valent metals using the difference
in standard redox potentials of the interacting metals and
their ions. Finally, the Pb2+ extracted by EDTA is recovered
as Pb0 using zero-valent iron (ZVI) as a reductant, which
will not only add economic value but also protect the envi-
ronment (Aikawa 2022).
Though Aikawa (2022) achieved the improved Cu/Zn
separation by extracting PbSO4 using EDTA, EDTA has
some disadvantages such as its high cost, low selectivity,
corrosiveness, and its difficulty for reuse due to its ability
to form complexes with metal ions (e.g., ferrous dissolved
from ZVI). For the application of this process to operation,
alternative extractants of anglesite to EDTA is necessary
to overcome these disadvantages of EDTA. In this study,
extraction of anglesite to decrease the recovery of sphalerite
in flotation was investigated using ammonium acetate and
sodium chloride-hydrochloric acid as alternative extract-
ants of anglesite to EDTA. Finally, effects of a pretreatment
extracting anglesite on the sphalerite floatability was inves-
tigated using ammonium acetate and sodium chloride-
hydrochloric acid.
MATERIALS AND METHODS
Materials
Sphalerite (ZnS) and PbSO4 samples used in this study are
the same as Aikawa (2022). In preparation for the flota-
tion experiments, ZnS was ground by a vibratory disc mill
(RS 200, Retsch Inc., Germany) and screened to obtain a
size fraction of 75 38 µm. For the flotation experiments,
potassium amyl xanthate (KAX, Tokyo Chemical Industry
Co., Ltd., Japan) and methyl isobutyl carbinol (MIBC,
FUJIFILM Wako Pure Chemical Corporation, Tokyo,
Japan) were used as collector and frother, respectively. Zinc
sulfate (ZnSO4) and sodium sulfite (Na2SO3) purchased
from FUJIFILM Wako Pure Chemical Corporation (Japan)
were used as depressants for ZnS. Sulfuric acid (H2SO4,
FUJIFILM Wako Pure Chemical Corporation, Japan)
and sodium hydroxide (NaOH, FUJIFILM Wako Pure
Chemical Corporation, Japan) were used as pH adjust-
ers. For the extraction experiments and coupled extrac-
tion-cementation, ammonium acetate (CH3COONH4,
FUJIFILM Wako Pure Chemical Corporation, Japan) or
sodium chloride (NaCl, FUJIFILM Wako Pure Chemical
Corporation, Japan) acidified with hydrochloric acid (HCl,
FUJIFILM Wako Pure Chemical Corporation, Japan) were
used. For the cementation experiments and coupled extrac-
tion-cementation, zero-valent Fe (ZVI) powder (Fe0, 45
µm, FUJIFILM Wako Pure Chemical Corporation, Japan)
was used as a reductant.
Experimental Methods
Extraction of Anglesite
Extraction experiments of anglesite were conducted in
50-mL Erlenmeyer flasks containing 0.5 g of PbSO4 and
the solution containing CH3COONH4, or NaCl acidified
with HCl (NaCl-HCl) (solid/liquid ratio: 0.5 g/10 mL),
as applicable. The flasks were shaken in a thermostat water
bath shaker at a shaking speed of 120 rpm and amplitude
of 40 mm at 25 °C. After this, the leachates were collected
by filtration using 0.2 µm syringe-driven membrane filters
and immediately analyzed using ICP-AES to measure the
concentration of dissolved Pb. The experiments were done
in triplicate to ascertain that the differences observed were
statistically significant, and the extraction efficiency of lead
(EPb) was calculated using the following equation
E 100
Pb
i #=6Pb@tot
6Pb@
where [Pb]tot and [Pb]i are total Pb (mM) and extracted Pb
(mM), respectively.
Cementation Experiments of Extracted Pb2+
Cementation experiments of Pb2+ extracted from PbSO4
were conducted in 50-mL Erlenmeyer flasks. A 10 mL of
the leachate obtained after extraction experiment was added
to the flask, and ultrapure nitrogen gas (N2 99.99%) was
introduced for 15 min to remove dissolved oxygen (DO)
in the leachate. Then, a known amount of ZVI was added
to the flask, and N2 was further introduced for 5 min. The
flask was tightly capped with a silicon rubber plug and
parafilm, and shaken in a thermostat water bath shaker at
a shaking speed of 120 rpm and amplitude of 40 mm at
25 °C. After this, the leachate was filtered using a 0.2 μm
separation difficult (Aikawa 2021). Therefore, a proper way
of depressing ZnS floatability during flotation of complex
sulfide ores containing PbSO4 should be established.
To address these problems, Aikawa (2022) developed
a sustainable process for complex sulfide ores containing
anglesite by combining extraction, flotation, and cemen-
tation of Pb. Firstly, removal of PbSO4 from the ores is
conducted by extracting PbSO4 with ethylenediaminetet-
raacetic acid (EDTA) as a pretreatment of flotation. After
solid-liquid separation, residues containing valuable miner-
als are fed to flotation and the filtrate containing extracted
Pb2+ is treated using cementation to recover extracted Pb2+
as zero-valent Pb (Pb0). Secondly, in flotation, zinc sulfate
and sodium sulfite are used as depressants for sphalerite
and extraction of PbSO4 prior to flotation is effective to
enhance Cu/Zn separation by depressing sphalerite float-
ability. Cementation is one of the effective methods to
recover metal ions as zero-valent metals using the difference
in standard redox potentials of the interacting metals and
their ions. Finally, the Pb2+ extracted by EDTA is recovered
as Pb0 using zero-valent iron (ZVI) as a reductant, which
will not only add economic value but also protect the envi-
ronment (Aikawa 2022).
Though Aikawa (2022) achieved the improved Cu/Zn
separation by extracting PbSO4 using EDTA, EDTA has
some disadvantages such as its high cost, low selectivity,
corrosiveness, and its difficulty for reuse due to its ability
to form complexes with metal ions (e.g., ferrous dissolved
from ZVI). For the application of this process to operation,
alternative extractants of anglesite to EDTA is necessary
to overcome these disadvantages of EDTA. In this study,
extraction of anglesite to decrease the recovery of sphalerite
in flotation was investigated using ammonium acetate and
sodium chloride-hydrochloric acid as alternative extract-
ants of anglesite to EDTA. Finally, effects of a pretreatment
extracting anglesite on the sphalerite floatability was inves-
tigated using ammonium acetate and sodium chloride-
hydrochloric acid.
MATERIALS AND METHODS
Materials
Sphalerite (ZnS) and PbSO4 samples used in this study are
the same as Aikawa (2022). In preparation for the flota-
tion experiments, ZnS was ground by a vibratory disc mill
(RS 200, Retsch Inc., Germany) and screened to obtain a
size fraction of 75 38 µm. For the flotation experiments,
potassium amyl xanthate (KAX, Tokyo Chemical Industry
Co., Ltd., Japan) and methyl isobutyl carbinol (MIBC,
FUJIFILM Wako Pure Chemical Corporation, Tokyo,
Japan) were used as collector and frother, respectively. Zinc
sulfate (ZnSO4) and sodium sulfite (Na2SO3) purchased
from FUJIFILM Wako Pure Chemical Corporation (Japan)
were used as depressants for ZnS. Sulfuric acid (H2SO4,
FUJIFILM Wako Pure Chemical Corporation, Japan)
and sodium hydroxide (NaOH, FUJIFILM Wako Pure
Chemical Corporation, Japan) were used as pH adjust-
ers. For the extraction experiments and coupled extrac-
tion-cementation, ammonium acetate (CH3COONH4,
FUJIFILM Wako Pure Chemical Corporation, Japan) or
sodium chloride (NaCl, FUJIFILM Wako Pure Chemical
Corporation, Japan) acidified with hydrochloric acid (HCl,
FUJIFILM Wako Pure Chemical Corporation, Japan) were
used. For the cementation experiments and coupled extrac-
tion-cementation, zero-valent Fe (ZVI) powder (Fe0, 45
µm, FUJIFILM Wako Pure Chemical Corporation, Japan)
was used as a reductant.
Experimental Methods
Extraction of Anglesite
Extraction experiments of anglesite were conducted in
50-mL Erlenmeyer flasks containing 0.5 g of PbSO4 and
the solution containing CH3COONH4, or NaCl acidified
with HCl (NaCl-HCl) (solid/liquid ratio: 0.5 g/10 mL),
as applicable. The flasks were shaken in a thermostat water
bath shaker at a shaking speed of 120 rpm and amplitude
of 40 mm at 25 °C. After this, the leachates were collected
by filtration using 0.2 µm syringe-driven membrane filters
and immediately analyzed using ICP-AES to measure the
concentration of dissolved Pb. The experiments were done
in triplicate to ascertain that the differences observed were
statistically significant, and the extraction efficiency of lead
(EPb) was calculated using the following equation
E 100
Pb
i #=6Pb@tot
6Pb@
where [Pb]tot and [Pb]i are total Pb (mM) and extracted Pb
(mM), respectively.
Cementation Experiments of Extracted Pb2+
Cementation experiments of Pb2+ extracted from PbSO4
were conducted in 50-mL Erlenmeyer flasks. A 10 mL of
the leachate obtained after extraction experiment was added
to the flask, and ultrapure nitrogen gas (N2 99.99%) was
introduced for 15 min to remove dissolved oxygen (DO)
in the leachate. Then, a known amount of ZVI was added
to the flask, and N2 was further introduced for 5 min. The
flask was tightly capped with a silicon rubber plug and
parafilm, and shaken in a thermostat water bath shaker at
a shaking speed of 120 rpm and amplitude of 40 mm at
25 °C. After this, the leachate was filtered using a 0.2 μm