XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3135
mainly include sulfur-oxy and oxidant [11–14], which
usually control the flotation separation of sulfide minerals
by regulating the redox potential of pulp, so as to achieve
the depression of pyrite. Organic depressants have received
substantial attention owing to their wide sources, rala-
tively low reagent cost and are environmentally friendly.
Carboxymethyl cellulose, starch, dextrin, chitosan, glyc-
erine-xanthate and sodium humate [15–20] have been
widely studied and used. Combined depressants have dem-
onstrated selective depression and better inhibitory effects.
Sultan et al. reported that the combined depressants of
lime and sodium tricarboxylate starch (TCSS) have a good
depression effect on pyrite, they produce a synergistic effect
[21]. Adding calcium species, can promote and enhance
the affinity between depressants and the surface of pyrite
[22]. Calcium hypochlorite-dextrin and lime-sodium
humate have also been reported as the combined depres-
sants of pyrite [23,24]. Calcium ions and the hydrolyzed
component (Ca(OH)+) largely strengthen the depression
effect of the depressants on the surfece of pyrite by pro-
viding the adsorption sites and enhancing bonding with
hydroxyl functionalities [10]. Obviously, the combinations
of calcium species and organic depressants have commonly
been used to depress pyrite, also the selective depressing
mecanism were comprehensively studied. However, limited
research has been conducted on the depressing mechanism
in the perspective of electrochemistry.
Galena and pyrite are semiconductors [25]. One elec-
trochemical factor influencing the separation of pyrite from
galena is the galvanic interaction between mineral-mineral
interaction in the flotation pulp. Compared with galena,
pyrite has a higher rest potential. Theoretically, galena would
serve as the anode in a galvanic couple consisting of galena
and pyrite, the oxidation and dissolution of which should
be accelerated pyrite would act as the cathode, on which
oxygen was preferentially reduced [26–28]. Although the
influences of galvanic interaction between galena and pyrite
couple on their flotation and surface oxidation have been
studied, the galvanic interaction between galena and pyrite
couple under depressant systems is not well understood.
This work aimed to evaluate the viability of achieving
effecient flotation separation of galena and pyrite using the
combined depressants CaCl2 and sodium humic (NaHA).
The effect of combined CaCl2 and NaHA on galena and
pyrite flotation behaviour was studied. Moreover, zeta
potential measurement, contact angle measurement,
Raman spectroscopy measurement, adsorption and electro-
chemical tests were employed to reveal the selective depres-
sive mechanism.
MATERIALS AND METHODS
Pure Mineral Samples and Reagents
The pure minerals of galena and pyrite were purchased from
Hunan and Guangdong, China, respectively. First, the bulk
pure mineral samples were selected by hand to obtain the
high purity samples with good crystallization. Then, the
high purity samples were crushed with a clean jaw crusher,
followed by grinding with ceramic ball mill. Finally, the
samples were dry screened with standard screens of 74μm
and 37μm to obtain different particle sizes. The prepared
samples were vacuumized and stored. The particle sizes of
–74+37μm were used for flotation tests and adsorption
tests. The particle sizes of –37μm were further ground to
below –2μm for chemical analysis, X-ray diffraction (XRD)
analysis, zeta potential measurement and Raman spectros-
copy measurement. The XRD spectra of galena and pyrite
were shown in Figure 1 and the main chemical composi-
tion of galena and pyrite were illustrated in Table 1. The
results showed that the galena and pyrite have good crystal-
linity and the purity of the galena and pyrite were 96.59%
and 95.24%, respectively.
Test reagents: calcium chloride (CaCl2) and sodium
humate (NaHA, C9H8Na2O4) were purchased from Tianjin
Guangfu Fine Chemical Research Institute, Tianjin, China
and used as depressant. Sodium dimethyl dithiocarbamate
(DDTC) and methyl isobutyl carbinol (MIBC) were used
as collector and frother, respectively, and purchased from
Zhuzhou Flotation Reagents Factory in Hunan, China.
Sodium hydroxide (NaOH) and hydrochloric acid (HCl)
were used to adjust the pulp pH. The reagents used in the
test were all analytically grade and the distilled water was
used in all tests.
Experiment Methods
Micro-Flotation
Micro-flotation test was carried out by hanging trough flo-
tation machine and the volume of the flotation cell was
40mL. The test spindle speed was 1602 r/min. The micro-
flotation test was carried out as follows. First, 2g mineral
samples were placed in a beaker with distilled water and the
pulp was ultrasonic for 5 min. Then, the supernatant of the
ultrasonic was poured away and the mineral after ultrasonic
cleaning transferred to the flotation cell and 35ml distilled
water was added. After that, the flotation pulp stirring for 1
min and the pH regulator, depressant,collector and frother
were added according to experimental requirements, the
flotation reagents conditioning time was 2 min,3 min, 2
min and 1 min, respectively. Finally, flotation was carried
out for 3 min. The foam product and the product in the
mainly include sulfur-oxy and oxidant [11–14], which
usually control the flotation separation of sulfide minerals
by regulating the redox potential of pulp, so as to achieve
the depression of pyrite. Organic depressants have received
substantial attention owing to their wide sources, rala-
tively low reagent cost and are environmentally friendly.
Carboxymethyl cellulose, starch, dextrin, chitosan, glyc-
erine-xanthate and sodium humate [15–20] have been
widely studied and used. Combined depressants have dem-
onstrated selective depression and better inhibitory effects.
Sultan et al. reported that the combined depressants of
lime and sodium tricarboxylate starch (TCSS) have a good
depression effect on pyrite, they produce a synergistic effect
[21]. Adding calcium species, can promote and enhance
the affinity between depressants and the surface of pyrite
[22]. Calcium hypochlorite-dextrin and lime-sodium
humate have also been reported as the combined depres-
sants of pyrite [23,24]. Calcium ions and the hydrolyzed
component (Ca(OH)+) largely strengthen the depression
effect of the depressants on the surfece of pyrite by pro-
viding the adsorption sites and enhancing bonding with
hydroxyl functionalities [10]. Obviously, the combinations
of calcium species and organic depressants have commonly
been used to depress pyrite, also the selective depressing
mecanism were comprehensively studied. However, limited
research has been conducted on the depressing mechanism
in the perspective of electrochemistry.
Galena and pyrite are semiconductors [25]. One elec-
trochemical factor influencing the separation of pyrite from
galena is the galvanic interaction between mineral-mineral
interaction in the flotation pulp. Compared with galena,
pyrite has a higher rest potential. Theoretically, galena would
serve as the anode in a galvanic couple consisting of galena
and pyrite, the oxidation and dissolution of which should
be accelerated pyrite would act as the cathode, on which
oxygen was preferentially reduced [26–28]. Although the
influences of galvanic interaction between galena and pyrite
couple on their flotation and surface oxidation have been
studied, the galvanic interaction between galena and pyrite
couple under depressant systems is not well understood.
This work aimed to evaluate the viability of achieving
effecient flotation separation of galena and pyrite using the
combined depressants CaCl2 and sodium humic (NaHA).
The effect of combined CaCl2 and NaHA on galena and
pyrite flotation behaviour was studied. Moreover, zeta
potential measurement, contact angle measurement,
Raman spectroscopy measurement, adsorption and electro-
chemical tests were employed to reveal the selective depres-
sive mechanism.
MATERIALS AND METHODS
Pure Mineral Samples and Reagents
The pure minerals of galena and pyrite were purchased from
Hunan and Guangdong, China, respectively. First, the bulk
pure mineral samples were selected by hand to obtain the
high purity samples with good crystallization. Then, the
high purity samples were crushed with a clean jaw crusher,
followed by grinding with ceramic ball mill. Finally, the
samples were dry screened with standard screens of 74μm
and 37μm to obtain different particle sizes. The prepared
samples were vacuumized and stored. The particle sizes of
–74+37μm were used for flotation tests and adsorption
tests. The particle sizes of –37μm were further ground to
below –2μm for chemical analysis, X-ray diffraction (XRD)
analysis, zeta potential measurement and Raman spectros-
copy measurement. The XRD spectra of galena and pyrite
were shown in Figure 1 and the main chemical composi-
tion of galena and pyrite were illustrated in Table 1. The
results showed that the galena and pyrite have good crystal-
linity and the purity of the galena and pyrite were 96.59%
and 95.24%, respectively.
Test reagents: calcium chloride (CaCl2) and sodium
humate (NaHA, C9H8Na2O4) were purchased from Tianjin
Guangfu Fine Chemical Research Institute, Tianjin, China
and used as depressant. Sodium dimethyl dithiocarbamate
(DDTC) and methyl isobutyl carbinol (MIBC) were used
as collector and frother, respectively, and purchased from
Zhuzhou Flotation Reagents Factory in Hunan, China.
Sodium hydroxide (NaOH) and hydrochloric acid (HCl)
were used to adjust the pulp pH. The reagents used in the
test were all analytically grade and the distilled water was
used in all tests.
Experiment Methods
Micro-Flotation
Micro-flotation test was carried out by hanging trough flo-
tation machine and the volume of the flotation cell was
40mL. The test spindle speed was 1602 r/min. The micro-
flotation test was carried out as follows. First, 2g mineral
samples were placed in a beaker with distilled water and the
pulp was ultrasonic for 5 min. Then, the supernatant of the
ultrasonic was poured away and the mineral after ultrasonic
cleaning transferred to the flotation cell and 35ml distilled
water was added. After that, the flotation pulp stirring for 1
min and the pH regulator, depressant,collector and frother
were added according to experimental requirements, the
flotation reagents conditioning time was 2 min,3 min, 2
min and 1 min, respectively. Finally, flotation was carried
out for 3 min. The foam product and the product in the