2178 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
For these reasons, in this research the effect of a residual
polyacrylamide type flocculant subjected to different levels
of mechanical degradation on the flotation of chalcopyrite
was studied. In this way, new knowledge can be developed
in qualitative and quantitative terms of the impacts gener-
ated in the floatability of this copper sulfide.
MATERIAL AND METHODS
Mineral Sample
The chalcopyrite used in this research had a high level of
purity. The initial samples corresponded to hand speci-
mens between 50.8×76.2 mm to 76.2×101.6 mm. With
the objective of reducing its size, a first stage of manual
comminution was carried out until obtaining a product less
than 2 mm. At the same time, identifiable impurities were
selected and removed from the sample. Subsequently, the
mineral was subjected to a magnetic concentration process
to eliminate impurities such as magnetic iron minerals,
which could have been released during the size reduction
process. The magnetic fraction was discarded, while the
non-magnetic fraction was stored in a freezer at a tem-
perature of 1 °C, in plastic bags purged with nitrogen and
vacuum sealed to avoid surface oxidation of the particles
over time. The result of this sample storage and conserva-
tion technique was regularly verified through micro-flota-
tion tests. From the stored samples, 3 samples were taken
at random and chemically analyzed, obtaining a copper
content of 33.1%, which corresponds to chalcopyrite with
96% purity.
On the other hand, to meet the granulometric and
operational requirements of the microflotation tests, a sec-
ond stage of size reduction of the previously stored samples
was carried out, using a 70 mm diameter × 90 mm height
stainless steel ball mill designed especially for this proce-
dure and steel balls of 13 and 17 mm diameter. Grinding
was carried out wet, using 3 g of mineral and generating
a pulp of 23% solids by weight. The optimal time for this
operation was determined through kinetic tests and granu-
lometric analysis. Finally, the product obtained at this stage
was classified between ASTM 40# and 400# sieves and
separated into 3 individual homogeneous samples.
Chemical Reagents and Aqueous Media
The reagents used for all experimental tests were purified
potassium amyl xanthate (PAX) as collector, methyl isobutyl
carbinol (MIBC) as foaming agent, a polyacrylamide type
flocculant (PAM), sodium hydroxide (NaOH) and hydro-
chloride acid (HCl) as pH regulators and sodium chloride
(NaCl) as the only component of the medium aqueous.
The manufacturers of PAM indicate that it corresponds to
a high molecular weight polymer that has a low degree of
anionicity.
Stock solutions were prepared at different concen-
trations of PAX, MIBC and PAM, with the aim of sub-
sequently taking a determined volume according to the
desired concentration in the experimental tests. It is impor-
tant to note that these solutions were replaced daily to avoid
degradation of the reagents. In the case of pH regulators,
they were added based on the value required in each experi-
ence, which was measured experimentally in each test.
Preparation of the flocculant stock solution requires a
longer conditioning time. In this sense, to ensure the com-
plete dissolution of these reagents, the procedure described
by Arinaitwe (2008) was followed. First, a 2 g/L solution
was prepared by stirring for 4 hours with a mechanical stir-
rer at 400 rpm and then the beaker was covered with an
aluminum film to avoid exposure to light and degradation
of the polymer. Finally, the solution was left to rest for 8
hours and, once this time had elapsed, a second reagent
dosage solution was prepared.
To achieve the different conditions of mechanical
degradation of the flocculant molecules, the stock solu-
tion described above was subjected to shear forces using a
40 mm diameter stainless steel paddle stirrer. In this way,
three mechanical degradation conditions were defined: No
shear (NS), moderate shear (MS) and strong shear (SS). To
generate the MS and SS conditions, after the rest time, the
PAM stock solution was sheared for 30 minutes at 500 rpm
and for 3 hours at 2000 rpm, respectively.
Experimental Procedure
Microflotation Tests
In order to evaluate the recovery of chalcopyrite in the pres-
ence of PAM, microflotation tests were carried out in a 150
mL Patridge-Smith cell depending on the pH of the sus-
pension and the level of mechanical degradation of the floc-
culant. Prior to the microflotation process, a conditioning
stage of the chalcopyrite was carried out, forming a mixture
of approximately 1 g of mineral and a certain amount of
0.01 M NaCl. In the first part of the conditioning, the pH
was regulated according to the test. Subsequently, the PAM
was added and left to condition for 3 minutes, after which
the PAX and MIBC were added and left to act for another
3 minutes. Next, the microflotation process began by trans-
ferring the pulp to the cell and introducing an air flow of
105 cm3/min for a period of 2 minutes, in which the foam
was removed manually every 10 seconds. Furthermore, to
maintain the level of pulp constant inside the cell, wash-
ing water with the same chemical composition as the origi-
nal aqueous medium was added. Subsequently, once the
For these reasons, in this research the effect of a residual
polyacrylamide type flocculant subjected to different levels
of mechanical degradation on the flotation of chalcopyrite
was studied. In this way, new knowledge can be developed
in qualitative and quantitative terms of the impacts gener-
ated in the floatability of this copper sulfide.
MATERIAL AND METHODS
Mineral Sample
The chalcopyrite used in this research had a high level of
purity. The initial samples corresponded to hand speci-
mens between 50.8×76.2 mm to 76.2×101.6 mm. With
the objective of reducing its size, a first stage of manual
comminution was carried out until obtaining a product less
than 2 mm. At the same time, identifiable impurities were
selected and removed from the sample. Subsequently, the
mineral was subjected to a magnetic concentration process
to eliminate impurities such as magnetic iron minerals,
which could have been released during the size reduction
process. The magnetic fraction was discarded, while the
non-magnetic fraction was stored in a freezer at a tem-
perature of 1 °C, in plastic bags purged with nitrogen and
vacuum sealed to avoid surface oxidation of the particles
over time. The result of this sample storage and conserva-
tion technique was regularly verified through micro-flota-
tion tests. From the stored samples, 3 samples were taken
at random and chemically analyzed, obtaining a copper
content of 33.1%, which corresponds to chalcopyrite with
96% purity.
On the other hand, to meet the granulometric and
operational requirements of the microflotation tests, a sec-
ond stage of size reduction of the previously stored samples
was carried out, using a 70 mm diameter × 90 mm height
stainless steel ball mill designed especially for this proce-
dure and steel balls of 13 and 17 mm diameter. Grinding
was carried out wet, using 3 g of mineral and generating
a pulp of 23% solids by weight. The optimal time for this
operation was determined through kinetic tests and granu-
lometric analysis. Finally, the product obtained at this stage
was classified between ASTM 40# and 400# sieves and
separated into 3 individual homogeneous samples.
Chemical Reagents and Aqueous Media
The reagents used for all experimental tests were purified
potassium amyl xanthate (PAX) as collector, methyl isobutyl
carbinol (MIBC) as foaming agent, a polyacrylamide type
flocculant (PAM), sodium hydroxide (NaOH) and hydro-
chloride acid (HCl) as pH regulators and sodium chloride
(NaCl) as the only component of the medium aqueous.
The manufacturers of PAM indicate that it corresponds to
a high molecular weight polymer that has a low degree of
anionicity.
Stock solutions were prepared at different concen-
trations of PAX, MIBC and PAM, with the aim of sub-
sequently taking a determined volume according to the
desired concentration in the experimental tests. It is impor-
tant to note that these solutions were replaced daily to avoid
degradation of the reagents. In the case of pH regulators,
they were added based on the value required in each experi-
ence, which was measured experimentally in each test.
Preparation of the flocculant stock solution requires a
longer conditioning time. In this sense, to ensure the com-
plete dissolution of these reagents, the procedure described
by Arinaitwe (2008) was followed. First, a 2 g/L solution
was prepared by stirring for 4 hours with a mechanical stir-
rer at 400 rpm and then the beaker was covered with an
aluminum film to avoid exposure to light and degradation
of the polymer. Finally, the solution was left to rest for 8
hours and, once this time had elapsed, a second reagent
dosage solution was prepared.
To achieve the different conditions of mechanical
degradation of the flocculant molecules, the stock solu-
tion described above was subjected to shear forces using a
40 mm diameter stainless steel paddle stirrer. In this way,
three mechanical degradation conditions were defined: No
shear (NS), moderate shear (MS) and strong shear (SS). To
generate the MS and SS conditions, after the rest time, the
PAM stock solution was sheared for 30 minutes at 500 rpm
and for 3 hours at 2000 rpm, respectively.
Experimental Procedure
Microflotation Tests
In order to evaluate the recovery of chalcopyrite in the pres-
ence of PAM, microflotation tests were carried out in a 150
mL Patridge-Smith cell depending on the pH of the sus-
pension and the level of mechanical degradation of the floc-
culant. Prior to the microflotation process, a conditioning
stage of the chalcopyrite was carried out, forming a mixture
of approximately 1 g of mineral and a certain amount of
0.01 M NaCl. In the first part of the conditioning, the pH
was regulated according to the test. Subsequently, the PAM
was added and left to condition for 3 minutes, after which
the PAX and MIBC were added and left to act for another
3 minutes. Next, the microflotation process began by trans-
ferring the pulp to the cell and introducing an air flow of
105 cm3/min for a period of 2 minutes, in which the foam
was removed manually every 10 seconds. Furthermore, to
maintain the level of pulp constant inside the cell, wash-
ing water with the same chemical composition as the origi-
nal aqueous medium was added. Subsequently, once the