2640 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
It utilizes sensors to classify run-of-mine ore based on spe-
cific pre-defined criteria, such as chemical composition,
mineral type, or physical properties, leading to the selective
separation of desired and unwanted material. Sensors based
on x-ray transmission (XRT) and x-ray fluorescence (XRF)
have shown in previous studies the capacity to sort lime-
stone rocks according to their calcite grade (Tomey, Seiler,
de Amores, &Sánchez, 2023 Paranhos, dos Santos, Veras,
Guadagnin, &Pasetto, 2020). SBS capitalizes on its dry
processing capabilities and suitability for coarse particles,
leading to a substantial reduction in energy consumption
associated with size reduction. This translates to both eco-
nomic benefits (lower processing costs) and environmental
advantages (simplified tailings disposal) due to the reduced
volume of fine fractions in the tailings stream.
Froth flotation is a well-established technique in min-
eral processing employed for the selective separation of
minerals based on their surface properties. In the context
of the Queguay Formation limestone, calcite, the primary
component, needs to be separated from the main impu-
rity, quartz, to achieve the calcite purity requirements of
various industries (90%). Although both minerals possess
hydrophilic characteristics, the introduction of specific flo-
tation reagents enables their selective separation. Previous
studies have shown that sodium oleate and sodium silicate
act as collector and depressant respectively, resulting in the
selective separation by direct flotation of calcite from quartz
(Rao, Bhaskar Raju, &Prabhakar, 2009 Dhar, Thornhill,
&Kota, 2020).
Conventional processing flowsheets include multi-
ple grinding and flotation stages to reach required grade.
However, this multi-stage approach often incurs significant
energy and water consumption, with demands escalating as
the desired purity increases. Dry processing, and particu-
larly SBS, reduce the water demand in mineral processing
and it is considered economically viable due to its low oper-
ational cost and capital investment (Peukert, Xu, &Dowd,
2022).
Driven by the operational or performance constrains
observed when the separations methods are independently
applied, this paper introduces a novel, integrated flowsheet
for Queguay Formation limestone beneficiation, synergisti-
cally combining both approaches for enhanced efficiency
and product quality. This approach integrates sensor-based
sorting (SBS) and froth flotation with the goal of mini-
mizing energy and water consumption while meeting
specifications required by more demanding industries. This
alternative is evaluated through laboratory experiments
and compared to a typical two-stage grinding and flotation
alternative.
MATERIALS AND METHODS
Sample and Reagents
A limestone belt-cut sample of 70 kg was obtained from a
deposit belonging to the Queguay Formation. The mate-
rial is currently used as feedstock in cement production.
The sample elemental composition was characterized by
x-ray fluorescence (XRF), and it is presented in Table 1.
The estimated calcite grade by XRF assuming that all the
calcium present in the sample is hosted as calcite is 70.4%.
Additionally, the loss on ignition (LOI) of the sample was
measured to compare to the LOI expected for the estimated
calcite grade, assuming that the LOI is only explain by the
CO2 release during calcite decomposition (Table 1). The
measured LOI is slightly higher than the expected based on
the calcite grade estimation. The difference between XRF
and LOI estimations can be explained by the presence of
magnesium probably hosted as dolomite.
The mineralogical composition of the sample was deter-
mined by x-ray diffraction (XRD), results are presented in
Figure 1. By comparing the XRD analysis reports with lit-
erature data, the presence of calcium as calcite and silicon
as quartz are confirmed (Rao, Bhaskar Raju, &Prabhakar,
2009 Deng, Yang, Liu, &Li, 2019 Rahimi, Irannajad,
&Mehdilo, 2017). XRF and XRD analysis confirm that
calcite and quartz are the major components of Queguay
Formation limestone. For the rest of this work, calcium and
silicon are expressed as calcite (CaCO3) and quartz (SiO2).
In terms of the particle size distribution of the sample as
received, the P80 was 15.3 mm with 44.2% of the material
under 44 µm.
All froth flotation experiments were carried with tap
water. Sodium oleate was used as collector. It was prepared
from sodium hydroxide technical grade and oleic acid
technical grade. Technical grade sodium silicate was used
as depressant. Methyl isobutyl carbinol was used as frother
agent.
Table 1. Elemental composition and loss on ignition quantification of the
belt-cut sample limestone from Queguay Formation
XRF (%wt/wt) LOI (%)
Mass loss Ca Si Mg Fe Al
28.1 ± 0.8 8.1 ± 0.1 0.9 ± 0.6 0.7 ± 0.1 0.7 ± 0.1 33.3 ± 0.2
It utilizes sensors to classify run-of-mine ore based on spe-
cific pre-defined criteria, such as chemical composition,
mineral type, or physical properties, leading to the selective
separation of desired and unwanted material. Sensors based
on x-ray transmission (XRT) and x-ray fluorescence (XRF)
have shown in previous studies the capacity to sort lime-
stone rocks according to their calcite grade (Tomey, Seiler,
de Amores, &Sánchez, 2023 Paranhos, dos Santos, Veras,
Guadagnin, &Pasetto, 2020). SBS capitalizes on its dry
processing capabilities and suitability for coarse particles,
leading to a substantial reduction in energy consumption
associated with size reduction. This translates to both eco-
nomic benefits (lower processing costs) and environmental
advantages (simplified tailings disposal) due to the reduced
volume of fine fractions in the tailings stream.
Froth flotation is a well-established technique in min-
eral processing employed for the selective separation of
minerals based on their surface properties. In the context
of the Queguay Formation limestone, calcite, the primary
component, needs to be separated from the main impu-
rity, quartz, to achieve the calcite purity requirements of
various industries (90%). Although both minerals possess
hydrophilic characteristics, the introduction of specific flo-
tation reagents enables their selective separation. Previous
studies have shown that sodium oleate and sodium silicate
act as collector and depressant respectively, resulting in the
selective separation by direct flotation of calcite from quartz
(Rao, Bhaskar Raju, &Prabhakar, 2009 Dhar, Thornhill,
&Kota, 2020).
Conventional processing flowsheets include multi-
ple grinding and flotation stages to reach required grade.
However, this multi-stage approach often incurs significant
energy and water consumption, with demands escalating as
the desired purity increases. Dry processing, and particu-
larly SBS, reduce the water demand in mineral processing
and it is considered economically viable due to its low oper-
ational cost and capital investment (Peukert, Xu, &Dowd,
2022).
Driven by the operational or performance constrains
observed when the separations methods are independently
applied, this paper introduces a novel, integrated flowsheet
for Queguay Formation limestone beneficiation, synergisti-
cally combining both approaches for enhanced efficiency
and product quality. This approach integrates sensor-based
sorting (SBS) and froth flotation with the goal of mini-
mizing energy and water consumption while meeting
specifications required by more demanding industries. This
alternative is evaluated through laboratory experiments
and compared to a typical two-stage grinding and flotation
alternative.
MATERIALS AND METHODS
Sample and Reagents
A limestone belt-cut sample of 70 kg was obtained from a
deposit belonging to the Queguay Formation. The mate-
rial is currently used as feedstock in cement production.
The sample elemental composition was characterized by
x-ray fluorescence (XRF), and it is presented in Table 1.
The estimated calcite grade by XRF assuming that all the
calcium present in the sample is hosted as calcite is 70.4%.
Additionally, the loss on ignition (LOI) of the sample was
measured to compare to the LOI expected for the estimated
calcite grade, assuming that the LOI is only explain by the
CO2 release during calcite decomposition (Table 1). The
measured LOI is slightly higher than the expected based on
the calcite grade estimation. The difference between XRF
and LOI estimations can be explained by the presence of
magnesium probably hosted as dolomite.
The mineralogical composition of the sample was deter-
mined by x-ray diffraction (XRD), results are presented in
Figure 1. By comparing the XRD analysis reports with lit-
erature data, the presence of calcium as calcite and silicon
as quartz are confirmed (Rao, Bhaskar Raju, &Prabhakar,
2009 Deng, Yang, Liu, &Li, 2019 Rahimi, Irannajad,
&Mehdilo, 2017). XRF and XRD analysis confirm that
calcite and quartz are the major components of Queguay
Formation limestone. For the rest of this work, calcium and
silicon are expressed as calcite (CaCO3) and quartz (SiO2).
In terms of the particle size distribution of the sample as
received, the P80 was 15.3 mm with 44.2% of the material
under 44 µm.
All froth flotation experiments were carried with tap
water. Sodium oleate was used as collector. It was prepared
from sodium hydroxide technical grade and oleic acid
technical grade. Technical grade sodium silicate was used
as depressant. Methyl isobutyl carbinol was used as frother
agent.
Table 1. Elemental composition and loss on ignition quantification of the
belt-cut sample limestone from Queguay Formation
XRF (%wt/wt) LOI (%)
Mass loss Ca Si Mg Fe Al
28.1 ± 0.8 8.1 ± 0.1 0.9 ± 0.6 0.7 ± 0.1 0.7 ± 0.1 33.3 ± 0.2