2
MATERIALS AND METHODS
Collection of Mining Tailings
The copper-gold mining tailing sample came from a min-
ing operation in northern Peru. The sample containing
25% solids was dried at a temperature around 50°C for 5
days [35]. This tailing was pretreated in order to eliminate
the percentage of sulfur [36].
Tailing Characterization
The Inductively Couple Plasma (ICP) analytical method
was used to determine the heavy metal concentrations in
each sample of liabilities.
Mineralogical Tests
To obtain the mineralogical composition, X-ray diffraction
(XRD) was used. The XRD analysis was performed with
the DRX Bruker equipment model D8 Discover with cop-
per radiation (Cu Kα =0.15418 nm), current of 40 mA
and acceleration voltage of 40 kV with a Lynxeye detector
with energy selectivity.
The analysis was performed in a range of angles (2θ)
from 5 to 80 degrees in steps of 0.02 degrees consider-
ing the time per step 1 second. To calculate the composi-
tion of the crystalline phases and the amorphous part, the
Reference Intensity Ratio (RIR) method was applied [37].
X-Ray Flourescence
One gram of material was selected for each sample, X-ray
fluorescence analyses. X-ray flourescence analyzes were per-
formed with the Bruker S8 TIGER wavelength dispersive
with opening angle of 0.23° and 0.46°. In addition to ana-
lyzer crystals: PET, LIF (200), LIF (220) and XS-55, and
two types of detectors: scintillation counter and propor-
tional flow. The evaluation model was for oxides and the
measurement time was ~17 minutes.
Chemical Speciation
The concentrations of heavy metals in the tailing were
determined using Inductive Couple Plasma (ICP) method.
To determine the concentrations of metals in the leaching
tests, the Atomic Absorption Spectroscopy (AAS) tech-
nique was used [38].
Acid Base Accounting (ABA) analysis
The acid mine drainage (DAM) prediction analyzes were
carried out following the procedure proposed by Skousen
[39]. Then, a sample of 2.0 g of pulverized sample were
placed into 250 mL conical flask and 90 mL of distilled
water was added. At the beginning of the test, between 1–3
ml of standardized 1,0 N HCl was added. Then the flask
was placed on a shaking apparatus. After 2 hours, a second
acid quantity was added. After 24 hours, distilled water was
added to bring a volume of 125 mL approximately. Then,
the pH was registered before start the neutralization up to
8.3 by adding a standardized solution of 0,5 N or 0,1 N
NaOH.
Radiometric Analysis
The radiometric analysis was carried out using gamma-ray
spectrometry with a 3x3’’ NaI(Tl) scintillation detector
to determine the activity concentrations (AC) of natural
radionuclides. The tailing samples were placed in cylindri-
cal hermetic containers to prevent radon leakage and stored
for a period of 28 days to reach secular equilibrium [40].
Quantifications were carried out by the efficiency
transfer method using the software ETNA and the standard
reference materials IAEA-412 and IAEA-465 with known
activities of 40K, 226Ra and 232Th. The 1460 keV, 1764.5
keV and 2614.7 keV gamma lines were used for estimating
ACs of 40K, 214Bi(226Ra), and 208Tl(232Th), respec-
tively [41,42].
Geopolymerization Process
For geopolymerization to be carried out, it will be necessary
to adjust the molar ratio of Si/Al and Si/Na. In this case, the
Si/Al ratio was fixed at 1 and 5 by adding aluminum oxide
to the mixture. In the case of the Si/Na ratio, this was set
between 0.5 and 2.5. The concentration of sodium hydrox-
ide used in the alkaline solution was set from 9 to 13 molar.
Six geopolymer recipes were prepared by varying the
ratios of Si/Al and Si/Na. All recipes were molded in cubic
molds of 5cm based on the ASTM C109 standard [43].
After molding, the geopolymers were cured at ambient
temperature for 15 days. After this period, the geopolymers
were further cured in a furnace at a temperature of 75°C
for 7 weeks.
Geomechanical Tests
The standard method provides a means of determin-
ing the compressive strength of hydraulic cement and other
mortars and results may be used to determine compliance
with specifications [43].
Leaching Tests
The tailings samples were mixed with the geopolymers to
obtain cubic bricks of five centimeters in measurement.
These bricks were subjected to leaching tests in order to
identify the metals that could leach after obtaining the geo-
polymerized cement [44].
MATERIALS AND METHODS
Collection of Mining Tailings
The copper-gold mining tailing sample came from a min-
ing operation in northern Peru. The sample containing
25% solids was dried at a temperature around 50°C for 5
days [35]. This tailing was pretreated in order to eliminate
the percentage of sulfur [36].
Tailing Characterization
The Inductively Couple Plasma (ICP) analytical method
was used to determine the heavy metal concentrations in
each sample of liabilities.
Mineralogical Tests
To obtain the mineralogical composition, X-ray diffraction
(XRD) was used. The XRD analysis was performed with
the DRX Bruker equipment model D8 Discover with cop-
per radiation (Cu Kα =0.15418 nm), current of 40 mA
and acceleration voltage of 40 kV with a Lynxeye detector
with energy selectivity.
The analysis was performed in a range of angles (2θ)
from 5 to 80 degrees in steps of 0.02 degrees consider-
ing the time per step 1 second. To calculate the composi-
tion of the crystalline phases and the amorphous part, the
Reference Intensity Ratio (RIR) method was applied [37].
X-Ray Flourescence
One gram of material was selected for each sample, X-ray
fluorescence analyses. X-ray flourescence analyzes were per-
formed with the Bruker S8 TIGER wavelength dispersive
with opening angle of 0.23° and 0.46°. In addition to ana-
lyzer crystals: PET, LIF (200), LIF (220) and XS-55, and
two types of detectors: scintillation counter and propor-
tional flow. The evaluation model was for oxides and the
measurement time was ~17 minutes.
Chemical Speciation
The concentrations of heavy metals in the tailing were
determined using Inductive Couple Plasma (ICP) method.
To determine the concentrations of metals in the leaching
tests, the Atomic Absorption Spectroscopy (AAS) tech-
nique was used [38].
Acid Base Accounting (ABA) analysis
The acid mine drainage (DAM) prediction analyzes were
carried out following the procedure proposed by Skousen
[39]. Then, a sample of 2.0 g of pulverized sample were
placed into 250 mL conical flask and 90 mL of distilled
water was added. At the beginning of the test, between 1–3
ml of standardized 1,0 N HCl was added. Then the flask
was placed on a shaking apparatus. After 2 hours, a second
acid quantity was added. After 24 hours, distilled water was
added to bring a volume of 125 mL approximately. Then,
the pH was registered before start the neutralization up to
8.3 by adding a standardized solution of 0,5 N or 0,1 N
NaOH.
Radiometric Analysis
The radiometric analysis was carried out using gamma-ray
spectrometry with a 3x3’’ NaI(Tl) scintillation detector
to determine the activity concentrations (AC) of natural
radionuclides. The tailing samples were placed in cylindri-
cal hermetic containers to prevent radon leakage and stored
for a period of 28 days to reach secular equilibrium [40].
Quantifications were carried out by the efficiency
transfer method using the software ETNA and the standard
reference materials IAEA-412 and IAEA-465 with known
activities of 40K, 226Ra and 232Th. The 1460 keV, 1764.5
keV and 2614.7 keV gamma lines were used for estimating
ACs of 40K, 214Bi(226Ra), and 208Tl(232Th), respec-
tively [41,42].
Geopolymerization Process
For geopolymerization to be carried out, it will be necessary
to adjust the molar ratio of Si/Al and Si/Na. In this case, the
Si/Al ratio was fixed at 1 and 5 by adding aluminum oxide
to the mixture. In the case of the Si/Na ratio, this was set
between 0.5 and 2.5. The concentration of sodium hydrox-
ide used in the alkaline solution was set from 9 to 13 molar.
Six geopolymer recipes were prepared by varying the
ratios of Si/Al and Si/Na. All recipes were molded in cubic
molds of 5cm based on the ASTM C109 standard [43].
After molding, the geopolymers were cured at ambient
temperature for 15 days. After this period, the geopolymers
were further cured in a furnace at a temperature of 75°C
for 7 weeks.
Geomechanical Tests
The standard method provides a means of determin-
ing the compressive strength of hydraulic cement and other
mortars and results may be used to determine compliance
with specifications [43].
Leaching Tests
The tailings samples were mixed with the geopolymers to
obtain cubic bricks of five centimeters in measurement.
These bricks were subjected to leaching tests in order to
identify the metals that could leach after obtaining the geo-
polymerized cement [44].