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Leaching of coarse caliche ore
Javier I. Ordez, Silvia Valdez, Luis Moreno and Luis A. Cisternas
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Introduction
Column leaching experiments
Physical characterization of caliche ores
Methodology
Results and discussion
Conclusions
MethodologyOutline ConclusionsResults & DiscussionIntroduction
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Sulphates Chlorides
Nitrates
Major
Iodates
Perchlorates
Minor
Quartz
Other silicates
Insoluble
Distribution
MethodologyOutline ConclusionsResults & DiscussionIntroduction
CompositionCaliche
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Processing
MethodologyOutline ConclusionsResults & DiscussionIntroduction
Prilled iodine
Prilled sodium nitrate
Prilled potassium nitrate
Main products
Caliche
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Caliche ore
Dissolution governed by
solubility differences.
Ores composed by ahigh
water-soluble fraction.
Relevant diminution ofparticle & heap sizes
during leaching.
Metallic ore
Dissolution governed by
chemical reactions.
Ores composed by low
fraction of reacting
species.
Non relevant diminution
of particle & heap sizes
during leaching
Leaching differences
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
One of the causes for poor performance of heap leaching
Inadequate understanding of the mineralogy and
the physical properties
Experiments of physical
characterization
Experiments of column
leaching
Objective
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Column leaching experiments
Soluble composition of caliche (g/100 g).
NO3- 4.7
IO3- 0.01
Cl- 8.5
SO42 9.5
ClO4- 0.03
BO33- 0.09
K+ 1.2
Ca2+ 0.8
Mg2+ 0.6
Na+ 8.6
Soluble
Halite
Humberstonite
Nitratine
Sulphate (widely distributed)
Insoluble Quartz
Albite
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Particles 14 cm were used, which were one-sideflattened and attached to wall column with silicone.
Remaining spaces were filled with glass particles.
Demineralized water was used as leachant.
The leaching was performed for 71 days.
MethodologyOutline ConclusionsResults & DiscussionIntroduction
Column leaching experiments
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Physical characterization of caliche ore
Apparent density
Open porosity
Capillary suction
Permeability
These characteristics give useful information to
understand the heap leaching phenomena associated to
the mineral.
Characteristics
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Physical characterization of caliche ores -Capillary suction
The capillary suction was measured in
terms of the capillary coefficient (kc):
Cube-shaped rocks were put in contact
with kerosene during 5 hours.
Kerosene was chosen because does not
dissolve caliche constituents.
=
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Physical characterization of caliche ores -Permeability
The permeability coefficient (K) was calculated:
Cubic samples with cross sectional areas of 50 cm2
and predrilled in the middle were used.
Samples were sealed and then saturated in
vacuum with kerosene (24 h).
= ln 3.5 m
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MethodologyOutline ConclusionsResults & DiscussionIntroduction
Column leaching experiments
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Relativerecovery
Time, h
NO3
Cl
Ca
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Relativerecovery
Time, h
ClO4
IO3
K
SO4
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Relativerecovery
Time, h
Na
Mg
B
The use of glass stones favors the channeling into the column.
A significant fraction of leachant pass directly through the column without
be used for leaching.
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Comparing the results of coarse (CL) and
fine particle leaching (FL).
The final recoveries of all ions weresimilar between both experiments.
Particle size is determinant in the
dissolution behaviour.
Leachant preferably flowed by the
periphery of rocks; however at the end,
all particles were completely wetted.
MethodologyOutline ConclusionsResults & DiscussionIntroduction
Column leaching experiments
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Re
lativerecovery
Time, h
NO3_FLNO3_CL
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Re
lativerecovery
Time, h
IO3_FLIO3_CL
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Relativerecovery
Time, h
Cl_FL
Cl_CL
0.0
0.2
0.4
0.6
0.8
1.0
0 250 500
Relativerecovery
Time, h
SO4_FL
SO4_CL
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When the porosity was determined by simple immersion
without vacuum, the porosity was significantly less.
The values of density are notably greater than other reported in
the literature.
MethodologyOutline ConclusionsResults & DiscussionIntroduction
Physical characterization Porosity & Density
Entity Density, kg/m3 Porosity, %
(Vacuum + immersion)
Porosity, %
(Only immersion)
Lowest value 2 102 2.4 2.2Highest value 2 468 16.3 12.4
Average value 2 309 9.5 6.9
SD 131 5.5 4.0
Density and porosity determinations (statistics of 14 samples)
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Small permeability coefficients were obtained.
Low permeability values are obtained not only in formationswith unconnected pores but also with small pores.
P1 P2 P3 Mean SD
7.4*10-18 5.7*10-17 8.1*10-17 4.9*10-17 3.8*10-17
Permeability coefficient (K, m2) determined for caliche samples
MethodologyOutline ConclusionsResults & DiscussionIntroduction
Physical characterization - Permeability
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A column leaching experiment was performed, using
large particles of caliche.
The particle size importance was no critical since high recoveries
were reached.
Caliche is a mineral with a wide variety of constituents,
therefore the determination of properties results
complex.
Range of values for apparent density, total porosity, capillary and
permeability coefficients were proposed in this work.
MethodologyOutline ConclusionsResults & DiscussionIntroduction
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