leaching of coarse caliche ore

8/9/2019 Leaching of Coarse Caliche Ore

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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


CompositionCaliche


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Processing


Prilled iodine

Prilled sodium nitrate

Prilled potassium nitrate

Main products

Caliche


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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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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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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.




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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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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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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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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.



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.


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


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.



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leaching of coarse caliche ore

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