CURRENT
PRODUCTION SYSTEMS
CALICHE & SALMUERA
COLD LEACHING PROCESS
The old systems of saltpeter and iodine extraction needed huge amounts of energy to heat the water to 40 degrees centigrade, the temperature at which the water could be used to extract the saltpeter through leaching. Then additional energy was required to cool the nitrate-rich solutions before the crystallization phase. The Guggenheim Method was the most efficient of the systems used but even this was energy intensive as well as needing a lot of manpower in the loading and unloading of the leaching vats. Aiming to reduce costs, throughout the 1980s new processes were tested for leaching, called cold heap leaching.
How a leach pile is constructed
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BLASTING
The caliche found beneath the surface is extracted using explosions to blast the ground.
TRANSPORTATION
The caliche boulders are loaded onto large mining trucks and taken to the heap leaching site.
BASES OF THE HEAPS
Before the caliche is put onto the heaps the ground is prepared and a thick sheet of polyethylene is laid down to ensure that the materials don’t leach into the ground.
STACKED OF THE CALICHE
The caliche is poured and stacked onto the polyethylene sheet to a height of 6 to 10 m.
THE PILE OF LEACHING
Each pile is 90 m wide and 400 to 500 m long.
The piles are enormous,
but here only a representative
section is shown.
BLASTING
ANATOMY OF LEACHING HEAP
Sprinkler systems on top of the heap distribute water at ambient-temperature to produce the leaching process.
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The salt-rich solutions are
collected in impermeable
drains on the sides of the heap.
Sprinklers
Polyethylene base
Brine collection
360º view of heap leach in construction
SOLAR EVAPORATION PONDS
The Atacama Desert is the driest place on the planet, and the Atacama salt flats contain large concentrations of lithium in their brines. The energy from the sun is used to obtain the lithium through the natural process of evaporation and concentration of the brines that are pumped out of the heart of the salt flats.
Is extracted from the salt flats, from a depth of over 30 m, from 380 active wells.
Engine
Pipes
THE BRINE
PUMPING WELLS
Exterior crust
Halites
Clays
Halites
Base
0,5-1 m
15-20 m
3-5 m
10-15 m
Halite with brine
Halite with brine
Halite with brine
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Extraction pump
Once the extraction point has been identified a pump is inserted into the halite layer where the brines are.
The solutions are pumped to the solar evaporation ponds that cover an area of 42 km2.
Engine
Extraction pump
PUMPING WELLS
CONSTRUCTION
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CONSTRUCTION
The ponds are made compacting the surface of the salt flats. They are then lined with plastic sheets to make them waterproof ponds.
FILLING THE PONDS
The brines from the extraction ponds are pumped to the solar evaporation ponds where the sun evaporates the water and concentrates the salts which precipitate in a certain order depending on the chemical composition of the brine.
Topographic measures are
used to periodically control
the scale of salts precipitation.
HARVEST
The final part of the process, the extraction or harvesting of the salts, yields about 14 million m3 a year, the equivalent of about 35,000 to 40,000m3 of salts a day.
NITRATE PRILLING
Pril or granulated size
The application of the product onto soil is done in prilled form: small spheres of 2 to 3 mm diameter. A prilling plant is used for their manufacture, which includes units of drying, melting, prilling tower, sieving and cooling.
Step by step of the prilling system
The granulation tower
The prill pots are 1.2m diameter and 1.2m high receptacles which can easily be replaced for cleaning or if the melted material solidifies.
Detail of the
upper part of the
prilling tower.
The nitrate melted at more than 400 centigrade is pumped into the 4 prill pots that have hundreds of perforations in their base through which the material drips, producing a sort of rainfall.
These nitrate raindrops fall by gravity and solidify when they receive the air pushed up from the base of the tower, so that they arrive at the bottom in the form of tiny spherical droplets or prills.
Prill pots