El informe sobre las reservas se basa en "el perfil de concentraciones de litio encontrado por la Orstom en el centro del salar", que es un cono invertido con base de 10 mil kilómetros cuadrados y una profundidad de 220 metros. "La alternancia de capas de sal y de arcilla es la encontrada por la Dukes en el centro del salar".
Además que "sólo se puede extraer el litio de la salmuera de las capas de sal, que tiene, según la Orstom, una porosidad de 40% promedio sobre todo el salar", indica el informe. Por otro lado, la Direb recuerda que en el pasado se realizaron varios análisis y pronósticos de las reservas y capacidad productiva.
La Orstom (Office de la Recherche Scientifique et Technique d’Outre-Mer) que ahora es la institución de investigación científica francesa, en 1989 perforó 120 metros de profundidad, en el centro del salar, sin alcanzar su base.
La Dukes University perforó otro pozo profundo en 2004, también en el centro del salar, aunque para estudios paleoclimatológicos de Suramérica, y llegó a una profundidad de 214 metros, sin tocar fondo.
Con este último estudio se confirmó el mismo esquema de alternancia de capas de costra salina en 170 metros con capas de arcilla en los restantes 44.
De todas maneras, "sólo con más perforaciones sobre la totalidad del salar, se logrará determinar la profundidad real que tiene la salmuera, su contenido en sales, y la reserva real de litio", señala el informe de Dirección de Recursos Evaporíticos (Direb).
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Salar de Uyuni, Bolivia
The Salar de Uyuni lithium containing salt lake is large but it is challenging to harvest and process. The lithium contained in the brine is likely to be processed into lithium carbonate.
But the potential for Uyuni has been overstated in the recent world press 2009 given the state of knowledge we have of the resource. Lithium mining is difficult and the processing in the case of Uyuni will be particularly tricky.
Some further strategic deep drilling exploration is required before we can accurately determine its realistic potential to produce lithium carbonate for batteries.
In a salt desert in southern Bolivia lies the world’s largest lithium reserves. While the mineral become increasingly important for the car industry, the Bolivian government has got an important trump card in negotiations with foreign companies and governments.
This is the future, says Marcelo Castro, chief engineer for the project in the lithium salt desert Salar de Uyuni. He simply spray the warm salt solution from the test pool between the fingers. Soon the liquid has dried in the wind and his hands are dyed white of a thin layer of mineral rich salt.
If all goes as planned, the same process is soon to be made on an industrial scale. The salt concentrations of lithium are worth gold. The world’s car industry looks for environmentally friendly alternatives and now the bolivian goverment is starting to build a state giant plant for mining near the village of Rio Grande in the Salar de Uyunis periphery.
In recent months a debate has been going on between experts about the extent of the world’s reserves of lithium. Some seek to show that the world has limited reserves of lithium – insufficient to justify the conversion of the world’s automobile fleet to electric vehicles powered by lithium batteries and run them sustainably. The reserves of lithium in the Salar de Uyuni have become a key factor in this debate.
The consultancy firm Meridian International Research states that the Salar de Uyuni only has 300,000 tonnes of lithium (metal) that is realistically recoverable, and this at a high cost to the environment.
Year after year, the USGS (United States Geological Survey) continues to publish that Uyuni has a reserve of 5.5 million tonnes of lithium.
In 1989, ORSTOM (Office de la Recherche Scientifique et Technique d’Outre-Mer, today IRD, French Scientific Research Institute) drilled a borehole to a depth of 120 metres at the centre of the Salar without reaching its base. This showed that layers of highly porous salt crust, saturated with brine, alternate with layers of highly impermeable clay, also saturated with brine. The study counted 11 layers of salt crust (more than 80 m) and 10 layers of clay (almost 40 m). It was also found that nearly all the samples contain the same quantity of dissolved salts, and that the lithium content tends to fall slightly at greater depths.
In 2004, DUKE UNIVERSITY drilled another deep borehole, also in the centre of the Salar, as part of a paleoclimatological study of South America, for which the Salar de Uyuni provides unique scientific evidence. This borehole was drilled to a depth of 214 metres, without reaching the base of the Salar. The Duke researchers confirmed the same formation of layers of salt crust alternating with layers of clay. They found a total of approximately 170 metres of salt crust and 44 metres of clay, with the height of the layer of salt tending to increase at greater depths. The presence of lithium in the deep brine was also proven.
Only by drilling more boreholes all over the Salar will we be able to determine the true depth of the brine, its salts content, and the real reserves of lithium.
Nevertheless, we can make a new estimate, based on the information available today and assuming the following hypotheses:
The Salar is an inverted cone, with an area of 10,000 km2 at its base and a depth of 220 m.
The pattern of lithium concentrations is the one found by ORSTOM at the centre of the Salar.
The layers of salt and layers of clay alternate in the manner found by Dukes University at the centre of the Salar.
Lithium can only be extracted from the brine in the layers of salt, and these, according to ORSTOM, have an average porosity of 40% over the Salar as a whole.
According to the data collected and based on the above hypotheses, we can state that there are more than 350 million tonnes of metallic lithium in the Salar. Even using the most modern extraction technologies, however, no more than 40% of the lithium in the brine can be physically recovered. This means that the reserves of lithium that are realistically available and could be supplied by Uyuni to the world are 140 million tonnes of lithium.
Given the probable reserves in Uyuni, there is sufficient lithium in the world to develop lithium batteries on a massive scale and enable motor vehicles with combustion engines to be replaced by electric vehicles.
