Lithium's kind of a big deal. It powers everything from our gadgets to our cars — really our entire modern world. And that's not changing any time soon; some analysts estimate that demand could grow up to 25 per cent over the next several years. But how does one harness the power of a metal that bursts into flame every time it gets wet? How do you even get it out of the ground?
What is Lithium?
Lithium (Greek for "stone") is the third element on the periodic table, a silvery-white alkali metal that's soft enough to be cut with a table knife. It's also the lightest metal on Earth, as well as the least-dense solid element. It has the equivalent density of a plank of pine wood, and half that of water. It floats in oil (and water too, though that'd end very badly since, you know, alkali go boom), and since it's reactive with moisture in the air, pure lithium is typically stored in anaerobic conditions and covered in either mineral oil, petroleum jelly, or some other such non-reactive liquid.
That's not to say that you can just dig a hole and pull out a chunk of lithium. No, it's far too corrosive and reactive for that; in fact, lithium never occurs freely in nature. Instead it's always found as a compound, often in pegmatitic minerals, as well as in ocean water, brines, and clays. Problem is, even though lithium is relatively abundant — it is the 33rd most common element — it's very diffuse throughout nature, which means that collecting and concentrating it into a commercially viable form is a massive pain.
How Did We Discover It?
Johan August Arfwedson first isolated lithium from petalite — a crystalline substance — in 1817. Over the next few decades, a number of researchers teased out the basic physical conditions of the metal. By 1855, chemists Robert Bunsen and Augustus Matthiessen had discovered a means of precipitating large amounts of lithium from lithium chloride via electrolysis, which led to small-scale production in 1916 and commercial-scale lithium production by 1923.
Lithium was used in WWII as a high-temperature grease for aircraft engines, thanks to its high melting point and the fact that it's significantly less corrosive than the calcium soaps used previously. Lithium also played a major role in the Cold War. The lithium-6 and lithium-7 ions were used to create tritium, a boosting compound used to increase the efficiency and yield of hydrogen bombs, as well as a solid fusion fuel itself.
From the late 1950s until the mid-1980s, the US was the dominant global lithium producer. Over roughly a quarter century, the US amassed a stockpile of 40,000 tonnes of lithium hydroxide from production sites in Nevada and North Carolina. America supplied 80 per cent of the global demand for lithium in 1976, and continued its dominance until 1984, when one of the largest deposits on the planet was discovered in Chile (and again in 1997, when mining began on another massive deposit in Argentina).
So, What Do We Do When We Find It?
Turns out the US only holds a fraction of the massive lithium deposits of Chile and Argentina. They're the two largest producers, in that order, churning out 60 per cent of the world's annual supply. Australia and China combine for another 30 per cent. The remaining 10 per cent accounts for smaller producers like the US and Russia. The US Geological Survey estimates total worldwide lithium reserves at 11 million tonnes. interestingly, half of that supply is thought to actually reside in Bolivia, along the eastern face of the Andes. Overall, the USGS estimates there's at least 4.9 million tonnes of lithium in the Bolivian hills.
Historically, lithium has either been mined from brines or from hard rock mining. Hard-rock lithium mining is just like other traditional mining operations: dig a big hole, pull out the rocks you want, send them off for processing. The problem with applying that to lithium is that extracting the substance from solid rock is an incredibly time-consuming, energy-hogging and cost-intensive ordeal. Since lithium is so diffuse, you have to pull a lot of rock out of the ground just to get a little bit of the good stuff.
Instead, far more economically efficient, brine-based extraction methods have been developed. Both Chile and Argentina (as well as China, Russia and the United States' only operating lithium mine in Clayton Valley, Nevada) use the brine pool method. Brine itself is, as Western Lithium explains:
The brines, volcanic in origin, are present in desert areas and occur in playas and salars where lithium has been concentrated by solar evaporation. In the salars (saline desert basins sometimes known as salt lakes or salt flats), the brine is contained at or below the surface and is pumped into large solar evaporation ponds for concentration prior to processing. When the basin surfaces are predominantly composed of silts and clays with some salt incrustation, they are referred to as playas. If the surface is predominantly salt they are called salars. Although the fundamental character of the deposits is similar, there is great variability in size, surface character, stratigraphy, structure, chemistry, infrastructure and solar evaporation rates.
The largest such brine pool resides in the world’s largest salt flat, Bolivia's Salar de Uyini.
The Foote Mineral company used to operate a lithium brine pool in Silver Peak, Nevada and provides this deeper look as to how lithium is extracted:
The Foote Mineral Company is recovering lithium from solar evaporated saline brines at Silver Peak, Nevada. The brines are pumped from beneath a playa surface inside a closed basin. The playa deposits consists of mixtures of clays, silts, sands, and evaporites, many of which are saturated with saline brines down to known depths of 600 feet. Brines are probably present below this depth, for gravity studies have indicated the unconsolidated sediments reach depths of 1500 feet. The genesis of the Silver Peak deposit is apparently related to volcanic activity and the area is characterised by hot springs, cinder cones, and lava deposits. The brine pumped from wells contains 300 ppm of lithium and 10-15 wt. % of other dissolved solids. The playa surface is well suited for solar evaporation. The brines are pumped into a series of solar evaporation ponds and after they reach saturation a series of salts are precipitated. The sequence of salts precipitated is NaCl, a mixture of NaC1 and glaserite (KNa(SO4 )2 ), and then these two plus Ka As a consequence of the evaporation, the lithium concentration is increased to approximately 5000 ppm. The effective evaporation season at Silver Peak begins in April and commonly continues through October. It is necessary to accumulate sufficient brine by October to operate the processing plant through the winter months. Lithium is recovered from the brine by precipitating lithium carbonate.
Just four companies — Talison Lithium, Rockwood Holdings, Sociedad Quimica y Minera de Chile and FMC — account for 95 per cent of worldwide lithium production and all use the industry standard method of precipitating pure lithium from molten lithium chloride (LiCl) using electrolysis. This process is of course performed in an air and water free environment to avoid a reaction.
Where Do the Batteries Come In?
In the video above, Leyden Energy offers us a view inside their li-ion battery plant and a behind the scenes tour of its production facility.
The Science Channel's How It's Made series also walks us through a more general form of the battery production process in the clip above.
We've got roughly 900 million vehicles on the road worldwide, and not enough lithium reserves to replace very many of them with battery-powered alternatives. "Since a vehicle battery requires 100 times as much lithium carbonate as its laptop equivalent, the green-car revolution could make lithium one of the planet's most strategic commodities," says Mary Ann Wright of Johnson Controls-Saft, a lithium-ion battery producer.
"To make just 60 million plug-in hybrid vehicles a year containing a small lithium-ion battery would require 420,000 tons (380,000 tonnes) of lithium carbonate - or six times the current global production annually," William Tahil, research director at Meridian International Research, told Barrons. "But in reality, you want a decent-sized battery, so it's more likely you'd have to increase global production tenfold. And this excludes the demand for lithium in portable electronics."
To span that supply shortage, numerous alternative sources for lithium have been explored. One promising system is to use the brine pulled up by geothermal pumps. A cadre of seven geothermal plants in the Salton Sea have been able to pull about 15,000 tonnes of lithium (as well as a fair amount of zinc) from their pipes annually. It's simply a matter of filtering the dissolved minerals from the water.