The Atacama Desert in South America is probably the closest thing to Mars found on Earth.
That’s not an exaggeration. NASA has tested instruments in the desert for use on Mars missions, and film crews have used it as a stand-in for the red planet.
Parts of the desert have never received any recorded rain, resulting in an extraterrestrial-like landscape void of plants and animals in those regions.
While an actual Mars rover may not be roaming the desert floor, Vermeer equipment is.
That’s because Atacama, which stretches approximately 620 miles (997.8 km) north to south in Chile, is rich in minerals, including copper and the world’s largest natural supply of sodium nitrate.
Also present are large reserves of iodine, which are found in the hard salt-cemented beds referred to locally as caliche. The Chilean reserves are one of the largest sources for the commercial extraction of iodine in the world.
Iodine has a broad range of uses and can be found in disinfectants, table salt, X-ray contrast media, liquid crystal displays (think: LCD televisions) and much more.
The Aguas Blancas deposit in northern Chile covers 45,000 acres (18,211 ha) and is mined by Atacama Minerals Chile (AMC). The company produces 1,323 tons (1,200 T) of iodine annually, which it says is about 3 percent of all the worldwide iodine production and makes it the fifth-largest producer in Chile.
AMC started production in 2001 using traditional drill-and-blast techniques. In 2006, it switched to a new method that has sped up the heap leaching process and increased the amount of iodine recovered.
These gains came after AMC stopped drill-and-blast mining and converted to mining with surface excavation machines. It now uses two Vermeer T1255III Terrain Leveler® surface excavation machines (SEM).
Consistent size leads to increased recovery
The 600 horsepower (447kW) T1255III can cut a swath up to 27 inches (68.6 cm) deep and 12 feet (3.7 m) wide in a single pass. It operates with a top-down cutting motion. The teeth on top of the cutting drum advance over the top of the unbroken material surface as the unit is in motion.
Heap leaching is a process used to extract precious metals from ore by placing them on a pad and dripping chemicals on them. The broad range in sizes resulting from drilling and blasting led to smaller material leaching faster than the larger material at AMC. In some cases, the leaching process could not be completed.
A big advantage with a Terrain Leveler SEM is that it produces a finer and more consistent particle size than explosives. Using the SEMs, the leaching process time for AMC has been reduced to 12 to 15 months from the typical 2 to 3 years, while iodine mineral recovery has increased by 8 to 12 percent.
“The recovery has increased due to the reduction in the range of particle sizes, which enables the completion of the dissolution to occur sooner,” says Cristian Gonzalez, AMC acting general manager.
At the same time, water usage has decreased because the leach piles don’t need to be irrigated as long. Water management is a major issue at mines worldwide, but it’s an especially big deal when you are mining in a desert and at a time when, like so many other mined commodities, the price of iodine has fallen.
“This obviously improves margins but also has enabled increased production without the increase in the water requirement, which is a very significant challenge in northern Chile,” Gonzalez says.
‘You won’t see a blade of grass’
These efficiencies are being realized in a place that was the subject of a National Geographic magazine article titled “The Driest Place on Earth.”
“There are sterile, intimidating stretches where rain has never been recorded, at least as long as humans have measured it,” the magazine reported. “You won’t see a blade of grass or cactus stump, not a lizard, not a gnat.”
You will, however, see Vermeer surface excavation machines.
Vermeer, the Vermeer logo, Equipped to Do More and Terrain Leveler are trademarks of Vermeer Manufacturing Company in the U.S. and/or other countries.
© 2016 Vermeer Corporation. All Rights Reserved.