COPPER
A-Chuquicamata-ta, it Means No Worries… or Does it?
May 2019
Codelco’s Chuquicamata mine and smelting center are located in Northern Chile, near the city of Calama and is the largest open-pit mine in the world. In 2018, Codelco—a state-owned Chilean copper mining company which produces 10% of the world’s copper—announced a planned US$5.55bn expenditure to convert the Chuquicamata mine from an open pit mine to an underground block caving operation—part of Codelco’s 10-year US$39bn overhaul of its core assets.

The large-scale change was a necessity; the Chilean Mine has been producing copper for almost a century but would have ceased to be profitable within the next decade if it kept using surface mining methods. Despite its necessity, the move, set to increase Chuquicamata life span by at least 40 years, has not been without its challenges.

 

 

Despite some stoppages at Chuquicamata during February, as heavy rains forced operations to temporarily halt, the world’s largest miner has seen general success and smooth operations while transitioning to underground mining at the site. Initial underground operations began in March, with Codelco aiming for full commercial production to begin in the second half of 2019.

The issues Codelco has faced largely stemmed from its Chilean smelting operations. The company halted significant smelting capacity in December of 2018 in order to bring it in line with new emissions standard and expected to bring it back online in early 2019. Codelco contracted SNC-Lavalin for the site work but missed initial March deadlines and continued to see delays. Upon inspection, Codelco also found numerous issues with the quality of work on site, and eventually removed SNC-Lavalin from the project entirely.

Removing SNC has caused significant delays to the re-activation of the smelter. Codelco anticipates related losses of around US$40m. The company has resumed works, but a full restart remains elusive—meaning that half of the company’s smelting capacity in the area remains curtailed. Ballooning costs have added to the initial US$2bn price tag of the smelter overhaul, placing the mining giant further into debt.

Despite these issues, Codelco remains optimistic that the Chiquicamata underground transition, which will utilise the high-efficiency block caving method, will spur the company back into good fortunes.

Block caving is an underground hard rock mining method that, as the name suggests, involves allowing an ore body to cave. First, a large section of rock is undercut, creating a drawing point to collect the rock as it caves under the influence of gravity. Then, the caving ore is collected into a previously developed series of funnels and access tunnels located underneath the broken rock. Drilling and blasting are often used as part of this method, to precipitate the rock caving or increase rock fragmentation for handling purposes. The block caving method is often investigated when a hard rock open pit operation reaches the end of its life span, as it offers similar rates and operating costs.

1.7Mt of copper ore reserves at 0.7% and molybdenum—a silvery-white metal that is used in steel alloys—at 502ppm have been identified under the open pit. The expected throughput rate is 140,000 tonnes per day of ore or 336kt of  copper and more than 18kt of fine molybdenum per annum at current recovery rate. The new block caving operation consists of four production levels: a 7.5km main access tunnel, five clean air injection ramps, and two air-extraction shafts, in addition to other work.

Codelco has now officially underground operation—ahead of schedule—with first ore extraction seen in early April, totaling more than 8kt. Commercial production is expected to start in the second half of the year. The company is also planning to jump on the automation and digitization train with the assistance of Sandvik. Indeed, Codelco has contracted the Swedish mining equipment manufacturer to implement AutoMine—a tele-remote for loading and hauling—and OptiMine—which offers a real-time view of underground mining operations—before the mine reaches commercial production.