Copper art

AFTER 102 years this mine lays claim to being the largest surface pit in the world and at 5km long, 3km wide and more than 1km deep it could well be right.
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A Komatsu haul truck at Chuquicamata fitted it with a Duratray body.

Noel Dyson

However, Chuquicamata (pronounced chu-ki-ka-mata) near the Chilean town of Calama is much more than that. It is the site of the world’s oldest recorded mine accident, a mining equipment museum, a showcase to some Australian mining technology, home to a ghost town and, if all goes to plan, will become the world’s largest blockcave mine.

The Codelco mine, known colloquially as Chooky,  has been extracting and treating copper oxide ore, turning out 8500 cathodes per day. Each cathode is 99.95% copper. Its electrolytic refinery has a nameplate of 855,000t of copper.

To turn that out the mine needs to deliver 230,000t of ore each day.

The mining operation is a fairly vanilla truck and shovel operation.

To get the ore out of the pit Chuquicamata has 92 trucks and 85 of them are in use on any given day with the remaining seven reporting for maintenance.

The truck fleet is split between Komatsu and Liebherr T282 trucks.

Many of those trucks are fitted with Australian-made Duratray truck bodies as well as Westech bodies from Australian company Austin Engineering.

Given Chile is seismically active, slope stability is a major concern.

Adding to the difficulties, a major fault line runs through the western side of the pit. This is where two tectonic plates butt together. A quirk of this is that there are two completely different soil types on the two plates. Still plenty of copper though.

Those pit walls are at about a 45 degree angle.

Australia’s Mining Monthly understands GroundProbe slope stability radars are being used to monitor the pit’s walls. GoundProbe surface radars are certainly in use at Chuquicamata’s near neighbour Radomir Tomic.

Chuquicamata is reaching the point though where it will no longer be economic to get much deeper.

That means the copper sulphide ore that has been identified at 1200m depth will need to be extracted another way.

Since 2011 Codelco has been developing an underground operation, cutting the access and transport tunnels for the mine.

The access tunnel will be for worker access and egress while the transport tunnel will shift the ore out of the mine via conveyors.

The underground operation is expected to extend Chuquicamata’s life another 50 years and have a peak production capacity of about 380,000tpa of fine copper.

At full flight the underground operation will have about 1000km of tunnels and be a three-level operation going 800m deep.

The plan is to have 20 major blocks per level. Those blocks will be between 200m and 400m high and have a 33,000sq.m base.

According to a Hatch report, the underground project has a $US4.3 billion capital expenditure price tag.

While the Chuquicamata mine has been going for a tick over a century, and with the underground operation could be going for 50 more, mining at the site stretches back centuries.

In 1899 a miner discovered the mummified remains of a miner who had suffocated in a collapsed tunnel, who became known as Copper Man.

Along with Copper Man was the discovery of various mining tools.

Carbon dating of the body put the age at about 550 years after the death of Christ.

One of the striking things about the discovery of Copper Man was the condition his remains were found in.

Experts postulated that it was the anti-microbial properties of the copper he was buried in, although some say it was the dry conditions of the Atacama Desert the mine sits in that helped with the preservation.

It seems Codelco has taken the site’s history to heart because dotted around the mine are examples of the mine’s old machinery.

In one corner there is an old shovel built in the 1940s. It contrasts well with the P&H electric rope shovel that has just been retired after operating for 16 years. The 1940s digger is more than 30m tall but its bucket could hold just 15t. The P&H shovel’s bucket holds 70t.

Near the haul truck maintenance shed are several examples of old haul trucks, including a “souped up” Electra Haul.

Alongside the mine is the town of Chuquicamata that was once home to 25,000 people.

Those people lived there rent free and did not have to pay for their electricity or water. 

However, changing health regulations caught up with the town and it was deemed too expensive to bring the buildings up to code. 

Instead they were shuttered and the workers were moved to Calama, 15km away.

They had to buy their own houses, however, Codelco chipped in 75% of the purchase price.

It has left the mine with a somewhat eerie legacy on its doorstep.

Many of the buildings look like the inhabitants have just stepped out on an errand.

It is the sort of film set that would have a film maker with dreams of producing a post-apocalyptic script licking their lips.

While age eventually wearied it, Chuquicamata was a very modern city in its day. 

In the 1960s it had Chile’s most advanced hospital and it also played host to the country’s first basketball stadium.