<p>five Sandvik D90 rotary blasthole drills have been working at Veladero mine since it opened in 2005 and are still performing at an impressive 84 percent availability rate.</p>
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five Sandvik D90 rotary blasthole drills have been working at Veladero mine since it opened in 2005 and are still performing at an impressive 84 percent availability rate.

Old time gold diggers

VELADERO, ARGENTINA. Five unstoppable Sandvik D90 crawler mounted blasthole drill rigs have been prospecting for gold in one of the world’s harshest environments – high up in the Andes – for over 16 years. With more than 100,000 hours on them each, these drills have been kept in top form, thanks to planning, parts and patience.

Mining for gold anywhere can be daunting, but getting the glittery ore out of a mountain is as challenging as it gets. This is why it is so impressive that the Veladero gold Mine in Argentina, one of the largest in the world, is producing an incredible 14 tonnes of gold a year high up in the sky.

A joint venture between Barrick Gold and Shangdong Gold, Veladero straddles the Andes close to the Chilean border in one of the most inhospitable places on earth. An eight-hour drive from the nearest city of San Juan, Veladero is in the gold-rich Frontera District. Over 5,000 metres above sea level at its highest, the temperature ranges at Veladero from 30o Celsius in the summer to an equally blistering below 50o C in winter.

Rigs as old as the mine

When heavy snowfall isn’t burying equipment, the wind blows at terrific force – with speeds of over 160 kilometres per hour, meaning everything needs to be tied down. But weighing in at 140 tonnes, being blown away is not a concern for five Sandvik D90 rotary blasthole drills that are central to the whole gold mining operation. These machines have been working at the mine since it opened in 2005 and are still – even with well over 100,000 hours each – performing at an impressive 84 percent availability rate.

Sandvik D90 is one of the most powerful self-propelled crawler-mounted blasthole drill rigs for mining on the market. It is designed to rotary drill 229- to 349-millimetre (9- to 14-inch) diameter holes – at depths of up to 85 metres. They boast good visibility, powerful slewing and strutless mast support, helping them drill at ahigh level of productivity. With blasting occurring on a continuous basis, all year round, the Sandvik D90s at Veladero are drilling 40 holes each a day, sufficient to bring down up to a million tonnes of rock with each blast.

These drills have been incredibly reliable and outlasted even our most optimistic expectations

That’s not to say they don’t break down. As Maximiliano Davico, Sandvik Mining and Rock Solutions (SMR) key account manager in Argentina, says: “In these conditions, ultimately everything breaks in the end. But these drills have been incredibly reliable and outlasted even our most optimistic expectations. They were forecast to last for 70,000 hours – or 11 years. But here they are, well north of 100,000 hours and 15 years, and still proving to be more productive than newer competitor machines on the site. Even the factory is surprised at how well they are working. They are proving to be worth their weight in gold.”

True productivity partners

The close relationship between customer and manufacturer is driving the success at Veladero, with Barrick sharing machine data and drilling plans, allowing Sandvik to establish an effective maintenance plan for each rig. The machines have enjoyed comprehensive overhauls during their lives, including replacement engines and compressors, subgroup assemblies and proactive component exchanges before failure. Despite their age, SMR’s focus on constant support has stabilized the reliability of the Sandvik D90s. Smart inspection tools help identify potential problems, which produce action reports that, over the years, have included, among many other things, the replacement of the entire 30-tonne mast assemblies. The extreme cold is also tough on frames, with temperatures swinging from minus 50oC on start-up to 40oC when at operating temperatures – a thermal shock of 90oC causing steel expansion that can lead to structural cracking.

<p>Given the remote location of the site and strict government import regulations, ensuring a ready supply of spare parts is crucial to keeping these essential machines operational.</p>

Given the remote location of the site and strict government import regulations, ensuring a ready supply of spare parts is crucial to keeping these essential machines operational.

Critical parts of the operation

Given its remote location and strict government import regulations, ensuring a ready supply of spare parts is crucial to keeping these essential machines operational. If the rigs fail, they can’t drill, meaning they can’t blast which ultimately means no gold. To prevent rig downtime, an ample supply of parts is kept at the mine through a consignment agreement in a buffer store in Buenos Aires.

“Having worked for so long at this site, we have had ample failure data to form accurate predictions on component lifespans at the site,” says Davico. “We base our replacement strategy on this, to prevent unplanned stoppages due to component failure. Key to the success of this is our good relationship between Barrick’s maintenance and operations departments, which helps to minimize the impact of taking machines out of the line for repair.”

Productive future ahead

It might be the natural habitat of cougars, foxes and Argentina’s national bird the condor, but this mountaintop mine is also home to some 5,000 workers, all housed in a well-appointed mining community; one that includes its own 4G communications and hospital. Barrick has committed to extend the life of the Veladero Mine for 10 more years and elevate it to a Tier One asset (one that produces over 500,000 ounces a year of gold). The fleet of Sandvik D90s, soon to be fitted and connected with Newtrax monitoring systems, have years of productive drilling ahead of them.

TECH SPECS: Sandvik D90 blasthole drill rig

Hole diameter: 228 – 349 mm

Maximum hole depth: 1800 RPM

Feed rate: 0 – 21.6 m/min

Rated horsepower: 447kW

Full load RPM: 1,800 RPM