Five Sandvik D90 crawler-mounted blasthole drills have been operating for over 16 years at the Veladero gold mine in Argentina – now a JV between Barrick and Shandong Gold, in what is one of the world’s harshest environments, high up in the Andes. With more than 100,000 hours on each machine, these drills have been kept in top form, thanks to the right approach to planning, parts and maintenance. Veladero straddles the Andes close to the Chilean border and is an eight-hour drive from the nearest city of San Juan. It is located in the gold-rich Frontera District at over 5,000 m above sea level at its highest, where the temperature ranges from +30°C in the summer to -50°C in winter. The operation is also subject to high winds of over 100 mph.

Central to the whole gold mining operation, the machines have been working there since it opened in 2005 and are still performing well with an 84% availability rate. The Sandvik D90 is one of the most powerful self-propelled crawler mounted blasthole drills for mining. They are designed to rotary drill 9” to 13.75” (229-349mm) diameter holes – at depths of up to 85m. They boast good visibility, powerful slewing and strutless mast support, helping them drill very productively. With blasting on a continuous basis, all year round, the Sandvik D90s at Veladero are working continuously, drilling 40 holes each a day, sufficient for up to 1 Mt of rock with each blast.

That’s not to say they don’t break down. As Maximiliano Davico, Sandvik’s 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.”

Much of the secret of success Sandvik says is a close relationship with client and manufacturer, 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, Sandvik’s focus on constant support has stabilised the reliability of the Sandvik D90s. Smart Inspections help identify potential problems, which produce action reports that, over the years, has included, among many other things, the replacement of the entire 30 t mast assemblies. The extreme cold is also tough on frames, with temperatures swinging from -50°C on startup to +40°C when at operating temperatures – a thermal shock of 90°C causing steel expansion that can lead to structural cracking.

Given its remote location, and strict government import regulations, ensuring a ready supply of spare parts is crucial to keeping these essential machines operational. To prevent rig downtime an ample supply of parts is kept at the mine (by a consignment agreement) and in a buffer store in the capital, 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 using this data, 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 minimise the impact of taking machines out of the line for repair.”

Veladero is also home to some 5,000 workers, all housed in a well-appointed mining community that includes its own 4G communications and hospital. Barrick has committed to extend the life of the mine for 10 more years and elevate it to a Tier One asset that produces over 500,000 oz a year of gold. The Sandvik D90s, soon to be fitted and connected by Newtrax with monitoring systems, have years of productive drilling ahead.