Barrick Gold’s recent appointment of a senior vice president for development of its troubled Lama project in Argentina has drawn attention as an indication of the company’s future plans for the gold-silver project.
Barrick announced in early September that it had selected George Bee as Senior VP for Lama and Frontera District Development, with immediate focus to be on advancing a starter project option at Lama, on the Argentinean side of the cross-border, Argentina/Chile Pascua-Lama project. Construction at the project has been suspended since the fourth quarter of 2013. When initially approved in 2009, project production capacity was planned at 750,000 to 800,000 oz/y of gold and 35 million oz/y of silver.
“Recent evaluation by the project team indicates that a modest, scalable starter project at Lama using underground mining methods may represent the best option to begin a phased development plan for Pascua-Lama,” the Barrick announcement said. “If successful, cash flow from Lama could be used to fund additional development on both sides of the border over time.”
Bee will advance initial conceptual work completed by the project team, working with Barrick’s Argentina Executive Director, Juan Ordoñez, as well as the Pascua-Lama team in Chile, which will continue to focus on optimizing the Chilean components of the Pascua-Lama project, while working to address outstanding legal, regulatory, and permitting matters.
Bee was a member of the team that developed Barrick’s Goldstrike operations in Nevada in phases between 1988 and 1995. “Just as the Goldstrike mine was completed in stages over time, we see significant benefits to approaching Pascua-Lama in the same way,” Barrick President Kelvin Dushnisky said. “We are confident that George Bee has the leadership capabilities, technical expertise, and regional experience to develop a compelling starter project option for Lama.”
As work on the Lama starter option advances, Bee will also begin developing an integrated development plan for the Frontera District, a 140-km stretch of prospective land on the El Indio belt controlled by Barrick.
Barrick Gold has reported details of successful projects to optimize production at the Pueblo Viejo mine in the Dominican Republic and the Goldstrike mine in northern Nevada. Pueblo Viejo is a joint venture owned 60% by Barrick and 40% by Goldcorp. Goldstrike is wholly owned by Barrick. Descriptions of the optimization projects and their results are included in Barrick’s report of its second-quarter 2016 financial and operating results.
Barrick, looking at a “modest” approach to Lama project development, also reports productivity improvement successes at Pueblo Viejo and Goldstrike, shown here. (Photo: Barrick Gold)
Optimizing Output at Pueblo Viejo
At Pueblo Viejo, four giant autoclaves are the key to unlocking the massive refractory orebody. Each weighs 780 mt and is roughly 38 m long and 6 m in diameter. Improving availability and throughput of the autoclaves has the potential to unlock substantial value for the mine.
Until recently, each autoclave required, on average, a 22-day maintenance shutdown every six months. Large metal walls that separate the compartments inside each autoclave begin to fail as a result of forces generated by continuous agitation of the ore slurry. A buckled or failed wall can interfere with normal operation, damaging agitator blades and shafts, and accelerating build-up of scale and sand, thereby requiring frequent maintenance.
Faced with this challenge, operations management at Pueblo Viejo came up with a plan to increase autoclave availability and throughput by extending the period between maintenance shutdowns from every six months to every seven or potentially eight months. To achieve this goal, the operations team proposed a number of critical modifications to the autoclaves.
High oxidization rates inside the autoclaves implied the number of interior compartments could be reduced, thereby mitigating the build-up of scale and the associated maintenance requirements. However, the remaining compartment walls would continue to fail at a similar rate, limiting the potential gains.
To solve this problem, the team worked with an engineering partner to develop a new design for the interior compartment walls. The design better integrates the walls into the autoclaves by using stronger titanium structure sections, improving bracing, and using larger bolts.
The new walls have been successfully installed in two of the mine’s four autoclaves. Initial results have been positive, indicating that increased run-time between shutdown maintenance is achievable. If successful in all four autoclaves, this initiative has the potential to increase autoclave availability from 84% to 86.5%, driving increased production, lowering unit costs, and generating additional free cash flow from the operation.
Other benefits include reducing materials cost for autoclave maintenance work (spare parts, valves, and ancillary equipment) and reducing contractor costs, due to fewer shutdowns per year.
Improving Haulage Performance at Goldstrike
At Goldstrike, conventional wisdom suggested that the technical limit for open-pit haul truck utilization was 79%. In simple terms, for every hour of potential operating time, the average truck achieved about 48 minutes of productive work time. At the end of 2015, the mine was operating a fleet of 29 Komatsu 930 haul trucks.
Motivated by a desire to challenge conventional wisdom, the open-pit management team at Goldstrike evaluated how to increase haul truck availability to previously unattained levels. They came up with a concept that allows some haul trucks to be parked, while significantly increasing utilization of the trucks remaining in service.
The solution: a new way of handling breaks for haul truck drivers. Typically, when haul truck drivers were scheduled to take a break, they simply pulled over in a safe location and enjoyed a rest, usually spent inside the cab of the truck itself. This had trucks standing idle rather than engaging in productive work.
Earlier this year, Goldstrike began testing a new system by installing a series of modular break rooms at strategic locations around the open pit where drivers can rest. While drivers are on break, relief drivers take over operation of the trucks. In just six months, the results have been impressive—a 6% improvement in haul truck utilization in the open pit, moving from 79% to 85%. And six haul trucks have been taken out of the fleet. Today, the mine is moving the same amount of material with fewer trucks.
This initiative, combined with other improvement projects, helped reduce open-pit mining costs at Goldstrike from $1.40/mt at the start of 2016 to $1.25/mt at mid-year. The shift to using properly-configured break rooms also increases safety, by promoting a more restful environment for operators.
The Goldstrike open-pit team is now evaluating how to further optimize shovel use at the mine, matching the right shovels with the right haulage plans and ore types.
