Four Atlas Copco Pit Viper rotary drill rigs help keep ore production on target

Four years after its initial feasibility study, a historic mine reopened by the Copper Mountain Mining Corp. is rewarding the Princeton, British Columbia, region with good jobs and the anticipation of an economic windfall from the mining of copper, silver and gold. It comes none too soon for this area of British Columbia, where logging has suffered from both pine beetle devastation and a downturn in the forest industry overall.

                During its previous life, the open-pit porphyry mine had already yielded 770,000 metric tons (mt) of copper, 9.1 million oz of silver, and 730,000 oz of gold from 23 years of continuous production before it closed in 1996, when copper prices were low. The combined evidence of past drilling and modern exploration by its new owner convinced stakeholders by 2006 that there were still at least 680,000 mt of copper left, with precious metal credits of more than 451,000 oz of gold and 4.5 million oz of silver.

                The overwhelming proof came from nearly 5,000 historical drill holes and more than 400 of the company’s own. Continued exploration of the deep-seated porphyry in the fall of 2010 had further confirmed the predictions. With a life of mine strip ratio estimated to be just 2:1, the mountain was promising it would reward the company with another 17 years’ worth of production.

                Although reopening a mine of this size is a formidable task, the project did come with some built-in benefits that ensured this profitability. There already existed a skilled workforce from previous mining operations in the area, as well as a pre-existing infrastructure at this site. Only 15 miles from the town of Princeton, a paved highway runs past the mine and the site has ample water resources with an ideal location for processing the extracted ore.

                Copper Mountain partnered with Japan’s Mitsubishi Materials early on, which provided security for the venture both in financial backing and by ensuring the mine a reliable buyer for the ore.

                The mine made a conscious effort to reduce operational risk in its choice of equipment. For instance, to move the 22.7 million mt of material by May 2011 in preparation for full startup in June, and then to move the additional 54.9 million mt anticipated during the first production year, all blasthole drilling was awarded in a three-year agreement to Altas Copco and its Pit Viper rig series, as well as all drilling rig parts, ancillary equipment and tools.

                Gary Wright, account manager for Atlas Copco Mining and Rock Excavation Technique, commented on the drill agreement: “It’s good for startups because it creates a partnership with the manufacturer and the mine. It includes everything from service to the steel and bits and allows everyone to work together.”

                The first rig, a diesel-powered PV-271 which had been in operation since September, was joined by its electric counterpart in November. A second electric model, a PV-351, joined the site in January 2011. Copper Mountain Mine Operations Manager Art Pratico said the electric unit has lower operating costs; other than that, the diesel and electric versions perform comparably.

                Pleased by the performance of the rigs, Copper Mountain added a refurbished Pit Viper 351, and they continue to contract with Atlas Copco for all rotary bits and drilling tools for the four machines. Wright said the mine is seeing a 93% availability rate from the rigs.

                Alastair Tiver, Copper Mountain’s chief engineer, said a mix of electric and diesel is working well. “Use of electric allows us to lower operating costs,” Tiver said. “The pit will be developed with a series of push backs, so having a diesel rig affords us some additional mobility to move a rig from one mining area to another, should additional drilling capacity be required.”

                In addition to the Atlas Copco drill fleet, the mine began operations with a $70-million package of Komatsu loading, haulage and utility equipment, including two PC8000 electric hydraulic front shovels with 42-m3 buckets, 13 240-ton-payload 830E-AC electric drive trucks, a WA1200 front end loader, two D375A dozers, and a WD600 wheel dozer.

                Peter Holbek, vice president of exploration and leader of the mine’s exploration team, explained the three-pronged approach the company undertook to realize the company’s production goals. They have incorporated and expanded all three pits of the mine under one all-encompassing “Super Pit.”

                First, the company will drill in areas of known mineralization from the previous operation. Second, they will drill in outer target areas that, although drilled previously, were not fully explored. And finally, they will go after deeper targets, confident in the corroborative data from the new and historical information.

                The company purchased the original, diesel-powered PV-271 for its ability to move quickly into other areas without the need to relocate power. The PV-271s, with ample 73.6 m3/min (2,600 cfm) air compressor packages, are well-matched to 270-mm (10⅝-in.) Epsilon rotary bits, which allow quick clearing of the holes.

                So how have the Pit Vipers been performing overall? Pratico said he is pleased with the machines. The diesel rig not only performs well, he said, but it is also used as a trainer. The rig’s high-tech upgrades give operators many options without alienating those who are new to the series. It “operates just like any other drill rig,” Pratico said, meaning it doesn’t require a steep learning curve to train an operator to be proficient on a Pit Viper.

                In addition, teaming with Atlas Copco for the complete supply of all required rock drilling tools not only provides Copper Mountain Mining the convenience of a one-source supply but also means Atlas Copco is in frequent contact with the company, maintaining instant access to customer support.

                Based on the 2008 feasibility study, Copper Mountain Corp. predicted its life of mine operational and financing costs to be about $1.30/lb, with copper selling at about $2.80/lb. The first quarter of 2012 was the first quarter of reporting for the mine, four years after its initial feasibility study. However, a strong Canadian dollar coupled with inflation for consumable unit costs adversely affected its original prediction: actual total cash cost for copper was $1.83. Yet this still yielded a margin of $1.90 at a $3.73/lb selling price. The mine announced total revenues of $71 million from 13.7 million lb of copper produced. It completed four shipments to its buyers in Japan for a total of 29,400 dry mt of concentrate that contained approximately 15.7 million lb of copper, 5,781 oz of gold and 124,546 oz of silver. Gross profit: $27.3 million.

                With the Atlas Copco rotary rigs efficiently driving 7.62-m (25-ft) lengths of drill pipe to prepare blast sites along the mine’s 15-m (49-ft) benches, the mine continues to meet scheduling goals. Copper Mountain President and CEO Jim O’Rourke said in his company’s August 2012 quarterly announcement of results that, “Management’s efforts are fully focused on optimizing mine and mill operations to incrementally increase the daily tonnage, working towards the concentrator design capacity of 35,000 tons per day. Production during the quarter totaled 16.6 million lb of copper, an increase of 21% over the prior quarter production.”

This article is based on a story published initially in Atlas Copco Mining & Construction USA, No. 1, 2011. The original article, authored by Joseph Bradfield, senior writer/editor for Ellenbecker Communications, was updated for publication in E&MJ.