Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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MINE DEVELOPMENT 66 E&MJ; • JUNE 2016 www.e-mj.com Underground mine development is hard. It's a complex, time-consuming process that can involve hundreds of people, thousands of decisions and often upward of a billion dollars in investment. It re- quires workers with specialized skills, poses more than a modicum of risk, and despite careful preplanning and exhaus- tive engineering attention, doesn't always result in a favorable outcome. As new deposits are found at greater depth and in remote locations far from industrial centers or infrastructure, de- velopment becomes even more complex from logistical, labor, materials procure- ment and quality control aspects. Greenfeld Development: Defated? Exploration and development spending is the air that foats the industry's balloon, but in today's capital-short, cost-con- scious mining environment, that balloon appears to be underinfated. Moody's Investor Services expressed concern in a research note, which observed that in recent years many of the investments that have been made by gold producers, for example, don't seem to be resulting in additional production. "...This points to suspended develop- ment projects," said the Moody's report. "This risk has become especially pro- nounced as we look beyond the next two years, when we anticipate future produc- tion could decline as a result of dimin- ished spending on growth and develop- ment in favor of conserving cash." Looking beyond gold to other mining sectors, SNL Metals & Mining noted re- cently, "Over the past 15 years, explo- ration budgets have been shifting away from the grassroots work upon which new discoveries largely depend. With risk aversion continuing to plague the sector, companies are focusing their exploration activity on existing or developing mines to ensure an adequate level of reserves to support production." In other words, starting from scratch is expensive and risky. That's why, for exam- ple, Vale is moving ahead with a massive deep development project adjacent to its existing surface mine at Voisey's Bay on the North Coast of Labrador. This pro- ject provides an excellent example of the growing complexity of underground devel- opment. In addition to underground con- struction of ramps, laterals and support- ing infrastructure such as a garage, refuge stations, material handling and pumping systems plus the ventilation system, the project will involve surface infrastructure that includes increased power generation capacity, additional permanent worker accommodations and expansions to offc- es, warehouses and maintenance shops. Add to that list the need for upgrades to water and sewage treatment facilities as well as construction of a paste backfll plant—and temporary quarters for mine construction. The current timeline for the project begins with the startup of surface and underground construction in 2017 and progresses to ramp-up to full produc- tion sometime in 2021. And, a recently completed under- ground project at Newmont's Leeville gold mine illustrates how even seeming- ly straightforward projects at established mines demand escalating levels of careful planning and attentive management. At the Leeville mine, located 27 miles north of Carlin, Nevada, a high-capacity vent shaft was needed to provide increased ventilation capacity suffcient to support underground expansions for exploration platforms and additional future opera- tions at Leeville. Completed last year, the Turf No. 3 vent shaft is one of the largest of its kind in North America, capable of moving 2.6 million cfm of air. Comments by Leeville Mine Manager Mark Ward in Newmont's Our Voice blog describe the yearlong planning, engineer- ing and labor effort required underground just to reverse the fow of fresh air through the mine. Ward explained that at the same time the Turf vent shaft and related facilities were being built on the surface, underground ventilation raises were being excavated and connected between all lev- els on the Turf side of Leeville. The addi- tional raises were needed to increase air fow through that part of the mine once the new shaft was completed and the ex- isting air fow was reversed. To complicate matters, active mining and development continued on the same levels where the raises and bulkheads were being constructed, adding to traffc congestion in an already confned area. According to Ward, careful management and movement of large, space-consum- ing materials needed for the underground construction—massive vent doors, sup- plies and heavy equipment—allowed ac- tivity to proceed without any safety issues and without signifcantly impacting pro- duction schedules. Arrested Development Can technological advances relieve some of the economic pressure that's stifing greenfeld mine development? By Russell A. Carter, Managing Editor De Beers is currently investing more than $2 billion to convert the Venetia open-pit mine in South Africa into an underground operation. (Photo: De Beers)