The Pumpkin Hollow open pit development is approximately 4 km west of the underground mine. It includes two large deposits and areas of potential expansion both in and outside of the projected pit walls.

DEVELOPMENT OF OPEN PIT

The open pit has several areas of possible expansion, such as a significant quantity of Inferred Resources (197M lbs Cu6) that were excluded from the current resource model. There is also the demonstrated potential to test the full extent of the deposit at depth and in areas within and outside of the current pit shell.

Open-Pit Mining

Open-pit mining provides significant proportions of many of the world’s major mineral commodities. In hard rock mining, much of the world’s annual output of copper, gold, and iron ore is won from open-pit operations. Other commodities produced from open-pit mining include diamonds, molybdenum, manganese, lead and zinc, uranium, and a variety of industrial minerals, such as borates, talc, and specialist clays.

The list of commodities is extensive, although the relative proportions mined underground and on the surface vary from mineral to mineral. Massive tonnages of hard coal and lignite are also produced from surface mines, although the terminology used – open cast or open cut, rather than open pit – indicates that the technology and engineering concepts used are often markedly different from those employed in the hard rock environment.

Open-pit mining differs from quarrying (with the possible exception of iron ore) in that the valuable mineral constitutes only a small proportion of the total tonnage of rock produced. In quarrying, the rock itself is the valuable commodity, with virtually all of the raw rock that is won being processed (often only by crushing and screening) to give saleable products. In open-pit mining, on the other hand, the metal content of the ore produced may be only fractions of a percent, meaning that a huge proportion of the rock produced is effectively waste material.

In addition, the ore body geometry may mean that large tonnages of barren rock also have to be mined and transported to access the ore in which the valuable mineral (or minerals) makes up only a small proportion. This has to be recovered from the rock matrix through both physical (crushing and grinding) and/or chemical processes such as flotation, meaning that processing costs are higher. This is reflected in metal commodity prices, with a ton of copper or zinc being valued much more highly than a ton of granite or basalt.