Modern Mining September 2015

COUNTRY FOCUS – NAMIBIA

Namib lead-zinc project

210 m below surface – and was accessed ini- tially by a 150 m deep vertical shaft. A 1,45 km long decline (the Junction decline) was devel- oped in 1986 and a start was made on a second decline (the North decline) designed to access the northern part of the orebody. Mining meth- ods were traditional and relatively labour intensive. As outlined in the DFS, the new mine will make use of the existing underground infrastructure and broadly follow the mining practices of the original owners, with longhole open stoping and shrinkage stoping being the primary extraction methods. However, there will be an element of mechanisation with truck and loader haulage being utilised. As regards processing, the proposed flowsheet comprises simple bulk crushing and milling, followed by lead and then zinc flotation. The DFS estimated the cost of the plant at just over US$18 million.

Announcing the results of the DFS in November last year, North River said the study demonstrated the “robust economics” of the project, with the payback period estimated at just 15 months. The DFS, however, assumed a zinc price of US$2 400/tonne, a lead

The Namib project site with a drill rig at work in the foreground and the tailings dump in the background.

price of US$2 300/tonne and a sil- ver price of US$21/ oz. Current prices are well below these levels and, as this article was being written, zinc was trading at approximately US$1 850/tonne and lead at US$1 700/tonne. Silver – as high as US$48/oz in 2011 – was also weak at around US$15/oz. Given the decline in the prices of these metals, does the project still make economic sense?

This core sample illustrates typical high-grade mineralisation.

Supplementary metallurgical testwork has defined an optimal process flowsheet.

feature

September 2015  MODERN MINING  37