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September 2015
MODERN MINING
37
feature
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.
The Namib project site with
a drill rig at work in the
foreground and the tailings
dump in the background.
Supplementary metallurgical
testwork has defined an optimal
process flowsheet.
This core sample illustrates
typical high-grade
mineralisation.
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
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?