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MODERN MINING
May 2017
MINING News
Nkuluwisi adds to the potential of New Luika
Shanta Gold, listed on AIM, has provided
an update from its ongoing exploration
programme within, and surrounding, the
New Luika Gold Mine (NLGM), located in
the Lupa goldfield of south-west Tanzania.
In March this year, Shanta released
encouraging drilling results from the
Nkuluwisi mineralised target, located
approximately 12 km north-west of the
NLGM’s central processing hub. Since
March, the company and its indepen-
dent resource consultants have worked
to produce a JORC-compliant Code (2012)
maiden resource for Nkuluwisi.
Total resources declared for Nkuluwisi
amount to 3,97 Mt at 1,1 g/t for 140 894
ounces of gold. The measured resources
total 224 000 t at 1,29 g/t for 9 266 oz of
gold while the indicated resources total
2,3 Mt at 1,13 g/t for 83 888 oz of gold. In
addition, the deposit has inferred resources
of 1,44 Mt at 1,03 g/t for 47 761 oz of gold.
Toby Bradbury, Shanta’s CEO, com-
mented: “The significant scale of Nkuluwisi
opens the door to possible expansion
options at our flagship New Luika Gold
Mine to target lower grade orebodies
which could increase production levels
and add to mine life. The NLGM already
has resources of 9,47 million tonnes at
2,24 g/t for 683 000 oz that sit outside the
recently updated Revised Mine Plan and
the Nkuluwisi maiden resource adds signifi-
cantly to that. Further upside remains along
strike at Nkuluwisi and also at a series of
highly prospective and proximate targets
in the Lupa goldfield identified through our
focused exploration programme.”
Weatherly International, whose shares are
quoted on AIM, reports that its Tschudi
copper project in northern Namibia pro-
duced 3 236 tonnes of copper cathode in
the March quarter. This was 24 % below
nameplate capacity due to slower than
anticipated leach rates for mixed oxide/
sulphide ore stacked in the later months of
2016 and in early 2017. It says that it was
unable to compensate for the shortfall due
to above average seasonal rainfall during
the quarter which prevented short-term
acceleration of mining and stacking.
Mixed oxide/sulphide ore stacked
earlier in 2016 had leached at rates as
predicted in the 2012 Bankable Feasibility
Study (BFS). However mixed ore stacked
later in 2016 showed slower leaching char-
acteristics over time, leading to the current
production shortfalls.
Investigations are continuing with
appropriate external assistance and advice
to determine how site operating param-
eters may be changed to ensure that
optimal conditions for bacterial leaching
of sulphide minerals are maintained in the
heap in order to maximise leach rates and
ultimate overall recoveries of copper from
stacked ore.
The changes currently under investiga-
tion include changes to solution chemistry,
potential for forced aeration of the heap,
modified irrigation strategies, and possible
changes to lift heights.
In the meantime, capital construction
of the stage two heap leach pad area has
commenced to provide additional time
for the leaching of copper from mixed
ore currently under irrigation, and also
for implementation of changed operating
parameters for this ore prior to sealing and
over-stacking.
Groundwater in the open pits had no
adverse effect on mining during the quar-
Slow leaching hits Tschudi’s first quarter production
The Tschudi project is an open-pit, heap
leach, SX/EW copper mine located near
Tsumeb (photo: Weatherly).
ter, with groundwater inflows managed
using the in-pit pumping systems. Detailed
investigations continue into opportunities
to reduce operating costs and produc-
tion delay risks via capital expenditure to
enable removal of groundwater before it
enters the pits.
During April, says Weatherly, rates of
stacking contained copper metal tonnes
onto the heap have improved and the
rate of leaching copper metal tonnes into
solution is expected to improve during the
June quarter. However April’s cathode pro-
duction tonnage will remain weak.
Full financial year production to June
2017, as previously advised byWeatherly, is
now forecast to be 14 500 to 15 000 tonnes.
The poor production result in the March
quarter has caused C1 quarterly operating
costs to increase to US$5 907/t. Full finan-
cial year C1 costs are now forecast to be
US$5 250 to US$5 350 per tonne.