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MODERN MINING
June 2015
MINING News
AIM-quoted Premier African Minerals
Limited says that the first concentrates
have been produced at its flagship RHA
tungsten project in Zimbabwe. The proj-
ect is located in the Kamativi tin belt of
north-western Zimbabwe and Premier is
planning two stages of development – a
first phase, low capex (US$4,8 million)
open pit, which provides an 18-month life
of mine, followed by an undergroundmine
(capex estimate – US$14,7 million) based
on mechanised long-hole open stoping.
The open-pit annual production will be
96 000 t (ROM) while the underground
production rate will be between 192 000
and 288 000 t (ROM).
The production of the concentrates fol-
lows hard on the heels of the delivery of
the process plant to the site in May. The
plant was designed and manufactured by
Appropriate Process Technologies (APT) of
Johannesburg, who were also responsible
for assembly on site and commissioning.
The earthworks and civil works programme
was successfully fast tracked to ensure that
the site was ready for offloading of the
plant.
Development of the open-pit mining
area remains on schedule, with waste strip-
ping underway and run of mine ore being
stockpiled. According to Premier, visible
mineralisation continues to confirm the
geological model.
The process plant is designed to meet
a throughput of 16 t/h or 8 000 tonnes per
month and achieve a wolframite recov-
ery of 82,8 %. The stated production rate
excludes any consideration of a pre-con-
RHA tungsten project produces its first concentrates
Trucks carrying the process plant arrive on site at the RHA tungsten project on 22 May (photo: Premier
African Minerals).
Open-pit operations at the project site (photo: Premier African Minerals).
centration circuit which, if implemented in
future, could increase the plant through-
put fivefold at a 20 % recovery loss as
determined in the metallurgical test work
announced on 10 September 2014.
Intermittent small scale mining has
been conducted at RHA and the adjacent
Tung mine (which Premier has an option
to acquire) 5 km away. Between 1931 and
1979 the mines jointly produced 1 247
tonnes of WO
3
in wolframite concentrate
at a reported average concentrate grade of
65 %WO
3
, i.e., approximately 1 919 tonnes
of wolframite concentrates. Infrastructure
from the historic mining includes a vertical
shaft, numerous adits and some under-
ground development.
Premier announced in March this year
that it had completed an off-take agree-
ment with Noble Resources International
for the sale of wolframite concentrates
from the mine. Under the agreement,
Premier will supply 500 tonnes of concen-
trate over an anticipated initial six-month
period whereafter Noble will have a right
of first refusal of all future concentrates
provided it matches terms offered by other
parties.
Concentrates are sold in metric ton
units (‘mtu’) where one mtu is 10 kg of
tungsten trioxide (WO
3
) contained in a
concentrate at a declared percentage,
normally 60 % to 65 % being a common
reference point. Premier anticipates pro-
duction during the open-pit phase of the
RHA mine of approximately 5 800 mtu per
month of WO
3
contained in a concentrate
at an average grade of 63 %.