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July 2016
MODERN MINING
7
MINING News
AIM-listed Bushveld Minerals has
announced results from pilot-scale met-
allurgical test work and plant design at
its Groenfontein tin deposit in Limpopo
Province, South Africa.
The test work was intended to assess
tin recovery on a plant-scale, gain insight
into potential concentrate grades, and to
fine-tune plant flowsheet design param-
eters. The test work indicates a recovery
using gravity concentration of over 70 %
for grind sizes of -1 mm.
Bushveld released a scoping study on
the Groenfontein and Zaaiplaats deposits
in September 2014, which envisaged a
mining rate of 691 000 t/a at a head grade
of 0,12 to 0,23 % SnO
2
to produce 610 to
1 130 tons of refined tin metal per annum
post smelting.
Following on from the 2014 scoping
study, the company decided to revise the
development plan for the project to focus
on mining the higher-grade zone of the
Groenfontein and Zaaiplaats deposits
and processing it using a relatively simple
gravity separation flowsheet to produce a
saleable concentrate product.
The scope revision was driven by the
company’s interest in executing a low
capex, near-term production operation.
The aim is to take advantage of a rela-
tively buoyant tin market and establish
Groenfontein as a standalone tin asset.
In order to assess tin recovery param-
eters on a plant scale, gain insight into
potential concentrate grades, and to fine-
tune plant flowsheet design parameters, a
large (500 kg) sample of surface ore from
historical workings at the Groenfontein
deposit was submitted for additional met-
allurgical test work at Peacocke & Simpson,
minerals processing experts specialising in
gravity recovery.
The results show that at a top size of
1mm, >70 % Sn recoveries are achieved for
enhanced gravity concentration, less than
15 % Sn is lost to tailings during spiralling,
and shaking tables achieve at least 85 %
recovery, giving over 50 % cumulative
recoveries and a final concentrate grade of
74,59 % SnO
2
(58,75 % Sn).
Consequently, a flowsheet has been
developed for gravity sep-
aration, with crushing and
screening and rod-milling
to -1 mm. Material is con-
centrated via spirals and
shaking tables to maxi-
mise recovery and SnO
2
concentrate grade. The
plant design envisages
a 164 160 t/a operation
producing up to 510 t/a of
SnO
2
.
Bushve l d s ays t he
next step is to complete
flowsheet design and
mine-planning studies to
determine mine capex and
opex parameters, which
will be incorporated in a
revised financial model.
Fo r t une Mo j ape l o,
CEO of Bushveld Minerals,
said: “ The encourag-
ing metallurgical results
achieved suppor t our
view that high- grade
cassiterite concentrates
can be produced from
the Groenfontein deposit
wi t h re l a t i ve l y good
Bushveld announces results of metallurgical test work
A drill rig working at the Mokopane tin project in Limpopo Province
(photo: Bushveld Minerals).
recoveries. With recently updated plant
capex and opex estimates at hand, we
look forward to finalising infrastructure
and mine cost estimates while continu-
ing to focus attention on accelerating
smaller-scale mine development and
commissioning. The tin market has been
particularly positive in a generally nega-
tive commodity environment with the
tin price up 18 % since the start of the
year on supply constraints.”