54
MODERN MINING
May 2014
CRUSHING, SCREENING
AND MILLING
feature
Metso
screen panels solve
pegging problem at
Tarkwa
Pictured at Tarkwa with
Metso’s screening panels are
(from left): Frank Gambrah,
Tarkwa’s General Plant
Supervisor – Metallurgy;
Samuel Leckey, Sales Engi-
neer, Metso Ghana; Prince
Essuah, formerly Business
Improvement Analyst (now
Business Improvement
Superintendent) at Tarkwa;
and Louis Baanuo, Ag Unit
(Metallurgical) Manager,
NHL (North Heap Leach
Plant) at Tarkwa.
Ghana’s Tarkwa gold mine faced a challenge: chronic
pegging of screening media was causing daily downtime,
inefficiency and wear. The solution was Metso’s modular,
rubber LS screening media, which helped the mine to
reduce downtime by 90 hours annually as well as achieve
savings in screen replacement costs and a
safer working environment.
T
he Tarkwa gold mine, located in
the Western Region of Ghana,
is owned and operated by Gold
Fields Ghana Limited. Tarkwa is a
centre of gold and manganese min-
ing and the open-pit mine is one of the largest
gold mines in southern Ghana, with four pits
currently in operation. Roughly 100 million
tonnes is excavated and processed each year
to yield around 24 tons of gold. The processing
involves an extensive system of conveyors and
comminution equipment to ensure the right
product is produced at the right capacity.
The Tarkwa mine has two processing
plants: a heap leach facility and a carbon-in-
leach (CIL) facility. The heap leach facility is
a three-stage crushing circuit with a 1 200 ton/
hour capacity. The tertiary screen is a two-deck
screen, which utilises rubber and polyurethane
on the top and bottom decks respectively.
These media were previously sourced from a
competing supplier.
However, problems arose when the near-
mesh rocks clogged the screening media
openings, impeding the passage of the under-
size material. This led to a higher recirculation
load. Mine operators had to stop the line every
day for about fifteen minutes to knock the
trapped material out of the screening media.
Moreover, the tertiary bins became over-filled
due to the bottleneck downstream.
Gold Fields evaluated several suppliers
to find a solution. Metso came in first for the
mine’s primary selection criteria. In January
