OPERATIONS
At Zimplats, also on the Great Dyke, southwest of Harare,
mining infrastructure consists of five portals (decline
shafts). The deepest operating depth is currently about
310m at Bimha Mine. The company employs mechanised
room and pillar mining to extract ore from stopes with a
nominal with of 2.5m at dips of less than nine degrees.
Each production team consists of 20 to 30 rooms
deploying a single boom face rig for drilling, a roof bolter
for support drilling, a 10-tonne Load and Dump (LHD) and
a 30-tonne dump truck.
A low angle shear in the deeper sections of the Bimha mine
impacted ground conditions over a large area resulting
in extensive support pillar failure that led to cascading
collapse of a larger footprint. Geotechnical investigations
recommended a new pillar layout, which was also adopted
at the Mupfuti and Bimha mines. The extraction ratio based
on the new pillar layout is below 70%, compared to above
80% on the old layout.
Favourable outlook
According to Muller, mechanisation remains top of mind,
although it is challenging, especially in established
conventional mines. “In 2014 Impala mechanised off-
reef horizontal development. However, mechanised reef
mining remained the big challenge. The Merensky reef
is easier to mechanise as it is wider than for example the
upper group two (UG2 reef ). Mechanised know-how from
Implats’ Zimplats mine, in Zimbabwe and its Two Rivers
mine, in Mpumalanga had been migrated to bord-and-
pillar sections of Impala Rustenburg mine’s Shaft 12 and
Shaft 14, where hybrid mechanisation was introduced,”
says Muller.
Impala Platinum continued with their three major
development projects during 2019. According to Muller
the construction phase of Impala Rustenburg’s 20 Shaft
capital project was concluded in 2019, while the 16 Shaft
project reached 92% completion at year-end. “Both
shafts are producing more than 50% of targeted steady-
state production and management focus has moved to
create the required mineable face length to complete the
production ramp-up,” says Muller.
He adds that the Mupani declines at Zimplats intersected
reef horizon during the final quarter of the financial year.
“The project remains comfortably ahead of schedule and
is well placed to provide the required future production
capacity to replace two older shafts as they approach the
end of their mine lives,” says Muller.
Despite its many challenges, the Bushveld Complex of
South Africa and the Great Dyke in Zimbabwe, have been
good to Implats and the market outlook for 2020 is good.
Muller says the company remains committed to its long-
term strategic intent to favour value over volume in a zero-
harm environment, embed operational improvements and
build sustainability by consistently producing in a safe,
productive, responsible and profitable way.
“The focus in 2020 will be on advancing the phased
restructuring of Impala Rustenburg, while taking
advantage of the operational improvements realised
over the past year and maintaining delivery from all other
operations. Our project focus will be centred on 20 Shaft,
ensuring that the continued commitment to invest and
operate is matched with improved project delivery and
accountability,” says Muller.
www. africanmining.co.za
African
Mining
Publication
January
2020
55
African Mining
African Mining January 2020
55