Opportunity Issue 104

EFFICIENCY IN MINING
Northam Platinum scores
environmental wins as it increases
output and improves efficiency
Unique and innovative systems help the group expand
production and go greener at the same time.
Northam Platinum’s expansion project at its
Metallurgical Complex has successfully combined
increased output and greater efficiency with
improved environmental outcomes.
Northam Platinum is a major producer of
Platinum Group Metals (PGMs) and Base Metals. These include
platinum, palladium, rhodium, gold, ruthenium and iridium. Base-
Metals such as copper and nickel are also produced. The PGM
concentrate is further refined through a Precious Metal Refinery
(PMR) to produce marketable products.
Improvements were introduced in terms of slag handling at
the PGM Furnaces where an innovative new process has broken
successfully with conventional PGM slag handling practices.
Part of the broader expansion project was to align the Base Metal
Removal Plant (BMRP) to the expansion of capacity at the Processing
Plant. The focus here was on the optimisation of the current plant.
In July 2021, the BMRP began to implement the first phase
of its expansion and debottlenecking project to address the
strategic production growth within the Northam Group. Among
the innovations used in the process was the installation of a
chilling circuit to enhance the process, which is unique to the
Zondereinde Refinery.
Slag handling at the PGM Furnace
Furnace slag across the PGM industry has historically been handled
in what is commonly known as a wet granulation process, which
involves molten slag being quenched in a launder containing
rapidly flowing water. The quenched slag forms granules
which is then transported through various means.
The water used during this process is circulated through
an array of ponds and cooling towers, then reused. Reusing
this water minimises the environmental impact but this
process does have significant water losses due to the steam
that is generated.
In a departure from the PGM industry standard, the Smelter
at Northam Platinum’s Zondereinde operation has taken a leap
into the future by completely changing the way furnace slag
is handled.
During December 2020, after months of planning and
preparation, the granulation system at one of Northam’s
Furnaces was demolished and replaced by built-for-purpose
slag bays.
In a PGM-industry first, molten slag is now deposited
straight into slag bays where it is allowed to cool. Once cooled
it is broken by means of Trackless-Mobile Machinery (TMM)
and transported to the slag stockpiles.
Among the benefits realised through this ground-breaking
innovation is a major reduction in the risk involved in the
slag-tapping and slag-handling processes. The exposure to
water in excess of 70 °C has been completely eliminated and
the frequency of opening and closing of tap holes has been
reduced significantly. Notably, 80% of the injury incidents in
the Smelter were related to this hot water.
A system that continually circulated 800m3 of water through
an intricate system of tanks, pumps, pipes and launders with
all the relevant wear, breakdowns and maintenance was
effectively made obsolete overnight, resulting in a 1 MW
power saving.
A major constraint of the wet granulation system is the fact
that there is a maximum tapping rate which inhibits the use
of slag tapholes during emergency events. The new process
allows the flexibility to run both slag tapholes simultaneously
for extended periods if the need should arise.
The biggest benefit has been the de-coupling of the
Furnace from the slag handling which was the single largest
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