Mine excursion
The final chrome product. Zimbabwe has the
potential to supply the world with close to
20% of its chrome needs.
takes to load the truck, dump it on
the stockpiles at the washing plant,
and then return the slurry material
back to site for rehabilitation, and
the payload on each truck. The
average distance from the mining
site to the plant is normally between
two and three kilometres. If the
distance is 2 600m to the plant,
for example, the trucks will take
about 26 minutes from loading to
dumping the rehabilitation material.
“On average, we take nine to 10
scoops and four minutes with the
excavator to load the dump truck,
and that gives us 19–21 tonnes in
the bin,” explains Richardson.
The same cycle takes place at all
seven sites and the team allocates
four trucks for one excavator.
However, this ratio can change,
depending on the hauling distance.
If the hauling distance is less than
one kilometre, only two trucks will
be sufficient. On the other hand,
if the distance increases to more
than three kilometres, five or six
Methods to extract the chrome are continuously being improved.
The installation of thickeners will reduce water usage and increase
efficiencies and the percentage of solids present in the slurry.
[18] MINING MIRROR JULY 2018
trucks are deployed. The trucks
consume between seven and 10
litres of fuel per hour, which is
a lot more economical than the
OEM recommendation of 10–12
litres per hour.
Two different sizes of Chinese-
manufactured tipper trucks are
used. The smaller MT50 has a
payload of about 21 tonnes, while
the bigger MT86 loads, on average,
have close to 35 tonnes into the
bin. According to Engelbrecht,
the bigger trucks have performed
exceptionally well. Equipment
used on the mine include four
dozers to assist in clearing and
rehabilitation; 15 prime-movers
(excavators); 38 RDTs, all of them
Chinese manufactured (RTT); and
six ADTs (Bell). In addition, there
are numerous support vehicles,
such as fuel bowsers, water carts,
graders, and LDVs.
Screening out the splits
Where the split is poor, the mine