Dust-collection system installed at Rand Refinery
Bateman Engineering has completed a R2 million lump-sum turnkey
project for Rand Refinery Ltd to upgrade an existing dust-collection
system by the addition of a new scrubber. The objective was to optimise
the gold recovery from the particulate matter in the off-gases from
the furnaces and minimise pollution of the environment.
The system comprises a Bateman Dynamic Wet Scrubber, with the appropriate
ducting and other equipment, to scrub the off-gas from the furnaces
and a Bateman Pinned-Bed Clarifier, to clarify the water after use
in the scrubber. The new system collects and cleans off-gas from up
to three of six refining furnaces prior to the off-gas being removed
to the existing gas cleaning facility. The wet scrubber treats 1,600
Am³/hr of gas from the furnaces with a dust load of 7.5 g/Am³
at a scrubber inlet temperature of 45ºC.
The overall dust-collection efficiency is 99.5 % in the 1 to 2 micron
particle-size range and a virtually solid-free, clean off-gas is produced.
The scrubber requires 2.1 m³/h water, of which less than 3 %
is lost due to evaporation and carryover in the clean-air discharge.
The effluent water from the scrubber, containing about 0.55 % of suspended
solids, is fed at a rate of 2.1 m³/h to the pinned-bed clarifier.
The clarifier produces an overflow containing less than 10 ppm of
solids, which is recycled to the scrubber, and an underflow of thickened
slurry at a rate of 25 l/min which is collected in a holding tank.
Approximately 90 kg of solids are captured as filter cake (the supply
of the filter organised by Rand Refinery) that is recycled to the
furnaces. The flocculant addition system was installed by Rand Refinery
in the beginning of 2006.
The contract for the project was signed in August 2005 and the new
dust-collection system was commissioned successfully in November 2005.
The equipment is working as per specification after the installation
of the flocculant dosing system. This was a brown-field project in
which the new equipment had to be installed in a very restricted area
in the plant with no interruption to production. A complicating factor
was the high-level of security demanded at the site. The changeover
from the existing to the new system was completed smoothly during
one weekend.
Bateman Engineering was given the job ahead of several competitors
because of the cost-effective solution offered to the problem of dust
collection at the refinery.
More details may be obtained from Dirk Schenk, General Manager,
Special Projects, or Jan Barwise, Project Manager,
on +27-11-899-9111 or email SpecialProjects@BatemanEngineering.com.
