BENEFICIATION
Feed material for C&D waste recycling.
Development Planning) have C&D waste as
one of their key focus areas.
“At national level, the Department
of Environmental Affairs has also been
considering C&D waste and I know there’s
a move internally to develop a project
specifically focusing on this area,” she adds,
“and we are hoping to be a part of developing
the terms of reference for that project.”
According to Nicolan Govender, regional
manager for sub-Saharan Africa at wet
processing equipment company CDE, there’s
huge cost involved in disposing of C&D waste,
including transport and disposal costs. What
C&D waste recycling does is remove the cost
associated with disposal of C&D waste by
transforming it into an income-generating,
high quality sellable aggregate.
Wet processing
C&D waste can generally be divided into two
types: inert materials such as sand, bricks and
concrete, and non-inert materials such as
plastic, glass, paper, wood, vegetation and other
organic materials (Ulubeyli et al., 2017). Prior
to processing, the waste is sorted to remove as
much undesirable material as possible.
With dry processing, which is the method
historically used in South Africa, the material
is then processed using either static or
mobile crushing and screening equipment
Recycled concrete material.
before being reused in one of a variety of
applications. For the smaller companies using
mobile equipment, this is often done at the
demolition site. However, for the contractor
the cost of doing this is high compared to the
profits they make. In this sort of arrangement,
it’s usually the big construction company
reaping the benefits because they are getting
their material rehandled, recycled and reused
on site, while the contractor benefits less
because of the low margins.
Nicolan Govender, regional manager for
sub-Saharan Africa for global wet processing
company CDE, says that the next step for
companies looking to increase their profits is
to add a wet process to their dry crushing and
screening operations to immediately achieve
a higher value product. “If you think about it,
dry crushing and screening simply reduces
the material used in constructing a building
– all the organics and contaminants are still
in there. With wet processing, you float off all
the lightweight organics and contaminants,
and then use a wet screening process to size
and clean the sand,” he explains.
CDE prides itself on being the market
leader in wet processing C&D waste recycling,
specifically of sand and aggregates. Govender
explains that a CDE processing plant will take
in your typical C&D waste – such as concrete,
bricks, blocks, some organics such as grass,
Guidelines
Guidelines are being developed to help C&D waste recyclers work within the parameters of
legislation and best practice as dictated by various professional bodies within the construction
industry. These laws and practices include:
•
Applicability of legislation and legal requirements
•
Best practice sourcing and separation at source
•
Best practice crushing and screening
•
Best practice stockpiling/blending of crushed materials
•
Material specifications for use in roads
•
Material specifications for use as concrete aggregates
•
Best practice design, construction and quality control
Source: Aspasa
plastics and wood – as feed material and
separate the sand from the stone to produce a
high quality washed, manufactured sand that
can be sold back to the construction industry.
“The CDE system comprises AggMax
scrubbers to clean up the material, an
EvoWash washing plant to wash the sand, an
AquaCycle thickener to recycle up to 90% of
the water used in the washing plant and, in
some cases, a filter press, which creates a solid
waste cake of fine material out of the sludge
from the Aquacycle,” says Govender.
A flagship project in this area for CDE is the
Germany-based CANDY Project (which stands
for ‘CompAct, highly mobile, Next generation,
CD&E waste recoverY system), backed by
the European Union’s Eco-Innovation Fund,
which aims to enhance the infrastructure
for the recycling of C&D waste in Europe.
The project’s technical objectives include
enhancing the mobility and reducing the
plant footprint of the waste recycling plant,
as well as increasing the quality of the washed
recycled sand and aggregate products.
The project also aims to offer new sludge
management technology with a focus on
maximising the recovery of process water for
recirculation to the washing plant.
There’s huge cost involved in dumping C&D
waste – including transport costs, dumping
costs at the landfill, and so on. According to
Govender, many CDE customers, including
the CANDY Project, are in waste removal.
“One of the advantages of a CDE plant is that
we take the mixture of waste that would
normally be dumped at a landfill and turn it
into a way to generate revenue rather than an
expense. Ordinarily, our customers in waste
removal would have a contract from a major
construction company to take the waste from
demolished buildings offsite and dump it,”
he says.
“The companies don’t really care where the
waste is going, they just nominate someone to
come in and take care of it. What we’re saying
to our customers is rather than paying to
QUARRY SA | MAY 2017 _ 25