BENEFICIATION
Interwaste
A solid recovered fuel in the form of fluff , baled and ready for transportation .
Industrial vs municipal waste – a SA perspective
Building on solutions that have already gained traction in the UK and Europe , Interwaste modified the plant according to a local context .
The Interwaste facility follows a different approach to European methodologies , predominantly because industrial clients ’ waste streams are purer than municipal waste , which is the standard waste source in Europe used to produce RDF .
“ We are sorting and separating dry industrial waste on our clients ’ sites , which is not mixed with any organic matter or moisture-rich content . Therefore , the waste stream is cleaner and thus allows for a simpler shredding and hydration process ,” says Aeren Young , environmental scientist at Interwaste .
The RDF plant in Germiston comprises a basic two-step shredding process : from a feeding platform , the waste is transferred by a conveyor to a primary shredder where it is shredded into a sub 100mm size fraction and then moves to the secondary shredder for further processing to a finer size fraction .
The high price of European ( especially the United Kingdom ) landfill taxes incentivise the public and industry to sort and separate municipal waste streams to an advanced level . Government provides a constructive legislative environment that
encourages and / or rewards the recycling and landfill avoidance of waste .
In South Africa , very little separation happens at source and thus retrieving RDF from MSW is a costly exercise which makes it difficult for the business case to succeed .
High quality fuel source
“ The feedback we are receiving from the Namibian cement producer is extremely positive ,” says Young . In fact , Interwaste struggles to keep up with demand .
Ironically , because of the lack of recycling infrastructure and best practice in South Africa , the calorific value ( CV ) of the RDF is far higher than the RDF produced in Europe . Because municipal waste is wetter than industrial waste , the CV count increases when using the latter as feedstock .
Young says the product Interwaste sends across the border to Namibia has an equivalent CV of A-grade coal . “ The RDF produced and sold to cement kilns in Europe and the UK averages at most 19 mega joules per kilogram . Interwaste is currently producing RDF at about 24 – 26 mega joules per kilogram ,” says Willcocks .
Most noteworthy , however , is the fact that the cost benefits of using a wastederived fuel in the production of clinker are substantial .
“ During clinker production , electricity costs amount to 30 – 40 % of cement producers ’ operational overheads . If you can provide a
“ Ironically , because of the lack of recycling infrastructure and best practice in South Africa , the calorific value ( CV ) of the RDF is far higher than the RDF produced in Europe .”
QUARRY SA | JANUARY 2017 _ 23