Quarry Southern Africa January 2017 | Page 24

Producing cement clinker is an energy-intensive process . Cement kilns consume approximately 3.3GJ of thermal energy for every tonne clinker produced . Not only is it a high source of combustionrelated CO 2 emissions , it is also one of the largest sources of industrial process-related emissions in the United States , according to the US Environmental Protection Agency .

Globally , cement producers are keeping up with innovation in producing and using alternative fuels to combat their carbon footprint .
In South Africa , the adoption of alternative fuels in industry , like fossil fuel guzzling cement plants , remains low . This is largely because legislation has not yet been implemented to incentivise or push industry toward using alternative fuels . These legislative drivers are in motion internationally and include principals like landfill tax and carbon credits or carbon tax . These are important drivers that will spur on the drive towards a green , circular economy .
RDF – a first for South Africa
The Refuse Derived Fuel ( RDF ) produced by Interwaste is a solid fuel source recovered through the shredding and bailing of pre-sorted dry industrial non-recyclable waste . Whilst RDF can also be recovered from Municipal Solid Waste ( MSW ), the RDF produced by Interwaste requires no heat for drying , produces a cleaner RDF and produces a much higher heating value RDF similar to that of A-grade coal . Its usage as a greener energy source is proving to be a cost and carbon cutting tool for cement producers in the northern hemisphere .
In February 2016 , JSE-listed Interwaste announced that this technology had arrived on South African shores with the commissioning of its first RDF plant in Germiston .
The Germiston plant is currently diverting 300 tons a month of unrecyclable waste from landfill to produce 300 tonnes of RDF per month to a cement kiln in Namibia .
Interwaste has earmarked KwaZulu-Natal , the Eastern Cape and the Western Cape as future expansion destinations , depending on waste supply and offtake in those regions .
The Germiston RDF plant receives its resource of RDF suitable waste from Interwaste ’ s corporate and industrial clients with whom they have existing waste removal contracts in place .
A few years ago Interwaste started investigating solutions for clients ’ nonrecyclable waste in response to optimising their recycling efforts and reducing their waste-to-landfill ratio . The production of RDF was the result .
It is important to note that the RDF fuel source comprises of non-recyclable waste fractions such as paper-backed foil , aluminiums and multi-layered packaging .
In order to produce RDF , Interwaste accesses clients ’ sites and separates the nonrecyclable waste streams from recyclable fractions such as glass , paper and plastic . The company then transports the nonrecyclable RDF suitable waste to their Germiston facility where it feeds the dry industrial RDF suitable waste into the RDF production plant to produce 300 tons of RDF per month .
Penta . net
Cement kilns consume about 3.3GJ of thermal energy for every tonne clinker produced .
22 _ QUARRY SA | JANUARY 2017