Co-processing is a more environmentally friendly and sustainable method of waste disposal
as compared to land filling and incineration because of reduced emissions and no residue
after the treatment. Co-processing refers to the use of waste materials in industrial processes
as alternative fuels or raw material (AFR) to recover energy and material from them. Due to
the high temperature in cement kiln, different types of wastes can be effectively disposed
without harmful emissions. As per the Basal Convention, variety of wastes including
hazardous wastes, get disposed in an environmentally safe and sound manner through the
technology of co-processing in cement kiln. Disposal of different categories of plastic
wastes through co-processing is practiced in many countries as a regular method for their
environmentally sound disposal.
Evaluation of Co-processing in cement kilns as an option for management of
Co-processing of plastic wastes in cement kiln is practiced substantially in different
countries as an environmentally sound option for management of plastic wastes. In
cement kiln, different kinds of hazardous and non-hazardous wastes including plastic
wastes get utilized as Alternative Fuel and Raw materials (AFRs). During the usage of
plastic wastes in cement kiln as AFRs, the material and energy value present in them
gets fully utilized in the cement kiln as replacement to the fossil raw materials and
fossil fuels that are conventionally utilized in the kiln.
The performance evaluation of co-processing of plastic waste was carried out in ACC
Limited, Kymore, Madhya Pradesh, in collaboration with Indian Centre for Plastic in
Environment (ICPE) and Madhya Pradesh Pollution Control Board (MPPCB). The
various trial parameters such as raw material & product testing and emission
monitoring was carried out by SGS Limited, which is a CPCB approved testing
Based on the results of trials - that included chemical & thermal parameters of raw
materials, clinker product, plastic wastes & coal and the emission monitoring during
and after feeding of plastics waste in the cement kiln as AFR. Based on their evaluation,
MPPCB forwarded the same to CPCB along with their recommendations. CPCB after
reviewing the trial report approved the results of the trial and declared co-processing
of plastic waste in cement kiln as a successful method for its environmentally sound
Based on this suggestion, several SPCBs have provided consent to various cement
plants and plastic waste generators to implement co-processing of plastic wastes.
Various cement plants are currently managing plastic wastes as AFRs in their kilns. A
list of cement plants having co-processing facility as shown at Annexure-I.
Infrastructural Requirement for Plastics Co-processing:
Every cement plant will have to have a separate feeding arrangement for undertaking coprocessing of AFRs. In case it already has one on the calciner or kiln inlet, then the same
can be utised for plastics as well. However, if it does not have any on the calciner or kin
inlet, then the same needs to be set up. This feeding facility will consists of proper covered storage along with conveying mechanism to move plastic waste from storage area to kiln.
This can be manual or can be automatic. The manual one consists of winch and hopper
arrangement and conveyor belts arrangements. At the feed point, it is desired that equipment
such double flap valves, shut off gates etc. are implemented to ensure uniform feed and
safety in operation. The feeding facility shall also be equipped with a lab to carry out the
calorific value, ash content, moisture content and chloride content.
Feeding of plastic waste material for co-processing:
Different feed points that can be used to feed the plastic waste materials into the cement
production process are given below.
• The main burner at the rotary kiln outlet end
• The rotary kiln inlet end
• The pre-calciner
• The mid kiln (for long dry and wet kilns)
Appropriate feed points amongst the above will have to be selected for the environmentally
sound co-processing of the plastic waste. Usually, plastic wastes, that are contaminated with
toxic components such as pesticides etc, should be fed to the main burner to ensure its
complete combustion in the high temperature and long retention time. For this, the plastics
may need to be shredded to less than 20 mm size. The non-recyclable plastic wastes, that is
not contaminated with toxic components, can be fed at the other feed points such as calciner,
kiln inlet or mid kiln depending upon its size. Process flow diagram for co-processing of
plastic waste in cement kilns along with the points of feeding of plastic waste
Feeding of plastic waste is not to be carried out during kiln start up and kiln shut down
Feeding of plastic waste needs to be initiated only after the kiln attains its stable
The Feeding of plastic waste should not be continued in case the continuous emission
monitoring system (CEMS) is not connected with CPCB and SPCB servers. Feeding of
plastic waste should be discontinued in case the emission values are not complying with
the prescribed emission standards for co-processing of incinerable waste (AnnexureII). It is necessary to depute trained person in the cement plant to handle whole
operation of co-processing of incinerable waste including plastic waste.
The cement plants shall ensure that the emission parameters are monitored as per the
prescribed monitoring protocol provided by regulatory bodies like CPCB, SPCB/PCC
Cement plants shall maintain proper records with regard to the amount of plastic waste
received, stored and co-processed.