Co-processing is a globally recognized technology through which waste is treated in energy intensive industries such as cement. It helps in solving societal waste challenges responsibly and in an environmentally sustainable manner. Co-processing completely destroys waste materials through high temperatures and long residence time. The 3 Ts - Time, Temperature and Turbulence in cement kilns provide an extremely high destruction removal efficiency (DRE) for all waste types.
During co-processing, the mineral part of the waste replaces primary mineral materials (such as limestone, clay or iron) and the combustible part provides the energy needed for clinker production. As a result, 100% of the waste input is recycled and recovered without producing any residue. The technology is referred to as co-processing because the process of cement manufacture occurs parallely with safe destruction of the waste materials at the high temperatures and long residence time existing in cement kilns (or other industrial processes).
Co-processing of waste in cement kilns ensures complete disposal of waste in a safe and environmentally sustainable manner. During co-processing, the mineral part of the waste replaces primary mineral materials (such as limestone, clay or iron) and the combustible part provides the energy needed for clinker production. As a result, 100% of the waste input is recycled and recovered without producing any residue.
Cement kilns are ideally suited for safe and sustainable management of waste through co-processing due to their specific properties including:
- High temperatures and long residence time which are in all cases more than 3” > 1100 °C. This allows for complete destruction of waste.
- Self cleaning process since the environment is alkaline with lime representing > 60% in mass
- Double valorization: organic gets completely destroyed and the ash gets incorporated in the final product.
It is thus a zero residue waste management option. Co-processing of waste leads to neither any untoward emissions nor detrimental effects on the final product. It is thus a zero residue waste management option. Co-processing of waste leads to neither any untoward emissions nor detrimental effects on the final product.
Pre-processing is the concept of converting a wide variety of waste materials into a homogeneous mix of defined characteristics. It involves shredding, blending, drying, impregnation and other mechanical operations.
Co-processing ranks higher in the waste management hierarchy compared to disposal based waste management options of land filling or incineration. It is a comprehensive, cost effective and win-win solution. Co-processing completely destroys waste materials through high temperatures and long residence time. Incineration and landfill both leave behind a residue while co-processing is a zero residue technology. Co-processing also utilizes any resource and energy value inherent in the waste and thus contributes to a regenerative circular economy. Therefore it is a more environmentally sustainable alternative to landfilling and incineration for waste that has been mixed, polluted or cannot be recycled for technological or economic reasons.
Co-processing as a waste management option has been in practice and evaluated for more than 40 years globally. Co-processing activities are endorsed by several international bodies and framed by specific regulations, standards and environmental permits to ensure enhanced environmental and safety standards. It is an approved technology by Basel Convention for disposal of all kinds of hazardous and other wastes. Trials conducted in cement kilns spread across the world have confirmed that wastes do not impact the cement kiln emissions or the product in any adverse manner.
Co-processing is fully recognized by many countries such as India, Mexico, Brazil, US, Europe and many others. In its recent communication, The European Commission advised Member States to take a long-term perspective and consider co-processing as an important lever for circular economy.
Many studies and trials around the world have shown that waste can be safely destroyed in cement kilns without having any impact on the emissions. This can be achieved due to the high temperatures, long residence times and alkaline environment existing in the kiln.
It is also important to understand the properties and chemistry of the waste materials that we are co-processing in the kiln (analyze all waste before pre- and/or co-processing). Once the waste inputs are properly controlled through systems and processes employed by Geocycle, it can be ensured that there is no untoward impact on emissions.
Co-processing reduces CO2 emissions since the energy value of the waste (if any) is recovered in the cement kiln helping to substitute fossil fuels that would otherwise have been used in the cement process. If these wastes would have been incinerated or landfilled, it would have led to corresponding GHG emissions. The below figure explains how waste co-processing in cement kilns reduces these emissions:
A wide range of waste material is suitable for co-processing, including hazardous and non hazardous industrial waste, sorted municipal waste and agricultural residues. However, a strict list of ‘banned waste’ is adhered to. The reasons for the same include risk of excessive emissions, health and safety provisions, negative impact on kiln operation, or the observation of the general waste hierarchy principles.
Banned wastes not to be pre-processed or co-processed:
- Radioactive waste
- Asbestos-containing waste
- Explosives and ammunition / weapons
- Anatomical medical waste
Banned wastes not to be co-processed:
- Electronic fraction of electrical and electronic waste (e-waste)
- Whole batteries as a targeted material stream
- Waste of unknown or unpredictable composition, including unsorted municipal waste
These wastes however can be co-processed after pre-processing to remove the banned portion of the waste.
Since the 1970s, Lafarge and Holcim have pioneered the co-processing of waste materials in cement kilns. The companies have developed innovative and tailored industrial and municipal waste management solutions for a wide range of customers for decades. Geocycle leverages this rich experience to offer highly specialized waste management services.
Holcim and Geocycle have a long-term commitment to their waste management activities. This includes ongoing investment, development of expertise and knowledge in the field, as well as long-term cooperation with customers and partners. We have a dedicated team of 2,000 people globally with significant experience in the waste management sector.