The best way to handle the problem of disposal of municipal or industrial waste is to burn it in cement kilns, says ACC Ltd. For this, however, some tweaking of the policy is required.
Burning waste in cement kilns is better than destroying them in incinerators or using them as landfill, says Ulhas Parlikar, Director – Geocycle Business, ACC Ltd.
This is because the temperature inside a cement kiln can go as high as 2,000 degree Celsius at the main burner. For technical reasons, the “residence time” of the gases is also “very, very long”—10 seconds. Furthermore, the emissions out of the kilns do not get influenced by the burning of these waste materials, Parlikar, who is also the Chairman of CII Initiative on Increasing AFR Usage in Cement Indutry, told
He said that this ‘co-processing’ was an established technology and burning waste in cement kilns was a routine thing in the developed countries.
Of course, it helps a lot if the waste were to be homogenous. Like industrial wastes. Take a car plant for example. It produces waste material such as paint sludge, sludge from effluent treatment plants and cotton wastes (from cleaning oily surfaces). Similarly, there are other types of wastes such as expired goods—medicines, foods and other FMCG products, or contraband items which, if not destroyed, could surface elsewhere as genuine products.
All these are best destroyed in cement kilns. Any organic matter will react with limestone in the kiln stacks and form calcium compounds that can be removed. All inorganic matter will become part of the clinkers. “Nothing leaves the kiln,” Mr Parlikar said.
For sure, this helps the cement company too because the waste replaces that much amount of fuel.
Carbon intensive
Parlikar said that the production of 1 tonne of clinker emits a minimum of 850 Kg CO2 which makes the cement industry one of the most carbon-intensive industry.
ACC, on its part, has been “actively pursuing” utilisation of alternative raw materials in kilns. The company is exploring the possibility of enhancing the utilisation of AFR such as marble slurry and lime sludge to not only reduce CO2 emissions but also conserve limestone.
In fact, ACC was able to bring down emissions to around 850 kg of CO2 per tonne of clinker, from 1,061 kg in 1990.
Policy push
ACC has begun doing this, for instance, at its plant at Baddi, Himachal Pradesh, but for a pan-country effort, some policy push is needed, Mr Parlikar said.
“What we want is not incentives, but framework,” he said.
Interstate movement of hazardous waste for co-processing should be encouraged, as it is a recovery option, where the use of waste (from within/outside the state) reduces the natural resource consumption of the state. In fact, the state receiving waste from surrounding states should be recognised for its attempt to reduce use of natural resources.
Currently, there is no emission norms set for cement plants undertaking co-processing activity. Maximum permissible emission norms should be put in place for cement kilns undertaking co-processing. A cement plant which fulfils the co-processing prequalification criteria should be issued a permit to co-process all types of waste, while remaining within maximum permissible emission norms
There is a need to create ‘waste banks’ that can combine, collate and share information on the different types (quantity, quality, etc) of waste available across the country. This information will facilitate in understanding the nature of waste and thus enable cement industry to prepare and strategise their utilisation.
The current Central Pollution Control Board Guidelines on co-processing are a start, but to truly encourage utilisation of AFRs by cement plants, we need a regulation, wherein co-processing will be recognised as a preferred technology for waste disposal. This is because co-processing is a recovery option and, therefore, should be preferred over disposal options like incineration and landfill keeping the principles of sustainable development in mind.