Disposal of hazardous industrial waste in cement kiln – A pilot study of acid tar sludge

Abstract

Acid tar sludge (ATS) is a hazardous waste generated in steel plants as a process by-product. ATS disposal is a major challenge for the steel industry around the world and specifically for developing nations. Hazardous wastes are usually disposed of in a dedicated expensive thermal treatment plant as per existing rules. Due to inadequate capacity of treating the total amount of hazardous waste, study of other economical options are required. India generates over 7.2 million metric tonnes of hazardous waste annually as per Central Pollution Control Board (CPCB), Government of India. Thus, co-processing of ATS in cement plant as an alternative means of disposal was studied based on a number of trials. During the five trials of 5 day each, feed rate of ATS was maintained at 0.4 tonne per hour (TPH) with an average coal feed rate of 10 TPH. No incremental variations in emissions were observed during the trials. The analysis further revealed insignificant impact on clinker quality, leach behaviour and cement property. The study also showed negligible impact on ambient air quality based on NO x, SO2, RSPM, SPM measurement at varying location around the cement plant. Thus, co-processing of hazardous waste such as ATS in cement plant can be an effective way to address the hazardous waste disposal problem in developing countries such as India.