Recovery of materials and energy from waste in Austrian cement works

摘要

During the few last years, the cement industry has developed to an important factor in waste management, as more and more waste fractions and industrial residues are utilised as secondary raw material and secondary fuel in the rotary kiln clinker process. Ideal combustion conditions like high bed-temperatures, oxygen excess and long residence times are creating perfect facilities for the decomposition of organic pollutants. Non volatile inorganic pollutants can be safely fixed in the alkaline matrix of the clinker by counter-current adsorption in the preheater cyclones. In Austria, cement works have become the main disposal facility for used oil, old tyres, fly ash and used foundry sands and recently the sorted plastic fraction of household waste is utilised as a fuel of high calorific value. The fundamental requirements for the thermal utilisation of waste in cement works are no significant increase of the emissions and no deterioration of the cement quality as well as no impairment of work place safety. These conditions only can be met by a packet of control measures, starting with quality control of the input material, development of new emission control techniques (e.g. for NO) for cement plants as well as ambient air quality control programs completed by biomonitoring methods for environmental impact assessment studies. In this paper, the salient features of air quality control measures in modem cement works which are utilising secondary materials are elaborated by way of practically oriented examples.