Úprava popílku ze spaloven odpadů s možností snížení environmentálních rizik.

Abstract

Dissertation thesis was dealing with possibilities of the waste incineration secondary energy products utilization. Focus was given on the municipal solid waste incineration (MSWI) fly ash (FA). Three samples of MSWI FA from Austrian incineration plants were used for examination. FA1 and FA2 come from the grate furnace MSW incineration plant, moreover FA1 contains of activated coke, which is injected during the process of flue gas cleaning. On the other hand FA3 comes from the incineration plant combusting refuse derived fuel partly mixed with sewage sludge in a fluidized bed furnace. The theoretical part of the thesis describes MSWI FAs, their hazard properties and possible environmental impacts of FAs landfilling. Hazard property H15 (Waste capable by any means, after disposal, of yielding another substance, e..g. a leachate) and increased concentration of heavy metals were specific for MSWI FA. Focus was given on FA chlorides washing and on the possibilities of reduction of mercury and lead concentration in FAs, which was achieved by a technology of FA separation on a cyclosizer. MSWI FAs contain of mineralogical phases having pozzolanic/hydraulic properties, for that reason they are useful as a construction material. Therefore the possibilities of the MSWI FA utilization in a construction industry were also described in a theoretical part of the thesis. Identification of FA physical and chemical properties is presented in an experimental part of the thesis. X-Ray fluorescence analysis and FAs leachates were executed. The X-Ray diffraction was used for the evaluation of the pozzolanic mineralogical phase’s content. It can be concluded that FA1 and FA2 were characteristic for the high concentration of chlorides and sulphates, Ca, Na, K, Al and Si. On the other hand FA3 had 4-7 times lower chlorides concentration and higher concentrations of Si and Al. High concentration of mercury in FA1 and FA2 were problematic due to the exceedance of Hg landfilling limits, thus they were treated as a hazardous waste. From the leachate analysis can be concluded that FA samples were highly alkaline with high conductivity. The content of pozzolanic phases in untreated FA samples (namely anhydrite, larnite and gehlenite) was from 9.19% (FA3) to 28.93% (FA1). Chemical extraction method (distilled water washing with 1:10 solid/liquid ratio) was used for decreasing of the chlorides content, with 98.4% effectiveness. Physical separation using cyclosizer equipment was used for the heavy metals content reduction. Heavy metals were concentrated in the fraction bellow 12 resp. 14 µm, this fraction was removed from the samples. The content of pozzolanic phases in treated FA samples was increased by 31% (FA1), 39% (FA2) and 45% (FA3). Treated FA samples were used as a partial Portland cement replacement in a concrete.