Acta Montanistica Slovaca (Sep 2000)
The prognosis of of the effect of selected groups of microorganisms on the structural and chemical composition of fly-ash deposits
Abstract
The results of study of the quantitative changes in the deposits of energy fly-ashes of various period of in situ deposition (0,5,10,20 years) and laboratory model study of the influence of contamination of fly-ash using selected species of autochtonous microorganisms of Actinomycetales (AC) order, Bacillus (BC) and Aspergillus (AN) genera are presented in this paper.The obtained results confirmed a phase and element transformation of in situ deposited material as a result of effect exogenous and biogenous factors depending on the period of deposition. The most significant changes were observed in a loss of amorphous vitreous phase , which gradually devitrificated forming the clay structures of illite and hydrargyllite after five years of deposition and halloysite and bohmite after twenty years of deposition. In additional to te formation of clay structures, creation of zeolite structures of phillipsite, clinoptilolite and mordenite has been also observed in consent with the theories on genesis of formation of natural zeolite.The obtained results also showed some changes in the structural bond of titanium depending on the period of deposition of fly-ash. From the comparison of phase analyses it follows that bonds of Ti whit Fe in form ilmanite dominate in the fresh fly-ash, while bonds of Ti whit Al and oxygen were identified after a twenty years deposition . Howewer, to confirm this fact it would bw necessary to verify, or exclude the influence of the non-homogenity of phase end element composition of combusted coall, as well as the influence of thermic mode on this process.The significant influence of biogenic catalysis on change in the element composition (Al,Fe,Si,Ti) was confirmed by results of laboratory experiments of extremely biogenous contamination of the sample of fresh fly-ash ussing selected species of autochtonous microorganisms in a biological-chemical leaching.The obtained results form a basis for theoretical assumptions, namely the possibility to use the intensified biogenous processes for extraction of some elements, i.e.Ti from fly-ash, as well as form monitoring and prediction of changes in the fly-ash deposits.
