Background: Urban and industrial wastes can play an important role in
heat and power generation, substituting a large part of conventional fuels. However,
combustion of these materials may create operational and environmental problems
related to their inorganic constituents.
Methods: In this work, the slagging/fouling propensities of ashes from municipal
and animal wastes were determined through the use of a combination of techniques,
such as X-ray diffractometry, ultraviolet and visible spectroscopy, atomic absorption
spectroscopy, inductive coupled plasma-mass spectroscopy and fusibility analysis.
Control methodologies for mitigating deposition tendency in boilers were
applied, i.e. leaching of raw fuels with water and blending them with higher quality
Results: The results showed that urban and industrial waste ashes were enriched in
Ca, P, Si and Mg minerals and micronutrients Cu and Zn. Their alkali-induced slagging/
fouling potential was high. For systems operating below 1000oC, no deposition
problems were anticipated. Mixing these waste materials with an agricultural residue
led to the production of ashes with melting behaviour and deposition tendency
between those of the individual samples.
Conclusion: Leaching of raw materials with water resulted in a significant decrease
of problematic elements K, Na, P, S, and Cl in ashes and consequently in a great reduction
of their slagging/fouling propensity.