COMPARISON OF METHODS USED IN THE STABILISATION OF
POST-INCINERATION ASHES
Krystyna Cedzynska
Technical University of Lodz
Stefanowskiego str. 4/10, 90-924 Lodz, Poland
Abstract
Products of incineration are bottom and fly ashes and gas. The toxicity of the ash results
from the content of leachable heavy metals, remains of organic compounds etc. This ash has
to be treated before disposal to avoid the leaching of toxic substances. Methods commonly
used to stabilise ash (eg. with cement or polimers) often do not effectively prevent leaching of
toxic elements to the environment. Vitrifiction (amorphisation or glassyfication) is an
innovative method used to stabilise toxic ash. As a result of this process a glass-like product is
obtained with significantly reduced volume and high chemical resistance. The aim of this
study was the application of a plasma vitrification process to transform toxic ashes generated
by waste incineration plants into a chemically stable material with possibly the smallest
negative effect on the environment. The vitrification was done in a plasma torch reactor
designed in the Technical University of Lodz and applied to treat the ash samples. The
properties of the vitrificates mainly depend on the chemical composition of the processed
ashes. The vitrificates were obtained from pure ash and ash with some various additives.
Substances commonly used in the glass industry were used as additives to obtain a product
with required properties. Leaching values for the obtained vitrificates were compared to
values for the untreated ash and cemented ash. Vitrificates are characterized by compact
structure with a smooth, shining, black surface. After vitrification the leaching of most metals
decreases even 100x and the leaching from vitrificate was smaller than from cemented ash.
When other compounds are added to the vitrified ash they change the properties of
vitrification products. In comparison to presently used solidification of ashes with cement the
plasma vitrification method can be more effective in the stabilisation of hazardous incinerator
ash.