Washing is very popular technological operation removing clay particles
from aggregates. The amount of mineral washing sludges increases.
Besides filling the excavations, there is no common method of their
utilization. The usage of sludges from washing aggregates in building
ceramics might be environmentally friendly way to utilize them.
This paper presents laboratory research on two type of sludges: from
dolomite and limestone aggregates washing. Selected properties of
sludges such as water content, particle size distribution (sieve and
areometric method), chemical composition (XRF), mineral composition
(XRD), thermal properties (STA/EGA, dilatometry, heating microscopy) and
stability of fired materials during steam exposure were determined.
It was found that dolomite sludge contains more clay minerals and less
carbonates, it is more finely grained than limestone sludge. Limestone
sludge has large fluctuations in water content and has high content of
potentially hazardous calcite grains. During heating up to 1300°C of
both dried sludges decarbonation and sintering take place. Dolomite
sludge softens, melts and flows below 1300°C. After firing sludges at
1000°C material made of limestone sludge is not resistant to steam.
The obtained result suggests that dolomite sludge can be used in
building ceramics technology without processing as main component of
ceramic mass. Limestone sludge have to be ground before its application
in building ceramic materials. Results suggest that it can not be used
as the main raw material in ceramic masses, but only as an additive.