Environmental Engineering Reference
In-Depth Information
Blast-Furnace Sludge as Sorbent Material
for Multi-metal Contaminated Water
Yuliya Kalmykova, Jesper Knutsson, Ann-Margret Strömvall,
and Kristina Hargelius
Introduction
Cost effective alternative technologies and sorbent materials are in great demand for
sustainable management and treatment of contaminated water. Natural materials and
industrial waste, that is low-cost adsorbents, are available in large quantities and
have the potential to be used for the treatment of metal contaminated water
[1, 2]
. Blast-
furnace sludge is generated during the manufacture of pig iron
[3]
. Pig iron is pro-
duced in large blast furnaces, where preheated air is blown into the lower part of the
furnace. A dusty gas is emitted from the top of the furnace and the gas is purified by
means of wet treatment in flue gas scrubbers. The particles in the washing water settle
through sedimentation, and the remaining muddy waste is termed blast-furnace
sludge. At present this sludge is deposited in landfills and the steel industry in
Europe produces ~500,000 t of the sludge yearly
[4]
.
Environmental research and publications pertaining to the use of blast-furnace
sludge are very limited
[5]
. The sorption capacity for metals in a single solution with
furnace sludge has been investigated and found to be effective for metals such as Pb,
Zn, Cd, Cu and Cr
[6, 7]
but the removal of Zn has been reported as low
[8]
. The
possible release of and environmental risk posed by iron-cyanide complexes from
deposited blast-furnace sludge has been found to be low
[9]
.
The sludge has been chemically and mineralogically characterized
[10]
; the main
elements found were C > Fe > > Ca > Si > > Al > Zn. Carbon was found in the form
of coke and graphite, and the main minerals were calcite/CaCO3 > quartz/SiO2 >
kaolinite/Al2Si2O5(OH)4 > hematite/Fe2O3 > magnetite/Fe3O4. Further stud-
