Redemption of Microscale Mill Waste into Commercial Nanoscale Asset |
| Journal |
Key Engineering Materials (Volume 380) |
| Volume |
Innovation in Materials Science |
| Edited by |
J. A. Sekhar and J. P. Dismukes |
| Pages |
229-255 |
| DOI |
10.4028/www.scientific.net/KEM.380.229 |
| Online since |
March, 2008 |
| Authors |
Abdul Majeed Azad,
Sathees Kesavan,
Sirhan Al-Batty
|
| Keywords |
Electron Microscopy, Heavy-Metal Remediation, Hydrogen Generation, Magnetic Resonance Imaging, Metal-Steam Reforming, Mill-Scale, Nanoscale Zerovalent Iron, Steel Industry Waste, X-Ray Diffraction (XRD) |
| Abstract |
Mill-scale is a porous, hard and brittle coating of several distinct layers of iron oxides
(predominantly Fe3O4) formed during the fabrication of steel structures. It is magnetic in nature
with iron content up to as high as 93%. About 1240 million metric tons of steel was produced in
2006 globally, 1.5 % of which by weight accounts for the mill-scale waste. Thus, 18.6 million
metric ton of mill scale waste was produced in one year alone. Most of the steel mill-scale waste
(almost 80%) end ups in a landfill; a small fraction of it is also used to make reinforced concrete in
Russia and some Asian countries. A purer commercial form of this oxide in combination with
nickel and zinc oxide is used in making ceramic magnets (soft ferrites) which are an integral part of
all the audio-visual and telecommunication media on this planet as well those in the space. The
mill-scale waste could be a valuable technological resource if properly processed and converted into
nanoscale species, in particular nanoscale iron particles for hydrogen fuel cell, medical imaging and
water remediation applications.
In order to achieve the much-discussed and sought-after hydrogen economy via an ‘econo’ viable
and ‘enviro’ friendly route, a roadmap for utilizing the mill-scale waste has been developed. The
method consists of reacting heated iron with steam, also appropriately called metal-steam reforming
(a route well-known to the metallurgists for centuries) generating high purity hydrogen, with a
twist. The innovation lies in the conversion of the coarse oxide scale into nanoscale iron by a novel
solution-based technique. This produces highly uniform zerovalent iron particles as small as 5 nm.
The scope of utilizing the mill-scale waste is broadened several folds as nanoscale iron and
nanomagnetite find potential applications in de-arsenification of drinking water, destruction of
perchlorate and reduction of hexavalent chromium ions in water sources. In addition, nanoscale iron
and magnetite are finding increasing application as the preferred contrasting agents in magnetic
resonance imaging - MRI. |
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