EXTRACTION OF NANOPARTICLE IRON, SILICA AND
CALCIUM SULPHATE FROM ELECTRIC ARC SLAG
Zaiton Abdul Majid,* Nor Aziah Buang and Muhammad Zamir Othman,
Department of Chemistry, Faculty of Science
Universiti Teknologi Malaysia
*Email: zaiton@kimia.fs.utm.my
Industrial waste material such as electric arc (EA) slag produced in the steel
industry consists largely of iron oxide, calcium oxide and silica. Studies on the EA
slag have mainly focused on utilization or recycling of the EA slag, namely its
application in the construction industry as recycled aggregate in the road
construction as well as its potential in the treatment of phosphate containing
wastewater. This research reports on a novel method of extraction of iron oxide from
EA slag to be used as a catalyst in the production of carbon nanotubes (CNTs). The
extraction process breaks down the perovskite structure of EA slag into nanoparticle
size using top down principle. Besides the iron oxide, the extraction method also
produced precious side products namely, silica and calcium sulphate. The slag used
in this study was obtained from Antara Steel, Pasir Gudang, Johor. The EA slag was
ground and sieved before treatment with ammonium nitrate followed by sodium
hydroxide and heat treatment at elevated temperature The filtrate collected in
ammonium nitrate and sodium hydroxide extraction processes were further treated to
produce silica and calcium sulphate. Field Emission Scanning Electron Microscope
(FESEM), Energy Dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD),
Fourier Transform Infrared Spectrophotometer (FT-IR), and BET Surface Analyzer
were used to characterize the treated slag, silica and calcium sulphate. The results
obtained showed that nanoparticle iron was successfully extracted from the EA
slagwith a surface area of 72.51 m2/g. The EDX analysis showed high percentage of
iron in the treated slag. Amorphous silica was successfully produced with a surface
area of 133 m2/g and >90% purity. The XRD diffractogram illustrates clearly the
existence of amorphous silica. This was further supported with the morphology of
the amorphous silca as shown by FESEM. Additionally, 99% of microsize calcium
sulphate was successfully produced. FESEM analysis suggests that the calcium
sulphate obtained is of high purity and have well crystalline structure of plane and
rod like shaped. With this novel and simple extraction process, high yield and purity
of iron oxide, silica and calcium sulphate were successfully extracted from EA slag.