Extraction OF NANOPARTICLE IRON (III), SILICA AND
CALCIUM SULPHATE FROM ELECTRIC ARC SLAG
Muhammad Zamir Othman, Zaiton Abdul Majid* and Nor Aziah Buang
Department of Chemistry, Faculty of Science
Universiti Technologi Malaysia
*Email: zaiton@kimia.fs.utm.my
Industrial waste material such as electric arc (EA) slag usually contains
precious metal oxides and is classified as a scheduled waste. The EA slag is
commonly used as a cement replacement material. Research has also shown the
potential of utilizing EA slag in the treatment of phosphate containing wastewater
and acidic wastewater. This research reports on a novel method of extraction of iron
oxide catalyst from slag. Our group has successfully used this 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. It was ground and sieved before treating it with ammonium nitrate
followed by sodium hydroxide and further heating at high temperature. The filtrate
collected in ammonium nitrate and sodium hydroxide extraction process were further
treated to produce silica and calcium sulphate. The treated slag was characterized
using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive
X-Ray Analysis (EDX), Fourier Transform Infrared Spectrophotometer (FT-IR), and
BET Surface Analyzer. The silica produced was characterized using X-ray
Diffraction (XRD), FT-IR, FESEM-EDX and BET surface analyzer while the
calcium sulphate produced was characterized using FESEM-EDX. The results
obtained showed that nanoparticle iron was successfully extracted from the EA slag
with 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. In addition, 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.