Abstract:
Laterite is used as the main alumina source for cement manufacturing process of
some countries, and it decreases the lifespan of limestone deposits due to the high
Fe content. This study focuses on the removal of iron oxide from laterite with
studying the effect of pH, sonication time, and temperature. The iron removal from
laterite was examined along with Cd and Mn. The raw and treated laterite were
subjected to Loss of mass on Ignition (LOI), moisture, pH, Atomic Absorption
Spectroscopy (AAS), X-ray Diffraction (XRD) and Fourier-Transform Infrared (FTIR)
to understand the physical, chemical and mineralogical nature of the samples. The
LOI, moisture, and p H of untreated laterite were 16.56%, 15.80% and 5.69,
respectively. XRD results of untreated laterite revealed goethite and hematite as
main Fe-rich minerals associated with gibbsite, kaolinite, and quartz. The solid to
liquid ratio (1:10) and the particle size (63 pm) were constant, throughout the
experiment. The optimal p H range for Fe, M n and Cd removal was examined with
HCl (pH 1-5) and NaOH ( pH 6-10) at 300 K for 1800 s. pH 5.69 was the neutral pH
value for this research. The Fe and M n removal efficiency were gradually increased
when the pH from 5 to 1 and Fe had a sudden increment from pH 2 to pH 1. Cd
removal efficiency was increased from pH 1-10. Therefore, the effective pH for Fe,
Cd, and M n were 1, 7 and 1, respectively. Effective temperature and sonication time
were conducted for pH 1 and 2. Fe removal w i t h temperature was examined with
313, 333, 353 and 373 K for 3600 s and 600, 900, 1800, 2700 and 3600 s at 300 K for
sonication time. All elements removal efficiencies were increased with the
temperature. Fe and M n had high removal efficiency at 900 s w i t h pH 1 , and Cd was
recovered within 600 s w i t h pH 2 when sonication. The optimal condition of Fe ion
removal for industrial applications is pH 1 w i t h 333 K temperature or pH 1 with
900 s sonication time. Under high temperature and basic pH conditions Cd can be
removed effectively. The optimal condition for Mn is pH 1 w i t h 900 s sonication
time. The goethite and hematite peaks can be identified in every XRD graphs of final
treated laterite samples.
Citation:
Goonetilleke, W.A.L.A.T., Ratnayake, A.S., & Jayawardena, D.T. (2019). The efficiency of iron oxide removal from laterite for industrial applications [Abstract]. In D.M.D.O.K. Dissanayake & G.V.I. Samaradivakara (Eds.), Proceedings of International Symposium on Earth Resources Management & Environment 2019 (p. 125). Department of Earth Resources Engineering, University of Moratuwa.