Photo induced reductive leaching of iron from ilmenite in hydrochloric acid solutions

Abstract

The rate of leaching of iron from ilmenite (FeTiO 3 ) in hydrochloric acid (HCl) solutions is greatly enhanced by the presence of ultraviolet (UV) light. The magnitude of the air purged UV light illuminated leaching rate is approximately twofold higher than the N 2 purged leaching rate under dark conditions. The enhanced rate is attributed to the photo dissociation of polymeric titanium oxy species via oxidising radicals OH and HO 2 formed through Fe 3z /Fe 2z /H 2 O Fenton type reactions. Photo dissociation and consequent non-deposition of polymer species in the pores of ilmenite particles cause the chemical reaction between FeTiO 3 and HCl acid in stirred solutions to become the rate determining step. The addition of H 2 O 2 to the reaction mixture, in the presence and absence of UV light, further enhances iron leaching rate, confirming the role of radical species.

Production of synthetic rutile from ilmenite via anion-exchange

“…The leaching of the ilmenite occurred according to the following chemical equations (Olanipekun 1999; Jayaweera et al 2011): …”

Leaching of ilmenite to produce titanium based materials: a review

“…This group further reports that iron leaching from ilmenite in HCl was greatly enhanced when exposed to UV light due to the photoinduced degradation of the titanium oxy polymers formed and non-deposition of Ti(IV) polymeric species in pores of ilmenite. The enhanced dissolution has taken place at high temperature and high concentration of HCl and interestingly, when air was purged during UV exposure, dissolution was further enhanced due to the formation of oxidizing radical species such as OH and HO 2 , confirmed by the enhanced dissolution observed with the addition of H 2 O 2 to the ilmenite HCl medium [57]. Figure 7 shows the main steps involve in weak acid digestion of ilmenite and subsequent production of TiO 2 .…”

“…Researchers from Sri Lanka have studied the digestion of Sri Lankan ilmenite in acidic solutions [47,48,57]. Production of rutile from natural ilmenite via anion-exchange was reported to produce rutile without any traces of iron.…”