Increased dissolution of ilmenite induced by high-energy ball milling

High-energy ball milling treatment leads to full dissolution of natural ilm enite sands containing both FeTiO3 and Fe2Ti3O9 phases in a sulphuric acid solution at 100 degrees C. The ilmenite material has been milled for variou s times in two environments (vacuum and air), and characterised by X-ray di ffraction, Mossbauer spectroscopy and surface area analysis. It is found th at after milling for only 10 h, 50% of the sample can be dissolved as a res ult of the increased surface area, nanocrystalline structure and high level of lattice distortion present in the milled sample. Complete dissolution o f the ilmenite is obtained on extended milling (200 h) in an oxygen free at mosphere. This occurs as a result of a gradual reduction of the Fe3+ phase (Fe2Ti3O9) to the relatively more soluble Fe2+ phase (FeTiO3) on milling in vacuum. The results overall show that the chemical reactivity of milled ma terials can be affected significantly by the milling conditions and environ ment. (C) 1999 Elsevier Science S.A. All rights reserved.