The current sulphate process for TiO2 production via ilmenite is vigorously digested with concentrated sulfuric acid, which discharges considerable dilute sulphuric acid waste in industry. This paper describes recent developments of a mechanical-activation process for the intensification of the ilmenite leaching using dilute sulphuric acid (e.g., concentration of 60 wt.%). The used sulphuric acid can be mixed with waste acid and recycled into the leaching process. The unactivated and mechanically activated ilmenites were carefully characterized by using X-ray diffraction, particle size analysis, BET surface area and scanning electron microscope techniques for the understanding the structural changes during the mechanical activation process. The results revealed that mechano-chemical activation significantly affected on the lattice deformation, crystal size specific surface area and the granule size in mechanical activation systems, which led to a significant increase of leaching rate (from 36% to ~73%). The wet milling was found to be more effective than dry milling due to surface regions with larger lattice strain, significantly larger surface area, and more smaller size crystallites. Moreover, the reaction principles of the mechanically activation were discussed and a possible mechanism was proposed. This methodology is economically and scientifically significant for energy-saving and intensifying the leaching process, which could be widely used in solid-liquid reactions.
Keywords:Titanium; Mechanical activation; Sulphuric acid leaching; Wet milling
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