A modified process for leaching of ilmenite and production of TiO2 nanoparticles

Titanium dioxide is an important material with a wide range of applications. Different methods and processes have been introduced and applied to produce pure TiO2 from available titanium ores and mineral sources. This paper describes the production of nano-sized titanium dioxide (TiO2) from ilmenite concentrate provided by the main Iranian Ilmenite processing complex. Ilmenite (FeTiO3) concentrate was decomposed using (70% wt.) potassium hydroxide solution at 220 degrees C and under air at atmospheric conditions. The decomposed product was leached using hydrochloric acid solution, and Ethylenediaminetetraacetic acid (EDTA) was applied for chelating and separating iron impurity from the leach solution. Ammonia solution was used for precipitation, and the anatase TiO2 nanoparticles were produced in the following filtration, drying, and calcination processes. The water content of the filtrate solution was evaporated, and it was dried to produce a powdery product. The crystal phases of ilmenite, decomposed ilmenite, and the TiO2 product were characterized by X-ray diffraction (XRD), and the chemical compositions of the ilmenite concentrate, products, and the filtrate were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The morphological study of the decomposed ilmenite and synthesized-TiO2 was performed using scanning electron microscope (SEM) and field emission scanning electron microscope (FESEM), respectively. The particle size measurement of the TiO2 product was conducted using dynamic light scattering (DLS) method. The crystal system and lattice parameters were calculated by the Rietveld refinement method. The purity of the produced synthesized-TiO2 was determined to be more than 90% with a mean particle size diameter of around 70 nm. The filtrate solution (as the main byproduct of the process) contained Fe-EDTA chelated complexes, sodium, potassium, and some other constituents that can be used in agricultural fertilizer production.