UK researchers claim TiO2 process breakthrough

Leeds, UK - Researchers at the University of Leeds have developed a simpler, cheaper and greener method of extracting higher yields of titanium dioxide (TiO2) - one of this most useful and versatile of minerals, which is widely used as an intensely white pigment to brighten everyday products such as paint, paper, plastics, food, medicines, ceramics and personal care products.

Despite its relative abundance in nature, TiO2 is never pureit’s natural occurrence, being bound with contaminant metals such as iron, aluminium and radio-active elements. Pigment-grade TiO2 is produced from mineral ore by smelting, then treating the slag with chlorine, or by directly introducing it into a sulphuric acid solution. These two processes generate toxic and hazardous wastes. The treatment of such wastes is expensive and complex.

The university’s patented process involves roasting the mineral ore with alkali to remove the contaminants, which are washed and leached with acid to yield valuable by-products for the electronics industry. The coarse residue left behind is then reacted with 20 times less than the usual amount of chlorine to produce titanium dioxide powder.

According to the scientists, the process gives an average yield of up to 97% TiO2, compared with the current industry average of 85%. This level of purity will reduce production costs of pigment grade materials and waste disposal costs. In addition, the process also recycles waste CO2 and heat. Furthermore, research team believe that the process can be further refined to yield 99% pure TiO2.

“Researchers have sought a sustainable replacement for current processes for many years. Our aim was to develop new technology for complex minerals of titanium dioxide that are particularly low-grade and whilst readily available in the world market, can’t yet be extracted economically,” said professor Animesh Jha, from Leeds University’s Faculty of Engineering.

“Our process is a real world breakthrough, because it can be used for both lower and richer grades of ores and it overcomes major environmental concerns about having to neutralise and discharge wastes generated in the process that end up going into contamination ponds, continued Jha. “We’re excited about the possibilities for this method of mineral purification; we believe it could be applied to other important minerals with similar complexity, making it a credible potential extraction process for the future,” he says.

Prof Jha and his colleagues have formed an industrial partnership with Millennium Inorganic Chemicals – the world’s second largest TiO2 producer - to develop this technology on a larger scale. The research was funded by the Sustainable Technology Initiative Programme of DTI in collaboration with the Engineering and Physical Science Research Council (EPSRC) and Millennium Inorganic Chemicals.