Fluorammonium method of titanium slag processing

Abstract

Titanium dioxide is the most common titanium-containing product on the world market, and the demand for it is increasing. The global consumption of TiO₂ is 7 – 7.5 million tons annually. Titanium dioxide is mainly obtained from ilmenite and rutile concentrates. The largest producers are China, USA, Germany, UK, Mexico, and Saudi Arabia. In addition to the natural resources of titan, there are man-made sources. This type of resource includes titanium-containing slags obtained as a result of pyrometallurgical processing of ores and concentrates containing titanium dioxide. These slags, in addition to titanium dioxide, contain silicon in the form of dioxide, silicates or aluminosilicates, whose chemical processing is difficult due to their high melting point (more than 2000 °C) and the chemical stability of these compounds in mineral acids (sulfuric, nitric, hydrochloric). Processing of such raw materials is carried out by “classical” chlorine and sulfuric acid methods. The use of fluorides in industry is realized in the production of aluminum, zirconium, uranium, beryllium, niobium, etc., which indicates the possibility of using fluoride methods for titanium slags processing. The article discusses a method for producing titanium dioxide based on the use of ammonium hydrodifluoride NH₄HF₂ , which has a high reactivity to a number of chemically resistant oxides (oxides of silicon, titanium, aluminum, etc.). The fluoroammonium method for processing titanium slag using NH₄HF₂ involves slag decomposition of in NH₄HF₂ melt followed by silicon admixture sublimation. Cleaning from iron, aluminum and other impurities is carried out using a solution of NH₄HF₂. Further precipitation of titanium with treatment of the precipitate by AlCl₃ and ZnCl₂ solutions followed by calcination allows to obtain a rutile modification of titanium dioxide.