Titanium dioxide (TiO2), is an oxide of the metal titanium and is the most used white pigment due to its brightness and very high refractive index. It is produced by combining titanium metal with oxygen in a manufacturing process known as a chloride. In the production of titanium dioxide, the most important basic raw materials used are titanium ore (mainly titanium dioxide and iron oxide), anhydrous (anhydrous means containing no water) sodium chloride, sulfuric acid and hydrofluoric acid.
The titanium dioxide production process can be subdivided into two main stages: the first one is the process of titanium ore dissolution and pre-treatment, and the second one is the chlorination or oxidation of the dissolved titanium ore to produce the desired pigment. In the first step, the reaction of titanium ore with anhydrous sodium chloride and sulfuric acid solution allows obtaining chlorine, sodium sulfate and titanium sulfate. The titanium sulfate solutions are then oxidized in the presence of chlorine and nitrogen monoxide at very high temperatures. This oxidation process produces an intermediate product (chloride of titanium dioxide) that is not in the correct form to be used as a pigment, thus further treatment is needed to transform it into the finished product.
At this stage, the yellowish-orange intermediate product passes through several sub-processes of purification and transformation before obtaining a white pigment that can be used in a wide variety of commercial applications. These processes involve effects such as washing with hydrochloric acid, hydrofluoric acid, phosphoric acid and sulfuric acid, filtration, crystallization, and drying in order to obtain the white pigment of commercial grade known as a TiO2 pigment.
The TiO2 pigment can be used in a wide variety of application fields, such as in paints and coatings, plastics, paper and printing, inks, construction materials, cosmetics, and food coloring. For these applications, the particle characteristics and the chemical composition of the TiO2 pigment should be controlled according to the commercial grade that is being produced.
In conclusion, Titanium dioxide (TiO2) is the most used white pigment in the world due to its brightness and refractive index. It is produced through a manufacturing process combining titanium ore, anhydrous sodium chloride, sulfuric acid and hydrofluoric acid. This process is subdivided into two main stages: the first one is the extraction and pre-treatment of titanium ore and the second is the oxidation of the dissolved titanium ore to obtain the desired pigment. After undergoing sub-processes of purification and transformation, the finished product is a white pigmented TiO2 that can be used in a wide variety of applications from paints and coatings to food coloring.
