Use of Ultrasound in the Washing Process of Titania Pigment Production: Water Saving and Process Optimization

Abstract

Washing of metatitanic acid (H₂TiO₃) consumes a large amount of water during the production of titanium dioxide (TiO₂) by the sulfate process. In this work, ultrasound technology is used for the pretreatment of a metatitanic acid slurry before washing. The water consumptions of washing process are compared in the absence and presence of ultrasound treatment. The effects of wash liquor properties, ultrasound time, and ultrasound power on removal of iron impurities are investigated. The washed product was characterized by X-ray diffraction, scanning electron microscopy, and particle size distribution. The effects of ultrasound on the crystal structure of TiO₂ and the mechanism of water saving are discussed. The results show that better removal of iron impurities from metatitanic acid is achieved using ultrasound. The saving wash liquor when using ultrasound was 93 mL for washing a 100 mL metatitanic acid slurry when using a pH 2 wash liquor, ultrasonic time of 30 min, and 185 W ultrasonic power. The average particle size was reduced from 2.11 to 1.02 µm, which improves washing performance. The crystal lattice parameters of TiO₂ exhibited no effect on rutile type or quality of product.

Keywords:

• Iron removal
• Metatitanic acid
• Ultrasound
• Vacuum filtration
• Water-saving

Additional information

Funding

The authors gratefully acknowledge the financial assistance from the Scientific and Technological Research Council of Turkey (No. 114M591)