Application Summary

Mixing titanium dioxide powders into liquid, especially in large quantities, requires sufficient shear in order to achieve optimal functionality. The basic objective is to disperse TiO2 into individual particles as these deliver greater opacity compared to agglomerates.

Most concentrated titanium dioxide slurries exhibit relatively low viscosity but can become quite dense and the mixer must be able to produce adequate product turnover under such conditions. Dust management is another critical factor in the mixing operation. Compared to traditional disperser mixers, new powder injection technologies enable faster material transfer and high shear powder wet-out while reducing dust generation.

Ross High Shear Mixers with SLIM Technology

The Ross Solids/Liquid Injection Manifold (SLIM) Technology is a proven method for wetting out and dispersing titanium dioxide powders to produce a homogeneous concentrated slurry. The SLIM consists of a unique rotor/stator generator specially designed to create a powerful vacuum for drawing solids and injecting them into liquid under high shear. Titanium dioxide powders are wetted out right within the rotor/stator assembly where vigorous mixing takes place. Dispersion is virtually instantaneous. At the same time, rapid product turnover helps to keep solids uniformly suspended in the slurry. Most formulas include a dispersant to prevent settling long after the mixing step.

The SLIM technology is available in both batch and inline designs, making it simple to retrofit into existing processes. This system can handle very high loadings of titanium dioxide (>65%) while operating within a wide viscosity range: from water-like to up to 10,000 centipoise during powder injection. Mixtures containing TiO2 and other fillers, especially thickeners, may be batched in a Ross Multi-Shaft Mixer with SLIM Technology which can provide satisfactory flow patterns even at elevated viscosities in the hundred thousand centipoise range.

The Ross SLIM is proven technology for fast and efficient dispersion of different types of solids including:

• Aginates
• Alumina
• Bentonite Clay
• Boric Acid
• Calcium Carbonate
• Carbomers
• Carbon Black
• Carrageenan
• Citric Acid
• Cellulose Gum / CMC
• Dye Powders
• Ground Rubber

• Guar
• Gum Arabic
• Hydroxyethyl Cellulose
• Magnesium Hydroxide
• Milk
• Pectin
• Starch
• Talc
• Whey
• Xanthan Gum

Processing advantages of the SLIM Technology

• Shorter cycle times. SLIM users report significant reductions in their overall mixing time, often by as much as 80% or more.
• Simple and straightforward operation. Just turn on the mixer and start inducting powders. No eductors or vacuum pumps to deal with.
• Increased yield and higher quality dispersions. By preventing the formation agglomerates and eliminating floating powders, the SLIM maximizes both yield and functionality of solid raw materials.
• Easier material handling. The inline SLIM mixer is usually installed at floor level so operators no longer have to climb up mezzanines carrying heavy bags of powder. Solids can also be delivered via automatic feeding devices.
• Cleaner and safer mixing. A "hose & wand" attachment is used for dipping into bulk bags or containers to conveniently induct lightweight powders without creating a dusty environment.
• Flexibility. A portable SLIM unit can be used in multiple process lines serving mix vessels of various sizes.