Application Summary

Catalytic slurries consisting of solid catalysts and support materials suspended in a liquid medium are commonly prepared in batch tanks agitated by low-speed mixers such as propellers, anchor paddles and pitched blade impellers. These devices can sometimes suffer from long cycle times and inadequate dispersion especially in large batches.

One alternative solution is to introduce the dry ingredients via sub-surface injection under high shear conditions. Technologies like the Ross Solids/Liquid Injection Manifold (SLIM) offer a more practical method of wetting out powders and quickly achieving the desired particle size distribution in high percent solids slurries.

Ross SLIM Technology

The Ross Solids/Liquid Injection Manifold (SLIM) is ideal for fast, high-volume dispersion of solids into liquid. At the heart of this technology is a ported rotor/stator device that draws powders sub-surface into a high shear mixing zone.

In conventional slurry mixing systems equipped with low-speed agitators, dry raw materials are gradually fed into a vortex on the liquid surface and prolonged mixing is sometimes necessary to achieve a homogenous suspension. By comparison, the four-blade rotor of a SLIM Mixer runs at tip speeds in the range of 3,000-4,000 ft/min within a close tolerance fixed stator. This induces high levels of mechanical and hydraulic shear but what truly differentiates the SLIM from other mixers is the way it combines solids and liquids sub-surface at precisely the point of intense mixing. It enables rapid addition of catalysts and carrier materials including fine aluminum oxide, nickel oxide, cerium zirconium oxide, barium sulfate, kaolin clay, fumed silica and titanium dioxide. Dispersion is virtually instantaneous; floating powders, foaming and excessive dusting are also eliminated.

The SLIM technology is available in both batch and inline designs, making it simple to retrofit into most existing processes. The inline version is particularly efficient because it can adapt to almost any size tank and can double as a recirculation pump. For optimal powder injection, liquid viscosity must be under 10,000 centipoise (cP).

The Ross SLIM is proven technology for fast and efficient dispersion of many other solids including:

• Alginates
• Alumina
• Bentonite Clay
• Boric Acid
• Calcium Carbonate
• Carbomers
• Carbon Black
• Carrageenan Citric Acid
• CMC
• Dye Powders
• Ground Rubber

• Gum Arabic
• Magnesium Hydroxide
• Milk Powder
• Pectin
• Rosin Ester Resin
• Starch
• Sugar
• Talc
• Titanium dioxide
• Whey
• Xanthan Gum

Processing advantages of the SLIM Technology

• Simple and straightforward operation. Just turn on the mixer and start inducting powders. No eductors or vacuum pumps to deal with.
• Shorter cycle times. SLIM users report significant reductions in their overall mixing time, often by as much as 80% or more.
• Increased yield and higher quality dispersions. By preventing the formation agglomerates and eliminating floating powders, the SLIM maximizes both yield and functionality.
• Easier material handling. The Inline SLIM is usually installed at floor level so operators need not climb up a mezzanine 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. The Inline SLIM can be supplied on a mobile cart to serve virtually any size vessel located anywhere in the plant.