High Speed Dispersion of Bentonite Clay

Background/Requirement

 

Bentonite is a naturally occurring aluminum silicate clay which can take up several times its own weight of water to form a highly thixotropic colloidal suspension or gel. The gel structure is derived from hydrogen bonds which develop between the clay particles (or platelets.) These bonds readily break down with shear, reforming again if the shear force is removed. One of the principal applications for bentonite is in drilling muds, however it is widely used as a suspending and stabilizing agent, and as an adsorbent or clarifying agent in many industries. Some examples are given in the table:

 

Industry	Use
Agrochemical	Anticaking agent for granular fertilizer, ingredient of pesticides, suspending agent
Civil Engineering	Foundations, asphalt emulsions, grout
Cosmetic	Antiperspirants, deodorants, lipstick, creams and lotions
Food/Animal Food	Binder, carrier and stabilizer in pet food. Clarifier for juice, wine and edible oil
Household	Detergent bulking agent, polishes
Miscellaneous	Paper coatings, paper de-inking, inks and paints
Oil	Drilling mud
Pharmaceutical	Stabilizing, thickening and suspending agent in creams and ointments

 

Despite the diversity of end uses, and the various processing methods and equipment used, there are a number of common processing requirements which must be satisfied in order to obtain maximized “functionality”.

• Conventional agitators do not produce sufficient shear to reduce particle size and activate the gelling effect.
• Upon addition of the water, the particles tend to agglomerate. The washing action of conventional mixers cannot break these down effectively.
• Long mixing cycles are required to obtain uniform dispersion and to complete hydration.
• With in-tank mixing, once viscosity increase has started, agitation of the solution becomes increasingly difficult reducing the mixer’s ability to provide shear to reduce particle size and maximize gelling effect.

The following problems can be encountered when using conventional agitators:

• Mixing equipment must be capable of rapidly incorporating and dispersing the powder into the base liquid.
• The bentonite particles must be reduced to their finest constituent parts to expose the maximum surface area to the surrounding liquid and activate the gelling effect.

 

Quadro's Approach

 

The above problems can be overcome using a Quadro Ytron Jet Mixer and Z Emulsifier. Bentonite Clay is made up of organic platelets, which under shear break apart to create multiple platelets, hence creating the viscosity increase. The Jet Mixer with a bypass assembly will introduce the Bentonite Clay powder into a solution dust free and the axial flow pattern of the Jet Mixer will blend to a uniform concentration within minutes. When the Bentonite Clay has been introduced and blended, we recommend a single pass of the solution through the high shear, fine radial tolerance Z Emulsifier to achieve the maximum viscosity building properties of the Bentonite Clay.

 

[go back]