DISPAL T25N4-80

The unique product characteristics of Sasol dispersible boehmites can lead to many
advantages for use in different systems. Some key features are:

• The high purity boehmites are produced under careful control to yield products with consistent quality and reliable performance.
• The powders are highly dispersible. Low-viscosity nano-sized particle sols can be prepared at room temperature in 10 to 30 minutes with concentrations of 10–40 wt.% AlOOH.
• The boehmites are versatile. They can be employed under a variety of application conditions, including low or high pH and low or high shear.
• Sasol also offers boehmites which are dispersible in polar and non-polar organic media.

The Sasol range of dispersible boehmites has traditionally been used in applications such as

• Sol-gel ceramics
• Catalysis
• Rrefractory materials
• Rheology control
• Surface frictionizing

Other applications include surface coating as well as paint detackification, polymer-
additives and functional fillers

Crystallite size
Crystallite dimensions in powdered boehmite samples are analyzed using X-ray diffraction techniques on X-ray diffractometers supplied by Siemens or Philips.

Dispersed particle size
The particle size distribution of diluted boehmite sols and dispersions is measured using
laser diffraction or photon correlation spectroscopy techniques on Malvern, Horiba or
Cilas instruments. Alternatively dispersed particle sizes can be measured using a disk
centrifuge supplied by CPS.

Dispersibility of boehmite powder
A specified amount is added to water or dilute acid under stirring. The mixture is then stirred for a specified period of time to form a dispersion. The dispersion is centrifuged, and the undispersed residue is isolated, dried and weighed to determine the percentage of non-dispersed material.

Surface area
The boehmite is first calcined at 550°C for three hours in preparation for analysis.  Alumina surface area is then measured using BET nitrogen adsorption techniques on instruments supplied by Quantachrome (Nova series) or by Micromeritics (Gemini series).

Trace element analysis
Trace element analysis is performed by using several methods, including X-ray fluorescence of pressed alumina disks and wet techniques (ICP/OES).

Pore volume and pore size distribution
The boehmite is first calcined at 550°C for three hours in preparation for analysis.  The
porosity is measured by nitrogen desorption using Autosorb instruments supplied by Quantachrome.

DISPAL boehmite powders are mildly abrasive materials having a Mohs hardness of 3.5 to 4.0. Therefore, handling and storage equipment should be designed for such materials. Examples are aluminum, abrasion resistant carbon steel and polypropylene or epoxy-lined steel. Blower or vacuum systems can be used to move the powders. A minimum of 4,000 ft/min fluidizing velocity is recommended. Boehmite powders will absorb atmospheric moisture and facilities should be designed appropriately. The liquids are readily pumpable using standard centrifugal or positive displacement pumps. Due to the pH range of available products, recommended materials for process equipment include stainless steel, or polymeric-lined steel.

DISPAL boehmite powders are classified as non-toxic nuisance dusts. Exposure to high concentrations of dust may cause physical irritation and drying of skin and eye tissues. Repeated or prolonged contact with alumina sols may cause irritation as well. Handling and shipping procedures should be designed to avoid such contact and to minimize the inhalation of airborne dust. Normal good laboratory practices and operating procedures should ensure personnel safety.