5000 Liter Batch of Xanthan Gum Dispersed in 30 Minutes
Constantin Istrate, Director, Facilities & Engineering, Bentley Mills – April 6, 1992
PROBLEM: Bentley Mills, City of Industry, CA, recently installed a state-of-the-art, computer-controlled carpet printing system. The turn-key system was supplied with color mixing and gum preparation equipment. The original equipment manufacturer specified a venturi-type eductor dispersion system for the preparation of a Xanthan gum pre-dispersion. This system was prone to several problems:
- The small annular space of the venturi eductor tended to plug up when the stabilizer gums contacted the water;
- The eductor system was not capable of dispersing high solids concentrations of the gum;
- If all the gum was not dispersed by the time all of the liquid had been added to the vessel, recirculation was necessary; and
- The quality of mixing decreased and the likelihood of plugging increased significantly if the liquid supplied to the eductor was already a higher viscosity mixture.
The computer controlled carpet printing system utilizes a fine jet printing head to provide up to 10 different carpet dye colors at the command of a computer designed pattern. The system makes possible the customized printing of intricate and interesting patterns that are tailored to individual customer needs. Xanthan gum imparts viscosity that holds the dye in the correct spot on the carpet until the dye can be fixed onto the carpet fibers. The complete dispersion of Xanthan gum bases for mixing with color dyes is an important, critical item in the preparation of intricate color printed carpets.
SOLUTION: Bentley Mills replaced the venturi-type eductor with a mechanical mixer/disperser known as the Model D-6000 DISPERSHEAR. The device contacts the gum/water mixture in a patented dispersion chamber with an 1800 RPM low shear mixing impeller. Complete and efficient dispersion of the gum particles is provided while dispensing the dispersion and pumping it to the top of a 2 meter tall, 5,000 liter processing/mixing tank. The mixing tank has an axial flow turbine mixer to provide blending of the dispersion.
Operators load the hopper of the Model D-6000 Dispershear with one complete barrel of the stabilizer powder, set the controls and allow the machine to operate totally unsupervised for the full 30 minute dispersion time. After the powders are dispersed and the final amount of water is added to bring the percent solids level to the correct point, the dispersion is ready to use.
