Mix-Granulating with a Lancaster K-Series Mixer
Many reasons compel industrial operations to enlarge solid particles for handling. Some objectives may be: enhancing flow properties, recycling, de-dusting, densifying, freezing ingredient distribution, improving mold filling properties, etc.
Size– Enlargement in the powder technology context include: agglomerating, pelletizing, granulating and
Most powders having the ability to fuse, or slightly dissolve in the presence of a liquid, can be granulated quite easily. Others may be coaxed to form granules by the introduction of some suitable binders. The binders may act as a medium for the solid particles to adhere to each other by modifying interfacial activities. Some may form a matrix to capture the particles. Others may involve chemical reactions to achieve the objective.
Mix-granulation versus Disc / Pan Granulation: Disc granulation (sometimes called pan granulation) is a continuous process. In its simplest form, powders and liquid are fed in steady streams and fixed proportions. The rotating disc is tilted at a certain angle to facilitate continuous overflow of the desired granules. Under steady-state conditions, particle residence time in the disc granulator is theoretically constant; hence product characteristics are also constant. Generally, disc granulation produces relatively uniform-sized granules in the order of 1/2” diameter and larger.
Mix-granulation in a Lancaster K-series unit is
As the Lancaster mixer is capable of inputting intensity and energy, independent of mixing-granulating time, a number of factors can be adjusted to influence granule characteristics. These mixer configurable parameters
Lancaster K-series mixers are especially useful for processes where some multi-ingredient solids need to be well mixed, and then granulated into nominally spherical products. Mixer and process parameters can be controlled to achieve desired properties. Size distribution usually follows a bell-shaped curve, with approximately 90 percent of granules falling within one order of magnitude.
- Charge Powders
- Dry mix (this step can be
skipedwith single component powder feed)
- Add liquid
- Wet mix and form seed
A door-to-door cycle can run anywhere between 3-4 minutes to over 10 minutes, depending on process and product requirements.
Peripheral Operations: Many productions can utilize the entire batch in downstream handling. Others may require a narrower cut, hence necessitating a screening and recycling step.
An example of a mix-granulating plant is illustrated below: