I do not know the workings of K99 technology, other than that it is a basic airflow classifier designed to suit the Wickepin kaolin ore, and what follows are words found on the Internet that relates to air classifiers.
For more accurate and finer separations, one can use a rotary air classifier. Sometimes these are referred to as "dynamic" or "whizzer" classifiers. In these devices the material to be classified is dropped onto a rotating circular disk that flings the material out to its edges. Below the disk is a fan generating an air stream such that particles flow upward all around the periphery of the disk. Coarser, heavier particles fall off the disk into a hopper. Finer, lighter particles are lifted by the air and flow up and over a wall into a separate hopper. The cut point can be changed by varying fan speed and adjusting directional vanes. While these types of classifiers are relatively inexpensive, they cannot make very sharp cuts and are generally limited to finenesses in the range of 300 microns down to 45 microns. – https://www.powderbulksolids.com/dust-collection/introduction-to-air-classification
The secondary classifier was ordered from RSG, (https://www.airclassify.com/), and my guess is that the following covers it.
Mill Classification System
Retrofits all types of vertical airswept mills (roller mills, bowl mills, hammer mills, cagemills & impactors)
Easily replaces existing whizzer or cone separator.
Dramatically increases production.
Increased top size control.
The last bullet point is vague, because it neither mentions a Mesh size nor a micron measure to suggest its top cut. WAK probably wants Mesh 325, or 45 microns, so that it can set its K99 classifier to Mesh 300# (about 49 microns), and thus leave it to do what the K99 plant is optimised to do. I like the idea of WAK remaining what it stated it would be when it floated with the kaolin reserves and resources as we know them, and to keep the K99 optimised for Wickepin kaolin as a core enabler. Desirable deviations from that can be met, if justified, by add-ons (as the secondary classifier is) and outsourcing.(which is now under discussion).
If anybody could throw more light on the above, that would be welcome.
