Depends what your target market is. There is no such thing as DSO kaolin for HPA feedstock - no mills toll treat, and the Chinese make HPA from refining alumina slags/offcasts and aluminium hydroxide precorsors. There's a reason that 99.99% is $25K a tonne, and it's not because it is a lack of DSO.
DSO kaolin for paper, filler, ceramics and other applications depends on a variety of material quality factors. For example, wettability, viscosity, calcined chemical grades, whiteness, fineness at various particle sizes, etcetera. Fine white ceramic grade kaolin has to have negligible iron (a discolourant) and titanium (brittleness, colour, plasticity at fusion, etc).
So, my advice, as someone who is broadly involved in the industrial clays scene now, is to think again of putting the acronyms "DSO" and "HPA" in the same sentence.Sure, this kaolin may be DSO for someone somewhere, for some industrial use, but even then it's not DSO, it's beneficiated by taking out the quartz.
This is also not particularly easy. For example, the **bin deposit contained too much water of crystallisation (17%) to be dry beneficiated, but was too far from a source of fresh water, to be wet beneficiated. So it sat around for years despite having an acceptable use in ceramics, paper coatings, etc, because it simply was too wet, and also too dry, at the same time, to separate the clay from the quartz. (Fetherstone, 2008, GSWA Report).
That's not applicable to HPA, because it is ideally fed into a chemical process, but given literally everyone in HPA land aside from A4N is dealing in kaolin, there's very little separating the kaolins at market in the ASX.
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