Ann: Superior Expandable Graphite and High Grade Concentrates, page-69

Matt, you might wish to read the announcement again.
“Premium priced product achieved with no chemical treatment” refers to 98% TGC achieved from flotation, which is undoubtedly a good result and is the premium priced product referred to.
Elsewhere the announcement refers to a caustic bake / acid leach process to achieve 99.8%.
It states Hcl and HF were not used, so some other acid must have been used in the acid leaching and I assume NaOH in the caustic bake, relatively benign as the announcement states.
That’s purification. Expansion, as you undoubtedly know well, is an entirely different process.
You are not comparing like with like in quoting chromic and sulphuric acid used for expansion. You may wish to check with Frank which acids MNS’ lab used to expand its graphite. Not disclosed in the announcement but I don’t think they used distilled water.
GLTAH.