The only information being presented on grade is some comments...

The only information being presented on grade is some comments in research forecasts. It a safe bet that a lot of the current product isn't getting to the 32-33% range or E25 would be putting it in their quarterlies that they have achieved PFS grades and are working on volumes.

I'm not sure if the original designs had a gravity concentrator system like DMS, but once they achieved good test results with their flowsheet of Dig, Crush, Wash, Size grade & Optical sort (ref 23 Mar 2020), they when with that. It would appear the test sample was washed to a much cleaner state than the log washer does. This means that within the test work the optical sorter didn't have the clay distortions that can cause a misread.

I'm not sure if its a typo, but my understanding is that DMS is a sub-category of a gravity concentrator circuit. DMS uses gravity to select different material densities but does this by having a liquid that is a lot heavier than water. Where water works to separate pumice from other rocks, with a heavier liquid you can select different densities. If for example all the material you wanted was 3.0x heavier than water then if you dialed in a liquid with this density anything lighter would float and be waste. You could also max the range to eliminate other heavier materials (and if really lucky with the ore, get a useful byproduct). If using DMS its unlikely you would need to use a 2nd gravity concentrator system.

DMS won't be fooled by traces of clay on otherwise quality manganese ore, hence its not surprising that it generates good beneficiation results.