Yep but they indicate that they will produce a cobalt sulfate...

Yep but they indicate that they will produce a cobalt sulfate end product and not look to sell the floatation product, which is what I think you were indicating in your earlier comment
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They can do it via conventional flotation with recoveries from 64%-88% however leaching provides greater levels of recovery (as you'd expect) and optimization is ongoing. They will need to weight up capex vs economics of a higher rate of recovery. Resource size isn't going to be an issue.
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I have questions with COB's process as well (specifically the thermal decomposition and leach steps to produce the elemental sulfur) but thats another story.