Mark it is possible I may have missed the 78.3% reference but I don't see it in the 2 sept 14 NR? I know I am getting old and the eyes are failing ...so if it is actually in the 2 sept NR I apologize. Are you sure you didn't mean a different NR?
Don Hains quote is about 2 years old and I don't see how it fits this situation. The 99.99% result was by LECO furnace which has a 1.4% plus or minus error factor. GDMS is the accurate measurement and the best result with GDMS is 99.95% (not that that is bad). I submit that the final caustic bake result is important and should have been reported in the 16 dec NR.
Clearly it is important to optimize any metalurgical process continuously. Vale has been optimizing their processes for over 100 years. My comment was regarding the time it is taking to get a result that satisfys a PEA.