maiden jorc resource, page-9

"they'd still produce a 62% concentrate, but they'd require about 13% less ore on average to feed into the plant to produce the same product... hence operating costs would come down. "

Either that or they keep tonnage leaving the mill the same but of a higher grade.
Would do that by having the same quantity of ore on the ROM but push the mass recovery to the right for a higher grade than 62% for a corresponding higher price per ton of ore even if they kept concentrate tonnage the same.