This paper aims to develop a new approach for determining the performance of regrinding tumbling mills, which is based on the grindability and floatability of locked particles through regrinding systems. The approach combines the grindability factor, in which the grinding of coarse particles is only considered, with the floatability of the regrind mill feed and product using the corresponding grade-recovery curves. The approach was examined in the Sungun industrial regrinding tumbling ball mill using various feed rates. The results showed that the efficiency of the regrinding mill is extremely low and some practical approaches and means are proposed to enhance its efficiency. (C) 2013 Elsevier Ltd. All rights reserved.