MINERAL PROCESSING Toll milling Halfmile 13/06/2012· The initial mill run focused on zinc recovery and it was found to be over 86% A concentrate grading 53% Zn % Pb and % Cu plus precious metals was made The next run will treat 40 000 to 50 000 tonnes of feed from Halfmile and test zinc regrind parameters and increased by product recoveries including lead liberation and pyrite