The ball mills crushed 78 tons per day and, after classification, the coarser part of this, amounting to 38 tons, was ground to about 250 mesh in the tube mill. The pulp fed into the mill contained: coarser than 40 mesh, 20.5 per cent.; 40 to 60 mesh, 43.8 per cent.; 60 to 100 mesh, 28.1 per cent.; 100 to 150 mesh, 7'6 per cent.