AbstractsEarth & Environmental Science

"This ore is mined from a quartz vein which is refined by small seams of graphitic clay material, and the walls of the vein consist of a sort of graphitic shaley material. The above graphitic materials break down under treatment into a rather peculiar clay which was called primary colloidal slime. The milling process in use consists of stamp milling followed by the separation into sand and primary slime in Dorr Duplex Classifiers. The primary slime overflow from these classifiers, which is all practically thru 220 mesh, is thickened and treated by flotation. Normally and with a good supply of fresh water, flotation is satisfactory, but, in winter, when they were short of water and had to reclaim water from the mill pulp, using lime to settle it, the bad effect of the foul water on flotation was very marked. So long as they could keep the primary clay unflocculated, flotation was satisfactory but the pulp was sensitive and the least impurity in the water flocculated the slime immediately. With unflocculated pulp it was possible for them to flow off the tops of the thickeners a small quantity of colloidal clay. There was insufficient thickner capacity any way, and with flocculated pulp the overflowing colloidal clay then entangled and carried over with it rich sulfide minerals...The problem was to improve the flotation extraction when using neutral water and if possible to find out some means of obtaining satisfactory results when using reclaimed foul water which contained of course lime which had been added for settlement purposes" – Milling Problem at the Plant of chosen Corporation Taiyudo Chosen (Korea), pages 15-16.