Fine tungsten metal powder by hydrogen reduction of WO3

As a part of the studies on the recovery of tungsten values from low grade scheelite concentrates obtained as by-product from the tailing dump of gold ore processing, laboratory investigations on 25 gms scale have been conducted on the production of fine tungsten metal powder by hydrogen reduction of WO3 with and without addition of hexamine. The use of hexamine in the hydrogen reduction of WO3 has been found to give the metal powder which is relatively finer than that obtained by the conventional hydrogen reduction. Moreover reduction rates are higher which shortens the reduction time - a factor favoring the formation of finer metal power. Other factors found to be favouring the formation of finer metal powder are : 1) lower reduction temperature, 7500-8000C, 2) higher hydrogen flow rate, 3) two stage reduction, 4) large spread of the oxide and 5) finer particles of WO3. (M.G.B.)