The Filblast Cyanidation Process incorporates the advantages of intense
high shear mixing, high dissolved oxygen concentration and high pressure
to achieve extremely rapid gold dissolution rates. This is made possible
by the unique design of the Filblast gas shear reactor. The reactor is a rugged and compact in-line device. The outer casing is
protected by a polyurethane coating and the internal parts are of wear
resistant polymer. The largest unit built to-date has overall dimensions of
1200 mm length by 300 mm diameter and has a capacity of 150 dry
tonnes per hour at 40 - 45 per cent solids. Service life at this throughput is
at least three months. The process may further be applied to high temperature leaching of
refractory gold ores or other metals. Wear resistant metal or ceramic
materials would be employed for this duty. Four mines are currently employing the Filblast Process for treating a
variety of ore types ranging from highly reactive, almost impossible to
treat, pyrrhotite/arsenopyrite to deeply weathered clay ore which forms a
highly viscous pulp. The effect of shear thinning has resulted in improved adsorption
kinetics resulting in higher carbon loading and reduced soluble gold loss.
Total tonnage treated is approximately four million. Operating costs which include leasing and maintenance charges for the Filblast and pump
power costs are about 16 cents per tonne. This is equivalent to about ten
per cent of savings. Laboratory scale units having capacities up to 30 litres/min are
available for test work but laboratory testing techniques so far developed
do not accurately reflect the oxygen and cyanide savings which have been
achieved in the plant.