A new lead refinery with a. capacity of 230,000 tons per year com- menced operation at*Port'Plsie in October, 1959. This plant' superseded the refinery which had operated from 1933 with the advent of the continuous lead refining process. The incorporation of new equipment following local metallurgical developments, together with the overseas demand for lead of extremely low antimony content, created difficulties in operating the original plant. The new refinery project was under- taken to cover this disability and to gain the full advantage of the new processes._x000D_
Desilverising and softening are carried out in units identical in size to those used previously. Metallic'zinc is now recovered from the entire output of desilverised bullion by vacuum distillation. Final refining is then carried out by batch'treatinent with caustic soda yield- ing lead of purity previously unattainable at Port Pirie._x000D_
These two processes have replaced continuous dezincing by oxidation, a high temperature process which caused large quantities of lead and antimony to be recirculated. As the final stage is a .batch process the product composition can be.checked before casting. Individual batches can be adjusted to produce special alloys to,consumer's specification._x000D_
Improved casting equipment has allowed the quantity production of pigs of good physical characteristics either as 56 lb bars or 2000 lb pigs. This, together with the high purity of the lead, has assured the B.H.A.S. position in world markets._x000D_
Automatic control systems have been extensively employed particularly on the vacuum dezincing unit._x000D_
The anticipated financial benefits have been achieved mainly by a reduction in the tonnage of recirculated materials, a smaller labour force, and reduced maintenance requirements.