text: Following the 120 kg/h test work, MIM decided to proceed to install a 5 t/h lead ISASMELT pilot plant in its Mount Isa lead smelter. It bought Aberfoyle's matte fuming furnace and transported it from Kalgoorlie to Mount Isa, where it was rebuilt and commissioned in 1983 to demonstrate the first stage of the process in continuous operation and for testing the reduction step using batches of high-lead slag.
  One of the key features of the pilot plant was that it was run by operations’ personnel in the lead smelter as though it was an operations’ plant. The high lead slag produced by the continuous smelting of the lead concentrate was subsequently treated in the sinter plant, thus increasing the production of the lead smelter by up to 17%. This gave the operations’ people ownership of the plant and an incentive to make it work, thus ensuring management and maintenance priority. It also gave MIM assurance that the process simple enough to be operable in a production environment, with normal staff and supervision, and that it was robust enough to withstand normal control excursions. In addition to the continuous operation of lead concentrate to produce high-lead slag, the pilot plant was used to produce lead metal from batches of the slag, investigate the wear rates of the furnace's refractory lining and lances, and initial work aimed at developing a low-pressure version of the Sirosmelt lance. The result was a lance design that allowed operation at significantly lower pressure than the initial values of about 250 kilopascal (gauge) ("kPag"), thus reducing operating costs.
  MIM built a second, identical furnace next to the first, and commissioned it in August 1985. This combination of furnaces was used to demonstrate the two-stage process in continuous operation in mid-1987. However, for most of the time the two furnaces were not able to operate simultaneously due to a constraint in the capacity of the baghouse used to filter the lead dust from the waste gas.
  A series of process improvements, particularly in the waste gas handling system, resulted in increasing the throughput of the plant from the initial design of 5 t/h to 10 t/h. The pilot plant had treated more than 125,000 t of lead concentrate by April 1989.
  The two furnaces were also used to develop a process to recover lead from the Mount Isa lead smelter's drossing operations.