Construction of a 15 t/h demonstration copper ISASMELT plant began in 1986. The design was based on MIM's 250 kg/h test work and operating experience with the lead ISASMELT pilot plant. It cost A$11 million and was commissioned in April 1987. The initial capital cost was recovered in the first 14 months of operation.
As with the lead ISASMELT pilot plant, the copper ISASMELT demonstration plant was integrated into copper smelter operations and justified by the 20% (30,000 t/y) increase in copper production that it provided. It quickly treated the entire backlog of converter slag concentrate, which could not be treated at high rates in the reverberatory furnaces without generating magnetite ("FeO") accretions that would necessitate shutting down the reverberatory furnaces for their removal.
The demonstration copper ISASMELT plant was used to further develop the copper process. Refractory life was initially shorter than expected and considerable effort was devoted to understanding the reasons and attempting to extend the life of the refractories. At the end of the life of the demonstration plant, the longest refractory life achieved was 90 weeks.
Lance life was also low initially. Inexperienced operators could destroy a lance in as little as 10 minutes. However, as a result of modifications to the lance design, the development of techniques to determine the position of the lance in the bath, and a rise in the operating experience, the typical lance life was extended to a week.
The demonstration plant was commissioned with high-pressure (700 kPag) air injected down the lance. Later, after extensive testing of low-pressure lance designs and trials using oxygen enrichment of the lance air, a 70 t/d oxygen plant and a 5 Nm3/s blower with a discharge pressure of 146 kPag were purchased. The new lance design was capable of operating at pressures below 100 kPag. Using enrichment of the oxygen in the lance air to 35%, the demonstration plant throughput was lifted to 48 t/h of concentrate, and the gross energy used during smelting was reduced from 25.6 GJ/t of contained copper to 4.1 GJ/t.