March/April 2007

Growth and acceptance of the ISASMELT process

By M.L. Bakker and P.S.Arthur, Xstrata Technology


The ISASMELT™ process is a submerged lance smelting technology operating in base metal smelters in Australia, the USA, Belgium, India, Germany, Malaysia, China, and Zambia. Further plants are under design or commissioning in Peru and Kazakhstan. Following the invention of the Sirosmelt lance technology,Mount Isa Mines recognized the commercial potential in the novel top-blown bath smelting process, and embarked on a development program that has lasted more than 25 years. After successful operation of pilot plants and demonstration plants producing copper and lead, Mount Isa Mines decided to license the technology to external companies. Since the purchase of Mount Isa Mines by Xstrata in 2003, Xstrata Technology has assumed responsibility for transferring the technology to ISASMELT™ licensees. This document updates the reader on the design of the most recently commissioned ISASMELT™ plant, namely the Mopani copper smelter in Zambia.

Technology development

The development of the Sirosmelt lance at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) during the 1970s opened up new opportunities for the non-ferrous pyrometallurgy industry. Prior to its introduction, the injection of gases into liquid slag or matte was achieved predominantly through tuyeres, with inherent design complications and refractory problems. Mount Isa Mines Limited was introduced to the submerged lance technology during the 1970s and recognized its potential for improving the efficiency of operations at its lead and copper smelters.The lance enabled the use of stationary furnaces with simple design but very high reaction rates. Following initial joint collaboration with CSIRO, the ISASMELT™ process was developed to commercial success at the Mount Isa smelting complex. The history has been summarized elsewhere (Arthur and Hunt, 2005).

Development of the process has centred on smelting of lead and copper concentrates or secondaries on a commercial scale. The first demonstration-scale lead furnace was commissioned in Mount Isa, Australia, in 1983 to treat lead concentrates. It was followed in 1987 with a demonstration-scale copper plant, which in turn was followed by construction of a full-scale copper plant in 1992. This 3.7-metre diameter furnace smelts all copper concentrate treated in the Mount Isa copper smelter.

During almost 25 years of developing and operating submerged lance technology on large-scale plants, significant technical improvements have occurred in areas such as furnace design, feed preparation systems, offgas handling, operating and process control strategies, refractory management,and operator training.The combined experience led to what is now known as the ISASMELT™ technology package, which is licensed to external clients. By 2009, commercial ISASMELT™ furnaces operated by Xstrata and external licensees will have a combined annual smelting capacity of more than seven million tonnes of concentrates or secondary raw materials. Many of the improvements implemented by plant operators have been passed on to, and adopted by, other licensees. Exchange of ideas and technical improvements occur through ad hoc visits to fellow licensee sites and through regular licensee workshops arranged by Xstrata Technology.

The table below shows the commercial plants that have been licensed to date.


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