ISASMELT

The ISASMELT process is an energy-efficient smelting process that was jointly developed from the 1970s to the 1990s by Mount Isa Mines Limited (a subsidiary of MIM Holdings Limited and now part of Glencore Xstrata plc) and the Australian government’s Commonwealth Scientific and Industrial Research Organisation ("CSIRO"). It has relatively low capital and operating costs for a smelting process.

ISASMELT technology has been applied to lead, copper, and nickel smelting, and by 2013 fifteen plants were in operation in ten countries, with another five in various stages of development. The installed capacity of the operating plants in 2013 was over 8 million tonnes per year (t/y) of feed materials, with additional capacity to come on line in 2013 and 2014.

Smelters based on the copper ISASMELT process are among the lowest-cost copper smelters in the world.

An ISASMELT furnace is an upright-cylindrical shaped steel vessel that is lined with refractory bricks. There is a molten bath of slag, matte or metal (depending on the application) at the bottom of the furnace. A steel lance is lowered into the bath through a hole in the roof of the furnace, and air or oxygen-enriched air that is injected through the lance into the bath causes vigorous agitation of the bath.

Mineral concentrates or materials for recycling are dropped into the bath through another hole in the furnace roof or, in some cases, injected down the lance. These feed materials react with the oxygen in the injected gas, resulting in an intensive reaction in a small volume (relative to other smelting technologies).

ISASMELT lances contain one or more devices called "swirlers" that cause the injected gas to spin within the lance, forcing it against the lance wall, cooling it. The cooling effect results in a layer of slag "freezing" on the outside of the lance. This layer of solid slag protects the lance from the high temperatures inside the furnace. The tip of the lance that is submerged in the bath eventually wears out, and the worn lance is easily replaced with a new one when necessary. The worn tips are subsequently cut off and a new tip welded onto the lance body before it is returned to the furnace.

ISASMELT furnaces typically operate in the range of 1000–1200 °C, depending on the application. The refractory bricks that form the internal lining of the furnace protect the steel shell from the heat inside the furnace.

The products are removed from the furnace through one or more "tap holes" in a process called "tapping". This can be either continuous removal or in batches, with the tap holes being blocked with clay at the end of a tap, and then reopened by drilling or with a thermic lance when it is time for the next tap.

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Wikipedia