Flash smelting furnace (Finnish: Liekkisulatus, literally “flame-smelting”) is a smelting process for sulfur-containing ores including chalcopyrite. The process was developed by Outokumpu in Finland. It was first applied at the Harjavalta plant in 1949 for smelting copper ore. It has also been adapted for nickel and lead production.

A second flash smelting system was developed by the International Nickel Company (‘INCO’). It has a different concentrate feed design compared to the Outokumpu flash furnace. The Inco flash furnace has end-wall concentrate injection burners and a central waste gas off-take. While the Outokumpu flash furnace has a water-cooled reaction shaft at one end of the vessel and a waste gas off-take at the other end. While the INCO flash furnace at Sudbury was the first commercial use of oxygen flash smelting, fewer smelters use the INCO flash furnace than the Outokumpu flash furnace.

Flash smelting with oxygen-enriched air (the ‘reaction gas’) makes use of the energy contained in the concentrate to supply most of the energy required by the furnaces. The concentrate must be dried before it is injected into the furnaces. In the case of the Outokumpu process, some of the furnaces use an optional heater to warm the reaction gas typically to 100–450 °C.

The reactions in the flash smelting furnaces produce copper matte, iron oxides and sulfur dioxide. The reacted particles fall into a bath at the bottom of the furnace. And in there the iron oxides react with fluxes, such as silica and limestone, to form a slag.

In most cases, the slag can be discarded, perhaps after some cleaning, and the matte is further treated in converters to produce blister copper. In some cases where the flash furnaces are fed with concentrate containing a sufficiently high copper content. The concentrate is converted directly to blister in a single Outokumpu furnace. The further converting is unnecessary.

The sulfur dioxide produced by flash smelting is typically captured in a sulfuric acid plant, removing the major environmental effect of smelting.

Refractories:

Reactor:  the most important working area with the worst working conditions. The dried materials and preheated air enter the reactor through concentrate nozzle mixing and high-speed spray. Under the action of high temperature (1500 ℃), reactions such as oxidation desulfurization, melting, and slagging are carried out. The formed melt enters the sedimentation tank and further completes the slag making process. The matte and liquid slag generated by the reaction settle in the furnace as a molten layer. Refractories working lining under over heat damage, unstable oxidation-reduction chemical atmosphere damage, copper slag sulphide, matte penetration etc. chemical attacks, vigorous erosion and severe temperature change damages. High grade refractories DMK and RMK Products are recommended for reactor working linings.

Settling Hearth: always being damaged by matte penetrating, strong slag attack reaction damages, gas flow erosions. Medium grade DMK and RMK Products are recommended.

Exhaust air duct: exhaust air of all types from copper smelting has rigorous erosion to refractories linings. MAGSCIE recommends ordinary DMK as exhaust air duct working linings.

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