flash smelting

{{Short description|Smelting process for sulfur-containing ores}}

{{Use American English|date = April 2019}}

file:Evolution copper smelting.svg

Flash smelting ({{langx|fi|Liekkisulatus, literally "flame-smelting"}}) is a smelting process for sulfur-containing ores{{cite web

| title = flash smelting | url = http://www.collinsdictionary.com/dictionary/english/flash-smelting | publisher=Collins English Dictionary - Complete & Unabridged 11th Edition. Retrieved November 03, 2012

}} including chalcopyrite. The process was developed by Outokumpu in Finland and first applied at the Harjavalta plant in 1949 for smelting copper ore.{{Cite web

| url = http://www.outokumpu.com/files/Technology/Documents/Newlogobrochures/FlashSmelting.pdf

| archive-url=https://web.archive.org/web/20110724043222/http://www.outokumpu.com/files/Technology/Documents/Newlogobrochures/FlashSmelting.pdf

| archive-date = 24 July 2011

| title = Outokumpu Flash Smelting | publisher = Outokumpu

| page = 2

| access-date = 2009-05-06

}}{{Cite journal

| title = Flash smelting and converting furnaces: A 50 year retrospect

|author1=Ilkka V. Kojo |author2=Ari Jokilaakso |author3=Pekka Hanniala

| journal = JOM: Journal of the Minerals, Metals and Materials Society

| publisher = Springer Boston | issn = 1047-4838 | issue = 2 | volume = 52 | date = February 2000

| doi = 10.1007/s11837-000-0049-5

| pages = 57–61

| bibcode = 2000JOM....52b..57K

| s2cid = 110355049

}} It has also been adapted for nickel and lead production.

A second flash smelting system was developed by the International Nickel Company ('INCO') and has a different concentrate feed design compared to the Outokumpu flash furnace.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=91–102}} The Inco flash furnace has end-wall concentrate injection burners and a central waste gas off-take,{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=91–102}} 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.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=73–90}} While the INCO flash furnace at Sudbury was the first commercial use of oxygen flash smelting,S Ellor, M Chamberland and H Davies, 'Development of models of INCO's smelting processes,' in: EPD Congress 1992, Ed. J P Hager (The Minerals, Metals and Materials Society: Warrendale, Pennsylvania, 1991), 1125–1145. fewer smelters use the INCO flash furnace than the Outokumpu flash furnace.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=91–102}}

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.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=91–102}}{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=73–90}} The concentrate must be dried before it is injected into the furnaces and, 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.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=73–90}}

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, where the iron oxides react with fluxes, such as silica and limestone, to form a slag.{{Cite book

|first1=W G |last1=Davenport

|first2=M |last2=King

|first3=M |last3=Schlesinger

|first4=A K |last4=Biswas

|title=Extractive Metallurgy of Copper

|edition=4th

|publisher=Pergamon Press |location=Oxford, England

|year=2002

|isbn=978-0-08-044029-3

|doi=10.1016/B978-0-08-044029-3.X5000-X

}}

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{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=187–198}} and 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.{{sfnp|Davenport|King|Schlesinger|Biswas|2002|pages=217–246}}

Outotec, formerly the technology division of Outokumpu, now holds Outokumpu's patents to the technology and licenses it worldwide.

INCO was acquired by Brazil's Vale in 2006.{{citation needed|date=April 2013}}

{{Gallery |align= center

|file:Flash smelting (Outokumpu furnace).svg|Outokumpu flash furnace, mainly designed for copper smelting

|file:Flash smelting (Inco furnace).svg|Inco flash furnace, mainly designed for nickel smelting (also efficient for copper smelting)

|file:Flash smelting (Kivcet furnace).svg|Kivcet flash furnace, mainly designed for lead smelting (also efficient for copper and zinc smelting)

}}