Chemie der Erde 72 (2012) S4, 3–8 Contents lists available at SciVerse ScienceDirect Chemie der Erde journal homepage: www.elsevier.de/chemer The metallurgy of antimony Corby G. Anderson ∗ Kroll Institute for Extractive Metallurgy, George S. Ansell Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, United States article info abstract Article history: Globally, the primary production of antimony is now isolated to a few countries and is dominated by Received 4 October 2011 China. As such it is currently deemed a critical and strategic material for modern society. The metallurgical Accepted 10 April 2012 principles utilized in antimony production are wide ranging. This paper will outline the mineral pro- cessing, pyrometallurgical, hydrometallurgical and electrometallurgical concepts used in the industrial Keywords: primary production of antimony. As well an overview of the occurrence, reserves, end uses, production, Antimony and quality will be provided. Stibnite © 2012 Elsevier GmbH. All rights reserved. Tetrahedrite Pyrometallurgy Hydrometallurgy Electrometallurgy Mineral processing Extractive metallurgy Production 1. Background bullets and armory. The start of mass production of automobiles gave a further boost to antimony, as it is a major constituent of Antimony is a silvery, white, brittle, crystalline solid that lead-acid batteries. The major use for antimony is now as a trioxide exhibits poor conductivity of electricity and heat. It has an atomic for flame-retardants. number of 51, an atomic weight of 122 and a density of 6.697 kg/m3 ◦ ◦ at 26 C. Antimony metal, also known as ‘regulus’, melts at 630 C 2. Occurrence and mineralogy and boils at 1380 ◦C. Antimony and the natural sulfide of antimony were known as early as 4000 BC. It was used as a coating for copper The abundance of antimony in the Earth’s crust is approximately between 2500 BC and 2200 BC. The sulfide was used as eyebrow 0.2 mg/kg. Antimony is a chalcophile, occurring with sulfur and the paint in early biblical times, and a vase found at Tello, Chaldea, was heavy metals copper, lead and silver. More than 100 minerals of reported to be cast antimony. Antimony is seldom found in nature antimony are found in nature. Some of the more common ones, as as a native metal because of its strong affinity for sulfur and metals summarized by the author, are listed in Table 1. such as copper, lead and silver. In fact, the word antimony (from the Industrially, stibnite (Sb2S3) is the predominant ore of interest Greek anti plus monos) means “a metal not found alone”. Metallic and importance. Stibnite deposits are usually found in quartz veins. antimony is too brittle to be used alone and in most cases has to The deposits frequently contain minor amounts of gold, silver and be incorporated in an alloy or compound. For this reason, its devel- mercury sulfides. opment was slow until military applications created new markets Antimony has been produced from ores in over 15 countries. and the Russo-Japanese war of 1905 triggered demand. Antimony As shown in Table 2 (Carlin, 2012), world reserves of antimony are was widely used in that time and during the First World War as estimated to about 1.8 million metric tonnes. As China, the leading it was found to be the best alloying material for lead to produce producer, accounts for about 90% of the world’s mined production munitions that capable of armor plate penetration. A variety of and the vast majority of the reserve base (i.e. reserves consist of compounds containing antimony as the major constituents were demonstrated resources that are currently economic. The reserve also used for other ammunition types such as detonators, tracer base consists of reserves plus marginally economic reserves and resources that are sub-economic). Moreover, China together with four three other minor producing countries, Bolivia, the Republic of ∗ South Africa, Tajikistan and Russia currently account for over 95% Tel.: +1 303 273 3580. E-mail address: [email protected] of the total world antimony production. 0009-2819/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.chemer.2012.04.001 4 C.G. Anderson / Chemie der Erde 72 (2012) S4, 3–8 Table 1 Common primary antimony minerals. Horsfordite Cu6Sb Dyscrasite Ag3Sb Stibiodomeykite Cu3(As,Sb) Aurostibite AuSb2 Breithauptite NiSb Breithauptite NiSb Ullmannite NiSbS Gudmundite FeSbS Stibnite Sb2S3 Stibiobismuthine (Bi,Sb)4S7 Tetrahedrite Cu12Sb4S13 Annivite Cu12(Sb,Bi,As)4S13 Freibergite (Cu,Ag)12Sb4S13 Bournonite PbCuSbS3 Stephanite Ag5SbS4 Ramdohrite Ag2Pb3Sb3S9 Andorite AgPbSb3S6 Geocronite Pb5(As,Sb)12S8 Zinckenite PbSb2S4 Jamesonite, Pb4FeSb6S14 Boulangerite Pb5Sb4S11 Falkmanite Pb3Sb2S6 Meneghinite Pb4Sb2S7 Cylindrite Pb3Sn4Sb2S14 Franckeite Pb5Sn3Sb2S14 Livingstonite HgSb4S7 Berthierite FeSb2S4 Famatinite Cu3SbS4 Stibioluzonite Cu3(Sb,As)S4 Bournonite PbCuSbS3 Stibioenargite Cu3 (As,Sb)4 Gerstleyite Na2(Sb,As)8S13·2H2O Kermesite Sb2S2O Gabrielite Tl6Ag3Cu6(As,Sb)9S21 Stibiocolumbite Sb(Nb,Ta)O4 Senarmontite Sb2O3 Romeite 5CaO3·Sb2O5 Stibiconite Sb2O4·H2O Stenhuggarite CaFeSbAs2O7 Cervantite Sb2O4 Stibio-tellurobismutite (Bi,Sb)2Te3 Valentinite Sb2O3 3. Uses and applications as in safety match compositions. In the production of red rubber, antimony pentasulfide is used as a vulcanizing agent. Antimony Antimony trioxide, Sb2O3, is the most important antimony compounds are also used in catalysts, pesticides, ammunition, and compound produced. Today, antimony trioxide is produced by medicines. As well, a variety of compounds containing antimony volatilizing antimony metal in an oxidizing furnace. It is used as the major constituent are also used for other ammunition such in halogen compound flame retarding formulations for plastics, as detonators, tracer bullets and armory. Also, as previously noted, paints, textiles and rubber. Most commercial grades of antimony antimony was widely used during the First World War as it was trioxide contain between 99.2% and 99.5% antimony trioxide with found to be the best lead alloy material to use for penetrating armor varying amounts of impurities such as arsenic, iron and lead. Com- plate. mercial suppliers offer various grades of antimony trioxide based Flame retardants continue to drive growth demand for anti- on the relative tinting strength of their product, which is a func- mony trioxide. The historic capacity of the world’s major tion of particle size. Antimony trioxide also finds growing use as a established producers as compiled by the author is listed in Table 3. catalyst for PET production. Antimony pentoxide and sodium anti- Table 4 lists a recent compilation of production capacities of global monate, NaSb(OH)6, are also used as flame retardants. Antimony mining operations (Roskill, 2011). compounds, primarily sodium antimonate, are also used in decol- Overall, it is estimated that the distribution of antimony uses orizing and refining agents for optical glass and CRT glass. In the and consumption worldwide is flame retardants 72%, transporta- electronics industry, Sb use grows for diodes. Antimony metal is tion including batteries 10%, chemicals 10%, ceramics and glass 4%, also used for production of antimonial lead, which is an impor- and other 4%. The USA, Japan and Western Europe which together tant product of the secondary lead smelter. A blast furnace charge account for around 70% of world demand dominate world con- containing used or discarded battery plates, type metal and bear- sumption of antimony. ing metal is reduced to lead bullion. The bullion is then refined in reverberatory furnaces to meet specifications. Lead–antimony alloys are used in starting-lighting-ignition batteries, ammunition, 4. The mineral processing of antimony corrosion-resistant pumps and pipes, tank linings, roofing sheets, solder, cable sheaths and anti-friction bearings. Originally antimony was mined and hand sorted to effect con- Currently, the major conservation practice within the antimony centration. Since the bulk of primary production is in China, where industry is the recycling of the metal in used lead acid storage labor is plentiful and cheap, surprisingly, hand sorting still finds batteries, type metal and babbit. Also, antimonial lead and anti- a large application. However, in recent years, many other unit mony metal are recovered from intermediate smelter products operations are used in the mineral processing of antimony. These such as slags, drosses, flue dusts and residues generated at copper include primarily conventional crushing and grinding followed by and lead smelters. The supply of secondary antimony substantially combined gravity concentration and flotation. First, as stibnite is exceeds that from primary sources for antimonial lead applications. the predominant mineral and China is the predominant producer, In other minor uses, antimony oxides are used as white pigments the industrial mineral processing of a typical Chinese stibnite ore in paints, whereas antimony trisulfide and pentasulfide yield black, will be elucidated. As well, the historical flotation operation of a vermillion, yellow and orange pigments. Camoflauge paints contain long term industrial North American silver bearing antimony tetra- antimony trisulfide which reflects infrared radiation. Antimony hedrite mining operation will also be discussed. trisulfide is also used in the liners of automobile brakes as well A typical stibnite deposit may contain the antimony sulfide along with pyrite and a gangue consisting