Handbook of extractive metallurgy: Ferroalloy Metals, Alkali Metals, Alkaline Earth Metals, Authors Name Index• Subject Index, Volume 4

338 Pages·1997·35.71 MB·English

by  Fathi Habashi

Handbook of Extractive Metallllrgy
Edited by Fathi Habashi
Volume IV: Ferroalloy Metals
Alkali Metals
Alkaline Earth Metals
Authors
Name Index
•
Subject Index
~WILEY-VCH
Weinheim . Chichester· NewYork·Toronto· Brisbane·Singapore
ProfessorFathiHabashi
UniversiteLaval
DepartementdeMinesetdeMetallurgie
Preface
QuebecG1K7P4
Canada
Extractivemetallurgyisthatbranchofmet presentfourvolumeswillfll1the gapformod
allurgythatdealswithoresasrawmaterialand ernextractivemetallurgy.
metalsasfInishedproducts. Itis an ancientart The Handbook is an updated collection of
Thisbookwas carefullyproduced.Nevertheles,theeditor,the autors and publisherdonotwarrantthe
informationcontainedthereintobefreeoferrors.Readersareadvisedtokeepinmindthatstatements, that has been transformed into a modt;rn sci more than ahundredentriesin UllmannsEn
data,illustrations,proceduraldetailsorotheritemsmayinadvertentlybeinaccurate. ence as aresult ofdevelopmentsinchemistry cyclopediaofIndustrialChemislly~rittenby
andchemicalengineering.Thepresentvolume over200 specialists. Some articles were writ
isacollectiveworkofanumberofauthors in tenspecifIcallyfortheHandbook. Someprob
whichmetals, theirhistory, properties, extrac lems are certainly faced whenpreparing such
tiontechnology, andmostimportantinorganic avastamountofmaterial. Thefollowing may
EditorialDirectors:KarinSora,UseBedrich
ProductionManager:PeterJ.Biel compounds and toxicology are systematically bementioned:
CoverIllustration:MichelMeyer/mmad described.
• Although arsenic, antimony, bismuth, bo
Metals are neitherarranged by alphabetical
ron, germanium, silicon, selenium, and tel
order as in an encyclopedia, nor according to
lurium are metalloids because they have
the Periodic Table as in chemistry textbooks.
covalentandnotmetallicbonds,they arein
The system used here is according to an eco
cluded here because most ofthem are pro
nomic classifIcationwhich reflects mainly the
duced in metallurgical plants, either in the
LibraryofCongressCardNo.appliedfor uses,theoccurrence,andtheeconomicvalueof
elementalformorasferroalloys.
ACIPcataloguerecordforthisbookisavailablefromtheBritishLibrary metals. First, the ferrous metals, i.e., the pro
• Each chapter contains the articles on the
duction ofiron, steel, and ferroalloys are out
metalinquestionanditsmostimportantinor
lined. Then.. nonferrous metals are subdivided
ganiccompounds.However,therearecertain
intoprimarY, secondary,light, precious,ref;ac
compounds that are conveniently described
tory, scattered, radioactive,rare earths,ferroai
togetherandnotunderthemetalsinquestion
loy metals, the alkali, and the alkaline earth
for a variety of reasons. These are: the hy
metals.
drides, carbides, nitrides, cyano compounds,
Although the general tendency today in
DieDeutscheBibliothek- CIP-Einbeitsaufnahme peroxocompounds,nitrates,nitrites,silicates,
teachingextractivemetaliurgy isbasedonthe
HandbookofextractivemetallurgyIed.byFathiHabashi. fluorine compounds, bromides, iodides,
Weinbeirn;NewYork;Chichester;Brisbane;Singapore;Toronto: fundamental aspects rather than on a system
sulfItes, thiosulfates, dithionites, and phos
WILEY-VCH ISBN3-527-28792-2 aticdescriptionofmetal extractionprocesses,
phates. These are collectedtogetherinaspe
Vol.1.Themetalindustry,ferrousmetals.-1997 it has been found by experience that the two
cialsupplemententitledSpecialTopics,under
Vol.2.Primarymetals,secondarymetals,lightmetals.- 1997 approaches are complementary. The student
preparation.
Vol.3.Preciousmetals,refractorymetals,scatteredmetals,radioactivemetals,rareearthmetals.-1997 musthave abasicknowledge ofmetal extrac
tionprocesses: hydro-, pyro-, and electromet .. Becauseoflimitationofspace,itwasnotpos
Vol.4.Ferroalloymetals,alkalimetals,alkalineearthmetals;Nameindex;Subjectindex.-1997
allurgy, and at the same time he musthave at sible to include the alloys of metals in the
his disposal a description ofhow aparticular present work. Another supplement entitled
©VCHVerlagsgesellschaftmbH- AWileycompany, metal is extracted industrially from different Alloysisunderpreparation.
D-69451Weinbeim,FederalRepublicofGermany,1997
rawmaterialsandknowwhatareitsImportant • Since the largest amount of coke is con
Printedonacid-freeandlow-chlorinepaper compounds. It is for this reason, that this sumed in iron production as compared to
All rights reserved (including those of translation into other languages). No part of this book may be HWldbookhasbeenconceived. othermetals, the articles "Coal" and "Coal
reproducedinanyform- byphotoprinting,microfilm,oranyothermeans- nortransmittedortranslatedinto
amachinelanguagewithoutwrittenpermissionfromthepublishers.Registerednames,trademarks,etc.usedin TheHandbookisthefIrstofitstypeforex ,Pyrolysis" are includedinthe chapterdeal
thisbook,evenwhennotspecificallymarkedassuch,arenottobeconsideredunprotectedbylaw. tractive metallurgy. Chemical engineers have ingwithiron.
Composition:JeanFran~oisMorin,Quebec,Canada alreadyhadtheirPerry'5ChemicalEngineers' . I amgratefultothe editorsatVCHVerlags
Printing:StraussOffsetdruckGmbH,D-69509Miirlenbach Handbook for over fIfty years, and physical gesellschaftfortheirexcellentcooperation, in
Bookbinding:WilhelmOswald& Co.,D-67433NeustadtlWeinstraBe metallurgists have an impressive 18-volume particularMrs. Karin Sora who followed the
PrintedintheFederalRepublicofGermany ASMMetals Handbook. It is hoped that the project since its conception in 1994, and to
vi HandbookofExtractiveMetallllrgy
Jean-Franyois Morin at Laval University for thereforebeusefultoindustrialchemistsaswell. Table ofContents
hisexpertiseinwordprocessing. Itcan also be useful to engineersand scientists
Thepresentworkshouldbeusefulasarefer from otherdisciplines, but itis an essential aid
ence work for the practising engineers and the fortheextractivemetallurgist.
students ofmetallurgy, chemistry, chemical en volumeI Part· RefractoryMetals
gineering,geology,mining,andmineralbenefi Seven 26 Tungsten 1329
Part One TheMetal Industry
ciation. Ei\.1ractivemetallurgy and the chemical 27 Molybdenum 1361
industry arecloselyrelated;thisHandbookwill FatMHabashi 1 TheEconomic Classifica- 28 Niobium 1403
tionofMetals , 1
29 Tantalum ........•.1417
2 MetalProduction 15
30 Zirconium 1431
3 RecyclingofMetals 21
31 Hafnium 1459
4 By-ProductMetals 23
32 Vanadium 1471
Part Two Ferrous Metals 33 Rhenium 1491
5 Iron 29
PartEight Scattered Metals
6 Steel 269
7 Ferroalloys .403 34 Germ?nium 1505
35 Gallium 1523
VolumeII 36 Indium 1531
37 Thallium 1543
Part Primary Metals 38 Selenium 1557
Three 8 Copper 491 39 Tellurium 1571
9 Lead 581
PartNine Radioactive Metals
10 Zinc 641
11 Tin 683 40 GeneraL 1585
12 Nickel 715 41 Uranium 1599
42 Thorium 1649
PartFour SecondaryMetals
43 Plutonium 1685
13 Arsenic 795
14 Antimony 823 Part Ten RareEarth Metals
15 Bismuth 845 44 GeneraL 1695
16 Cadmium 869 45 Cerium 1743
17 Mercury 891
18 Cobalt. . 923 volumeIV
PartFive LightMetals
Part Ferroalloy Metals
19 Beryllium 955
Eleven 46 Chromium 1761
20 Magnesium 981
47 Manganese 1813
21 Aluminum 1039
48 Silicon 1861
22 Titanium - 1129
49 Boron 1985
~'olumeIII
Part Alkali Metals
PartSix Precious Metals Twelve 50 Lithium 2029
23 Gold _ :..1183 51 Sodium 2053
24 Silver 1215 52 Potassium 2141
25 PlatinumGroup 53 Rubidium 2211
Metals 1269 54 Cesium 2215
viii HandbookofExtractiveMetallllrgy
Part Eleven
55 Alkali Sulfur
Compounds 2221
Ferroalloy Metals
Part Alkaline Earth Metals
Thirteen 56 Calcium 2249
57 Strontium. 2329
58 Barium 2337
H He
Authors 2355
Name Index 2375 Li Be N 0 F Ne
I
SubjectIndex 2379 Na Mg Al P S Cl AI
K Ca Sc Ii V Fe Co Ni eu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Ic Ru Rh Pd Ag Cd In Sn Sb Ie I Xe
Cs Ba Lat Hf Ia W Re Os Ir Pt Au Hg II Pb Bi Po At Rn
Fr Ra Ac+
46 Chromium
JAMESH.DOWNING(§§46.1-46.7);GERDANGERt(§46.4);PAULD.DEELEY(§46.8);HERaERTKNOPF,PE"IERSCHMIDT(§§
46.9.1-46.9.5 EXCEPT 46.9.2.2; 46.9.10); JOST HALSTENBERG (§§ 46.9.1-46.9.6 EXCEPT 46.9.2.2; 46.9.10); MANFRED
OHLINGER(§§46.9.2.2,46.9.11,46.10.3);KLAUSHOCHGESCHWENDER,GEORGUECKER(§§46.9.7-46.9.9);ULRICHKORAL
LUS(§46.9.11);MANfREDMANSMANN,DIETERRAnE,GERHARDTRENCZEK,VOLKERWILHELM(§46.10.1);GERHARDADRIAN,
KARLBRANDT(§§46.10.2.1-46.10.2.4);GONTERETZRODT(§§46.10.2.5,46.10.4);HELMUTJAKUSCH,EKKEHARDSCHWAB,
RONALDJ.VEITCH(§46.10.3)
o
46.1 History 1761 46.9.4.3 flIerClIromates : 1790
46.2 Properties ; 1762 46.9.5 OtherChromiumCompounds 1792
46.9.6 Analysis 1792
46.3 ResourcesandRawMaterials 1762 46.9.7 Transportation,Storage,and
46.4 Ores 1763 Handling 1793
46.4.1 OreDeposits 1764 46.9.8 EnvironmentalProtection 1793
46.4.2 OreBeneficiation 1767 46.9.9 Ecotoxicology 1794
46.5 Production 1767 46.9.10 EconomicAspects 1795
46.9.11 ToxicologyandOccupational
46.6 Uses 1770
Health 1795
46.7 EconomicAspects 1771 46.10 Pigments 1797
46.8 Alloys 1771 46.10.1 ChromiumOxidePigments 1797
46.9 Compounds 1772 46.10.1.1 Properties 1798
46.9.1 SodiumDichromate 1773 46.10.1.2Production 1798
46.9.1.1 AlkalineRoasting 1774 46.10.1.3 QualitySpecijicatiollSand
Analysis 1800
46.9.1.2 LeaclIingo/tlIeRoast 1775
46.10.1.4 StorageandTrmlSportation 1800
46.9.1.3 Acidification 1776
46.9.1.4 Crystallization ; ' 1776 46.10.1.5 Uses ~ 1800
46.10.1.6EconomicAspects 1801
46.9.2 ChromiumOxides 1777
46.9.2.1 ClIromium(lll)Oxideand 46.10.1.7ToxicologymIdOccupational
ClIronuunlJ(vdroxide..........•1777 HealtlI 1801
46.10.2 ChromatePigments 1801
46.9.2.2 ClIromium(IV)Oxide(ClIromium
Dioxide) 1779 46.10.2.1 ClIromeYellow : 1801
46.9.2.3 ClIromium(VI)Oxide 1780 46.10.2.2 ClIromeOrange 1803
46.9.3 Chromium(IIl}Salts 1782 46.10.2.3 ClIromeGreenmlI:JFastClIrome
46.9.3.1 GeneralProperties 1782 Green 1803
46.9.3.2 ClIromium(1l1)Sulfatesand 46.10.2.4 Toxico/~gymIdOccupational
ClIromeTanningAgents 1783 .Hea1tlI 1804
46.9.3.3 OtlIerClIromium(lll)Salts 1785 46.10.2.5A1lticorrosiveClIromatePigmellts.1805
46.9.4 ChromicAcidsandChromates(V1)1787 46.10.3 ChromiumDioxide 1806
46.10.4 ChromiumPhosphate.; 1807
46.9.4.1 ClIromicAcids 1787
46.9.4.2 AlkaliClIromatesandDiclIromates 1788 .46.11 References 1807
46.1 History [1-5] During the 19th century, ferrochromium
and chromium were produced by avariety of
Chromium was discovered by VAUQUELIN, techniques. However, a commercial process
was not developeduntil 1893, when MOlSSAN
in the mineral cmcojte, PbCrO4' in 1797. In
produced ferrochromium in an electric fur
1798he isolatedchromiummetalby reducing
nace by the reaction of chromium oxide
the oxide with carbon. Soon afterthe discov
(CrZ03) and carbon. In 1898, GOLDSCHlvlIDT
ery ofchromium, the commercial process for produced chromium by the aluminotheImic
manufacturing chromates by roasting reduction' of Cr 0 • Other advances have in
Z 3
chromitewithsodaashwas developed. cludedthe application ofsilicothermicsto the
1762 HandbookofExtractiveMetallllrgy Chromium 1763
production oflow-carbonferrochromium and 46.3 Resources and Raw. The 1983 production and reserves of Minerals. Ofthe many minerals that contain
chromium, production ofchromium by'aque Materials chromite are shown in Table 1. Generally, chromium only the chromium spinels are of
ouselectrolysis,andproductionoflow-carbon [4] richer lumpy Cr bearing ores have been pre economicimportance. Theformula forthe se
fcehrrroomchiurommibuymhiagnhd-termefpIenriantgureofvaecluecutmrolpyrtoic Chromite is a spinel FeO·Cr203. In nature fceornretednftolresssmtehlatinng4,0w%hehraevaes tbheoesnewusiethdCinr2r0e 3 ries of isomorphous mixtures of chromium
cessing. itis amixturedescribedby the formula (Fe2+, spinelsthatform geologicaldepositsis
fractories.
Althoughchromiumisfoundinmanymin Mg)O'(Cr, Al, Fe~P3' Chromite ore rarely (Fell,Mg)O'(Cr,AI,Few}zO,
erals, chromite is the only commercial source containsmorethan50%Cr 0 ;otherminerals
2 3
ofchromium. Mostofthemineralcamefrom suchasSi0 canalsobepresent. 46.4 Ores [27-39] The proportion of Cr 0 in the chromium
2 2 3
theUralMountainsupto 1827,whendeposits Chromite is found in stratiform and podi spinels varies widely, causingthe Cr:Fe ratio
were discovered in the United States. These form deposits. Stratiform deposits occur in The distribution ofchromium in terrestrial (also known as the Cr-Fe factor) to vary as
supplied a limited market up to about 1860, layersuptoameterthick. TheBus~weldIgne rocks isclosely linked to magmaticintrusions well; this can have a profound effect on the
when large deposits were found in Turkey. and their crystallization. The average content
ous Complex (Transvaal, Republic of South evaluation ofadeposit. In an ideal chromium
Since that time chromitehas beenmined pri intheten-milecrustoftheearthis 100ppmof
marilyintheeasternhemisphere. Africa), the Great Dyke (Zimbabwe) and the chromium [33]. Table 46.2 contains a world spinel (FeO'Cr203; 67.8% Cr203, 32.2%
Stillwater Complex (Montana, United States) . FeO)thechromium:ironratiois2.As aresult
Chromium was electrolyzed from a solu wideestimateofchromiumoreresources.
areexamples. Podiformdepositsrange insize of the isomorphous inclusion of MgO, the
tionofchromiumchloridebyBUNSENin 1854. The most important applications of chro
However, large-scale commercial production but atypical commercial deposit will be over Cr:Fe ratio may rise to between 2.5 and 5.
mium ores are inthe manufacture ofstainless
100000 t. Deposits occur in the Ural Moun
of electrolytic chromium did not begin until Figure46.1 showsthe region ofisomorphism
steel, grey cast iron, iron-free high-tempera
tains, Albania, Zimbabwe, and the Philip
1954. ture alloys, and chromium plating for surface withvaryingcompositionofthespinels.Natu
pines.
protection. In the nonmetallic mineral indus ral chromiumspinelsusually contain33-55%
46.2 Properties [6-8] Table46.1:Chromiteproductionandreserves,1983[4]. try, chromiteis processedinconjunctionwith Cr203, 0-30% Fep3, 0-30% Al203, 6-18%
Produc- Reservesb, Reserve magnesite (sintered magnesia, calcined mag FeO,and 10-32%MgO.Table46.4listssome
Atroomtemperaturechromiumisresistant tion",10't 106t baseb•c,106t nesia) and binders(clay, lime, gypsum, baux physicalpropertiesofchromiumspinels.
to ordinary corrosive agents, which explains NorthAmerica ite, corundum). The products are intendeq to
its use as an electroplated,protective coating. Canada 0 4 ChromiUmalsooccursinall groupsofsili
have good resistance to pressure, fIre, and
It dissolves in nonoxidizing mineral acids, SouthAmerica cateswherechromiumreplacesAI3+,Fe3+,and
such as hydrochloric and sulfuric acids, but CBruabzail 828 38 39 tpermoppeerrtaietusrbeecthwaenegne,baasswiceallndasagcoidoidcinmsausloantirnyg. Mg2+. SulfIdicchromiumoresdonotoccuron
notincoldaquaregiaornitricacid,whichpas Europe Thechemicalindustry uses chromium oresin earth. Chromates and chromium iodates are
saicvtastewtihthemhaeltoalg.eAnst,elseivliactoend,tebmorpoenr,atnuirteroigteren , FAilnblaannida 27576 167 2290 the production ofchromjum compounds. Ta described, which originate from the weather
oxygen,andcarbon. Greece 15 1 1 ble 46.3 shows quality requirements ofchro ingzone of~ulfIdiclead deposits (e.g., croco
FormerUSSR 855 129 129 miumoresfordifferentareasofapplication. ite,PbCr0 ).
Chromium and chromium-rich alloys are Africa 4
brittle at room temperature and this has lim Madagascar 13 7 7 Table46.2:Estimatedreservesofchromiumore[93].
ited their application [9]. Selected physical Rep.SouthAfrica 688 828 5715
Sudan 8 2 2
propertiesofchromiumareasfollows: . Zimbabwe 147 17 75 Metallurgical", Chemical", Refractory",
Total
Ar 51.9961 Asia : >45%Cr203 >40%Cr20, >20%AlP3
Atomicnumber 24 India 112 14 60 SouthMrica 20006 100(5%) 1900(95%)
mp 1857°C Iran 16 1 1 Zimbabwe 600 300(50%) 300(50%)
Pakistan 1 1
bp 2672°C Philippines 75 14 29 Turkey 10 9(90%) 1(10%)
Densitypat20°C 7.19glcrn3 Turkey 103 5 73 Philippines ..;:. 7.5 1.5(20%) 6(80%)
Crystalstructure cubic,bodycentered Vietnam 5 1 1 UnitedStates 8 0.4(5%) 7.4(92.5%) 0.2(2.5%)
Specific.heatat25°C 23.25Jmor1K-1 Oceania Canada 5 5(100%)
MolarentropyS"298 23.64Jmol-1K-1 NewCaledonia 30 2 2 Finland 7.5 7.5(100%)
Heatoffusion 16.93kllmol Australia 2 Others 11.35 8.175(72%) 0.2(2%) 2.975(26%)
Total 2649.35 '419.075(16%) 2220.1(84%) 10.175(0.4%)
Latentheatofvaporizationatbp 344.3kllmol •Estimatecl
Linearcoefficientof bShippinggradeoreisdepositquantityandgradenormalizedto USSRandotherEasternbloccountries 51.5 26.5(51%) 15(29%) 10(20%)
thermalexpansionat20°C 6.2X106 45%Cr,G]forhigh-Crandhigh-Fechromite,and35%Cr,O]for Toralworldwide(roundedoff) 2701 446(17%) 2235(83%) 20(1%)
high-aluminachromite.
Resistivityat20°C 12.9X10-8Om 'Reserve baseincludes deposits currently economic (reserves), •GradedaccordingtoCr,O]orAI,O]contents.
Thermalc·onductivityat20°C 67Wm-1K-1 marginallyeconomic,andsomecurrentlysubeconomic. bOrescontaining30-50%Cr,O].
1764 HandbookofExtractiveMetallurgy Chromium 1765
Table46.3: Qualityrequirements (massfractions in%) deposits. Mainrepresentatives are Selukwe, alsoatdepthsofseveralhundredmetersbelow bodies are small. A new open-cast mine was
forchromiumores(accordingtoU.S.BureauofMines).
Guleman,andTiebaghi. thepresent-daylandsurface. putintoproductionnearDonskoye,asisapro
Metallurgi- Refractory Chemical Variousintermediatetypessuchasadjacent cessing plant with a throughput of 106 t1a.
cal(high-Cr (high-Al (high-Fe Chromite transformation in the course of
chromite) chromite) chromite) "seam" pockets, striated chromite slabs, mot more recent tectonic superficial modification Strongprospectioneffortfornewoccurrences
Cr:Feratio 3:1orhigher tled ores, and vein-like deposits also occur. under pneumatolytic or hydrothermal condi is being made in the Northern Urals, but be
Cr203 >48 >31 >44 "Placer" deposits, i.e., enrichment due to tions has resulted in the striking colors ofre cause ofthe rough climate no mine has been
Cr203+Al203 >58 chromitelumpsand grains onornearprimary. cent uvarovite, smaragdite, and karnmererite openedupto 1986.
Fe <12 deposits, arenow achieving economic impor
formations which act as pathfinders in pros
SSi02 <0<.808 <6 <5 tanTceh.e seam-like deposits reveal layers or pecting and exploring for chromite deposits. Bmuinsihnvgeblde.gaInninthteheB1u9s2h0vseilndtw(SooduitshtriActsfr:icthae)
P <0.04 Table 46.5 shows some analyses of selected
CaO <1 strata of chromite enrichment, with thick chromiumores. Lydenburgdistrict(EasternBushveld) andthe
nesses ranging from centimeters to decime Rustenburgdistrict(WesternBushveld).
Hagnesiochromite ters; the layers are regularly interlaminated Former Soviet Union. The former Soviet Fromageologicalandpetrologicalpointof
MgO'CrZ03 Magnesio with banded series of olivine-rich or pyrox Unionisoneofthe most importantproducers viewthisisalargeintrusion of500 x 250km
ferrite ene-richrocks. TheMainSeamofthe Western ofchromiumoreintheworld.Allthedeposits with athickness ofover 5 km. The chromite
MSpgiOne·lAIZO ~=-----:::-....-:f'\---_'=::" MgO·FeZ03 Bushveld is, for example, 1.10-1.30 m thick are distributed in ultrabasite massifs in the "seams" are located in the pyroxenite-norite
J andcanbetracedforover65 km withoutany CentralandSouthernUrals. zone of the basal section ofthe intrusion, al
significantchangeinthe mineral composition
The deposits that are most important at ways below the platinum-bearing Merensky
orthickness.
present were found in the late 1930s in the Reef. InthecaseofRustenburgthere areupto
Thedemarcation betweenthe chromiteen
Akhtiubinsk region (North Kazakhstan). The 25 chromite seams ontop ofeach other. The
richment andtheunderlyingbedisusually ra
Hercynite Chromite Magnetite zor-sharp; in the direction of the overlying Donskoye deposit, which is associated with thickness ofthe individual seamsvaries from
FeO'AIZOJ FeO·CrZOJ FeO·Fez03 layer,disintegrationintolayersormottledores theminingsettlementofKillom Tau,contains a few centimeters to 1.80 m. The seams are
high-gradechromiumoresforferrochromium workable from 0.3~ m upward, especially if
Figure 46.1: Ternary spinel system showing main iso as aresult ofincreased silicate content is ob
production and low-grade ores for chemical they can be combined into mining units
morphousregion. served.
purposes. Mining is carried on in numerous (Cr0 content in the crude ore 30-40%;
Table46.4:Physicalpropertiesofchromiumspinels. The chromite bodies that are sack-like to open-pit mines, which implies that the ore Cr:2Fe3ratio=1.6-2.3).
tube-like in appearance are usually aligned
Properties Notes
Specificdensity:3.8-4.8 increasesasFeandCrcon with the direction ofthe magmatic stratifica Table46.5:Chemicalanalyses(massfractionsin%)ofsomechromiumores(crudeores,concentrates).
tentsincrease tion, i.e., the lowest sections are massive Country Cr0 FeO Si0 MgO Al0 CaO vp~ Cr:Feratio
MohsHardness:4.5-8 increaseswithincreaseinthe chromiteores;inthedirectionoftheoverlying 2 3 2 2 3
SouthMrica n.d."
ferrochromitecomponent, layer, these merge into striated slabs or mot Rustenberg(c)' - 44.5 26.4 3.5 10.6 14.1 0.4 1.7:1
veryhighforAlspinels
tledores. Lydenburg(c) 44.3 24.6 2.3 11.2 1~.1 1.8:1
Meltingpoint:1545- inclusionofMgraisesmelting
The internal texture of the chromite ore Zimbabwe
1730°C point,inclusionofFe2+re-
ducesit bodies varies widely. The closest chromite GreatDyke(m) 48.5 18.3 5.6 13.4 11.5 0.8 2.6:1
GreatDyke(r) 50.7 16.4 4.3 13.2 13.0 0.8 3.1:1
Color:darkbrownto reddishwithhighCr203con- crystal packing results in the formation of Selukwe(m) 47.0 12.0 5.7 15.5 12.6 1.8 3.9:1
black tent massive ores containing 75-85 vol% of Selukwe(r) 42.0 15.7 8.6 15.8 13.8 0.3 2.7:1
Streakonporcelainplate; importantfeaturefordifferen- chromite. Sphere orleopard ores, which con Turkey
hammerstrikingmark: tiatingfromserpentine
brown sistofround chromite crystal aggregates0.5 (m) 48.3 14.1 5.1 16.8 13.0 0.9 3.4:1
(r) 37.0 15.2. 4.3 17.7 24.3 0.2 2.4:1
2em indiameterin a silicate matrix(olivine,
Philippines
pyroxene, serpentine), are also characteristic.
46.4.1 OreDeposits (Masinloc)(r) 33.3 13.2 4.6 19.6 28.2 0.4 2.5:1
Bandedoresarecloselyrelatedto themassive
Finland(Kemi)
Chromiumore depositscanbedividedinto ores, but they are frequently richer in silicate Crudeore 26.5 15.0 18.5 19.5 9.5 n.d. 0.04-0.1 1.8:1
two geneticallydifferenttypes: and then form a link with the mottled ores Concentrate 45.7 33.8 0.4 2.9 13.6 0.1 1.4:1
(chromitesinglecrystalsinsilicatematrix). Albania
• Seam-likedeposits, alsocalledstratiformor (m,r) 43.0 16.2 9.8 22.2 7.9 0.1 2.6:1
During transformation (serpentinization),
anorogenic deposits. Main representatives the silicate content within the chrornite ore USSR
areBushveld, GreatDyke,andStillwater. (m) 53.9 1:2.6 5.8 13.3 9.6 1.1 4.3:1
bodieshas resultedinthe formation offriable
(r) 39.1 14.0 9.4 16.1 17.4 0.7 2.8:I
• Deposits which are shaped like sacks or and pulverizable masses (friable ore) which
tubes; they are called podiform ororogenic are encounterednot only nearthe surface but 'em)=metallwgical,(r)=refractory,(c)=chemical.
bn.d.=notdeteITI1ined
1766 HandbookofExtractiveMetallurgy Chromium 1767
In the Lydenburg district, which is geneti havebeenforcedtoclose. Themostimportant Albania. Since 1960,Albaniahasbecomethe At the chromite concentration plant at
cally very similar to the Rustenburg district, regions belong essentially to the alpidic era, third largestproducerin the world. All actual Kemi in Finland a fraction of the crude ore
only two seams are being mined; the Cr203 e.g.,Bursa,Mugladistrict,andElazig,includ data arebasedonestimatesbecausethe Alba (70%)iscrushedtobelow 10mIllinaprimary
content is 44% and the chromium: iron ratio ing the Guleman chrome ore field. Open-pit nian government withholds production and crusher plant at the open-pit mine. After fur
1.6-1.7. The iron content is frequently high, mining, andinsomeplacesunderground min export figures. Albanian deposits belong to ther grinding (rod and ball mill) and removal
which may cause difficulties in the case of ingatshallowdepths, areemployed. the podiform type and normal grades are re ofsludge, the intermediateproductis dried in
metallurgical ores; however, these ores are portedto be43% Crp3with a Cr:Feratio of arotarykiln. Themagneticseparation(acom
Iran. Chromite deposits are described in two
higWyvaluedaschemicalores. 3:1. The largest chrome ore mines are bination of weakand strong fields) produces
regions of Iran: northwest of Sabzawar near
Great Dyke. The Great Dyke (Zimbabwe) is Mashadand200kmnortheastoftheGulfport Bulquize and Matanesh with conce?tration two concentrates: concentmte 1 containing
anintrusionwhich is610kmlongand6-9km ofBandarAbbas. These deposits are pocket plantsoDOO000t/aeach. 45.9% Cr203, which is sold or used as mold
thick - a remarkable length: thickness ratio like, sometimes containing only 500 t ofore. ing sand, and concentrate2 containing42.0%
which is unique in the world. The internal Extractionisbyopen~pitminingandbyprimi 46.4.2 OreBeneficiation Cr203fortheproductionofferrochromium.
structure is similar to that of the Bushveld. tiveunderground mining. Onlyhardlumpore
Fromnorthtosouth,theindividualcomplexes for metallurgical applications is sometimes The simplest method of concentrating 46.5 Production!
areMusengezi,Hartley, Seluk."we, and Wedza. exported. chromite is by hand picking; this is still em
Selukwe consists of sack-like deposits con ployed today at many pits, including those in
Philippines. On the Philippine island ofLu Extraction. Chromium is extracted from its
taining 48% Cr203 and even more, with a zonthe most importantchromite deposits are Turkey, Brazil, Iran, and the Philippines. Be oresbyalkalineoracidicdissolution. Inalkali
chromium:ironratiogreaterthan2.8(ahigWy cause the mining of richer ores continues to
tobefoundinthe Cotoregion(nearMasinloc, dissolution, finely ground chrome ore is
valued metallurgical ore). In the Hartley re decline, concentratingprocedures, chiefly us
gion, on the otherhand, numerous bands and province of Zambales). These are chromite ing the gravity method, have beendeveloped roasted with Na2C03under oxidizing condi
seams andpockets withinlayered dunites and tions at ca. 1100 °C. The sodium chromate is
seams 2-75 cm thick are being mined; these to separate the serpentine from the chromite.
harzburgites. They are classical metallurgical leached from the calcine; most ofthe gangue
are separated by serpentinized peridotite lay For example, in South Mrica or Brazil the
andrefractory ores. More recently anewtype is insoluble. The solution containing hexava
ers, some of which are very thick and make chromite ores are enriched by crushing, mill
of chrome ore has been put into production: lent chromium can be reduced with S02 and
mining very difficult. However, the Cr203 ing, screening, and sophisticated gravity pro
content varies between 48 and 57%, and the chromitefrom lateriticsoils. Theconcentrates cedures. InSouthMrica, spirals and diampnd used for electrowinning, or Na2Cr207can be
aresuitedforthechemicalindustry. crystallizedfromit.TheN~Cr207canbecon
chrAomcciourmdi:nirgotnorcaotinoseisrvoavteivre2.e8st(iTmaabtlees4,61.6k)m.2 Finland. In 1959 a fairly large deposit of poafnRseiacrheesrttacnodnaersdaenqduRipemicehnetr.tAspicroalmsbhiansaatiloson verted to cr03for use in electrolysis or to
ofthe GreatDyke contains around 1.4x 106t chromite was discovered near Kemi, which beenemployed. Althoughthecostsarehigher, Cr203foruseinmetallothermics.
ofcrudeore, whichcorrespondsto assuredre has been developed into a productive mine. the use of hydrocyclones for separating the Chrome ore can be dissolved in acid if an
serves of600x 106t (geologically 4.6 x 109t Chromium ore occurs in a serpentinite-an finechromitegrainsfromwasteisofgreatim 9xidizing agent is present. However, Fe, Al,
arepossible). orthositemassif12kmlongand 1-2kmwide; portance in the recyclmg of tailing dumps. and Mg also dissolve and must be removed.
Table46.6:AnalysisofchromiumoresfromZimbabwe. theorezone, however, isonly 15 100m thick Somechromiumorescontainmagnetitewhich The preferred acidic dissolution technique is
Cr0 con- Proportion, and dips at an angle of60° toward the north. canberemovedbymeansofmagneticsepara to reduce the ore with carbon, forming ferro
t2ent3,% Cr:Feratio '¥o TheCr203contentofthecrudeoreofthevari tion.However,ifthemagnetiteispresentasan chromium, which is ground and dissolved in
Metallurgical over48 over2.8 80 ousorebodiesvariesbetween17.5and21.9% individualphasewithin\thechromitegrainsor sulfuric acid. The only significant impurity
Chemical 45-48 2.2-2.5 17 (locally even up to 30.5% Crp3); the as a fringe around the grains, this method is carriedoveris Fe, whichis removed by crys
Refractory 42-46 1.8-2.0 3 chromium:ironratioislow(0.81-1.87).. onlysuitableifCr203isfurtherenriched. Flo ctahlrliozmatiiuomn ains tihroens(oIIl)utaiomnmisoniniutmhes+ul3favtea.leTnhcee
Madagascar. On the island of Madagascar, tation and electrostatic processes have so far
Yugoslavia. The deposits ofchromite in Yu stateandwithadditionalpurificationisusedto
chromium ores are being mined since 1967 enjoyed little success in the concentration of
goslavia are restricted to the Radusa massif produceelectrolyticchromium.
with an annual productionofaround 60000 t near Skopje, but the mining of metallurgical chromium ores. If the Cr203 content or the
ofmetallurgical gradeore. Total outputiscal chromium:ironratioissufficient,fine-grained
orestherehasfallen considerably. Nativeores ProductionofChromium Metal. Chromium
culatedto be almost 2 x 106t sincethe begin chromite concentrates can be briquetted or
are being processed in a new plant, whereas metalisproducedbythereductionofCrp3or
ning of the operation (50-52% Cr2q3)' The ores imported from Albania are being pro pelletedwiththeaidofbinders. the electrolysisofCr(Ill) solutions. Themetal
reservesaresaidtobearound5.5X 10 t. cessed inthe oldone. The chromiumores are Theyield(65-85%ofthechromiteactually canalsobeobtainedfrom Cr(VI)solutionsby
Turkey. Turkey still is the traditional country always associated with serpentinized ultraba contained in the crude ore) depends on many electrolysis, but the process is less efficient
for chromitedeposits ofmetallurgical quality, sites. Thestriated slabtypepredominates, but factors including the nature ofthe chromite ~ndisusedprimarilyforplating.
butbecauseoffallingpricesontheworldmar massivechromeores are encounteredinsome serpentine intergrowth, grain size, and Cr203
ket and exhaustion of reserves, many mines places. contentoftheoreorindividualgrain. 1ForFerrochromium,seeSection7.5.
1768 HandbookojErtractiveMetallurgy Chromium 1769
Aluminothermic Reduction. Aluminum is the [Fe(NHJzCSOJ:zJ, which is recrystallized to High-carbon ferrochromium
most important reducing agent for producing recoverthecoprecipitatedchromium. ~
.
rcihtyromAilumpofwrodmerCarnZd03C.CrZl0o3sealyresibzelednhdiegdh-apnud itatTiohneochfrcohmroimume aislufmur.thTerrapnusfroifrimedatbiyonproefctihpe GrindIingj
charged into a vessel lined with refractory, Cr(lIl) to an insoluble salt requires aging at H2S04
which is usually Al:P3' The charge is ignited 30°C. Afterfiltration the motherliquoris re _-M-ak----.:.eup-----,j
either with a KClOrAl powder "wick" or circulatedto the leachtank. Thechrome alum
electrically. Theexothermicreactionresultsin crystals are redissolved to make the cathode
aleatdesmtpoearactuleraengserepaatreartiothnaonf2sl0a0g0f°roCm, mwhetiaclh. fwehedic.hTihsereodvuecretldowbyaSnOolzy,ttehecroenbtyaingsenCerra(VtinI)g, LeaIc·hingl'-_~~~'!..-~t..:r_"~~ _
Thepurityofthe chromiummetaldependson additionalHzS04. Thereducedanolyteis also I
the purity of the reactants, particularly the cycled to the leach tank. The stripped Crystallizing
CrZ03' Originally this oxide was made by re catholyte is recycled. Dissolvedchrome alum ~
duction of sodium chromate with sulfur, re crystals are used to bring the chromium con r
sulting in Cr 03 of high sulfur content. centration in the catholyte feed up to the de Filtering
Z
Proprietary processeshave beendeveloped to siredlevel. ------.1
produce Cr:P3 of higherpurity. Analysis of ....7..4-
The details ofthe cell reactions are shown Crude ferrous 'o
aluminothermically reduced chromium is Aging ammonium sulfate g::l
inFigure46.3 [11]. Adiaphragm isnecessary
giveninTable46.7. !
to prevent migration ofCr(VI) into the cath
Chromium is also produced by carbon re odecompartmentwhereitsreductionbyCr(II) Conditioning
duction. Chromiumoxideandcarbonarecare would lead to loss ofcurrent efficiency. Flow Mother liquor !
fully weighed, mixed, briquetted, and heated is maintained into the anode compartment
inafurnaceat 1400 °Cataminimumpressure from the cathode compartment by a higher EEOJ E Recrys!tallizing
°of40Pa. Theheatingcycle is 100h. The C+ level ofsolution in the latter. The pH ofthe .s: ":i:iil
w
contentis~1.5%(Table46.7). catholyte must be controlled. At too low a Filtering
Solutions suitable for electrolytic plVduc value, Hz evolution increases; at too high a I
Dissolving I
tion ofchromiumcan be derivedfrom ore by value, precipitation of Cr(0H)3 occurs. This l I .
oxidativeroasting inalkali, orby directsolu can be seenby an examinationofthe pH-po I Ferrous ammOnium
Clarifying L~u~a.!..e _
tion ofchromite in sulfuric acid; however, a tential diagram [12]. The pHis controlled by Diluent
commercial.processwasnotachieveduntilthe chromiumconcentration,currentdensity,tem
Water l -
electrolytewasmadeby dissolvingferrochro perature,anddifferentialheightofsolutionbe
mium in H S0 and reduced anolyte. Figure tween cathode and anode compartments.
2 4 Electrolysis
46.2 [10] shows the essential aspects of the Wateris fed to the anode to control the con
~
process for electrolytic production of chro- centratiop.ofH2S04, Catholyte overflow r 2 t IL-...:C::.:h:..:ro:::m::.:iu:::m:.c...•.,
miummetal. . Chromium is plated onto stainless steel Sulfur dioxide i'
f~ ~
MilledFeCrisleachedwithhotreducedre cathodes until it attains a thickness of ca. 3 wastng
cycled anolyte, chrome alum mother liquor, mID. The plate is stripped from the cathode
Reducing Degassing
and makeup HzS04• The iron precipitates on anddegassedbyheatingat420°C. Theanaly Reduced anolyte l
cooling as iron(lI) ammonium sulfate sisoftheflake isshowninTable46.7.
Market
Table46.7:Analysisofvariousgradesofchromiummetal(in%). Figure46.2:Flowsheetforproducingelectrolyticchromiumfromferrochromium[10].
Cr C 0 Si S P N AI
For many applications the o;,"ygen content duced from chrome alum solutions than on
Aluminothermic' 99.4 0.05 0.10 0.10 0.010 0.010 0.02 0.10
E1ectrolyticb 99.1 0.02 0.5 0.01 0.03 0.01 0.05 om of the electrolytic chromium is too high. chromium from hexavalent solutions [14].
E1ectrolyticb., 99.5 0.05 0.02 0.05 0.04 0.01 0.002 0.0158 Deoxidation is carried out on a commercial The second technique involves heating bri
Carbonreducedb 98 1.5d 0.1 0.02 0.001 0.1 scalebytwotechniques [13].Inthefirsteither quettes ofground electrolytic flake and care
•Shield.llayCorp. flake orbriquettesofpowderedflake arecon fully controlled trace amounts of C in a
bElkemMetalsCo. tacted with Hz at elevated temperature. The vacuumfurnace to form CO. The heating cy
c:Vacuumtreated.
dC+O. procedure is less effective on chromium pro- cle is 90 h, the maximum temperature is
1770 Handbooko/ExtractiveMetallllrgy Chromium 1771
1400 cC, and the pressure is 13Pa. The prod-. Chromium enhances an alloy's hardenability, Chromium chemicals are used in a variety ing high-temperature exposed components in
uct is cooled inhelium to prevent contamina creep and impact strength, and resistance to of applications. The largest amount is con chemicalandpetrochemicalindustries.
tion. Analysis of the vacuum-treated product corrosion,oxidation,andwear. Ferrousalloys, sumed to manufacture pigments for use in Chromium-based alloys have found a
isshowninTable46.7. paints and inks. Other applications include unique application in power stations as sup
mainlystainlesssteels,accountformostofthe
leather tanning, metal corrosion inhibition, portsforheatexchangerpipes. Thebalanceof
There areseveralothertechniquesforpuri consumption. These steels have awide range.
drilling muds, textile dyes, catalysts, and cobalt- and nickel-based high-chromium al
fying chromium. These include iodide refin
ofmechanicalpropertiesaswell as beingcor
woodandwatertreatment. loys are used mainly in components for gas
ing [9, 14], zone melting [9, 14], and treating
chromium with a flux containing an alkaline rosion and oxidationresistant. Castironsmay Chromite is·used in the refractory industry turbine engines and for parts requiring resis
earthmetal [15]. Chromiumpreparedbythese containfrom0.5%to30% Cr,whichprovides tomakebricks,mortar,andrammingandgun tance to elevated temperature, oxidation, and
methods is purer ·but more expensive, and hardenability, toughness, hardness, and corro ningmixes. Chromiteenhancesthermalshock hotcorrosion. .
therefore is used only in, electronic applica si01Iandwearresistance. Chromiumis widely and slag resistance,.volume stability, and Chromiummetalinpowderform is used in
tions. used in nonferrous alloys, including those strength. themanufactureofcermets [18]. The cermets
ofcommercialimportanceareasfollows:
based on nickel, iron-nickel, cobalt, alumi
CennetLT-l:77%Cr,23%Al 0
46.6 Uses [4] num, titanium, and copper. In Ni, FeNi, and 46.7 EconomicAspects CermetLT-IB:59%Cr,19%A2lp33'20%Mo,2%Ti02
Co, Cris used for oxidationand corrosionre CermetLT-2:25%Cr,15%Al203,6%W
Chromium is used in ferrous and nonfer sistance. In AI, Ti, and Cu it controls the mi The world productionofchromiumfluctu These particular cermets have very good
rous alloys, in refractories, and in chemicals. crostructure. atedbetween 1973 and1983;however,growth thermalstabilityandcorrosionresistance.
is expectedtothe endofthe century. Datafor Chromium metal from electrolytic or alu
Cathode Diaphragm An+ode worldwideproductionareasfollows[4]: minothermic processesis used inabriquetted
aluminum powdercompactto provide the al
(ell feed Direction of solution flow Year Production,1!Yt Year Production,1!Yt
loying addition to both cast and wrought alu
(atholyte Relative 1973 1999 1979 2936
makeup density 1974 2207 1980 2973 minum products [19]. Two grades ofsmelted
control 1975 2540 1981 2786 binary aluminothermic chromium-aluminum
(atholyte 1976 2669 1982 2489 alloys (10% chromium and 20% chromium)
bleed 1977 2883 1983 2490 , arealsoused.
1978 2820 2000 5625"
Anolyte Otherbinary aluminothermicchromiumal
bleed •Probableprojecteddemand.
loys available for special alloying require
ments are chromium-molybdenum (30% Mo)
46.8 Alloys
and niobium-chromium (30% Nb). Chro
mium-tungsten binary alloys were once used
In the manufacture ofsteel, chromium is butarenowr.edundant [20,21].
(r3-.e-_ (r2- 202-.4e-- O2' Padudreedchursoumaliluyminmethtael,foprrmoduocfedfebrryocehlerocmtroe . botMhectaolalitced.charnodmicuomredpowwedldeirnsgareeleuctsreoddeisn.
(r2-.2e-_(rO (r3-_3e-_ (r6- lytic oraluminothermicprocesses, isusedfor Small quantities of pure chromium are used
alloying nonferrous engineering materials. foranodesinX-raytubes andalsoforvacuum
2W+2e--H 1 The mostcommonmaterials are nickel-based vaporizationorsputtering.
2
and cobalt-based alloys, most of which are Chromium powder, as well as ferrochro
usedathightemperature. inium powder, has been used in considerable
H'
NH4 The only true chromium-based alloys that quantitiestoproducechromiumcoatings.
(r6+ have been developed and used commercially Theso-calledpackchromecoating [21, 22]
are a few chromium-nickel alloys developed is applied to cast and wrought steel parts by
sot
bytheInternationalNickelCo. (INCO).These immersing the article in a mi>.'ture of chro
materials contain 50---60% chromium; the re mium powder; an inertmaterial, e.g., kaolin,
(r6-.3(r2-_ 4(r3- (r6••3(r2•_ 4(r3- mainingpercentage is nickel, witheithernio alumina,ormagnesia; andmixturesofvarious
bium (columbium) or titanium specifed as salts, suchas ammonium, iodide, orchloride.
carbonandnitrogenscavengers. Thesealloys, The packed part is then heated in an inert at
aswellasmaterialscitedin [16, 17],oftenre mosphereat900-1300 cC (heatingtimeis de
Figure46.3:Idealizedelectrolyticcellreactions. ferred to assuperalloys, areused inconstruct- pendentonpartsize).