smelting polymetallic copper ores

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SMELTINGSMELTINGPOLYMETALLICPOLYMETALLIC

COPPER COPPER ORESORES

Alloys of CopperAlloys of Copper

Ancient miners first utilized the oxidizedAncient miners first utilized the oxidizedsecondary ores of copper to produce earliestsecondary ores of copper to produce earliestextracted metals.extracted metals. They also came across richThey also came across richdeposits of primary copper ores in areas wheredeposits of primary copper ores in areas whereerosion has exposed them at the surface. Theyerosion has exposed them at the surface. Theywere able towere able to overcome the difficulty ofovercome the difficulty ofextracting copper from sulfide ores. Finally theyextracting copper from sulfide ores. Finally theycame across polymetallic ores of copper thatcame across polymetallic ores of copper thatmay contain arsenic, antimony, zinc and leadmay contain arsenic, antimony, zinc and leadtogether with iron. These were together with iron. These were Fahlerz Fahlerz type orestype oresform at lower levels of copper depositsform at lower levels of copper deposits..

FAHLERZ TYPE ORESFAHLERZ TYPE ORES

• Major copper deposits may contain arsenic andantimony as impurity.

• During the weathering of such ores, arsenic andantimony is collected in the secondary enrichmentzone together with chalcosite (Cu2S) and willforms minerals such as:

Tetrahedrite: ((CuFe)12Sb4S13)

Tennantite: ((CuFe)12As4S13)

FORMATION OFFORMATION OFSECONDARY ORESSECONDARY ORES

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APPEARENCE OF Cu-As ALLOYSAPPEARENCE OF Cu-As ALLOYSEARLIEST Cu-As ALLOYSEARLIEST Cu-As ALLOYS

• Nahal Nishmar

• Arslantepe

• Ikiztepe

NAHAL MISHMARNAHAL MISHMAR

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CHEMICAL ANALYSIS RESULTS OFCHEMICAL ANALYSIS RESULTS OFNAHAL MISHMAR SAMPLESNAHAL MISHMAR SAMPLES

0.860.861.431.432.992.992.642.6490.790.761-17961-179CrownCrown

1.401.400.180.1822,522,56.296.2965.765.761-9461-94StandardStandard

0.230.230.300.303.703.703.483.4887.187.161-24961-249MaceheadMacehead

0.380.380.220.225.905.903.003.0075.075.061-40061-400MaceheadMacehead

1.001.000.080.0818.318.38.228.2271.371.361-11561-115MaceheadMacehead

0.400.400.090.090.540.542.182.1888.588.561-31161-311MaceheadMacehead

TrTr3.983.980.190.193.783.7887.487.461-27861-278MaceheadMacehead

0.040.048.278.270.070.072.522.5279.479.461-22661-226MaceheadMacehead

0.300.300.250.254.204.202.242.2470.070.061-35161-351MaceheadMacehead

% Bi% Bi% Ni% Ni% Sb% Sb% As% As% Cu% CuNo.No.SampleSample

METHODS OF PREPARING Cu-METHODS OF PREPARING Cu-As ALLOYSAs ALLOYS

• Direct reduction

• Co-smelting

• Cementation

DIRECT SMELTINGDIRECT SMELTING

When the primary copper ores that contain arsenic(Copper sulpharsenide) are roasted they will turn intocopper arsenate (olivenite).

CuAsS + O2 CuAsO4 + CuO + As2O3 + SO2

Reduction of cupper arsenate by charcoal will yield Cu-Asalloy

CuAsO4 + CO Cu-As (alloy) + CO2

(olivenite)

During roasting over 50% of arsenic is lost as As2O3.

Reactions are not balanced.

CO-SMELTINGCO-SMELTING

Secondary copper ores are smelted together with Secondary copper ores are smelted together with sulfidicsulfidicores of arsenic.ores of arsenic.CuCOCuCO33 + Cu + Cu33AsSAsS44 Cu-As + SO Cu-As + SO22 + CO + CO22

enargiteenargite

““ + FeAsS + FeAsS ““ + FeO + SO + FeO + SO22 + CO + CO22

ArsenopyriteArsenopyrite

““ + As + As22SS3 3 ““ + SO + SO22 + CO + CO22 Orpiment Orpiment

Charcoal is not necessary in this experiment because COCharcoal is not necessary in this experiment because COis not needed for reduction.is not needed for reduction.Reactions are not balancedReactions are not balanced

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CEMENTATIONCEMENTATION

A mixture of arsenic ores such asA mixture of arsenic ores such asCuCu33AsSAsS4, 4, FeAsS or AsFeAsS or As22SS3 3 withwithcharcoal powder is added on tocharcoal powder is added on tomolten copper metal in a crucible.molten copper metal in a crucible.Arsenic is quickly reduced andArsenic is quickly reduced andincorporated into copper.incorporated into copper.

REPLICA OFREPLICA OFİİKKİİZTEPEZTEPE

CRUCIBLECRUCIBLE

USING BOWL FURNACEADDING ARSENIC ONADDING ARSENIC ON

MOLTEN COPPERMOLTEN COPPER

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ARSENICAL COPPER METALLIC ARSENIC AT THEMETALLIC ARSENIC AT THESTEM OF FUNNELSTEM OF FUNNEL

_____________________________________________________ % Cu % As % Fe % S

_____________________________________________________Experiment 1 82.2 (70.3) 9.95 (13.6) 5.82 (5.18) 1.75Experiment 2 89.3 (90.0) 5.08 (10.1) 3.99 (3.34) 1.61Experiment 3 88.6 (86.8) 5.82 (7.31) 3.95 (3.45) 1.38Experiment 4*96.3 (87.0) 2.08 (2.50) 0.43 (1.00) 1.13_____________________________________________________Values in parenthesis are atomic absorption results, * Copper metaland arsenopyrite are heated together

PREPARATION OF ARSENICAL COPPERPREPARATION OF ARSENICAL COPPER

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ADVANTAGES OF CU-AS ALLOYSADVANTAGES OF CU-AS ALLOYS

•• Copper that contains about 5% arsenic melts aboutCopper that contains about 5% arsenic melts about150150ooC lower temperature. Thus, casting becomesC lower temperature. Thus, casting becomesmuch easier and better products are produced.much easier and better products are produced.

•• Copper that contains 4% arsenic can be hot or coldCopper that contains 4% arsenic can be hot or coldforged much easier.forged much easier.

•• When 4% arsenic containing copper is 50 % workedWhen 4% arsenic containing copper is 50 % workedhardened it becomes nearly 50 % harder than purehardened it becomes nearly 50 % harder than purecopper.copper.

•• Arsenic retards the corrosion of copper objects.Arsenic retards the corrosion of copper objects.

•• Copper that contains over 9% arsenic attains a silveryCopper that contains over 9% arsenic attains a silverycolorcolor

Cu-As PHASE DIAGRAMCu-As PHASE DIAGRAM

Region whereRegion whereCu and As formsCu and As formsSolid solutionSolid solution

HARDNESS OF Cu- As ALLOYSHARDNESS OF Cu- As ALLOYSHOROZTEPE BULLHOROZTEPE BULL

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•• Presently at the Boston Museum of FinePresently at the Boston Museum of Fineartsarts

•• Made by Made by Hattian Hattian metal smiths aroundmetal smiths around2100 BC.2100 BC.

•• The bulk of the bull metal is The bulk of the bull metal is bronz bronz withwithless than 0.001 % arsenic.less than 0.001 % arsenic.

•• There is a 10µ layer of arsenic rich layerThere is a 10µ layer of arsenic rich layerof of domeykite domeykite (Cu(Cu33As) which containAs) which containabout 28% arsenic and gives the bull itsabout 28% arsenic and gives the bull itssilvery color.silvery color.

Domeykite Domeykite layer is produced bylayer is produced bycementation. In this method thecementation. In this method the

bronze bull is heated in a mixturebronze bull is heated in a mixtureof Asof As22OO33,, KK22COCO33 and charcoal at and charcoal at

45045000C for some time. TheC for some time. Thereduced arsenic diffuse intoreduced arsenic diffuse into

copper in the solid form.copper in the solid form.

ARSLANTEPEARSLANTEPE

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Cu-As ARTIFACTSCu-As ARTIFACTS METAL ARTIFACTS FROM ROYAL TOMBMETAL ARTIFACTS FROM ROYAL TOMB

İİKKİİZTEPEZTEPE

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İİKKİİZTEPE SPEARHEADZTEPE SPEARHEADWITH DECORATIONWITH DECORATION

IKIZTEPE DIADEMSIKIZTEPE DIADEMS

SPEARHEAD WITH FIGURINESPEARHEAD WITH FIGURINE(I/80-494)(I/80-494)

0.070.070.090.090.050.050.150.159.529.5286,486,4I/80-494I/80-494

% Sb% Sb% Fe% Fe% Zn% Zn% Ni% Ni% As% As% Cu% Cu

ANALYZED IKIZTEPE METALANALYZED IKIZTEPE METALARTIFACTSARTIFACTS

222272728888177177TotalTotal

66OtherOther

33AnkletAnklet2020OtherOther

99PinPin66ChiselChisel

1010SpiralSpiral1313BladeBlade33ArrowheadArrowhead

66PendantPendant1616EarringEarring55Flat axeFlat axe2727DaggerDagger

1616EmblemEmblem2828BraceletBracelet3535PiercerPiercer147147SpearheadSpearhead

SymbolsSymbolsJewelleryJewelleryToolsToolsWeaponsWeapons

10

0

1

2

3

4

5%

As

LC EB I EB II EB III MB I

ARSENIC CONCENTRATION OF IKIZTEPEARSENIC CONCENTRATION OF IKIZTEPE METALS ACCORDING TO PERIODS METALS ACCORDING TO PERIODS

ARSENIC CONCENTRATIONARSENIC CONCENTRATIONACCORDING TO TYPESACCORDING TO TYPES

0

1

2

3

4

5

As

%

Wea

pons

Tools

Jew

elle

ry

Symbols

DISTRIBUTION OR ARSENICDISTRIBUTION OR ARSENICCONCENTRATION IN IKIZTEPECONCENTRATION IN IKIZTEPE

OBJECTSOBJECTS

0

10

20

30

40

50

60

70

80

Nu

mb

er o

f S

amp

les

< 1.0 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10 >10

As %

0

2

4

6

8

10

12

0 100 200 300 400 500 600 700 800 900Mass (gr)

As (

%)

As-Mass DISTRIBUTION OFAs-Mass DISTRIBUTION OFIKIZTEPE SPEARHEADSIKIZTEPE SPEARHEADS

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IKIZTEPE CRUCIBLESIKIZTEPE CRUCIBLESSTRABOSTRABO’’S ANATOLIAN MAPS ANATOLIAN MAP

LOCATION OF IKIZTEPELOCATION OF IKIZTEPE ARSENIC SOURCES FORARSENIC SOURCES FORIKIZTEPE METALURGISTSIKIZTEPE METALURGISTS

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DURAGAN ARSENIC SOURCEDURAGAN ARSENIC SOURCE

Realgar and Orpiment ores:Realgar and Orpiment ores:

AsS and As2S3

TavşandağBakırçay

valley

TAVSANDAG ARSENOPYRITETAVSANDAG ARSENOPYRITEDEPOSITDEPOSIT

Arsenopyrite: AsFeSArsenopyrite: AsFeS

SMELTINGSMELTINGPOLYMETALLICPOLYMETALLIC

COPPER ORESCOPPER ORES((LaboratoryLaboratory Experiments)Experiments)

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ORE DEPOSITS OF TAVSANDAGORE DEPOSITS OF TAVSANDAG MERZIFON BAKIRÇAYCOPPER DEPOSITS

CHEMICAL ANALYSIS OFBAKIRÇAY SLAGS

-Nd0.05Nd1.582.100.0536.924.27.5996/702

0.01Nd0.04-Nd-1.4917.80.231.2295/705

0,010.60Nd0.243.554.074.7314.422.236.095/704

0.08Nd0.02-0.69-6.1927.414.91.7095/703

Nd0.40NdNdNd0.020.0416.60.240.4795/702

CoBiNiAgSbAsZnFePbCuSample

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BAKIRÇAY SLAGS METALLIC PRILLMETALLIC PRILLFROM BAKIRÇAYFROM BAKIRÇAY

ChemicalChemicalComposition:Composition:

Cu:Cu: 56.2 %56.2 %Pb:Pb: 19.2%19.2%Fe:Fe: 5.07%5.07%Sb:Sb: 6.86%6.86%Zn:Zn: 4.69%4.69%As:As: 5.77%5.77%

BAKIRÇAY POLYMETALLICBAKIRÇAY POLYMETALLICORESORES

CHEMICAL ANALYSIS OFSMELTING CHARGE

0.6931.71.6557.31.010.90Speiss

ndNd2.5419.810.621.5Unroasted

ndNd1.9019.710.521.3Roasted

SbAsZnFePbCu

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BAKIRÇAY CHALCOPYRITEAND SMELTED METAL

BOWL FURNACE FORBOWL FURNACE FORSMELTINGSMELTING

CHEMICAL ANALYSIS OF PRILLSCHEMICAL ANALYSIS OF PRILLSFROM SMELTING EXPERIMENTSFROM SMELTING EXPERIMENTS

2.66Nd-8,50As

0.060.01-0.15Zn

2.170.09-2.17Fe

1.930.06-5.70Pb

75.959.2-93.1Cu

Average (%)Range (%)Element

WHY Cu-As ALLOYS WEREWHY Cu-As ALLOYS WEREABANDONEDABANDONED

•• Roasting of sulfide ores with arsenic causedRoasting of sulfide ores with arsenic causedarsenic to be lost as a sublimatearsenic to be lost as a sublimate

•• Due to the volatility of arsenic, itsDue to the volatility of arsenic, itscomposition in copper could not be easilycomposition in copper could not be easilycontrolled.controlled.

•• The availability of recognizable arsenic richThe availability of recognizable arsenic richores were limitedores were limited

•• Toxic effect of arsenic was detrimental toToxic effect of arsenic was detrimental tothe health of the smith.the health of the smith.