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 EMOVAL OF IMPURITIES THROUGH ALKALINE

 ULPHIDE LEACHING

 ENIOR DESIGN PROJEC IN PROCESS METALLURGY( )7007K

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BACKGROUND

• Exhaustingprimary metalreserves

• Growing interest foralternativesources; scraps,

slag, and slimes

• Decopperizedanode slimes

containsvaluables metals

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BACKGROUND CONT.......

• Impurity elements such as As, Sb, Bi,and Hg are the challenge.

•Difficult to remove from the metalliccopper

• A selective pre-treatment process for the

removal of these impurities isnecessary

• Reduced environmental problems and

simplified metallurgical processes.

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OBJECTIVES

• Screening of the factors affectingleaching of impurity (As, Sb,…) byalkaline sulfide

•  To optimise the impurity(As,Sb, ..)removal from decopperized anode

slimes produced at Rönnskärcopper smelter.

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LITERATURE REVIEWCONT...

Decopperized anode slimes• Oxides and other compounds

deposited at the bottom of anelectrolytic cell during electro-

refining of copper.

• Contain significant amounts of Au,

Ag and variable Cu, Ni, Pb, As, Sb,Bi, Te and PG metals

•  There are types of anode slimes

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A.LITERATURE REVIEWCONT...

• Slimes from concentrates - Au,Ag, Te and se.

• Slimes from scraps- Pb, Sn, andAg.

• Ag:Se< 1,7 - AgCuSe formed

• Ag:Se<1,7, - AgSe formed

• Pb present as PbSO4

• As, found in electrolyte as arsenic

acid

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 CONT..... 

Element % ‘ ’nto slimes % ntoelectrolyte

 Cu < ,0 2 <99,8 Au 100 0 Ag <99 <1 Se 98 2 Te 98 2 Pb 98 2

 Bi % , %60 with 0 1 Pb in anode 40

Sb % , % ,60 with 0 1 As,Bi Pband Sb

( )each in anode 

40

Element

% nto‘ ’limes

% ntoelectrolyte

As % , %25 with 0 1

 As in anode 75

S 1 99

 Ni 1 99 Co 1 99

Fe 0 100Zn 0 100

:able 1

 Impurities behavior during

- .Electro refining

LITERATURE REVIEW

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LITERATURE REVIEWCONT....

Pd/Pt SLIME

Se RECOVERY

CRUDE SELENIUM

SILVER 99,99%

GRANULES

GOLD 99,99%

INGOTS/GRANULESES

SMELT SLAG

TO COPPER 

PLANT

COPPER TELLURIDE

NICKEL SULPHATE

ANODE SLIME

SOLUTION

TO THE

TANKHOUSE DRYING

KALDO SMELTING&

REFINING

CASTING OF ANODES

SILVER ELECTROLYSIS

GOLD REFINNING WCC

GOLD SLIME LEACHING

PRESSURE LEACHING

 ecopperized anode slimes treatment

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 CONT...

FERRIC ION,

H2SO4 AND

THIOUREA

Na2CO3 AND

CARBON

Pb-Sn

SOLDERING

ALLOY

SILVER METALCOPPER METAL

LEACHING

S/L SEPARATION

ELECTROLYSIS

LEACHING

S/L SEPARATION

ION EXCHANGE

SMELTING

ANODE SLIMES

H2SO4 AND O2

CA

KE

CA

KE

 ecopperized anode slimes

treatment

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 CONT...

BULLION 

HCl LEACHING

Sb , As

Te, (Cu)

Cu, (Te )

Se

KOH LEACHING

ALKALINE ROASTING

WATER LEACHING AT ROOM

TEMPERATURE

H2SO4 LEACHING

SMELTING

ANODE SLIMES

 ecopperized anode slimes

treatment

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 CONT...

 lkaline sulphide leaching theory

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 CONT...

 lkaline sulphide leaching

theory

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MATERIAL AND METHODS

Material:• Decopperized anode slimes from

Boliden Rönnskär smelter electro-refining cell.

Methods:

•

Particle size analysis: CILAS-1064 liquid equipment(1.5 g sampleweight used)

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MATERIAL AND METHODSCONT..

• Mineralogical characterisation: - XRD analysis

•

Statistical experimental design: -Rechtschaffner experimental

design method

•

Leaching experiments: - Mechanically stirred glass reactor,

auto-regulated heating system.

MATERIAL AND METHODS

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MATERIAL AND METHODSCONT..

Parameter Level 1 Level 2

Leaching tempera (oC) 60 100

   Na2S

concentration(g/l)

100 200

Leaching time (hrs)4 24

Solids concent. (g/l) 50 200

 NaOH Concentration(g/l)

( )20 constant

: :ab l e 1 P a r am e t e r s an d t h e ir l e v el s T a b l e 2

 x p er i m en ta l d e s i g n m a tr ix

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MATERIAL AND METHODSCONT..

Figure :1  x p e r i m e n t a l s e t up

:a b l e 3 R a n d o m i z ed

 x pe ri me nt al o rd er

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RESULTS AND DISCUSSION

 igure 2 : Particle size distribution of the crushed.anode slime sample

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 CONT..

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RESULTS AND DISCUSSIONCONT..

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FUTURE WORK 

• Evaluation of chemical analysesresults

• Evaluation of XRD results

• Statistical optimization

• Completion of the report

•

Final presentation of the findings