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SILVER CYANIDATION

2011-05-31 Metallurgical Engineering

RiantikaRafni

(333408

1636)

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OUTLINE

2011-05-31 Metallurgical Engineering

Prefac

e The Kinetic of DissolutionFactors Affecting The

Dissolution RateApplicationReferences

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Preface

What is leaching??

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What is

cyanidation??

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Click icon to add picture The Kinetic of Dissolution Rat

Schematic representation of the dissolution of silver in cyanide solution

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Click icon to add pictureFactors Affecting The DissoluRate

Graphic of cyanide concentration

Effect of cyanide concentration

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Effect of Hydrogen Concentration

Diagram betweenconcetration and rate

of dissolution

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Effect of Temperat

Increasing the tempercause increase the ra

dissolution

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Click icon to add pictureEffect of OxygenConcentration

At low cyanidconcentration, the

dissolution dependsthe cyanide concen

while at high cyaconcentration th

depends only on thepressure

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Rate of dissolution of silver at different

pressure and differentNaCN concentrations

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Effect of Foreign Io

1. Accelerating effect

e.g : lead, mercury, etc.

2. Retarding effect

e.g :

Ø. FeS : consumption of oxygen

solution

Ø. ZnS : formation of complex cya

Ø. S2- : formation of thiocyanate

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Application

Silver is by-product from goldleaching

at PT. Antam

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References

•

Habashi. 1980. Principles of ExtractMetallurgy vol.2. Science Publisher:

• Deitz G.A, Halpern J. 1953. ReactioSilver With Aqueous Solutions of Cy

and Oxygen.• http://extractivemetallurgy.blogspot

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T hank ’s f o r  y o ur  at t e nt i o n

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Revision

1. Why the rate decrease when the pH above 12?Because when the pH above 12, the pH is increapOH will be decrease. So the cyanide ion evaporate. The cyanide ion that evaporate in largcan decrease the recovery and the rate of dissolu

(Reference : Laporan Kerja Praktek PT. Antam)

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Revision

2.

[KOH] comes from? The reagant that usually used for cyanidation NaCN. If we use KCN for cyanidation, the reactioncyanidation become :

4 Ag + 8 KCN + O2 + 2 H2O 4 KAg(CN)2 + 4 KO

so from that reaction we know the KOH coKCN.

(Reference : Principle of Extractive Metallurgy by

2011-05-31 Metallurgical Engineering