CURRENT EFFICIENCY IN ELECTROMETALLURGY

M.Haris Hidayat3334090554

1

OUTLINE

IntroductionCurrent efficiency <100%Current efficiency >100%ConclusionReferences

2

INTRODUCTION

3

4

INTRODUCTION (CONT)

Current efficiency is similar like recovery in concentration in mineral processing.

5

INTRODUCTION (CONT)

since RECOVERY value proportional with concentrat percent

R ≈ kso: ↑R ≈ ↑k

INTRODUCTION (cont)

“Current efficiency is the effective utilization of current”

6

7

INTRODUCTION (cont)

The best current efficiency is when it close to 100%

BUT IN PRACTICE…

Ex: PT.SMELTING current efficiency target 98.0%

CURRENT EFFICIENCY < 100%

1. Mechanical losses of substances formed at the electrodes.2. Evaporation of the metal from the cathode.3. Reaction of electrolysis product with the electrolyte.4. Dissolution of the metal in the electrolyte.5. Current losses due to presence of moisture.6. Deposition of unwanted products

8

9

1. Mechanical losses of substances formed at the electrodes

Some human error and mechanical work may make losses substances

SOLUTION?

USE SYSTEM OPERATING for massive production

2. Evaporation of the metal from the cathode

“This is likely happen if the metal is produced at a temperature near its boiling point”

Example: Sodium (BP: 892oC) producedfrom molten sodium chloride (MP: 801oC)

10

4. Dissolution of the metal in the electrolyte

“a metal may dissolve in its own salt thus causing loss of output and lowering of

apparent current efficiency”

11

5. Current losses due to presence of moisture

“Some molten salts may be higroscopic”

HIGROSCOPIC?

“Higroscopic is the property of absorbing moisture from the air”

12

6. Deposition of unwanted productsElectrolysis of Solution ZnSO4

Cathode : Zn2+ + 2e- Zn Anode : 2 H2O 4H+ + O2 + 4e-

13

CURRENT EFFICIENCY >100%

• The difference in nobility between the cathode substrate and the metal in solution (ELECTROPLATING)

Q & A.htm

14

CURRENT EFFICIENCY >100% (cont)• Experience has suggested that the

current is dependent on a range of factors, including mass transport (stirring), applied potential, temperature, and the amount (weight or surface area) of feed available for oxidation

AIWO1-PR30-Campbell-Kelly.pdf

15

16

CURRENT EFFICIENCY >100% (cont)Electrodialysis is enhanced by other, than

electromigration process, more particularly by ion exchange (Donnan dialysis through anion exchange membrane). Thus the hydroxyl exchanges with the borate present in the diluate boundary layer.

9086.pdf

Conclusion

• Current efficiency mean parameter success of electrometallurgy process

• Presence of additives of impurities can effect current efficiency

17

References• H.S. RAY and A.GHOST. PRINCIPLES OF

EXTRACTIVE METALLURGY.• TERKEL ROSENQVIST. “PRINCIPLES OF

EXTRACTIVE METALLURGY 2nd edition.• PE Ted mooney. 2011. How can electroplating cathode

current have efficiency less than or more than 100%? http://www.finishing.com/570/25.shtml. [26 Maret 2012]

• R.P. Campbell-Kelly, T.J. Paget. Electrorefining of Cerium in LiCl-KCl Molten Salts. Proceedings of the First ACSEPT International Workshop. 2010. http://www.acsept.org/AIWOproc/AIWO1-PR30-Campbell-Kelly.pdf. [25 Maret 2012]

18