Electrochemical Method to Recover Copper from Alloy Scrap

In he conventional method of refining copper, used for many years, the copper scrap is melted in a converter or directly in an anode furnace, and cast into a massive anode. The anodes with a copper content of 93% are suspended in cells filled with sulfuric acid-based electrolyte, containing 130-200 g/L sulfuric acid and 15-50 g/L cupric tons. Cathodes consist of a thin sheet of copper, which is negatively charged. When a voltage is applied, copper passes into solution, while other elements, like precious metals or elements forming insoluble compounds such as lead, end up in an anode slime. The lead content in the anode is critical because if it exceeds 0.2-0.3% the anode surface gets passivated by lead sulfate. High purity copper is deposited on the cathode.

The pyrometallurgical processing of scrap for producing anode generates intermediate products like flue dust and metal-rich siag, which have to be melted down under reducing conditions. It is necessary to process those intermediate products by

Ladle Refining Furnace ProcessElectrochemical MethodCementation Process CopperPyrometallurgical CopperLead Dioxide Anode

PbOj + PbS04 + Na2C03 + Na2SO, + H20 - PbC03.Pb(0H)2 + 2 Na2S04 PbS04 + PbOj + 2 NaHSOj + Na2C03 - PbC03,Pb{0H)2 + 2 Na2S04

PbO + H2SiF6 -> PbSiFe + H20 or PbO + 4 HBF4 - 2 Pb(BF4)2 + 2 H20

Pyrometallurgical Methods

dioxide in the sodium carbonate. In general, the amount of sulfur dioxide evolved in the soda ash smelting of the battery is lees than 1% of the total sulfur in the original sample. The sodium sulfate solution is preheated and introduced into an evaporator/crystallizer from where a steam of crystal laden brine is removed and centrifuged. It is recovered as anhydrous "detergent-grade" chemical of greater than 99.5 percent purity.

Electrowinning Copper
Figure 7.15. Electrowinning of lead (Prengaman and McDonald, 1990)

Some major lead recycling operations are listed in Table 7.4. Generally, most

Information About Lead Recycling ProcessElectrochemical Lead RecyclingCopper Scrape Treatment
Figure 7.22. Schematic illustrating aluminum recycling (CANMET, 1993)
Recycling Garbage Schematic

2000)

Figure 7.28. Principle of zone melting (Sillekens et al., 2000)

Figure 7.28. Principle of zone melting (Sillekens et al., 2000)

usually ^less than 1%. Casting idloys may ^ntoin the samedement/as wrought, but in

Before subjecting it to further treatment, initial upgrading of the shredded scrap is done by screening. This results in a cast (undersize) fraction and a mixed cast-wrought

to be processed. 8 ^

wrought fractions (Ambrose et al, 1983^ Brawn et al, WSS). tn Ms^rocess.Te low eutectic temperature of Al-Si casting alloys is made use of. The cast and wrought mix

Copper Scrape TreatmentMix Alloys
Eutectic H20
7.8.
itive sample of scrap for
4 Au + Oj + 8 NaCN + 2 H20 4 NaAu(CN)2 + 4 NaOH (7.29)
Eutectic H20100 Squats Day For Men
2 Sn + 4 NaOH + 02-> 2 Na2Sn03 + 2 H2 (7.36)

Fe2(Mo04)3 + 3 Na2C03 -> 3 Na2Mo04 + F^CC^a (7.39)

Scrap Iron Fe2

SCRAP MAGNETS

RIBBON MATERIAL AND SLUDGE

SCRAP MAGNETS

IRON JAROSITE

Figure 7.46. Recovery of neodymium from magnet scrap (Lyman and Palmer, 1991)

tin from bronze turnings (Rabah, 1998)
Metallurgical Palmer
1979) ^ "pro ( ey
Air Elutriation And Deagglomeration
Figure 7.52. Metal content of middling fraction as a function of elutriator water velocity (Bilbrey et al, 1979)
Simple Gravity Elutriator
Figure 7.53. Barite media separation process (Bilbrey et al., 1979)
Metallurgical Palmer
United States, U.S.' Department of the Interior/u.S.^Geological Survey, Circular 1196-A-M

Veasey, T. J., Wilson, R. J., Squires, D. M„ 1993. The Physical Separation and

Chapter 8

METALLURGICAL SLAGS, DUST AND FUMES

Metal Specific Gravity TableScrap Metal Alloy Composition

Property

Slag Type and Value

Air-Cooled

Expanded

Pelletized

Specific Gravity

2.0 - 2.5

Compacted Unit Weight, kg/m3 (lb/ft3)

1120 -1360 (70-85)

(8001040) (50-65)

840 (52)

Absorption (%)

1-6

Angle of internal friction

40-45

^s(Moh's scale of mmeral

5-6

Process

Fe,„,ai

Fc!-

CaO

r^bn

MiO

MnO.

Thomas

«

lîT

Ladle processed -first slag

tjH

-tb

-if

-o-

£

«

Ladle processed-

23.4

u.o

47.2

4.6

2.5

2.2

3.5

Slag Composition

Table 8,6. Variability of Non-ferrous Slag Composition (Sudbury and Kemp, 2006).

  • Si02 % FeO % MgO % CaO % A1,03 % Sum _Cr203
  • Si02 % FeO % MgO % CaO % A1,03 % Sum _Cr203

Table 8,6. Variability of Non-ferrous Slag Composition (Sudbury and Kemp, 2006).

Smelter Type

Copper

36

47

1

2

4

-

90

Nickel

36

46

3

3

6

-

94

Nickel Laterite

54

U

32

»

2

1

100

PGM Nickel

42

12

19

15

5

2

95

Lead Sulphide

22

35

1

20

4

-

82

Table 8.7. Examples of Residual Base Metal Content of Non-ferrous Slags (Sudbury and Kemp, 2006)

Component % Cu

% Ni + Co

%Pb

%Zn

Copper 0.9

0.3

3

Nickel 0.34

0.36

-

-

Ferro-nickel

0.16

-

-

PGM 0.15

0.15

-

-

Lead

-

1

7

Slags 277

Metallurgical SlagPgm Content Nickel Laterite

59% chromium with 6.7% yield, while the tabling produces a low grade containing 29.25 chromium.

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Responses

  • innocenzo
    How to recover copper from scrap?
    9 years ago
  • BINGO FAIRBAIRN
    How to recover copper in copper solution?
    8 years ago

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