Nickel sulfide anodic electrolysis

The nickel sulfide anode is gradually dissolved in the electrolysis process, the anode potential is 1.2V, and the precious metal elements such as gold and platinum whose standard potential is higher than the anode potential in the anode are insoluble and enter the anode mud, and iron , copper , lead , zinc, etc. which are lower than the anode potential. Dissolved into the solution, most of the sulfur enters the anode mud; the nickel ions in the solution are electrodeposited at the cathode. Therefore, the quality of the electro-nickel can be ensured by selecting the appropriate electrolyte composition and electrolysis technology conditions.

The composition of the catholyte is in addition to Ni 2 + and , But also contains a certain amount of Cl -, Na +, boric acid, and organic impurities. The cation has depolarization effect, the migration speed is fast, which is beneficial to reduce the cell voltage and improve the current efficiency; the sodium ion can improve the conductivity of the electrolyte, reduce the cell voltage and power consumption; boric acid is the electrolyte buffer, and the pH is stabilized. The effect of flattening the surface of the electric nickel plate. Organic matter should reduce the cathode mass, and its content should be reduced as much as possible (<1mg/L); the lower the content of impurity elements, the better the quality of nickel. Since the current efficiency of the anode and the cathode differs by 12% to 14% during electrolysis, and the purification slag removes part of the nickel liquid, in order to ensure the stability of the nickel ion concentration in the anolyte, it is necessary to replenish nickel. The chemical composition of the catholyte is listed in Table 1.

Table 1 Main chemical constituents of various raw materials for melt-casting nickel sulfide anode plates (%)

raw material name

Ni

Cu

Fe

Co

S

Secondary nickel concentrate

66.5

2.8

2.3

1.00

23.8

Anode residue

68.1

3.3

1.5

0.98

24.5

Smoke

20.9

2.9

2.1

0.52

8.1

Sorghum residue

68

3.3

2.0

0.80

30.9

The main technical parameters of nickel anodic electrolysis of various manufacturers are listed in Table 2.

Table 2 Main parameters of nickel sulfide anode electrolyzer

factory

Jinchuan Company

Chengdu Electric Steel Factory

Chongqing Electric Metallurgical Plant

Electrolysis temperature / °C

65~70

60~65

65

Current density / A · m - 2

230~250

180~220

170~200

Slot voltage / V

3.2 to 4.5

2.6~3.5

Same level center distance / mm

190

190

190~200

Catholyte flow rate / (L ·) (A · h) - 1 )

Anolyte flow rate / (Ml · (min · bag) - 1 )

0.065

380~420

0.08

300

0.085

Yin-anode area liquid level difference / mm

30~50

>20

50~60

Anode cycle / d

9 to 10

9 to 10

6 to 9

Cathode cycle /d

4~5

3

6~7

New liquid dosage / (m 3 · t - 1 (nickel))

65~70

60~80

The main equipment for nickel sulphide anodic electrorefined steel is electrolysis tank and purification device. The electrolyzer is generally a reinforced concrete structure with a lining as if it were a material. It must also be equipped with a diaphragm frame and a diaphragm bag. The main parameters of the electrolytic cell of the domestic production plant are listed in Table 3.

Table 3 Main parameters of nickel sulfide anode electrolyzer

factory

Jinchuan Company

Chengdu Electric Steel Factory

Chongqing Smelter

Annual production capacity / t

40000

5000

600

Electrolytic cell, length × width × depth / (m × m × m)

7.34×1.15×1.48

5.0×1.43×1.19

7.60×0.70×1.20

Total number of slots / one

384

166

17

Among them, the liquid tank

96

56

Slotted trough

38

6

1

Electrolytic cell material

Reinforced concrete lining epoxy

Reinforced concrete lining epoxy phenolic resin

Reinforced concrete lining epoxy

Anode, length × width × thickness / (mm × mm × mm)

840×340×(50~55)

750×320×(35~40)

470×650×(25~30)

Number of anodes per slot

382

252

41

Cathode sheet, length × width (mm × mm)

880×860

860×920

490×670

Number of cathodes per slot

37

29

40

Same pole center distance / mm

190

190

190~200

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