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Gold adsorption mechanism of activated carbon (4)

Table 5   Relationship between strength and activity of activated carbon at various stages of on-site production

Activated carbon

Strength /%

Adsorption capacity / ( k g· t -1 )

Adsorption speed

New charcoal

98.4

1.053

45.32

Desorbing charcoal

98.79

1.032

38.69

Recycled carbon

97.69

1.058

44.22

After the long-term intense wear and wash of the activated carbon in the carbon slurry process, the anti-wear ability of the carbon is obviously increased, and the activity is significantly reduced. After regeneration, the activity is significantly restored, while the abrasion resistance is reduced. The reason for the above phenomenon is that the difference between the strength and activity of different activated carbons is due to the difference in the microporous structure of carbon and the degree of development of the surface active center, while the strength and activity of the same kind of activated carbon move with the movement of carbon in the process. The change is mainly due to the change in the microporous structure of the charcoal due to wear. Due to the non-uniformity of its structure, activated carbon is first lost in its active components during use. The activity of charcoal is reduced by physical loss (not including the activity caused by pollution factors). After being regenerated, the activated carbon produced a new microporous structure and the activity was significantly restored. Thus use of activated carbon - Wear - regeneration - abrasion is then extracting gold CIP process in the main contradiction. The activity changes of the new activated carbon before and after grinding are shown in Table 6.

Table 6   Activity changes before and after new activated carbon grinding

Activated carbon

Before grinding

After grinding

Adsorption capacity / ( k g· t -1 )

Adsorption speed /%

Adsorption capacity / ( k g· t -1 )

Adsorption speed /%

A

23.2

70.9

19.9

54.6

B

23.3

68.8

21.4

49.6

C

24.2

67.5

21.3

42.4

D

24.9

65.4

23.2

51.3

E

22.1

64.2

20.5

47.8

F

25.7

60.8

twenty three

49.4

G

25.1

60.5

24.5

53.5

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There is a very close relationship between the density of activated carbon and its intensity and activity. The carbon (light carbon) with low density is developed with micropores, and the adsorption speed is relatively high, but the strength is low. The dense carbon is the opposite. However, the adsorption capacities of heavy carbon and light carbon are not much different. Figure 10 is a graph showing the adsorption rate and adsorption capacity of two activated carbons of different densities.


The performance of the same batch of activated carbon at different density levels also has the above relationship. Grinding comparison tests on the light and heavy grades of the same batch of charcoal showed that the wear loss of carbon increased with the increase of grinding time (see Figure 11).

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