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Carbon slurry gold extraction process

The so-called carbon slurry method (CIP) generally refers to a process of performing carbon adsorption after cyanide leaching is completed. The carbon leaching method (CIL) is a process in which the leaching and adsorption processes are carried out simultaneously. Both of them absorb gold from the pulp, and there is no essential difference. However, the carbon slurry method is carried out in the respective tanks by leaching and adsorption, and the carbon leaching method is carried out by leaching and adsorption in the same tank. This tank is called a leaching adsorption tank or a carbon immersion tank. In fact, in the carbon leaching process, the first 1 or 2 tanks are not filled with carbon (referred to as pre-cyanide). Therefore, there is no strict limit between the two, but the number of stirred tanks in the carbon leaching method is less. .
1. Carbon slurry process The typical carbon slurry process (CIP) process consists mainly of cyanide leaching, activated carbon adsorption, desorption and carbon regeneration. The process flow is shown in Figure 1.

The characteristic is that fresh (or regenerated) activated carbon is added in the last adsorption tank, the moving direction of the carbon is opposite to the flow direction of the slurry, and finally the gold-loaded charcoal is extracted from the first adsorption tank, so that the carbon is countercurrently adsorbed. The grade of gold in the solution from the front to the back of the carbon adsorption tank is gradually reduced, and the grade of gold-loaded charcoal extracted from the tank is gradually increased, and finally is proposed by the first tank. Due to the desorption of carbon or fresh carbon after acid pickling and thermal regeneration in the countercurrent adsorption method of carbon, the activity is the strongest and the adsorption rate is the fastest, which can minimize the final gold grade of the tail liquid and reduce the dissolved gold from the tail. The chance of loss in the liquid increases the adsorption rate. [next]
2. Carbon leaching process
The carbon leaching method (CIL) is developed on the basis of the carbon slurry method. It has the advantages of reducing the number of leaching tanks and shortening the process, thus reducing capital investment and production costs; while leaching and absorbing, improving the dissolution power of gold Learning conditions are conducive to gold leaching and adsorption. Because the carbon leaching method has obvious advantages over the carbon slurry method, the carbon immersion process is newly adopted in the newly designed carbon slurry plant in foreign countries (Fig. 2).

The CIP process and the CIL process are quite different in terms of process length, carbon storage in the process, carbon concentration, adsorption tank volume, amount of slurry to be transported for string charcoal, and amount of metal accumulated in the process. See Table 1. [next]

Table 1   Comparison of CIP process and CIL process parameters

( Based on design parameters of 2000t/d scale)

Process

Slurry feed rate / ( m 3 · h -1 )

Leaching series

Single leaching tank volume / m 3

Adsorption number

Single adsorption tank volume / m 3

Carbon storage / t

CIP

188.5

9

698.4

7

127.4

17.84

CIL

188.5

2

698.4

7

698.4

24.14

Process

String charcoal speed / ( k g· h -1 )

The amount of slurry to be transported by string charcoal / ( m 3 · h -1 )

The amount of accumulated metal in the process / kg

In charcoal

In solution

In ore

Total backlog

CIP

136.37

6.8

32.24

34.75

2.04

69.03

CIL

136.37

27.62

42.9

8.4

2.04

53.34

It can be seen from Table 1 that the CIP process is longer than the CIL process, but the CIL process has a large amount of carbon storage and a low carbon concentration. The amount of slurry to be transported for string charcoal is four times that of the CIP process. The amount of metal accumulated in the CIP process is relatively large, and the distribution of the accumulated amount of metal in the two processes is different. In the CIP process, the metal distribution on the activated carbon and in the solution is basically the same, but in the CIL process, the metal is mainly accumulated on the activated carbon.
The gold content of the solution in the process is also different, see Table 2. CIL has a higher gold content than the CIP process solution, which is determined by the process structure. The CIL process is adsorbed while leaching, and new dissolved gold enters the solution continuously, so the gold in the solution is continuously replenished, and the gold content of the solution is relatively high. The CIP process is a single adsorption, and the amount of gold dissolved in the solution is small, so the gold grade is low.

Table 2   Comparison of gold content between CIP and CIL process solutions

Adsorption level

1

2

3

4

5

6

7

CIL process

3.11

1.19

0.46

0.18

0.07

0.03

0.01

CIP process

2.48

0.88

0.32

0.13

0.05

0.02

0.01

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