Factors affecting the adsorption process

The main factors of the adsorption process are: the time of the adsorption process, the amount of the resin was added, adsorption period, the operation capacity of adsorption of gold and silver, and the resin adsorption stages and the flow rate of the pulp. These factors are mutually influential to some extent.
1. Adsorption time
When the adsorption process is carried out simultaneously with the liquefaction leaching, the adsorption leaching time is usually determined by the dissolution rate of gold and silver. At this time, the adsorption leaching time refers to the precious metal dissolution and adsorption time required for the recovery of gold and silver on the ion exchange resin to a maximum. It is usually determined experimentally based on the dissolution and adsorption rate of precious metals during cyanidation. This value is generally 8~24h. If the adsorption is carried out after cyanidation leaching, the time of the adsorption process is determined only by the ion exchange rate, and is independent of the metal dissolution rate. In this case, the adsorption time is obviously better than the adsorption. The leaching time is shorter. Adsorption leaching time is the most important process parameter, which is related to the loss caused by dissolved gold and tailings discharge.
In a production workshop, the volume V(m 3 ) and quantity N of the adsorption equipment are constant, and the time Ï„(h) of the adsorption process is regulated by the slurry flow rate Q (m 3 /h), and the relationship between them can be used. Expression:

If a plant has 6 adsorption tanks with an effective volume of 200 m3 each, if the minimum adsorption time is determined to be 8 h, the maximum slurry flow rate of the plant into the adsorption process should not exceed:

It can be seen that the time required for the adsorption process to proceed depends first on the slurry flow rate, which in turn is determined by the processing capacity of the ore and concentrate in the adsorption section. Obviously, it is closely related to the concentration of the slurry supplied to the adsorption section. Under the same slurry flow rate, the concentration of the raw material (ore or concentrate) can be increased by increasing the concentration of the slurry.
However, in production practice, sometimes the adsorption time is not guaranteed even at the lowest slurry flow rate, because the lower part of the Pachuca adsorption tank is often filled with ore, or it is operated at a low slurry level, which makes the tank effective. The volume is not fully utilized, so to achieve the specified adsorption time, to ensure that the gold recovery index will not be reduced, in addition to the given slurry flow should be maintained properly, another important condition is that the adsorption tank should be used to the maximum extent. Effective volume. [next]
2. Resin once added
The amount of resin added at a time is the amount of resin present in the adsorption tank at the same time, expressed as a volume fraction, which indicates the content of the ion exchange resin in the slurry.
Practice has proved that the amount of resin added to the ore of the ore is 1.5%~2.5%; when processing the concentrate, the amount of resin added in the slurry is 3%~4%; the resin content <1.5% can not guarantee the required The ion exchange rate, >3%, will increase the wear and consumption of the resin.
In the normal adsorption operation, in order to maximize the adsorption rate of the resin to the dissolved gold, the same resin concentration should be maintained in each adsorption tank.
3. Adsorption cycle
The resin adsorption cycle refers to the time from the addition of the resin to the last adsorption tank to the discharge of the saturated gold-loaded resin from the first adsorption tank, that is, the residence time of the resin in the adsorption tank during the entire adsorption process. An adsorption cycle (Ï„c) is calculated from the ratio of the resin addition amount (E) to the resin flow rate (q):

In the case where the longest adsorption time in the cyanide slurry is 6-8 hours, the total residence time of the resin in each adsorption tank is 160-180 h. When the time is too short, the resin does not reach the saturation limit state, and the adsorption capacity of the resin to gold does not reach the optimum value; when the time exceeds 200 hours, the resin is strongly worn, resulting in an increase in resin loss.
4. Resin flow
In production practice, the adsorption process is carried out on the principle of countercurrent. During the adsorption process, the flow of pulp and resin is interrelated. When adsorbing the cyanated pulp, the resin flow rate (q) is calculated by the following formula:

Where Q is the slurry flow rate (m 3 /h); [next]
Cp——the gold content of the pulp (g/m 3 );
AH - the operating capacity (g/kg) before resin regeneration;
Ap - residual capacity of the metal after resin regeneration (g/kg);
W-——metal recovery rate (%);
Q——resin flow;
2.5—The conversion factor of the resin from dry to wet.
When the adsorption process is carried out simultaneously with the cyanidation of the ore, the Q in the above formula is replaced by the ore treatment capacity P(t/h), and the Cp is replaced by the metal grade C (g/t) in the ore, so that the resin flow rate is pressed. Calculation:

The resin flow rate is a basic parameter for adjusting the adsorption process. The resin which is returned to the new or recycled state is preferably continuously and uniformly added by a feeder, and the resin is added in an equal amount according to the calculated flow rate every hour. In order to obtain a good adsorption index, the transfer of the resin between the adsorption tanks should be uniform and should not be drastically changed.

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