Desorption of gold loaded carbon: after removing sawdust and slime, the gold loaded carbon is sent to desorption column for gold and silver desorption.

At present, four methods can be used to desorb the gold loaded carbon.

1.Zadrafa:This is a famous method invented by Zadra in 1952.

This method uses 85-95X. Of hot 1% NaOH and 0.1% ~ 0.2% NaCN mixed liquid to pass through two desorption columns in sequence from bottom to top under normal pressure. After the electrowinning, the gold-removing solution (lean solution) is returned to the No. 1 desorption column, and the desorption time is about 40-72 hours.
When the Homestake Gold Concentration Plant in the United States uses this method to desorb gold-loaded carbon with a gold load of 9 kg / ton, the desorption time is 50 hours and the residual gold content in the carbon is 150 g / ton of carbon. This method is suitable for gold processing plants with small processing capacity, and the equipment investment and production costs are low.

2.Organic solvent method:

The method invented by Haining of the US Mining Bureau is also called alcohol desorption method. Use 10% -20% alcohol, 1% NaOH + 0.1% NaCN hot solution (80P) for desorption, the operation is carried out under normal pressure, and the desorption time is 5 to 6 hours. The heating and reactivation of activated carbon can be performed once in 20 cycles. The disadvantage of this method is that alcohol is volatile, toxic, flammable and explosive, and it needs to be equipped with a good condensation system to capture alcohol vapors to prevent fire and explosion accidents. The above shortcomings limit the popularization and application of this method.

3.High pressure method:

Invented for Porter of the US Mining Bureau. It is desorbed under the conditions of 160P and 354.64 kPa (3.5 atm) with 1% NaOH and 0.1NaCN solution. The desorption time is 2 ~ 6 hours. The disadvantage of this method is that it requires high temperature and high pressure, and the equipment cost is relatively high. The advantage is that it can reduce the desorption time, reduce the consumption of chemicals and carbon storage. This method is suitable for gold processing plants with large processing capacity and high activated carbon load.