How to extract gold from activated carbon

  • Carrie Ge
    Jan 20
    Activated carbon is a kind of specially treated carbon. It heats raw materials such as coal and wood in the absence of air, and then reacts with the gas. It has a developed pore structure, a large specific surface area, and a strong adsorption capacity. The general name of materials.

    First, the gold-bearing ore is cyanided. Among them, gold and silver are preferentially melted down to form complexes.

    The dissolution rate of gold depends on the pH of the solution, and the preferred pH is 10.3. Gold can only be adsorbed by activated carbon after cyanidation. There are two methods for the adsorption of gold on activated carbon: one is the heap leaching method and the other is the carbon slurry method.

    1. Heap leaching method

    After crushing the ore to a certain particle size, it is stacked in the leaching equipment and rinsed repeatedly from top to bottom with a certain liquid NaCN solution until the gold content in the leaching solution reaches a certain concentration. activated carbon powder for sale In the future, the gold-containing cyanide solution is successively passed through a set of adsorption columns filled with activated carbon. The cyano-gold complex is adsorbed on the huge surface of the internal pores of the carbon.

    1. Carbon slurry method

    Crush the gold-bearing ore to a fineness of 300 mesh. Add water and stir to form a uniform suspension slurry. Add potassium cyanide (or sodium cyanide) solution to the slurry to form a cyano-gold complex that can be dissolved in water. The cyano-gold complex-containing ore slurry is in full contact with the granular activated carbon in the series of adsorption tanks under stirring. The cyano-gold complex is mostly adsorbed on the inner surface of the activated carbon. The tailings of the slurry containing only a small amount of gold cyanide compounds are separated from the activated carbon and discharged.

    There are two ways to recover gold from gold charcoal. One of the more primitive and uneconomical methods is to send gold charcoal to a smelter for roasting, and then smelting at high temperature to obtain gold. activated carbon suppliers usa The other is a more commonly used method, that is, using a mixture of 0.1%-1.0% hot NaCN and NaOH to desorb the cyano-gold complex on the gold carbon, and then electrolyze to obtain pure gold.