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Activated carbon is a material widely used to adsorb metal ions, including gold. In the process of gold extraction and recovery, activated carbon is often used to adsorb gold ions from solution. However, the adsorbed gold needs to be separated from the activated carbon for further purification and recovery. This article will detail how to separate gold from activated carbon and provide practical steps and precautions.
Common gold separation methods include incineration and electrolysis, each with its own applicable conditions and advantages and disadvantages. The following will elaborate on the separation process of gold and activated carbon from these two aspects.
Incineration
The incineration method is to burn the activated carbon at high temperature to extract the gold. This method is simple to operate and is suitable for gold recovery processes in some small or specific environments.
The whole operation process:
Drying gold-loaded activated carbon: Dry the activated carbon (gold-loaded charcoal) that has adsorbed gold to remove excess water for easy incineration.
High-temperature incineration: Put the dried activated carbon into a high-temperature furnace (usually at 600°C to 800°C) for incineration. The activated carbon is completely oxidized into carbon dioxide at high temperature, leaving behind a gold-containing residue.
Smelting and gold extraction: Smelt the residue after incineration, add a flux (such as borax), and remove impurities to extract pure gold.
Electrolysis
Electrolysis is a more environmentally friendly and commonly used method of gold extraction, which separates gold from gold-loaded carbon through an electrochemical reaction. This method can separate the gold while retaining the activated carbon, which is convenient for subsequent regeneration and reuse.
The whole operation process:
Desorption of gold-loaded carbon: Place the activated carbon adsorbed with gold into the desorption tank, add high-temperature and high-pressure cyanide solution and alkaline solution (such as NaOH). Through the desorption process, gold is desorbed from the surface of the activated carbon and a gold-rich solution is formed.
Electrolytic deposition: Introduce the gold-rich solution into the electrolytic cell and pass direct current. The gold ions are reduced on the cathode and gradually deposited into gold mud.
Gold mud recovery: Collect the gold mud produced by electrolysis, dry it, smelt it, and finally extract pure gold.
Activated carbon regeneration: The desorbed activated carbon is usually regenerated at high temperature to restore its adsorption performance so that it can be reused.
Comparison between incineration and electrolysis
| Comparison Dimension | Burning Method | Electrolysis Method |
|---|---|---|
| Process Complexity | Simple, suitable for small-scale applications | Complex, suitable for industrial large-scale applications |
| Environmental Protection | Produces smoke and carbon emissions, more pollution | Environmentally friendly, no smoke or dust emissions |
| Activated Carbon Reusability | Cannot be reused, completely consumed | Reusable and recyclable |
| Gold Recovery Rate | Relatively low, about 90% | High, up to 98% or more |
| Equipment Investment | Low investment, suitable for small operations | High equipment requirements, large initial investment |
Conclusion
In actual production, desorption-electrolysis is the most commonly used industrial method, while incineration is more used in special scenarios or small-scale production. Choosing the right method according to specific needs and conditions can achieve efficient gold recovery and cost optimization.