Efficient Gold Recovery from Cyanide Solution Using Magnetic Activated Carbon

Activated carbon has been used for gold recovery in the gold mining industry commercially for decades. The high specific surface area and porosity, good affinity to aurocyanide ions, and abundant resources make activated carbon an efficient and economical material for the adsorption of aurocyanide. However, the separation of activated carbon from the slurry is usually a challenge, and the adsorption rate of activated carbon is limited by the coarse particle size. Herein, a simple and sustainable way to recover gold from cyanide solution using magnetic activated carbon synthesized via a solvothermal method has been developed. The synthesized magnetic activated carbon possesses good magnetism (44.57 emu/g) and specific surface area equal to 249.7 m²/g. The magnetic activated carbon showed 99.1% recovery efficiency of gold from 10 mg/L solution within 5 h, which is much faster compared to the commercial granular activated carbon, and the magnetic activated carbon can be easily separated from the solution with an external magnet. The adsorption ability of this magnetic activated carbon has been tested under different conditions in the cyanide solution, the adsorption isotherm and kinetics are also investigated. The magnetic activated carbon was also recycled in the adsorption-desorption tests and showed good reusability.