Mercury-bearing minerals are commonly associated with gold ores. One of the main potential sources of mercury air emissions at gold ore processing facilities has historically been from carbon regeneration kiln stacks. In view of this potential, air pollution controls are required at these facilities. Elution of the carbon, then, is one of the keys to minimizing mercury emissions. Sodium cyanide, sodium hydroxide, and acetic acid have been studied as eluting agents; eluant type and concentration, temperature, and time of elution are key parameters. With sodium cyanide and caustic as eluants, optimal temperature was in the range of 80°-90°C. After 24 hours of elution, about 95% of the Hg(CN)_(2(aq)) was eluted at 80°C. Acetic acid is an excellent and effective eluant of mercury cyanide. After about 4 hours of elution at 80°C with 10 vol% acetic acid at 3-4 bed volumes/hr, about 85% of the adsorbed Hg was stripped, while only about 0.2% of the Au(CN)_2~- and Ag(CN)_2~- was eluted.
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