Abstract
The current paper introduces for the very first time recently invented electrodeposition-redox replacement (EDRR) method in continuous leaching-recovery-solution purification process. The mini-pilot study reveals that longer duration of the EDRR process is beneficial as it increases gold recovery per stage and decreases the specific energy consumption of the EDRR. This extraordinary behavior is postulated to be inherent to the EDRR process, as during the EDRR the cathode surface is gradually transformed from stainless steel surface to gold(±copper) surface, thus increasing process performance with time. In addition, gold concentration of 1 mg/L in the PLS was established as the minimum concentration required for efficient operation of the EDRR process.Gold extraction from ore to solution throughout the pilot test reached up to ca. 90%, whereas in reference cyanidation test only 64% of gold was dissolved. Overall, after 150 h of pilot experiment, 83% of dissolved gold was recovered from solution on the cathode, resulting in 68.5% holistic recovery of gold from ore. Furthermore, process simulation model was built, and it suggested that closed-loop operation of cupric chloride leaching – EDRR recovery – copper precipitation process can recover in total over 84% of gold from refractory telluride ore to the cathode product, providing further evidence of true potential of EDRR in sustainable gold extraction.
Highlights
Gold has been traditionally used for a variety of purposes, like jewelry, finance, electronics [1], but more recently it found new appli cations in biotechnology [2], medicine [3], sensors [4], energy con version [5] and carbon dioxide reduction [6] among many others
Cyanide is highly toxic, hazardous substance that may cause great harm to human oper ators in the plant, and to the environment if not handled properly [99]. It is highly desirable form safety perspective to avoid the cyanide, if possible, and the chloride process offer such possibility. This mini-pilot study demonstrated the first application of an inno vative electrodeposition-redox replacement (EDRR) method for gold recovery from chloride leaching solution in a continuous operation
The results revealed that a longer duration of the EDRR process is beneficial, as it increases gold recovery per stage and decreases the specific energy consumption of the EDRR
Summary
Gold has been traditionally used for a variety of purposes, like jewelry, finance, electronics [1], but more recently it found new appli cations in biotechnology [2], medicine [3], sensors [4], energy con version [5] and carbon dioxide reduction [6] among many others. The cyanide process for treating gold-bearing ores is one of the most widely used hydrometallurgy processes because of its economy and simplicity [9,10]. Thiosulfate leaching is the only alternative method implemented in industry, thanks to its high efficiency in treatment of preg-robbing gold ore [30]. It still has drawbacks such as complexity of the process, high reagent consumption and limited recy clability, sensitivity to the pH and redox conditions, challenging process control [31].
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