PILOT AND PULL SCALE-PLANT TRIALS USING THIOUREA ENHANCED ZADRA STRIPPING OF ACTIVATED CARBON

Bench scale rests have been carried out to determine ways of improving the relatively slow kinetics of elution of gold from activated carbon . These indicate that a solution of 3.0 wt% thiourea, 2.0 wt% NaOH and 0.05 wt% NaCN represents the best prospects for greatly improved thro ughput in industrial cells. This paper presents the results of pilot p lant trials of this solution. Pilot plant results reflected the result s obtained in the laboratory and encouraged the subsequent introductio n of the solution as a modification to the commercial Zadra plant oper ation. Although the initial plant trials were disappointing slight mod ifications to ai!low for staged additions of the NaCN and increased fl ow rates did result in significant improvement in the elution rates. T his improvement in the kinetics of elution is reflected in the overall recovery and consequently in the throughput rates for the plant. (C) 1997 Elsevier Science Ltd.