Evaluation of the Preg-Robbing Effect in Gold Recovery Using the Carbon-in-Leach Technique: A Comparative Study of Three Reactor Types

This study evaluates the preg-robbing effect on gold recovery through a carbon-in-leach process, comparing three reactor types: glass, stainless steel, and stainless steel coated with ceramic resin. Protonated activated carbon (PAcC) and anthracite carbon (PAnC) were used as adsorbents. The results show that PAcC achieved a significantly higher gold adsorption rate of up to 99.87%, compared to PAnC, which achieved a maximum of 66%, mitigating the preg-robbing effect. The stainless steel reactor performed best, with gold recovery rates exceeding 90%, as confirmed by a multi-criteria decision matrix evaluating factors like durability, mechanical strength, and corrosion resistance. A 2⁴⁻¹ fractional factorial design identified key variables for optimal recovery, with aeration of 9.31 L/min, a PAcC pulp density of 2.5 g/L, and the use of Puerto Berrío ore resulting in the highest gold recovery, reaching 18.38 ppm. The mass balance confirmed that gold adsorption on PAcC was the most efficient, leaving less than 0.13% gold in the leachate. These results demonstrate the superiority of PAcC and stainless steel reactors in mitigating the preg-robbing effect, offering an effective solution for scaling up gold recovery processes.