Optimization of Recovery Process of Silver from Obsolete Printed Circuit Boards (PCBs)

Aims: The aim of this work was to optimize the Silver recovery from Printed Circuit Boards (PCBs) of waste computers using statistical method by varying various parameters affecting the recovery.

Methodology: A total of 50 experimental runs was generated using central composite design, these were designed to study the effect viz; Thiourea conconcentration, H2SO4 conconcentration, Temperature, Particle diameter and time. Optimization was carried out using response surface methodology and validation of the result was also carried out.

Results: Statistically significant quadratic model was obtained. A quadratic model predicted the optimum silver recovery of 66.01% at optimal condition of thiourea concentration, 0.01 g/ml, sulphuric acid concentration, 0.01 M, particle size, 0.027 mm, temperature, 20°C and time of 60 min. The optimal condition was validated and 66.1% of silver recovery was obtained.

Conclusion: Response surface methodology was successively used to optimize thiourea leaching recovery of silver from PCBs of the waste computers. The result obtained could be scaled up to pilot plant.