Taguchi method optimization for efficient recovery of heavy metals from mining solid waste.

Environmental contamination by heavy metals poses a significant challenge, particularly in regions affected by mining activities. This study focuses on the optimization of leaching conditions for the recovery of iron (Fe), aluminum (Al), magnesium (Mg), and cadmium (Cd) from mining solid waste using nitric acid. Utilizing the Taguchi method (L18 experimental design), a robust statistical approach, a series of experiments were designed to systematically vary key process parameters, including acid concentration, temperature, and leaching time, to identify the optimal conditions for maximum metal recovery. The experimental design considered three levels of acid concentration (2%, 5%, and 10%), stirring time (15, 30, and 60 min), and two levels of temperature (24 °C and 50 °C). The results indicated that the most effective leaching of Mg occurred at a concentration of 10%, a leaching time of 30 min, and a temperature of 50 °C. For Al, increasing nitric acid concentrations improved the leaching efficiency, with an optimum leaching time of 30 min and lower temperatures being favorable. Cd leaching was more efficient at higher concentrations and higher temperatures, with 30 min leaching time. Fe leaching showed improved performance with an increasing concentration, peaking after 45 min of leaching and favoring lower temperatures.