Optimization of Zinc Recovery from Sphalerite Using Response Surface Methodology and Particle Swarm Optimization

Hydrometallurgical leaching process has been identified as a viable procedure for recovering metals of value from their matrices. The optimization of zinc recovery from sphalerite in nitric acid solution was carried out in this study. The Central Composite Rotatable Design (CCRD) of Response Surface Methodology (RSM) and Particle Swarm Optimization (PSO) tool in matlab were deployed for the optimization studies. RSM modeling gave optimum conditions of 73.0 °C leaching temperature, 3.48 M acid concentration, 0.027 g/mL solid/liquid ratio, 411.02 rpm stirring rate, and 82.82 minutes leaching time; with a zinc yield of 87.67 %. With PSO, about 86.9 % zinc was recovered at a leaching temperature of 69.1 °C, acid concentration of 1.8 M, solid/liquid ratio of 0.031 g/mL, stirring rate of 270 rpm and leaching time of 85 minutes. Thus, PSO and RSM proved to be good optimization tools

Kinetics of Owhe kaolinite leaching for alumina recovery in hydrochloric acid solution

Recovery of alumina from kaolinite presents a sustainable alternative to its recovery from bauxite, a major source of alumina which is depleting in quantity globally. Owhe kaolinite proves to be a reliable resource for this process given its rich alumina content. This study focused on the leaching of alumina from Owhe kaolinite in hydrochloric acid (HCl) solution. Effects of parameters such as acid concentration, stirring rate, leaching temperature, particle diameter and solid/liquid (S/L) ratio, were investigated. The experimental data was analyzed using relevant kinetic models to establish the best model of fit. Alumina leaching rate increased as the temperature, stirring rate, and acid concentration increased, and decreased with increase in solid/liquid ratio and particle diameter. The experimental results fitted into the solid film diffusion model while chemical reaction was found to be the rate-determining step, with activation energy (Ea) of 34.79 kJ/mol and a pre-exponential factor of 120.37 s–1. The result revealed an average alumina leaching rate of 85 % with an overall reaction constant of 0.983 s–1. Post-leaching analysis by energy dispersive spectrophotometer (EDS) also confirms over 80 % alumina leaching rate, which is in line with the experimental result. Hence, hydrochloric acid proved to be a viable lixiviant for alumina recovery from Owhe kaolinite

Investigation of functional and sensory properties of plantain flour in citric acid

Purpose: This study investigated the effects of process variables on the proximate, functional, and sensory properties of plantain flour. Research Methodology: The plantain fruit was sorted and hand-peeled using kitchen knives. It was then cut into various slices of 2 – 6 mm and steeped in citric acid solutions with concentrations ranging between 1 – 5 %. The steeping time varied between 30 – 120 min. The pretreated plantain slices were processed into flours. Process parameters were analyzed using the response surface methodology of Design Expert software. Results: The proximate parameters of the flour samples showed no significant difference (p > 0.05), but there were significant effects (p< 0.05) on the functional and sensory properties of the flour samples. The functional properties were found to differ significantly. Limitation: This study did not consider the application of other optimization methods such as genetic algorithm and particle swarm optimization in estimating the optimum points. Future studies could focus on these areas. Contribution: The validation of the optimization processes showed success in the application of citric acid in the production of novel plantain flour