AN ENVIRONMENTALLY BENIGN APPROACH FOR GOLD RECOVERY FROM GOLD-BEARING ORE: MODELING AND OPTIMIZATION

Abstract

The current work focuses on the extraction of gold using alpha-cyclodextrin (α-CD) from the Kimpese quarry in the Democratic Republic of the Congo, through an environmentally friendly gold process as an alternative to the amalgamation process. The ore was sampled and characterized using atomic absorption spectroscopy (AAS) prior to the experiments, and the analysis revealed 0.08% of gold. The ore was then leached with modified aqua regia (MAR). Time, HBr concentration, pH, and stirring speed were all varied during leaching to highlight the parameters that influence the leaching yield. The optimum conditions were determined using analysis of variance (ANOVA) and response surface methodology (RSM), implying time, HBr concentration, pH, and stirring speed of 6 hours, 80g/l, 1, and 800rpm, respectively, and a leaching percentage of 98.6928%. Following leaching, neutralization tests with potassium hydroxide (KOH) were performed by varying the following parameters: time, KOH concentration, and pH. The following factors were varied in the extraction tests after neutralization: time, α-CD concentration, pH. The optimal parameters were as follows: time of 30 minutes, α-CD concentration of 8.8639g/l, and pH of 6, with yield of 89.7350%. This method of recovering gold from ore using α-CD is inexpensive and does not harm the environment.