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The leaching process of Malaysian low grade manganese ore (LGMO) using bamboo sawdust (BSD) as reducing agent in acidic medium (H2SO4) and the dissolution kinetics of this ore was investigated. Acid concentration, reaction temperature, and BSD loading were chosen as experimental parameters through application of response surface methodology (RSM). For analysis of the kinetic data in this study, the SCM with surface chemical reaction and diffusion through product layer, the mixed control modelled and also new variant SCM were evaluated. The reaction kinetics of this leaching process was determined, and it is observed that it fits the model of 1-23X-(1-X)23=kt with activation energy of 69.3kJ/mol. The reaction rate for LGMO leaching using BSD was found to be diffusion through product layer.

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The gold extraction from Malaysian mesothermal lode gold ore through the cyanidation method was performed. The effect of hydrogen peroxide (H2O2) and lead nitrate Pb(NO3)2 were investigated on the percentage of gold recovery. The statistical analysis method using a response surface design-central composite design was applied to find the optimum condition for gold extraction. The studied parameters were NaCN concentration (300-500 ppm), H2O2 concentration (205-410 ppm), and Pb(NO3)2 concentration (50-150 ppm). It was found that increasing the amount of NaCN and H2O2 as well as decreasing the amount of Pb(NO3)2 in the studied range, increased the gold recovery. The analysis of variance suggested the linear model for the gold extraction with the optimum condition at 467.3 ppm NaCN, 94.96 ppm Pb(NO3)2, and 340 ppm H2O2. The gold extracted from the ore at the optimum condition was 88.97% as compared to 62.02% from conventional cyanidation. The characterization study of the gold ore indicated that the finely gold particles interlocked in the aluminosilicate phase (grain size of ~10.0 µm). The Van't Hoff differential method justified that the cyanidation was of second order with a specific reaction rate of 0.0501/hour.

Refractory gold ore understudied showed traces amount of gold from X-ray fluorescence analysis. Phases identified are quartz, muscovite and calcite. Statistical approach using response surface methodology - central composite design were performed at varying concentration of NaCN, Pb (NO3)2 and H2O2. Cyanidation experiments were conducted at room temperature at pH 11. Using the response surface methodology followed by path of steepest ascent, gold cyanidation was found to be at 467.3 ppm NaCN, 94.96 ppm Pb (NO3)2 and 0.01M H2O2, at the vicinity towards the optimum condition where 88.97% Au extracted from the ore, equivalent to 1.7231 g/t Au.