Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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KINETICS ANALYSIS FOR ALUMINUM DISSOLUTION OF WEST KALIMANTAN BAUXITE THROUGH DIGESTION PROCESS
No full textKinetics model was developed for aluminum dissolution of West Kalimantan bauxite based on shrinking core model. A series of digestion tests was carried out to study aluminum dissolution from the ore sample with particles size distribution of 100% passing 60 mesh in 129 gpL of NaOH. The digestion tests were conducted at 140; 150 and 160°C under stirring speed of 500 rpm. The experimental result shows that after a certain period of diges- tion time, thus aluminum dissolution was fluctuated due to the formation of DSP as a result of the reaction of sodium aluminate solution with reactive silica in the ore. Aluminum dissolution data were analyzed and treated with Matlab software to predict time required for complete dissolution (t). By using the obtained t, hence fittings experimental data using 3 different rate-determining steps of kinetics models (i.e. interface reaction, film diffusion and diffusion through solid product layer) and dummy data were performed. Prediction of the rate-determining step of aluminum dissolution was then made by evaluating the value of square correlation coefficient (R2) from the regression equation of the models and then obtained the activation energy. The kinetics study which considers aluminum precipitation during digestion reveals that alumina dissolution mechanism is altered from interface chemical reaction with energy activation (Ea) of 29.57 kcal/mole to difussion through reaction product (ash) layer (Ea=2.77 kcal/mole)
MINERALOGY CHARACTERS OF CIJULANG PHOSPHATE ROCKS RELATED TO BIOLEACHING PROCESS
No full textResearch on potency test of selected phosphate solubilizing microfungi (PSM) isolates had been conducted. The purpose was to obtain the most potential indigenous microfungi to solubilizing phosphate in bioleaching process. Identification with moist chamber showed that the selected PSM belonged to Penicillium genera. Bioleaching process through measuring process growth and oxalic acid production was effective on the 8th day. Chemical analysis showed that bioleaching process using selected indigenous PSM of phosphate rock was able to increase P2O5 content from 38.40 to 49.70% or improve around 11.30%. Experimental condition for such a recovery was -140+200# of sample size an 5% of percent solid. Mineralogy characters of the leached phosphate rocks showed some micro cracks as well as encapsulation by clay minerals. Not all phosphor element was leached by oxalic acid produced by microfungi
