BIOOXIDATION OF MANGANESE SULPHATE AFTER LEACHING FROM LAMPUNG MANGANESE ORE BY BACILLUS ARYABHATTAI STRAIN SKC-5

• Main Author: Marshel
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39172
• Institution: Institut Teknologi Bandung

Manganese is one of the most usable metal on earth either in the form of pure metal, alloy, or oxide. The common application of manganese is increasing corrosion resistance in Al-alloy, dark color pigment for glass industry, and electron acceptor in dry cell battery. Naturally, manganese ore usually has low purity with high content of iron therefore it should be leached then oxidized selectively for the manganese alone. Mostly, the application of low grade manganese is in form of MnO2 unfortunately the production of MnO2 is commonly done by conventional electrometallurgical method that requires high temperature (>90°C) and high amount of electric current. Therefore, an alternative method is needed to oxidize manganese at room temperature which can be done by bacterial action called as bio-hydrometallurgy. The intentions of this experiment are measuring ability of Bacillus aryabhattai strain SKC-5 to oxidize Mn2+ and measuring purity of the formed deposit. Besides, the polymorph of the formed manganese dioxide will be observed as well to determine the application of MnO2 deposit. The experiment is started by the preparation of manganese ore by sampling with coningquartering dan rifle-splitting method where sample is divided until each sampel weigh 300 grams of ore. Small proportion of sample is taken for ore characterization by XRD, XRF, SEM, and FTIR. Next stage is leaching of ore in acidic solution (1M of sulphuric acid) with oxalic acid as reducing agent. The next step is screening of bacteria by measuring Eh, pH, and optical density. Number of variations are done to determine the best condition for Mn2+ oxidation by calculating the percentage of oxidation and the purity of formed deposit. Supporting data is collected by characterization with XRD, XRF, FTIR, and SEM-EDS for confirming the formation of MnO2 and identify the formed polimorf. The characterization of manganese ore shows that dominant elements are silicon (51,6%), iron (22,9%), and manganese (20,1%) where the manganese is mainly associated in minerals such as manganoan grossular ((Ca,Mn)3Al2(SiO4)3), sodalite group, and bixbyite (Mn,Fe)2O3 with +4 oxidation number. According to bacteria screening, the best bacteria to oxidize Mn2+ is Bacillus aryabhattai strain SKC-5. The result of variations conclude that the optimal initial Mn2+ concentration is 840 ppm (percentage of oxidation 94,9%), optimal ferrous ion addition is 210 ppm (percentage of oxidation 97,99%), mix medium with aquadest : sea water = 1 : 1 shows the optimal result (percentage of oxidation 99,14%), and zeolite as solid substrate can improve the oxidation of Mn2+ up to 99,14%. XRD indicates the formed deposit is MnO2 with polimorf of ?-MnO2 which is applicable for EMD (Electrolytic Manganese Dioxide).