STUDY OF LEAD BIOLEACHING FROM Pb-Zn ORE IN MODIFIED SKC-BROTH MEDIUM USING MIXOTROPHIC ACIDOPHILIC BACTERIA

• Main Author: ANDINI SRI HARDINA (NIM : 12514060), DINA
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/26670
• Institution: Institut Teknologi Bandung

Generally, lead is produced from extraction of galena ore or concentrate. Pyrometallurgy is commonly applied for large-scale lead extraction. There is imperial smelting process in pyrometallurgy. In which zinc is vapoured at the top of furnace and then condensed, thus resulting in volatile lead compounds in the vapour. This gas is known to be harmful for human health if it is inhaled. In the hydrometallurgical studies, leaching is conducted using acids such as nitrate acid, sulfate acid, chloride acid, or organic acid. This option is more developed because it is more environmentally friendly than pyrometallurgy. Moreover, the studies of lead bioleaching have been performed in which one of them uses chloride-rich medium so that it does not produce PbSO4 which is an insoluble lead. In this study, lead bioleaching was conducted with Pb-Zn ore from Bogor using the bacterium Alicyclobacillus ferrooxydans in the modified SKC-broth medium. <br /> <br /> The experiment was started with ore preparation, including grinding, sieving, and sampling. The aim of Pb-Zn ore bioleaching was to investigate the effects of bioleaching medium, FeCl3 concentrations (5 g/l, 7.5 g/l, and 10 g/l), pulp density (1%, 5%, and 10% w/v), particle size fraction (-80+100 mesh and -100+200 mesh), and inoculum size (5%, 12%, and 15% v/v) on lead extraction, change in Eh-pH of leaching solution, and bioleaching selectivity to Zn and Cu. Direct bioleaching was performed in this study using the bacterium Alicyclobacillus ferrooxydans and was cultured for 23 hours on rotary shaker of 180 rpm at room temperature. <br /> <br /> The highest lead extraction (61.49%) was obtained on seventh day of bioleaching experiment with selectivity to Zn and Cu of 0.786 and 0.863, respectively, at bioleaching parameters of 1% (w/v) solid, 5% (v/v) bacterial inoculum, ore size fraction of -200 mesh (75 &#61549;m) with the modified SKC-broth consisting of: seawater, 10 g/l NaCl, 7.5 g/l FeCl3, and 0.5 g/l urea. Increasing FeCl3 concentration up to 7.5 g/l could enhance Pb extraction. Highest lead extraction was achieved at 1% (w/v) pulp density. The greater the ore size fraction of -80 + 100 mesh (-180+150 &#61549;m), the higher the lead extraction value. Decreasing the inoculum size up to 5% (v/v) could also increase lead dissolution.