A STUDY OF CALCIUM BIOLEACHING FROM THE KRAKATAU POSCO STEEL SLAGS USING THE FUNGUS PENICILLIUM SP.

• Main Author: Murti Firdaus, Aldi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68814
• Institution: Institut Teknologi Bandung

Calcium (Ca) is a group II-A alkaline earth metal used in various industrial applications, one of which is a crucial calcium compound such as calcium carbonate as a soil cementation agent. A source of calcium comes from the by-product of the metal extraction process, slag, especially from the steel-making process. The conventional calcium carbonate production process and the leaching of steel slag require high operating costs due to the operating temperature and the high consumption of leachate reagents. Therefore, an alternative method that is cheaper and environmentally friendly is needed to overcome the problems that occur, one of which is bioleaching. Bioleaching is an alternative extraction process by utilizing heterotrophic microorganisms such as fungi. In this study, the process of extracting calcium of steel slag from PT. Krakatau Posco was studied with the help of the fungus Penicillium sp. The study began with preparing steel slag samples through comminution, sieving, and sampling. Initial characterization of steel slag samples was carried out by XRD, XRF, SEM-EDS, and FTIR. Furthermore, fungal culture was carried out in Calcite Medium Agar (CMA), and fungal inoculation was carried out in Calcite Medium (CM) as the master stock for bioleaching experiments. The next stage is fungal screening to determine the best fungi used in the core bioleaching stage. The core bioleaching experiment was carried out with several variations, including bioleaching method, organic carbon source, sample size fraction, and pulp density, to study its effect on the percent calcium extraction and leaching selectivity of iron and magnesium. The results of the characterization of steel slag showed three dominant elements, calcium (28.42%), iron (28.41%), and silica (4.25%), where the association of the three metals was found in the synthetic minerals larnite Ca2SiO4, srebrodolskite Ca2Fe2O5, and wuestite FeO. Based on the screening results, the best fungus in bioleaching calcium from steel slag is Penicillium sp. The stages of variation showing the optimum conditions were experiments using the direct bioleaching method, organic carbon source in the form of molasses, sample size fraction of - 200 +400 mesh (-75 +38 m), and pulp density of 5%. Calcium bioleaching process of steel slag from PT. Krakatau Posco is very selective to iron, with the lowest selectivity being 0.95.