FERROMANGANESE MAKING FROM LOW GRADE MANGANESE ORE USING COKES, COAL, PALM KERNEL SHELLS AND CHARCOAL AS REDUCING AGENT IN MINI ELECTRIC ARC FURNACE.

• Main Author: Iman Supriyatna, Yayat
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70381
• Institution: Institut Teknologi Bandung

Manganese is a strategic element that has several important applications in industry. Up to now, 90% of manganese production is consumed by steel industry in the form of ferromangan or silicomanganese. Manganese as an alloy element is added to increase strength, ductility, hardness, and workability of the products, particularly steel. The average consumption of ferromangan is 10,6 kg/ton crude steel. To fullfill these needs, most of ferromanganese in Indonesia is imported. Indonesia has quite large potential reserves of manganese ore. Until January 2014, manganese ores is exported. Therefore, this research will study ferromanganese making by utilizing of local manganese ore using cokes, coal, palm kernel shells and charcoal as reducing agents in mini electric arc furnace. A series of experiments were conducted to study the effect on the ferromanganese production. Preliminary experiments is conducted to see the effect of time on the ferromanganese production. The process time variations is 40, 50, and 60 minutes (fixed variable is 5.5 kg of cokes, 7.5 kg of limestones , 30 kg of manganese ore). The variations of cokes additions are 6 kg of cokes (1,5 stoichiometry), 7 kg of cokes (1,8 stoichiometry) and 8 kg of cokes (2,1 stoichiometry) with fixed variable 30 kg of manganese ore, 5 kg of limestones, and 60 minutes of process time. Experiments of limestones additions ratio are 5 kg of limestones (theoritical basicity slag = 0,43), 7 kg of limestones (theoritical basicity slag = 0,56) and 9 kg of limestones (theoritical basicity slag = 0,7) with fixed variable 8 kg of cokes, 30 kg of manganese ore and processing time is 60 minutes. Experiments variations of process time are 60, 70 and 90 minutes with fixed variable 8 kg of cokes, 7 kg of limestones and 30 kg of manganese ore. Final experiments are variation of reducing agents (cokes, coal, palm shells and charcoal). The fixed variables are 30 kg of manganese ore, 7 kg of limestones and processing time 70 minutes. Reductant additions for each of reductant are 6 kg and 8 kg of cokes, 11 kg and 16 kg of coal, 21 kg and 32 kg of palm kernel shells, 6 kg and 9 kg of charcoal. Experiment results compared with thermodynamic calculations use Factsage. Metal products and slag experimental are analyzed use AAS and OES. The highest results for the experimental variation of the processing time is 70 minutes (FeMn = 6.95 kg, Mn content = 77.42% and manganese recovery = 53.83%). The best reductant additions ratio is 2,1 stoichiometry/8 kg of coke (FeMn = 6.65 kg, Mn content = 72.5% and manganese recovery = 48.24%). The best limestone additions ratio is 7 kg limestone (FeMn = 6.6 kg, Mn content = 74.54% and manganese recovery = 49.22%). Variation of reducing agent showed the highest result are obtained using 16 kg of coal (FeMn = 8.4 kg, levels of Mn = 76.33% and the manganese recovery = 64.15%). Result indicated ferromanganese with Mn content ???? 60% can be produced from Indonesian low grade manganese ore. Palm kernel shells can be used as alternative reducing agent in the ferromanganese production.