EFFECTS OF RED MUD AND IRON OXIDE ADDITION ON COAL PYROLYSIS PRODUCT CHARACTERISTICS

• Main Author: Al-Ghifari Taufan, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/78423
• Institution: Institut Teknologi Bandung

Coal is still the most widely used energy source in Indonesia. However, most of the remaining coal reserves are low rank coal (LRC) which has a low selling value. Therefore, it is necessary to improve the quality of LRC coal to optimize its value and use. One of the efforts that can be done is pyrolysis (heating under inert conditions) which produces three products namely char with higher calories, tar, and gas. However, the large amount of harmful heavy fraction tar and the low price at which it is produced are the drawbacks of this process. In order to reduce the content of heavy fraction tar, additives are added to the coal so that tar cracking occurs during pyrolysis. In this study, the effect of adding red mud, bauxite ore processing residue, and iron oxide (for comparison), to coal pyrolysis on the characteristics and composition of the pyrolysis products (char, tar, and gas) was studied. Two types of coal, LRC and bituminous (for comparison) were used in this study. The experiment started with the preparation of comminution of coal to -60 mesh and red mud and iron oxide to -35 +60 mesh. Red mud and iron oxide were then activated using HCl and ammonia at 60? for a total of 5 hours and calcined at 600? for 5 hours. Both coals without or with the addition of 5% red mud/iron oxide that have been activated are then pyrolyzed in a vertical tube furnace with a heating rate of 20 ?/min, pyrolysis temperature of 600 ?, and held for 45 minutes. Afterwards, the char, tar, and gas produced were analyzed. Char was analyzed using fouriertransform infrared spectroscopy (FTIR), proximate analysis, and ultimate analysis. While tar and gas were analyzed by gas chromatography-mass spectrometry (GCMS) and gas chromatography (GC) respectively. The experimental results show that the red mud activation process can increase the Fe2O3 content in red mud from 36.8% to 46.4% and decrease the reactive silica. LRC pyrolysis without red mud/iron oxide addition produces more tar and gas and less char than bituminous coal pyrolysis without red mud/iron oxide addition. The addition of red mud or iron oxide to coal pyrolysis also changes the peaks of O-H, C=C, and C-O functional groups on the char. The analysis showed that the addition of iron-based additives caused tar cracking characterized by a decrease in the weight fraction of LRC and bituminous coal pyrolysis products by 1.10% and 1.93% (red mud), respectively, and 4.73% and 3.62% (iron oxide). This is also supported by the increasing composition of monoaromatic and aliphatic compounds, while the composition of phenol, heteroatom, and polyaromatic compounds decreases. The composition of H2, CH4, CO2, and CO, which are gaseous products of cracking, also increased with the addition of red mud or iron oxide.