STUDY OF MAGNETIZATION ROASTING AS THE BENEFICIATION PROCESS OF BAUXITE RESIDUE USING COAL REDUCTANT

• Main Author: Rifardi, Yashthafi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57892
• Institution: Institut Teknologi Bandung

Bauxite residue is a waste generated during Bayer process for alumina production. Currently, the total accumulated amount of bauxite residue is over 4 billion tons. There is no wide-scale application of this abundantly residue except stock-pilling. Moreover, this residue has properties that makes it toxic to the environment generating air, water, and soil pollution. The significant presence of valuable minerals makes bauxite residue a potential source to be extracted, especially the iron oxide. High iron content in bauxite residue is very potential for iron and steel production as feed. In 2019, Indonesia’s total consumption of steel was 19 million tons annually. It is estimated that in 2050 will be 125 million tons per year. This growth must be supported by the increase number of inputs for iron production. Therefore, the beneficiation process for bauxite residue by magnetizing roasting is studied to improve the values of iron. Series of experiment of partial reduction followed by magnetic separation have been carried out to study the effect of carbon reductant dosage variation and isothermal-temperature gradient on the grade of magnetite, also grade and recovery of Fe in magnetic concentrate. The effect of particle size is also studied on the grade and recovery of Fe for magnetic separation process at -200+270#, - 270+325#, and -325#. Magnetization roasting is studied at 0.62, 1.22, 1.8, 2.36, 2.9, and 3.42%C of carbon reductant dosage. It was initially heated at 500 °C for 10 minutes. The temperature was gradually increased at heating rate of 8.05 °C/min into 700 °C. Lastly, the temperature was gradually increased into 900 °C at 7.29 °C/min. It was kept at 900 °C for 10 minutes. The grade and recovery of Fe in magnetic fraction was determined by ICP (Inductively Coupled Plasma). Based on research results, the optimum values of grade and recovery of Fe from roasted briquettes was obtained at 0.62%C which was heated at 700 °C. It is, respectively, 48.14% and 46.40% in magnetic fraction at -200+270# size. The increase of carbon dosage tends to improve the reactivity of reduction iron oxide with CO gas producing the increase of magnetite content on roasted briquettes. Increasing the carbon dosage decreases the grade of Fe in magnetic fraction. However, it increases the recovery of Fe by magnetic separation. Increasing the temperature showed a significant impact on converting mineral iron oxide into magnetite. The increase of temperature could decrease the grade of Fe in magnetic fraction while the recovery of Fe is increased. The result showed that there is no significant segregation between iron oxide and its gangue minerals. On magnetic separation process, the smaller particle size improves the grade of Fe while the recovery is decreased.