THE STUDY OF SMELTING REDUCTION OF RED MUD AND BAUXITE MIXTURES AS PART OF MODIFICATION OF THE PEDERSEN PROCESS: REVIEW AND PRELIMINARY EXPERIMENTS

• Main Author: Swara Ananda, Ghema
• Format: Final Project
• Language: Indonesia
• Subjects: Metalurgi
• Online Access: https://digilib.itb.ac.id/gdl/view/51427
• Institution: Institut Teknologi Bandung

In 2017, approximately 95% of bauxite in the world was commercially produced into alumina through the well-known process named Bayer. In producing alumina, the Bayer process also produce a by-product called red mud which has a negative impact on the environment. In 1927, Harald Pedersen discovered a process for producing alumina, known as Pedersen process, that was more environtmentally friendly and had proven applicability on an industrial scale. In this study, the information about the Pedersen smelting reduction process has been reviewed comprehensively which include its developments at the commercial scale, pilot scale and laboratory scale. Bauxite is the main source of alumina and red mud is a material that has a high Fe2O3 content (typically 48-54%). The posibility of utilization of bauxite and red mud mixture in the Pedersen reduction process has been estimated by thermodynamic calculation through the FactSage simulation. Furthermore, the preliminary experiments have also be conducted in order to evaluate and complement the FactSage simulation results. Literature review started with the collection of papers, books and proceedings related to the Pedersen process. The literature was then read and analyzed to obtain the information which have been used as the discussion points to answer the objectives that have been formulated. The FactSage simulation was implemented at the Na2O variation: 25%, 50% and 75% and at the red mud fraction variation in the range 0 to 1. The preliminary experiments were conducted at Na2O variation: 29% and 80% and at the red mud fraction variation 0.2: 0.4: 0.6: 0.8. Last, the conclusions and suggestions are drawn. The results of the literature review suggest that the Pedersen process is still being developed to become an alternative process for producing alumina that is techno-economically viable. In addition, some important points are obtained: (1) Na2O is a potential flux that can enhanced the metal-to-bauxite weight ratio; (2) The increase in operational temperature leads to an increase in the metal product; (3) The fast cooling rate will produce a glass-like slag with low leachability property; (4) When CaO flux is used, the presences of MgO and TiO2 in the feed has an effect on alumina yield. At 29% Na2O flux addition, the results of the FactSage simulation support the result of the preliminary experiments where the increase of red mud fraction results in the increase of the metal-to-bauxite weight ratio. This point indicates that the smelting reduction of bauxite and red mud mixture needs to be further studied as a solution for the utilization of the red mud waste.