EXTRACTION OF MAGNESIUM FROM VARIOUS RAW MATERIALS CONTAINING MAGNESIA THROUGH A SILICOTHERMIC PROCESS IN VACUUM CONDITIONS USING A VERTICAL RETORT

• Main Author: Agastya Hilmy Alfitra, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/65040
• Institution: Institut Teknologi Bandung

The processing and refining industry of nickel class-2 is currently experiencing a very rapid increase. One of the nickel class-2 products that are commonly produced is ferronickel product. Rotary Kiln-Electric Furnace (RKEF) technology is the main ferronickel processing technology in the processing of laterite nickel ore with various advantages. RKEF produces ferronickel slag in large quantities around 14 tonnes of ferronickel slag for every tonne of ferronickel produced. Ferronickel slag contains 20-35% MgO so it has the potential to be used as a raw material for magnesium production. In this research, the magnesium production process has been studied with various experimental variations including the amount of added CaO, the amount of FeSi reducing agent, and the type of mixture (calcined dolomite or dolomite) at a certain ratios of CaO/SiO2. The reduction experiment was carried out using a vertical kiln with a vacuum of about 10 - 20 Pa at a temperature of 1200°C for 4 hours. The ferronickel slag reduction experiment was carried out by varying the additive CaO (0%, 40%, and 80%) and reducing agent FeSi (40% and 50%) with the addition of a constant CaF2 additive of 3%. In addition, experiments on the reduction of ferronickel slag and mixed materials in the form of calcined dolomite or dolomite were carried out at particular variations of CaO/SiO2, addition of FeSi reductant by 2x the stoichiometric requirement, and addition of a constant CaF2 additive of 7% of MgO in the mixture. The reduction experiments of ferronickel slag + calcined dolomite was carried out at a CaO/SiO2 ratio of 0.99 and 1.99, while the reduction experiment of ferronickel slag + dolomite was carried out only at a CaO/SiO2 ratio of 1.99. The experimental products in the form of magnesium metals were analyzed using Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS). Meanwhile, the remaining residues from the reduction were analyzed using SEMEDS, X-ray Diffraction (XRD), and X-ray Fluorescence (XRF). For the reduction of ferronickel slag, the amount FeSi reductant has various effects on the effectiveness of silicothermic reduction depending on the experimental conditions. Meanwhile, increasing the amount of CaO from 0% to 61% gave an increase in the effectiveness of the reduction as indicated by an increase in the percentage of magnesium extraction from 36% to 61%. For the reduction of ferronickel slag + calcined dolomite mixture, increasing the CaO/SiO2 ratio from 0.99 to 1.99 decreased the magnesium extraction percentage from 88% to 79%. While for the reduction of ferronickel slag + dolomite mixture, the reduction process was successfully carried out with 86% magnesium extraction percent and the dominant phase was Ca2SiO4.