PRELIMINARY STUDY OF MANUFACTURING OF SILICON, FERROSILICON AND IRON METAL USING METHANE GAS AND HYDROGEN GAS REDUCTOR

• Main Author: Ghani Putri, Widyadhara
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/72898
• Institution: Institut Teknologi Bandung

Currently, silicon is widely applied in electronic devices and solar cells. The industrial production of silicon utilizes an electric furnace through the carbothermic reaction, but this process generates carbon dioxide emissions of 4,7-5 tons per 1 ton of silicon. Silicon production has not been carried out in Indonesia. Besides silicon, one of the most important metals in our lives is iron. Iron is further processed into steel and applied in various sectors such as construction, infrastructure, and transportation. Iron is reduced through the carbothermic process and generates carbon dioxide emissions of 1,3-1,8 tons per 1 ton of steel. Increased carbon dioxide gas can lead to an increase in the earth's surface temperature. Therefore, the metal smelting industry needs to find environmentally friendly alternative reductants. This research aims to study the influence of the type of reducing gas, the ratio of silica sand and iron ore composition, and the reduction holding time, specifically focusing on experiments with methane gas, on the silicon and iron content in the metal and slag. The experiment involved mixing silica sand and iron ore at composition ratios of 0:100, 20:80, 40:60, 60:40, 80:20, and 100:0. The mixture was placed in an alumina crucible boat and reduced in a horizontal tube furnace at a temperature of 900°C using methane gas (30 minutes and 3 hours) and hydrogen gas (3 hours). The reducing gas was supplied at a rate of 0.75 L/minute, while argon gas was supplied at a rate of 0.25 L/minute. The reduced samples were melted in a vertical tube furnace for 2 hours at a temperature of 1550°C with an argon gas flow rate of 1 L/minute. The reduced samples were analyzed using XRD to determine phase changes. Meanwhile, the melted samples were analyzed using SEM-EDS to determine the chemical composition of the metal and slag. Methane exhibited a more aggressive reduction rate compared to hydrogen in the silica sand samples, with a silicon content of 71.39% in the metal. The iron content in the metal from the reduction of iron ore using methane for 30 minutes and hydrogen for 3 hours did not show significant differences. The silicon content in the metal increased with an increase in the amount of silica sand in the mixture, while the iron content decreased. The mixture with a composition of 60% silica sand - 40% iron ore yielded the highest silicon content in the metal at 28.9%. A 3- hour holding time in methane reduction of the iron ore and the mixture samples resulted in carbon deposition and metal dusting. Meanwhile, in the 100% silica sand sample, the silicon content in the metal increased with an increase in the reduction holding time.