TORREFACTION OF BIOMASS USING MODIFIED FURNACE AS A REDUCTANT FOR SAPROLITE NICKEL ORE SMELTING

• Main Author: Fadhila Qinthara, Hanif
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87017
• Institution: Institut Teknologi Bandung

Nickel metal production on an industrial scale is carried out using coal as a reductant. The use of coal results in CO? emissions of 70 tons per ton of nickel. In 2019, nickel production contributed 0.27% of the total global CO? emissions. One alternative to reducing emissions in the reduction process is the use of biomass as a reductant. However, biomass has lower fixed carbon content compared to coal, which can decrease nickel recovery. Therefore, preprocessing in the form of torrefaction is needed. Torrefaction involves heating at 200–300°C under inert (oxygen-free) conditions to increase the fixed carbon content of the biomass. The purpose of this research is to determine the effects of biomass torrefaction operating conditions and biomass roughness levels on the proximate composition of biomass, the effect of biomass type on the nickel content in reduced nickel ore, and the effect of mixing biomass with coal on the nickel content in the metal. The parameters varied include the roughness level of torrefied biomass categorized as fine (0.4–0.5 mm) and coarse (1–2 cm), torrefaction duration of 1 and 3 hours, and temperatures of 200°C and 300°C. Proximate analysis was conducted on the torrefaction products to determine the effects of biomass type, roughness level, torrefaction time, and temperature. The torrefied biomass was mixed with coal at biomass ratios of 50% and 100%. These mixtures were then used as reductants to reduce 5 grams of saprolite nickel ore. The amount of reductant used was calculated on a 1:1 stoichiometric basis. The reduced nickel ore was analyzed using SEM-EDX. The experimental results showed that variations in time and temperature significantly affected the increase in fixed carbon content. In the torrefaction conducted at 300°C for 3 hours, the fixed carbon content of candlenut shell increased from 23.90% to 37.25%. The experiments also found that the biomass roughness level did not significantly affect the increase in fixed carbon content, as indicated by the ANOVA P-value of 0.57 for the effect of biomass roughness on fixed carbon increase. Furthermore, using 100% torrefied biomass as the reductant yielded the highest nickel content in the metal at 13.77%, achieved by using fine candlenut shell torrefied at 200°C for 1 hour. In another case, a reductant composed of 50% torrefied biomass and 50% coal resulted in Fe and Ni contents in the metal of 82.88% and 6.84%, an increase from the previous 68.62% and 5.71%. Meanwhile, the levels of impurities in the metal, namely Cr and Si, decreased to 3.12% and 5.73% from 5.59% and 17.65%, respectively. From this research, torrefied biomass in the form of candlenut shells and palm kernel shells can be used as alternative reductants in the reduction of saprolite nickel ore.