Agave Bagasse Biomass as Reducing Agent for the Reduction of Ilmenite

Abstract

Biomass is a renewable energy source, and its application represents a diminution of CO₂ emissions, low fossil fuels exploitation, better management, and low cost because biomass is considered a waste. Agave bagasse biomass obtained from the Tequila industry has remarkable characteristics such as low S, N, and ashes contents, which are useful for the reduction of the ferrous minerals such as ilmenite (FeO∙TiO₂). Reduction of ilmenite requires high temperatures and long residence times; coke is a common reductant but has elevated cost and limited reserves. Therefore, the reduction of ilmenite is a challenging process and the integration of renewable reductant sources such as agave bagasse offers a good alternative. This work focuses on reducing ilmenite by agave bagasse; the effect of temperature, residence time, and molar ratio of ilmenite:carbon from agave bagasse (I:AB) were assessed by X-ray diffraction, scanning electron microscopy, and metallization percentage. At 1373 K, 30 min, and I:AB = 1:2.1, the reduction of ilmenite produced TiO₂ and 85.6% of total iron was converted in metallic iron. Agave bagasse is transformed in the same step as ilmenite reduction, avoiding the pre-treatment of the biomass. A correlation of the experimental results with the thermodynamic data demonstrates that ilmenite reduction depends highly on the carbon generated, but the volatile matter creates porosity. Agave bagasse biomass is an excellent reducing agent for the ilmenite at short residence times, achieving a high metallization percentage. It is a substitute for carbon sources, contributing to the utilization of waste for a more sustainable process.

Graphical Abstract