Abstract
Iron ore pelletization is a critical step in steelmaking, traditionally reliant on bentonite as a binder. However, bentonite is a non-renewable resource with high silica content, increasing energy consumption and slag volume. This study investigates the utilization of lignin, a byproduct from pulp and paper mills, as a sustainable organic binder alternative. Lignin was extracted from black liquor via acid precipitation and characterized using FTIR, TGA, and particle size analysis. Pelletization experiments were conducted with varying lignin dosages (0.5–2.0 wt%) and compared with bentonite (0.5 wt%) and a control (no binder). Green pellets were tested for compressive strength, drop number, and moisture content, while indurated pellets were evaluated for compressive strength and porosity. Results show that lignin at 1.5 wt% achieves green compressive strength of 12.5 N/pellet and indurated strength of 2450 N/pellet, comparable to bentonite (11.8 N/pellet and 2520 N/pellet, respectively). Drop number improved from 2.1 (control) to 4.8 (1.5% lignin). Porosity analysis revealed higher porosity in lignin-bonded pellets (28.5%) vs. bentonite (24.2%), potentially aiding reducibility. Lignin dosage optimization and economic analysis suggest a 15–20% cost reduction compared to bentonite, with additional environmental benefits from waste valorization. This study demonstrates that lignin is a viable, sustainable binder for iron ore pelletization, contributing to circular economy principles in the steel industry.
Keywords
lignin, iron ore pelletization, sustainable binder, pulp and paper mill waste, organic binder, circular economy, green pellets, compressive strength