Thermochemical Aspects of Substituting Natural Gas by Hydrogen in Blister Copper Deoxidation

This study employs computational thermodynamics to evaluate the feasibility of replacing methane with hydrogen as both burner fuel and reductant during blister copper deoxidation, aiming to enhance deoxidation efficiency and reduce CO2 emissions. A comprehensive thermodynamic model was developed using FactSage 8.3 for dilute Cu–O and Cu–S–O melts containing trace impurities (Fe, Ni, Pb, Zn), incorporating methane thermal decomposition and temperature-dependent variations in liquid copper density with oxygen and sulfur content. Model parameters were optimized against over 105 deoxidation simulation data points, yielding temperature- and composition-dependent expressions for rapid density estimates. Benchmarking against existing literature models demonstrated improved accuracy. Key findings include: (1) increasing impurities contents from electronics waste recycling (Fe, Ni, Pb, Zn) reduces oxygen activity, deteriorating the deoxidation efficiency; (2) under global equilibrium, methane provides greater reducing power per mole than hydrogen due to full thermal cracking, but real-world mass transfer limitations render hydrogen more consistently effective up to 1200 C, with methane gas needing to achieve at least 472 C to match hydrogen’s performance; (3) adiabatic flame equilibrium studies show that O2/H2 ratios of 0.5 to 1 yield liquid copper oxygen activities comparable to industrial O2/CH4 ratios of 2 to 3, supporting the direct substitution of methane with hydrogen in oxy-fuel anode furnace burners without compromising metal quality.