Optimized rotary hearth furnace utilization with blast furnace and electric arc furnace: Techno-economics, CO2 reduction

Two strategies to use a rotary hearth furnace (RHF) are discussed from the perspectives of techno-economics and CO2 reduction. One is to use the RHF to produce low-reduced iron (LRI), which is then used in a blast furnace (BF); the other is to use the RHF to produce direct reduced iron (DRI) and use it in an electric arc furnace (EAF). Using a phenomenological model of the furnaces, we compared the mass and energy balances of the two strategies and estimated the unit production cost of the products. The main result is that integration of the RHF with the BF (193 US$ t(-1) manufacturing cost; 0.75 tCO(2)-eq t(-1) carbon emission) was more beneficial than with the EAF (656 US$ t(-1); 2.62 tCO(2)-eq t(-1)). The key difference was the productivity because the two utilization routes require different operating times to reach a specified metallization degree. To optimize the operation of the RHF process, dual objectives of minimizing cost and minimizing CO2 emission were simulated. The Pareto front showed that the emission was reduced by 30% by increasing the cost by 35%.