Carbon-Material-Energy Flows Nexus Analysis of Electric Arc Furnace Steelmaking Processes in China

Abstract

Integrated analysis of carbon flows (CFs), material flows (MFs) and energy flows (EFs) has gradually attracted the attention in cleaner production and emission reduction in iron and steel industry. Electric arc furnace (EAF) steelmaking realizes the recycling of waste scrap resources and improves the sustainable development. However, there is still no public reports about the CFs-MFs-EFs of EAF steelmaking, which leads to the lack of data support and directionality for saving and reduction optimization. To fill this gap, the China-style EAF steelmaking with hot metal (HM) and scrap is concentrated. The carbon-material-energy flows nexus (CME-FN) is determined by the successively established mathematical models of MFs, EFs and CFs based on the steelmaking mechanism and chemical reactions. The EAF actual production data and literature data are used to verify these models. The effects of electricity, carbon powder and natural gas on CME-FN are further discussed. The results reveal that in EAF steelmaking with full HM (EAF-FHM) and full scrap (EAF-FS), the metal charge and material consumption to produce 1000 kg of molten steel are 1103.4/1298.4, and 1037.9/1077.4 kg, respectively. Considering the energy demand of 549.9 and 437.2 kWh, the input energy of 678.0 and 65.3 kWh leads to the surplus energy of 128.0 and -371.9 kWh. The direct and embodied equivalent carbon dioxide is 166.7/2884.7, 13.5/46.1 kg CO₂ eq. EAF-FS enjoys better reduction benefits on material consumption and carbon emission, but shows less energy supply performance than EAF-FHM. Electricity changes the HM ratio, strengthens the HM surplus energy utilization, and has positive effects on CME-FN. Carbon powder and natural gas slightly aggravate the material and energy consumption and direct carbon emission, but cut down the embodied carbon emission. Although the China-style mode is focused, the method and analysis can be extended to other EAF patterns of related countries and technologies.