Reduction Smelting of the Waelz Slag from Electric Arc Furnace Dust Processing: An Experimental Study

Abstract

Waelz slag is an iron-containing waste generated during electric arc furnace (EAF) dust processing in a rotary kiln named the Waelz process. This study focuses on the reduction smelting of the Waelz slag to produce iron-based alloy. The thermodynamic simulation using FactSage 8.0 software was carried out to predict temperatures of the metal and slag obtained as well as their compositions. Based on the simulation results, reduction smelting experiments were performed on a laboratory scale using two approaches, with and without preliminary froth flotation of carbon, respectively. The experiments have confirmed the technological possibility of reduction smelting of the Waelz slag from EAF dust processing. The approach using preliminary flotation of carbon and reduction smelting at 1500 °C resulted in high-copper cast iron production, while the approach without flotation, where the Waelz slag was smelted at 1650 °C with the addition of SiO2 flux, led to obtaining low-silicon ferrosilicon with high Cu content, as well as slag attractive for construction industry.

The Waelz Slag from Electric Arc Furnace Dust Processing: Characterization and Magnetic Separation Studies

“…An important target of the Waelz process is to prevent substantial charge smelting, thereby avoiding skull formation. The addition of an excess of coke breeze is one of the possible solutions to avoid skull formation at elevated temperatures [73]. Although it results in a higher consumption of coke breeze, the zinc recovery into the Waelz oxide increases, and the zinc content in the Waelz slag decreases.…”

Multi-Source Ferrous Metallurgical Dust and Sludge Recycling: Present Situation and Future Prospects

“…The rotary kiln process is the most widely used process in the harmless treatment of Zn-containing FMDS [82,83], and the representative processes are the SPM method and Waelz method.…”

The Effect of Electric Arc Furnace Dust (EAFD) on Improving Characteristics of Conventional Concrete

“…According to estimates, an EAF produces 10-20 kg of dust for every ton of steel made from iron wastes [14,15,[21][22][23][24]. Every year, the world produces around 7.5 million tons of EAFD, only 45% of which is recycled [25,26].…”

“…As a result, it reduces greenhouse gas emissions [35,36]. Due to the significant depletion of high-grade iron mineral reserves, together with the mining of deposits with lower grades and complex compositions, recycling of iron-containing wastes is an appealing alternative at the moment [25,37]. However, the additional treatment of the leftovers is challenging and has negative environmental effects [38].…”