The Potential of Recycling the High-Zinc Fraction of Upgraded BF Sludge to the Desulfurization Plant and Basic Oxygen Furnace

Abstract

In ore-based steelmaking, blast furnace (BF) dust is generally recycled to the BF via the sinter or cold-bonded briquettes and injection. In order to recycle the BF sludge to the BF, the sludge has to be upgraded, removing zinc. The literature reports cases of recycling the low-zinc fraction of upgraded BF sludge to the BF. However, research towards recycling of the high-zinc fraction of BF sludge within the ore-based steel plant is limited. In the present paper, the high-zinc fraction of tornado-treated BF sludge was incorporated in self-reducing cold-bonded briquettes and pellets. Each type of agglomerate was individually subjected to technical-scale smelting reduction experiments aiming to study the feasibility of recycling in-plant residues to the hot metal (HM) desulfurization (deS) plant. The endothermic reactions within the briquettes decreased the heating and reduction rate leaving the briquettes unreduced and unmelted. The pellets were completely reduced within eight minutes of contact with HM but still showed melt-in problems. Cold-bonded briquettes, without BF sludge, were charged in industrial-scale trials to study the recycling potential to the HM deS plant and basic oxygen furnace (BOF). The trials illustrated a potential for the complete recycling of the high-zinc fraction of BF sludge. However, further studies were identified to be required to verify these results.

Reuse and Recycling of By-Products in the Steel Sector: Recent Achievements Paving the Way to Circular Economy and Industrial Symbiosis in Europe

“…Moreover, some examples can be provided about the recovery of valuable metals from by-products [29] as well as the selective leaching processes tested or applied to reclaim pure zinc compounds or metallic zinc from EAF secondary steelmaking [30]. Furthermore, although research towards recycling of the high-zinc fraction of BF sludge is limited, recent studies have been performed in order to incorporate this fraction in self-reducing cold-bonded briquettes and pellets [31] (see some examples in Figure 4). Exemplar of cold-bonded briquettes, agglomerates and pellets produced at VDEh-Betriebsforschungsinstitut GmbH.…”

Modern blast furnace ironmaking technology: potentials to meet the demand of high hot metal production and lower energy consumption

“…These BFs are among the most efficient in the world in terms of CO2 efficiency [41]. Feasibility of recycling of high-zinc fraction of upgraded BF sludge to the hot metal (HM) in deS plant and BOF was recently studied [42]. The BF sludge was incorporated in self-reducing cold-bonded briquettes and pellets.…”

“…Beside the efficient utilization of by-products and waste fines, potentials were conducted on partial substitution of cement with biomass lignin from the pulp and paper industry [42,43]. The replacement of cement with biomass lignin up to 25% has demonstrated good mechanical strength and enhanced the reducibility of the briquettes.…”

Zinc Evaporation from Brass Scraps in the Atmosphere of Inert Gas

“…Cupriferous wastes are, e.g., casting waste, copper smelting dusts or flotation tailings. In this area, the offered solutions with regard to zinc removal from these wastes are primarily based on pyrometallurgical [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] and hydrometallurgical [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] processes. In hydrometallurgical processes, various leaching materials are applied such as sulphuric acid, hydrochloric acid, acetic acid or ammonia solutions.…”