Pyrometallurgical removal of zinc from basic oxygen steelmaking dust – A review of best available technology

Abstract

Approximately 20 kg of dust and sludges are produced per ton of liquid steel produced via the blast furnaces (BF)/basic oxygen furnace (BOF) production route. Many of these dusts are recycled through the sinter plant or blast furnace route without issue, but high zinc content dusts are routinely landfilled. Hydrometallurgical techniques, such as alkaline leaching, that are often utilized to remove zinc from electric arc furnace dusts are inappropriate for recovery of material from BOS dust due to the lower zinc concentration present and extra post-processing steps to utilize the separated iron product. Pyrometallurgical treatment through a rotary hearth furnace (RHF), in processes such as FASTMET ® , can currently be considered as the most commercially attractive option for the processing and recovery of iron and zinc units when employed as part of an integrated steelworks. The crude zinc oxide produced is suitable for sale to zinc smelters, and the direct reduced iron produced provides process benefits through use, such as reduced blast furnace coking rates and increased productivity. The advantages and disadvantages of variations and alternatives are reviewed with regard to future developments.

Recent Developments in Steelmaking Industry and Potential Alkali Activated Based Steel Waste: A Comprehensive Review

“…In particular, sintering returns approximately 80–90% of mill scale steelmaking processes, while 85–90% of slags are commercialized to other industrial process [ 28 ]. Previous papers addressed a wide range of steel manufacturing pathways, from economic and environmental aspects to technological highlights [ 3 , 29 , 30 , 31 ]. This review, in contrast, will concentrate on alkali-activated cement application in the most often used integrated steel production pathway.…”

Coupled Thermodynamics and Phase Diagram Analysis of Gas-Duct Concretion Formation in Pyro-Processing Ironmaking and Steelmaking Dust

“…This amount corresponded to more than 100 million tons of dust, accounting for approximately 8%-12% of the crude steel output. Dust containing heavy metals and cyanide is classified as hazardous waste [1][2][3], and poses a threat to the environment. To reduce resource consumption and environmental pollution, such dust has been used as raw materials for blast furnace ironmaking [4][5][6].…”

“…Roasted materials are treated as raw materials in ironmaking and steelmaking. In high-temperature reduction methods, dust is treated via in-flight reduction technology [26], microwave heating [27,28], and roasting in rotary kilns [1,2] or rotary hearth furnaces [1,29]. A large number of oxides in dust are reduced, and the products with lower boiling points, such as zinc and lead, form metal vapor and escape with the flue gas.…”

Hydrometallurgical Processes for the Recovery of Metals from Steel Industry By-Products: A Critical Review

“…For instance, the zinc content of BF and BOF sludges is too low for zinc recovery, but too high to recycle the by-products to the BF via the sinter plant. Stewart and Barron suggested the reason for the sensitivity to zinc is that, once charged into a blast furnace, any zinc component is reduced to elemental zinc [1]. Due to its low boiling point (907 °C) compared to the blast furnace (1600-1650 °C), the vapor re-condenses, leading to the condensation of zinc scaffolds (accretions) on the blast-furnace walls.…”