A1 Journal article (refereed)
Two-stage leaching of calcium and vanadium from high-calcium steelmaking slag (2024)

Kokko, M., Kauppinen, T., Hu, T., Tanskanen, P., Kallio, R., Lassi, U., & Pesonen, J. (2024). Two-stage leaching of calcium and vanadium from high-calcium steelmaking slag. Environmental Technology, Early online. https://doi.org/10.1080/09593330.2024.2316671

JYU authors or editors

Publication details

All authors or editors: Kokko, Maria; Kauppinen, Toni; Hu, Tao; Tanskanen, Pekka; Kallio, Rita; Lassi, Ulla; Pesonen, Janne

Journal or series: Environmental Technology

ISSN: 0959-3330

eISSN: 1479-487X

Publication year: 2024

Publication date: 13/02/2024

Volume: Early online

Publisher: Taylor & Francis

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1080/09593330.2024.2316671

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/93552

Publication is parallel published: https://urn.fi/URN:NBN:fi:oulu-202402191845

Abstract

Vanadium (V) is a critically important element in many industries. A widely used recovery process is a combination of roasting and leaching. However, roasting is an energy-intensive stage. Generally, basic oxygen furnace (BOF) slag is high in calcium (Ca) but low in V. Ca content and its chemical nature can prevent V leaching. This study presents a potential two-stage leaching process for Ca and V from BOF slag. The method is environmentally friendly using low temperatures and enabling leachate recycling. Furthermore, the utilisation rate of the slag can be higher due to Ca recovery. Ca is first leached using ammonium nitrate and nitric acid solution. The V-containing residue is directed to the second stage, where V is leached using ammonium carbonate ((NH4)2CO3). Ca leaching efficiency was 71% achieved with a low temperature (40°C) and in 20 min. > 99% of the dissolved element was Ca. Increasing the total nitrate concentration increased the leaching efficiency. Reducing the L/S ratio improved selectivity. The solid material was analysed after the leaching stages and a clear change was observed after the Ca-stage. The V leaching efficiency was 50%. > 88% of dissolved element was V (L/S 8, [(NH4)2CO3] 200 g/L, 60°C, and 60 min). Increasing [(NH4)2CO3] and L/S ratio slightly improved the leaching efficiency but decreased selectivity. The studied process implements circular economy principles and has been developed for side streams with low V concentrations. However, further optimisation and developments are required regarding the effectiveness of the process.

Keywords: vanadium; calcium; hydrometallurgy; dissolution (active); steel industry; slag; circular economy

Free keywords: vanadium; calcium; direct leaching; BOF slag; hydrometallurgy

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2024

Preliminary JUFO rating: 1