Leaching behaviour of air-cooled blast-furnace slag under intermittent and continuous wetting
2011 (English)Report (Other academic)
Air-cooled blast-furnace slag is commonly utilised as a construction material in roads, fill and embankments. Materials used in such constructions do not remain continuously wetted, but is often subjected to cyclic wetting and drying under various exposure conditions. However, its leaching behaviour is often assessed based on tests performed under continuous wetting. This work was conducted to evaluate the leaching behaviour of an air-cooled blast-furnace slag under intermittent and continuous wetting. Four different leaching tests were performed, including a static leaching test without leachant renewal and three dynamic leaching tests: a column leaching test with continuous flow of the leachant, a tank leaching test with sequential renewal of the leachant and an intermittent leaching test with periodical flow of leachant. Leaching of the studied material under cyclic wetting and drying led to less alkaline and more oxidised eluates than leaching under continuously wetted conditions. The eluates are expected to maintain a mildly alkaline pH for long time periods during wetting, drying and oxidation of the material because the material has considerable acid neutralising potential. The leaching of soluble elements such as Ca and S was lower under intermittent than under continuous flow of the leachant which could be due to the shorter contact time between the leachant and material, and the precipitation of secondary phases on the particle surfaces during intermittent leaching. During exposure of the BFS to cyclic wetting and drying, the leaching of these elements decreased and the speciation of S in the eluates shifted towards more oxidising forms. The leached amounts of constituents were low in all performed tests, which indicate that the material was resistant to leaching under the conditions that were investigated here.
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2011. , 22 p.
Technical report / Luleå University of Technology, ISSN 1402-1536
Research subject Waste Science and Technology
IdentifiersURN: urn:nbn:se:ltu:diva-23282Local ID: 657c7626-7799-4540-aef8-b104915677cbISBN: 978-91-7439-237-1OAI: oai:DiVA.org:ltu-23282DiVA: diva2:996331
Godkänd; 2011; 20110327 (soli)2016-09-292016-09-29Bibliographically approved