Accelerated carbonation of ferrous and non-ferrous slags to produce clinker-free carbonate-bonded blocks : synergetic reduction in environmental leaching
Srivastava, Sumit; Snellings, Ruben; Nielsen, Peter; Cool, Pegie (2022-08-11)
Srivastava, S., Snellings, R., Nielsen, P., & Cool, P. (2022). Accelerated carbonation of ferrous and non-ferrous slags to produce clinker-free carbonate-bonded blocks: Synergetic reduction in environmental leaching. Construction and Building Materials, 348, 128630. https://doi.org/10.1016/j.conbuildmat.2022.128630
© 2022 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2022122773899
Tiivistelmä
Abstract
Clinker-free, carbonate-bonded monoliths are prepared by accelerated carbonation for immobilization of hazardous elements present in: a stainless-steel slag, two copper slags, and one lead slag. In addition to the studies on individual slags, mixes of copper slags and lead slags with 33 % and 66 % replacements of stainless-steel slag are also studied. Combinations of two temperatures (30 and 60 °C) and three CO2-pressures (1, 5, and 10 barg) are studied. Among the non-ferrous slags carbonated individually, lead slag carbonated at 10 barg exhibited carbonate-cementation. The carbonate-bonded monoliths containing stainless-steel slag exhibited high compressive strengths, individually or as in its mixes with other slags. In stainless-steel slag, while its individual carbonation also showed a decrease in Cr-leaching, the Cr-leaching from its mixes with non-ferrous slags are disproportionately lower: possible chemical synergy of stainless-steel slag with sulfidic non-ferrous slags is discussed. For lead slag individually, carbonation significantly decreases Pb-leaching; while Co, Zn, and Mn leaching first increase and then decrease with an increase in CO2-pressure. In mixes of lead slag with stainless-steel slag, Pb, Co, Zn, and Mn leaching are significantly decreased. Temperature does not have a significant influence on the product properties. Copper slag remained relatively insensitive towards carbonation. Comparisons are made with the Flemish legislative limits.
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