Understanding dissolution characteristics of steel slag for resource recovery
Autor: | Raghavendra Ragipani, Sankar Bhattacharya, Suresh K. Akkihebbal |
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Rok vydání: | 2020 |
Předmět: |
Basic oxygen steelmaking
Aqueous solution 020209 energy Sodium molybdate Carbonation Slag Industrial Waste 02 engineering and technology 010501 environmental sciences Raw material Carbon Dioxide 01 natural sciences chemistry.chemical_compound chemistry Chemical engineering Solubility Metals Steel visual_art 0202 electrical engineering electronic engineering information engineering visual_art.visual_art_medium Leaching (metallurgy) Waste Management and Disposal Dissolution 0105 earth and related environmental sciences |
Zdroj: | Waste management (New York, N.Y.). 117 |
ISSN: | 1879-2456 |
Popis: | Steel slags are generally alkaline with a high calcium content and are viewed as a potential feedstock for carbon dioxide sequestration and utilization, mostly through aqueous mineral carbonation routes. For recovery of multiple metals such as Ca, Fe, Mg, and Si, and generation of value-added products by dissolution and precipitation reactions in aqueous media, enhancing the metal selectivity and extraction efficiency are important. However, there is limited understanding of independent parameters that influence these important characteristics. In this work, a systematic attempt was made to correlate these key dissolution characteristics of basic oxygen furnace slag in acidic media with its mineralogical and physical characteristics, the changes in aqueous chemistry, and the role of potential secondary precipitates. The findings from this study substantiate that steel slag is a potential feedstock because of the calcium being mainly present as orthosilicates, which were found to leach congruently without forming a leached layer that might hinder calcium extraction. The leaching of Fe(II) from the slag is the main source of impurity and its slow oxidation-precipitation leads to a pH plateau at the end of the dissolution step. Oxidation-precipitation of Fe(II) is controlled by hydroxyl concentration in the aqueous solution, which necessitates a pH-swing step by addition of a base after dissolution. Use of surface complexing agents, such as sodium molybdate, can significantly reduce iron impurity in the leachate and obtain an iron-rich slag residue for recycle to iron and steel industry. |
Databáze: | OpenAIRE |
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