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Calcium and sodium recovery from microwave‐pretreated red mud with added solid ammonium chloride
Author(s) -
Kim JinSeok,
Jo Ho Young,
Choi NagChoul
Publication year - 2019
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6198
Subject(s) - red mud , leaching (pedology) , chemistry , ammonium chloride , microwave , nuclear chemistry , ammonium , sodium , organic chemistry , physics , environmental science , quantum mechanics , soil science , soil water
BACKGROUND Many studies have used an NH 4 Cl solution as a solvent during microwave‐assisted metal leaching processes. However, in this study, solid NH 4 Cl instead of an NH 4 Cl solution was used as a chlorinating agent during the microwave pretreatment of red mud to induce a rapid temperature increase by minimizing heat loss by water. Red mud only and red mud–solid NH 4 Cl samples were pretreated by microwaves under various conditions. Leaching tests were then conducted on the microwave‐pretreated red mud only and red mud–solid NH 4 Cl samples using deionized (DI) water as a leaching solution. RESULTS The leached Ca and Na concentrations from the microwave‐pretreated red mud–solid NH 4 Cl samples were significantly higher than those from the microwave‐pretreated red mud only samples at the given test conditions. In contrast to the red mud only samples, the leached Ca and Na concentrations from the microwave‐pretreated red mud–solid NH 4 Cl samples increased with increasing microwave output power. The leached Ca and Na concentrations from the microwave‐pretreated red mud–solid NH 4 Cl samples at 5000 W were significantly higher than those from the microwave‐pretreated red mud–solid NH 4 Cl samples at 500 and 1100 W and from the non‐microwave‐pretreated red mud–solid NH 4 Cl samples. CONCLUSION Adding solid NH 4 Cl to the red mud during the microwave pretreatment process is effective to recover Ca and Na at a microwave output power of 5000 W. The leached solutions with elevated Ca and Na concentrations from the microwave‐pretreated red mud–solid NH 4 Cl samples at 5000 W can be used for aqueous mineral carbonation to sequester CO 2 . © 2019 Society of Chemical Industry