Title: Valorisation of phosphogypsum waste as K₂SO₄ fertiliser and portlandite Ca(OH)₂

Authors: H. El Alaoui-Belghiti; I. Zdah; Y. Ennaciri; R. El Ouatib; M. Bettach

Addresses: Laboratory of Physical Chemistry of Materials (LPCM), Faculty of Science, Chouaib Doukkali University, Route Ben Maachou, BP. 20, El Jadida 24000, Morocco ' Laboratory of Physical Chemistry of Materials (LPCM), Faculty of Science, Chouaib Doukkali University, Route Ben Maachou, BP. 20, El Jadida 24000, Morocco ' Laboratory of Physical Chemistry of Materials (LPCM), Faculty of Science, Chouaib Doukkali University, Route Ben Maachou, BP. 20, El Jadida 24000, Morocco ' Laboratory of Physical Chemistry of Inorganic Materials (LPCMI), Faculty of Science Ain Chock, University Hassan II Casablanca, Route d'El Jadida, Km 7, B.P: 5366 Maârif, Casablanca, Morocco ' Laboratory of Physical Chemistry of Materials (LPCM), Faculty of Science, Chouaib Doukkali University, Route Ben Maachou, BP. 20, El Jadida 24000, Morocco

Abstract: Series of experiments were performed to follow the reactivity of Moroccan phophogypsum with KOH in order to valorise this environmentally harmful solid waste. The experiments were carried out in aqueous solution under different conditions: with excess of reagent KOH or in stoichiometric proportions and by varying reaction duration at room temperature. The complete decomposition of phosphogypsum (PG) waste into portlandite Ca(OH)₂ and arkanite K₂SO₄ was evidenced by X-ray diffractometry and Fourier transform infrared spectroscopy. The optimum decomposition was obtained with stoichiometric mixture using 0.6 M phosphogypsum and 1.2 M KOH. The full decomposition of phosphogypsum was achieved at room temperature in one hour. The results show how phosphogypsum can efficiently converted to valuable products with high purity and in mild conditions.

Keywords: phosphogypsum; wet process; conversion; portlandite; arkanite; industrial waste.

DOI: 10.1504/IJEWM.2021.114421

International Journal of Environment and Waste Management, 2021 Vol.27 No.3, pp.363 - 377

Received: 01 Mar 2019
Accepted: 29 Aug 2019
Published online: 21 Apr 2021 *

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