EXAMPLES OF CHEMICAL ENGINEERING IN
HYDROMETALLURGICAL PROCESSES:
DEMANGANIZATION OF WATER AND
DECADMIATION OF INDUSTRIAL PHOSPHORIC
ACID

Sanaa Kouzbour, Bouchaib Gourich, Fabrice Gros, Christophe Vial

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To cite this version:

Sanaa Kouzbour, Bouchaib Gourich, Fabrice Gros, Christophe Vial. EXAMPLES OF CHEMICAL ENGINEERING IN HYDROMETALLURGICAL PROCESSES: DEMANGANIZATION OF WATER AND DECADMIATION OF INDUSTRIAL PHOSPHORIC ACID. International Chemical Engineering and Material Symposium, SICHEM 2022, Nov 2022, Bucarest (Roumanie), Romania. hal-04869163

HAL Id: hal-04869163

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# EXAMPLES OF CHEMICAL ENGINEERING IN HYDROMETALLURGICAL PROCESSES: DEMANGANIZATION OF WATER AND DECADIATION OF INDUSTRIAL PHOSPHORIC ACID

Sanaa KOUZBOUR¹,², Bouchaib GOURICH¹, Fabrice GROS²,*, Christophe VIAL²

¹Laboratory of Process and Environmental Engineering, Higher School of Technology, Hassan II University of Casablanca, Casablanca, Morocco

²Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut Pascal, F-63000 Clermont-Ferrand, France

**Abstract:** Examples of the use of polyphasic reactors for hydrometallurgical processes are presented focusing on the demanganization of water and the decadmiation of phosphoric acid. A classical chemical engineering approach is developed to support these examples.

**Key words:** Multiphase reactors; Water treatment; Demanganization, Phosphoric acid purification, Decadmiation

The occurrence of metals in water can bring serious concerns for human health, animals as well as for the ecosystem. Specifically, manganese (Mn) an abundant transition metal, can be found in both surface water and groundwater. A high concentration of manganese in drinking water can cause health trouble. Hence the mitigation of soluble manganese Mn(II) from drinking water should be studied. It can be removed by simple aeration process using pneumatic reactors including bubble column and airlift reactor operating in semi-batch conditions.

In this work, the effects of operating conditions such as aeration flow rate, initial pH, Mn(II) concentrations, and amount of MnO₂ particles on the Mn(II) removal efficiency are analyzed. Meanwhile, to determine the appropriate reactor for the demanganization of drinking water by oxidation using atmospheric oxygen, a comparison of the performance of the two reactors in terms of Mn(II) ion removal as a function of the energy consumed is performed [1].

The second example is focused on the removal of cadmium ion contained in industrial phosphoric acid; indeed, this metal may also cause severe health problem when present in the fertilizers. Hence, a purification technique based on sulfide precipitation is developed adopting a novel approach to improve the cadmium removal performance. It is based on the use of NaHS rather than Na₂S as a precipitating agent.

The study has been carried out in both batch and continuous modes for cadmium removal from synthetic and also industrial wet phosphoric acid. The use of NaHS has improved the decadmiation of synthetic phosphoric acid in comparison to Na₂S.

<footnote>* Corresponding author: fabrice.gros@sigma-clermont.fr</footnote>
An apparent kinetic model is developed taking into consideration the reaction mechanisms and supersaturation to predict the residual cadmium concentration in phosphoric acid solutions. The findings obtained through this work provide useful insights into the feasibility of chemical precipitation using NaHS as a technology of phosphoric acid decadmiation in the industry [2].

[1] Kouzbour, S.; El Azher, N.; Gourich, B.; Gros, F.; Vial, C.; Stiriba, Y. Removal of Manganese (II) from Drinking Water by Aeration Process Using an Airlift Reactor. *Journal of Water Process Engineering* 2017, 16, 233–239.

[2] Kouzbour, S.; Gourich, B.; Gros, F.; Vial, C.; Stiriba, Y. A Novel Approach for Removing Cadmium from Synthetic Wet Phosphoric Acid Using Sulfide Precipitation Process Operating in Batch and Continuous Modes. *Minerals Engineering* 2022, 187, 107809.