Vacuum Drying of Magnesium Hydroxide Using Steelmaking Ladle Hot Air as an Alternative Heat Source

Document Type : Research Article

Authors

Biosystems Engineering Department, Shahid Bahonar University of Kerman, Kerman, Iran.

Abstract

The growing application of magnesium in strategic industries underscores the need for sustainable and energy-efficient routes for producing high-purity magnesium compounds. In this study, a vacuum drying system was designed and fabricated to enable the recovery of magnesium hydroxide from desalination effluent, and its drying performance was evaluated. Experiments were carried out at three operating pressures (0.10, 0.05, and 0.02 bar) and three temperatures (150, 210, and 250°C), utilizing hot air recovered from steelmaking ladles as an industrial waste-heat source. The results showed that reducing the operating pressure significantly decreased the drying time while enhancing the mass transfer rate. At 0.02 bar, the time required to reach the target final moisture content was markedly shorter than that at 0.10 bar, with an average reduction of approximately 50%. Moreover, increasing the drying temperature from 150 to 250°C led to a substantial acceleration of the drying process, resulting in an overall reduction of 69.2% in total drying time. Drying kinetics were analyzed using logarithmic and two-term exponential models. Statistical evaluation revealed that the logarithmic model provided superior predictive performance, exhibiting a high coefficient of determination (R² =0.99) and lowest root mean square error (RMSE=0.012) across all operating conditions. Overall, this study demonstrates that the integration of vacuum drying with the utilization of steelmaking waste heat represents an efficient and sustainable approach for the recovery of magnesium hydroxide from desalination effluents, offering both technical effectiveness and industrial relevance.

Keywords

References

[1] Polmear, I., StJohn, D., Nie, J.-F., Qian, M., 2017. Light alloys: metallurgy of the light metals. https://doi.org/10.1016/B978-0-08-099431-4.00001-4
[2] Fontana, D., Forte, F., Pietrantonio, M., Pucciarmati, S., Marcoaldi, C., 2023. Magnesium recovery from seawater desalination brines: a technical review, Environment, Development and Sustainability, 25(12), 13733–13754. https://doi.org/10.1007/s10668-022-02663-2
[3] Pan, S.-Y., Chiang, P.-C., Chen, Y.-H., Tan, C.-S., Chang, E., 2013. Ex situ CO2 capture by carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed, Environmental Science and Technology, 47(7), 3308–3315. https://doi.org/10.1021/es304975y
[4] Li, P., Ma, C., Chen, Z., Wang, H., Wang, Y., Bai, H., 2023. A review: study on the enhancement mechanism of heat and moisture transfer in deformable porous media, Processes, 11(9), 2699. https://doi.org/10.3390/pr11092699
[5] Mujumdar, A.S., 2014. The making of the handbook of industrial drying, Vol. 32, Taylor and Francis, 627–628.
[6] Pasten, A., Vega-Galvez, A., Uribe, E., Carvajal, M., Mejías, N., Araya, M., Goñi, M.G., 2024. A comparison of the effects of low-temperature vacuum drying and other methods on cauliflower’s nutritional–functional properties, Processes, 12(8), 1629. https://doi.org/10.3390/pr12081629
[7] Mansour, N.E., Metwally, K.A., Tantawy, A.A., Elbeltagi, A., Salem, A., Dewidar, A.Z., Okasha, A.M., Moustapha, M.E., Elwakeel, A.E., 2025. Automated vacuum drying kinetics, thermodynamics, and economic analysis of sage leaves, Scientific Reports, 15(1), 18779. https://doi.org/10.1038/s41598-025-03367-z
[8] Šooš, Ľ., Urban, F., Čačková, I., Kolláth, Ľ., Mlynár, P., Čačko, V., Bábics, J., 2024. Analysis of thermodynamic events taking place during vacuum drying of corn, Sustainability, 16(2), 879. https://doi.org/10.3390/su16020879
[9] Droste, R.L., Gehr, R.L., 2018. Theory and practice of water and wastewater treatment, John Wiley and Sons.
[10] Jouhara, H., Khordehgah, N., Almahmoud, S., Delpech, B., Chauhan, A., Tassou, S.A., 2018. Waste heat recovery technologies and applications, Thermal Science and Engineering Progress, 6, 268–289. https://doi.org/10.1016/j.tsep.2018.04.017
[11] Tehranizade Kermani, N., Maharlooei, M., Mortezapour, H., 2020. Study the drying kinetics, energy consumption and quality parameters of Echium amoenum in an IR equipped solar dryer, Journal of Food Science and Technology (Iran), 17(102), 161–174. https://doi.org/10.52547/fsct.17.102.161 [in Persian].
[12] Battaglia, G., Romano, S., Raponi, A., Marchisio, D., Ciofalo, M., Tamburini, A., Cipollina, A., Micale, G., 2022. Analysis of particle size distributions in Mg(OH)2 precipitation from highly concentrated MgCl2 solutions, Powder Technology, 398, 117106. https://doi.org/10.1016/j.powtec.2021.117106
[13] Tan, K.E.B., Choi, A.E.S., 2023. Development of separation techniques for magnesium recovery: a mini-review, Chemical Engineering Transactions, 106, 55–60. https://doi.org/10.3303/CET23106010
[14] Romano, S., Trespi, S., Achermann, R., Battaglia, G., Raponi, A., Marchisio, D., Mazzotti, M., Micale, G., Cipollina, A., 2023. The role of operating conditions in the precipitation of magnesium hydroxide hexagonal platelets using NaOH solutions, Crystal Growth & Design, 23(9), 6491–6505. https://doi.org/10.1021/acs.cgd.3c00462
[15] Bergman, T.L., 2011. Fundamentals of heat and mass transfer, John Wiley and Sons.
[16] Silva Neto, L.D., Anchieta, C.G., Duarte, J.L., Meili, L., Freire, J.T., 2021. Effect of drying on the fabrication of MgAl layered double hydroxides, ACS Omega, 6(33), 21819–21829. https://doi.org/10.1021/acsomega.1c03581
[17] Piperopoulos, E., Fazio, M., Mastronardo, E., Lanza, M., Milone, C., 2021. Tuning Mg(OH)2 structural, physical, and morphological characteristics for its optimal behavior in a thermochemical heat-storage application, Materials, 14(5), 1091. https://doi.org/10.3390/ma14051091
[18] Luo, S., Liu, M., Yang, L., Chang, J., 2019. Effects of drying techniques on the crystal structure and morphology of ettringite, Construction and Building Materials, 195, 305–311. https://doi.org/10.1016/j.conbuildmat.2018.11.078
[19] Doymaz, İ., 2017. Drying kinetics, rehydration and colour characteristics of convective hot-air drying of carrot slices, Heat and Mass Transfer, 53(1), 25–35. https://doi.org/10.1007/s00231-016-1791-8
[20] Mortezapour, H., Noroozi, A., Abdi, A., 2024. Development of an indirect forced flow greenhouse solar dryer for barberry drying, Biomechanism and Bioenergy Research, 3(2), 31–38. https://doi.org/10.22103/BBR.2024.22906.1079
[21] Rostami, A., Jafarinaeimi, K., Maghsoudi, H., 2025. Mathematical modeling and investigation of the effect of power on effective moisture diffusivity and activation energy of turnip slices in microwave drying, Biomechanism and Bioenergy Research, 4(2), 26–39. https://doi.org/10.22103/BBR.2025.24863.1117
Chemical Process Design
Volume 5, Issue 2
December 2026
Pages 63-76

Files

Share

How to cite

Statistics