Characterization of Mg(OH)2 powders produced from real saltworks bitterns at a pilot scale

The growing demand for a reliable supply of minerals has pushed the European Union toward seeking novelmineral sources. In the present work, the recovery of magnesium, in the form of magnesium hydroxide, Mg(OH)2, from saltworks bitterns was investigated at a pilot scale. The natural bittern collected from Margi saltworks(Trapani, Italy) was treated with synthetic sodium hydroxide (NaOH) solutions. The influence of differentreactant concentrations, flow rates and pH environments, on Mg(OH)2 particle sizes, filtration characteristics,Mg2+ extraction performance and the Mg(OH)2 solid purity was thoroughly assessed. The presence of additionaldissolved salts in NaOH solutions was also analyzed. The pH environment was found to be the most crucialparameter. On the one hand, high pH values ensured high Mg2+ recovery and powder purities, i.e. > 98%, withboron content complying with market requirements. On the other hand, filtration characteristics considerablyworsened due to the lyosorption phenomenon.