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 novel
mineral 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 different
reactant 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 additional
dissolved salts in NaOH solutions was also analyzed. The pH environment was found to be the most crucial
parameter. On the one hand, high pH values ensured high Mg2+ recovery and powder purities, i.e. > 98%, with
boron content complying with market requirements. On the other hand, filtration characteristics considerably
worsened due to the lyosorption phenomenon.