Recovering a caustic solution via calcium carbonate crystal aggregates

An apparatus for converting a portion of a carbonate to hydroxide in a solution comprising between 1.0M (moles per liter of solution) to 4.0M hydroxide and between 0.1M to 4.1M carbonate, comprising:

• a slaker configured to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH)2);
• a fluidized-bed reactive crystallizer in fluid communication with the slaker and configured to react the Ca(OH)2 with an alkaline carbonate solution and grow calcium carbonate (CaCO3) crystal aggregates of between 0.0005 mm3 to 5 mm3 volume, the fluidized-bed reactive crystallizer comprising a discharge output for a basic solution slurry that comprises the CaCO3 crystal aggregates;
• a conditioning unit in fluid communication with the discharge output and configured to receive the basic solution slurry and prepare the CaCO3 crystal aggregates for calcination;
• and
• a calciner in communication with the conditioning unit and configured to convert the CaCO3 crystal aggregates to CaO and carbon dioxide (CO2).