RECOVERING A CAUSTIC SOLUTION VIA CALCIUM CARBONATE CRYSTAL AGGREGATES

摘要

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm3 to 5 mm3, include a slaker 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 that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

主权项

1. A method for growing crystalline calcium carbonate solids in the presence of an alkaline carbonate solution in a fluidized-bed reactive crystallizer such that each of at least a portion of the crystalline calcium carbonate solids reach a volume of 0.0005 mm3 to 5 mm3, the method comprising:
reacting, in a slaking process, quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH)2); introducing the slurry of primarily slaked lime and an alkaline solution comprising between 0.1M to 4.0M hydroxide and between 0.1M to 4.1M carbonate into a fluidized-bed reactive crystallizer that comprises a solid bed mass; reacting the Ca(OH)2 slurry and the alkaline carbonate solution to deposit a portion of the precipitated calcium carbonate (CaCO3) onto the existing bed of solids that (1) causes the solids to grow in volume, (2) decreases a concentration of dissolved carbonate, and (3) increases a concentration of dissolved hydroxide; and discharging a portion of the crystalline calcium carbonate solids and the alkaline carbonate solution, the solids comprising particles that each comprise a volume within the range from about 0.0005 mm3 to about 5 mm3.