Sodium carbonate recrystallization

A process for producing sodium carbonate monohydrate from a feedstream comprising anhydrous sodium carbonate and impurities, the process comprising:

• (a) adding the feedstream to a saturated sodium carbonate brine solution at a rate of at least about 100 g/l/min under a condition to create supersaturation of at least about 5 g/l;
• (b) processing within a parameter that preferentially relieve the supersaturation by rapid growth of existing sodium carbonate monohydrate crystals over nucleation, wherein the step of relieving comprises adding sodium carbonate monohydrate seed crystals to the saturated sodium carbonate brine solution, maintaining a solids content of at least about 40% and agitating the brine solution at an agitation index of at least about 4;
• and
• (c) recovering a portion of the sodium carbonate monohydrate crystals from the saturated brine solution, wherein said recovering step comprises removing a portion of the sodium carbonate monohydrate crystals from the brine solution, dispersing the sodium carbonate monohydrate crystals by the addition of brine solution and recovering sodium carbonate monohydrate crystals from insoluble impurities on a size separation basis.

A process for producing sodium carbonate monohydrate from a feedstream comprising anhydrous sodium carbonate and impurities, the process comprising:

• (a) adding a feedstream having a particle size of less than about 100 mesh to a saturated sodium carbonate brine solution at a rate of at least about 400 g/l/min under a condition to create supersaturation of at least about 5 g/l;
• (b) processing within a parameter that preferentially relieve the supersaturation by rapid growth of existing sodium carbonate monohydrate crystals over nucleation, wherein the parameter comprises adding sodium carbonate monohydrate seed crystals having a particle size of from about 150 mesh to about 100 mesh to the saturated sodium carbonate brine solution, maintaining a solids content of at least about 60% and agitating the brine solution at an agitation index of at least about 4;
• and
• (c) recovering a portion of the sodium carbonate monohydrate crystals from the saturated brine solution, wherein said recovering step comprises removing a portion of the sodium carbonate monohydrate crystals from the brine solution, dispersing the sodium carbonate monohydrate crystals to a solids content of less than about 25% by weight by the addition of brine solution and recovering sodium carbonate monohydrate crystals having a particle size of greater than at least about 100 mesh from insoluble impurities on a size separation basis.