A boundary layer carbonation process for producing sodium bicarbonate crystals having specific surface area in the range 0.4 m2/g to 2.5 m2/g from Trona, wherein in one embodiment the process comprises the steps of: providing Trona particles having a particle size range of −4 +120 mesh; pre-wetting the Trona particles with water to provide a plurality of pre-wetted Trona particles each having a liquid water solution boundary layer deposited thereon; and carbonating the pre-wetted Trona particles across the water boundary layer to provide a product comprising sodium bicarbonate crystals.