CaCO3 was pptd. in aq. 0.5-2 M urea by using Solvay's aq. satd. NaHCO3 and waste distn residue (NH3 recovery step) at 333 K. Bulk and tap ds., flow p., and habitus of CaCO3 were detd. The residue was aq. CaCl2 and NaCl with solids and SO, as impurities which were removed by clearing and filtration. The NaHCO3 soln. was prepd. from crude NaHCO3 taken from the filtration step. The longer the reactants dosing time, the higher the bulk and tap ds. and the lower the CaCO3 flow p. The higher the urea concn., the lower the tap d. (min. at 606 g/l. in 2 M urea), regardless of the dosing time. Urea made the calcite type to cryst, yet conglomerate was the most frequent habitus type.