Abstract: Sodium carbonate having a high bulk density and pseudo-cubic crystal structure is prepared from impure trona purge liquors from the crystallizers containing high concentration of organics, silica and sulfate by a sequence of steps involving (1) treatment of the liquors with MgO; (2) separation of the treated liquor from the insoluble reaction products; (3) addition of Ca and Mg compounds to the liquor; (4) evaporating the solution to obtain sodium carbonate monohydrate crystals; (5) separating the crystals from the mother liquor; and (6) heating the crystals at temperature of about 150.degree.-200.degree. C. to convert to dense ash.