Abstract: A process for the preparation of anhydrous sodium from a thenardite ore containing sodium sulfate comprising the steps of: crushing the thenardite ore; lixiviating the crushed ore in a first lixiviation step with water or with an exhausted solution from a succeeding step, at a temperature between about 28.degree. C. and 40.degree. C., obtaining a suspension comprising a sodium sulfate saturated solution, sludges and insoluble material, settling the sludges and insoluble material from the saturated solution to separate a clarified solution; crystallizing the clarified saturated solution in a first crystallization step at a temperature between 32.degree. C. and 20.degree. C., maintaining the height of the solution not exceeding about 15 centimeters, to obtain a Glauber salt with large crystals of sodium sulfate and ten molecules of water. When the clarified saturated solution is crystallized, an exhausted solution is produced which is drained and recycled back to the first lixiviation step.

Abstract: This invention is related to a process for the secondary obtention of sodium carbonate from a waste liquor (known as FLP waste liquor) containing principally sodium chloride, ammonium bicarbonate, ammonium chloride and carbon dioxide, which is obtained in the filtering section within the solvay process for the primary obtention of sodium carbonate, by adding a compound or a mixture of compounds sodium ions to the FLP waste liquor in the presence of carbon dioxide, in order to precipitate sodium bicarbonate therefrom, and treating the precipitation and sodium bicarbonate to obtain the secondary production of sodium carbonate.