The Solvay process is a method of making sodium carbonate from the raw materials sodium chloride, ammonia and calcium carbonate (limestone). This process was first used by Ernest Solvay in Belgium in the 1860s in an attempt to find a use for ammonia. Ammonia was being produced as a by-product in the coke industry. The successful manufacture of sodium carbonate also made the manufacture of soap and glass less expensive.
The Solvay process is a method of making sodium carbonate (Na2CO3) from the raw materials: I. Sodium Chloride (NaCl) – Obtained from brine (salt water) II. Ammonia (NH3) – This is reused during the process so it is not really a raw material. III. Calcium Carbonate (CaCO3) – Obtained from limestone in the ground.
First limestone is converted to calcium oxide and carbon dioxide.. CaCO3------------CaO+CO2 The carbon dioxide reacts with ammonia and sodium chloride to make sodium hydrogen carbonate (baking soda!) in an Ammoniating tower. CO2+NH3+NaCl+H2O------------NaHCO3+NH4Cl Calcium oxide reacts with water to produce calcium hydroxide(Slaked Lime!). CaO+H2O--------------Ca(OH)2 Calcium hydroxide is used to recover ammonia from ammonium chloride. Ca(OH)2+2NH4Cl---------CaCl2+2H2O+2NH3 Sodium hydrogen carbonate is heated to produce sodium carbonate. 2NaHCO3---------------Na2CO3+H2O+CO2
16.6.2:Outline The Basic Reactions of Solvay process
16.6.3:Develop A Flow Sheet Diagram Of Solvay Process
The main environmental issue associated with the Solvay process is the waste product, calcium chloride. Its discharge into rivers causes unacceptable increase in chloride ion concentration. Some calcium chloride has been used for de-icing roads, however much more waste calcium chloride is produced than can be used. The Solvay process produces less pollution than previous methods of producing sodium carbonate. The reactions take place in a tower, designed by Solvay, and by-products such as ammonia, calcium oxide and carbon dioxide are re-used.