There are two processes in sodium sulfate production. 

1. Chemical process Feed sodium chloride (≥97) and sulfuric acid (H2SO4 ≥98) into Mannheim furnace, and the reactant is sodium sulfate. The process is as following: 2NaCl + H2SO4 Na2SO4 + 2HCl ↑- Q Actually, the reaction is proceeded in two steps: NaCl + H2SO4 NaHSO4 + HCl↑ + Q(1) NaHSO4+ NaCl Na2SO4 + 2HCl↑ - Q(2) The first step is an exothermal reaction that can be carried out at lower temperature, NaHSO4 is form first. While the second reaction is a strong endothermic reaction, the reaction can be carried out only at 500 °C to 600 °C. The heat required by the reaction is supplied by burning of gas in the burning chamber of the furnace. The gas is generated by a coal gas generator. The temperature in the burning chamber should be maintained around 1200 °C.
2. Extracted from Glauberite rocks Crushed Glauberite rocks are fed into a tank, and then is extracted by water. Remove impurities in the extract. The clean extract is evaporated and centrifuged. Finally this wet sodium sulfate is dried to obtain product sodium sulfate. The process is proceeded as following: Na2SO4.CaSO4 + 2H2O = Na2SO4 + CaSO4.2H2O