Solvay Process Lab Report

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The Solvay (ammonia-soda) process for the production of sodium carbonate (soda ash)
Generally, the ammonia will react with carbon dioxide and water to produce ammonium bicarbonate (NH4HCO3). Then, NH4HCO3 will react with salt to form sodium bicarbonate. Sodium bicarbonate will be calcined to form sodium carbonate.
The Solvay process comprises of the following steps:
1. Purification of brine
The first step in the Solvay process is brine purification. This step is done to produce a pure sodium chloride solution. Brine contains impurities namely calcium and magnesium salts. Sulfates also can be found in some brines. These impurities have to be eliminated because they will produce unwanted insoluble salts by reacting with alkali and carbon dioxide,
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Ammonia and carbon come from the gaseous from distillation stage. Here, the sodium chloride content will be decreased due to of the increase in the specific volume which is caused by ammonia addition and water dilution. These reactions are exothermic and the chemical equations are as follows.
NH3 + H2O → NH4OH + heat
2NH4OH + CO2 → (NH4)2CO3 + H2O + heat
4. Precipitation of bicarbonate
The precipitation of sodium carbonate is an exothermic process.
NaCl + NH4HCO3 → NaHCO3 + NH4Cl + energy
This reaction involves the reaction between ammoniated brine and carbon dioxide. The ammoniated brine comes from the absorption stage whereas carbon dioxide comes from the lime kiln or calcination stage. The ammoniated brine is propelled to the top of one of the columns which is used to precipitate bicarbonate (NaHCO3). Sodium bicarbonate precipitation occurs after receiving the kiln gas and bicarbonate calciner gas.

5. Filtration of Bicarbonate
Bicarbonate crystals are separated from the main solution by using vacuum filters, band filter and centrifuges. The gas containing ammonia and carbon dioxide is cleaned and released to the atmosphere when these filters are used. The solutions will be send to the distillation phase for ammonia
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