Uses of lime

Lime has various uses in the industry, which can be used in the cement industry, sugar production, steel industries, building construction, disinfectants, sodium carbonate production by the Solway method, etc. pointed out.

Sodium carbonate (Na2Co3) is a white, crystalline powder with a molecular weight of 106. The first commercial unit for sweetening of salt and lime was made in France. In this unit, common salt reacts with sulfuric acid and sodium sulfate and hydrochloric acid are obtained. There are various processes for producing baking soda and sodium carbonate, the oldest of which is the solvey process. The raw materials of the process are common salt and limestone, ammonia is also used in this process, but it is not consumed and only a small amount of it is wasted. Therefore, it cannot be considered as one of the raw materials required for the process.

The reaction in the whole process is as follows:

CaCo3 +2 NaCl Na2Co3 + CaCl2

This reaction does not take place directly in one step and takes place in several steps.
The lime decomposition process is as follows:

CaCo3 Cao + Co2

Common salt reacts with ammonia and carbon dioxide to an almost saturated and pure state, and then the material obtained is ammonium chloride and sodium bicarbonate.Sodium bicarbonate precipitates and is separated by filter. Then it is decomposed at 200 degrees Celsius and converted into carbonate.

The product under the filter contains ammonium chloride, some sodium chloride and a large amount of ammonia in carbon dioxide, which is present as bicarbonate ion.

In the next step, ammonia is recovered and used again. The hot solution containing ammonium chloride and salt is reacted with milk of lime to recover the fixed ammonia.

As mentioned earlier, the salt used has impurities that must be purified.

Salt is usually purified by the reaction with lime – soda ash. In this reaction, magnesium is precipitated with slaked lime (2 Ca (OH)) and calcium is precipitated with soda, then the salty solution is separated from impure sediments and is separated into units. Ammonia absorption is sent.