Development History
4.1.1 soda ash Laboratory Methods
Laboratory Preparation of sodium carbonate :
.
4.1.2 soda ash Lv Bulan Law
First in 1791 , the ancients began with salt , sulfuric acid, coal, limestone as raw material to produce sodium carbonate , is Lv Bulan method.
This method does not fully utilize the raw material , poor working conditions, poor product quality , and gradually replaced by Solvay process .
4.1.3 soda ash Solvay process
1859 , Belgian Solvay , with salt , ammonia , carbon dioxide as raw materials, at room temperature to precipitate sodium bicarbonate from the solution, heating it, and that the decomposition of sodium carbonate , alkali people this method is known as the Soxhlet this method has been in use ever since.
4.1.4 soda ash Houde Bang Law
1943 Chinese people studying abroad returned Houde Bang , he combined Mainland China ‘s national conditions and lack of salt on the Solvay process improvements , the two industrial joint soda ash and ammonia , while the production of sodium carbonate and ammonium chloride fertilizer , greatly improved salt utilization, is Hou soda method.
Reaction principle
Soxhlet soda method and the main chemical reaction Hou soda method are :
Reaction one :
NaHCO3 ( sodium bicarbonate ) soluble only under these conditions , greater than the solubility of sodium bicarbonate dissolved under this condition , the precipitated solid sodium bicarbonate , filtered to afford solid sodium bicarbonate .
Reaction II:
Hou alkali and alkali Soxhlet method different method is the preparation of the Soxhlet process is recycled NH3 :
And Hou law throughout the preparation process , NH4Cl directly as a byproduct of soda ash —- fertilizer.
So Soxhlet products are sodium carbonate, calcium chloride byproduct ; while Hou law product is sodium carbonate, ammonium chloride byproduct .
Hou alkali method
Namely:
① NaCl ( saturated ) + NH3 + H2O + CO2 ==== NH4Cl + NaHCO3
②
Ammonia and carbon dioxide reacts with the water molecule of ammonium bicarbonate , which is the first step .
( 1 )
The second step : the reaction of sodium bicarbonate and precipitates of sodium bicarbonate and ammonium chloride , sodium bicarbonate and the reason is because precipitation of the less soluble .
(2) NH ₄ HCO ₃ + NaCl ( saturated ) ==== NH ₄ Cl + NaHCO ₃ ↓
Part can be directly synthesized sodium bicarbonate factory sales , and the rest will be thermal decomposition of sodium bicarbonate to produce sodium carbonate, carbon dioxide can be generated back to the first step !
( 3 )
According NH4Cl solubility than NaCl, at a low temperature than the solubility of NaCl principle , 278K ~ 283K (5 ℃ ~ 10 ℃) when , salt powder was added to the mother liquor , leaving to crystallize for doing NH4Cl nitrogen alone .
Advantages of this method : the ammonia soda process retains the advantages , it eliminates the drawbacks that increase the utilization of salt to 96%; NH4Cl do nitrogen ; ammonia plant with a joint , so that the ammonia feed gas CO into CO2, leather In addition to this process CO2 CaCO3 system .