Solvay process has another name as ammonia soda process, and
uses salt (NaCl) and limestone (CaCo3) as raw materials. Ammonia, which is also
used in the process, is almost totally regenerated and recycled. The reason why
this process is famous because the availability of the raw materials. Raw materials can be found out almost
everywhere in the world and therefore allows operating production units
relatively closer to the market, Thus having negligible logistics cost.
The solvay process produces Light Soda ash, with density
of around 500kh/m3.
It is used mainly for the detergent market and certain
Soda ash Light is transformed by recrystallization firstly
to monohydrate form of Sodium Carbonate and finally to dense soda ash which is
mainly used in glass industry and has pouring density of 1t/m3.
Modification to this Process:
Dual process: Which allows production units to
co-produce in nearly equal quantities ammonium chloride, which is also used in
manufacturing of fertilizers used in rice cultivation.
Akzo or dry lime process, which uses dry
lime instead of lime milk for ammonia recovery.
Trona and Nacholite based process:
All these process are based treatment of the ore from which
the impurities have to be stored underground or in tailing ponds.
Mining using room and pillar or Long wall method.
Calcined to produce Soda Ash which is impure.
It is dissolved and solution is settled followed
my filtration to remove the coarse impurities.
Filtration with Micro pore size membranes to
remove fine impurities.
The purified liquor is sent to evaporators where
The monohydrate slurry is concentrated in
centrifuge before drying and transformation into dense soda ash.
Deposits from trona lakes and solution mined trona are
processed as follows:
Dissolving trona in wells
Carbonation of the solution
Filtration of the slurry
Calcination of the bicarbonate to get light
grade of soda ash.
Monohydrate method is used to transform SAL to
soda ash dense
Carbon dioxide enrichment
There are many more process like
Nepheline syenite process, Carbonation of Caustic Soda and