Process for the joint production of sodium carbonate and sodium bicarbonate

Abstract

Process for the joint production of sodium carbonate and sodium bicarbonate crystals, according to which: a solid powder derived from sodium sesquicarbonate, having a mean particle diameter comprised between 0.1 and 10 mm is dissolved in water; the resulting water solution is introduced into a crystallizer, wherein a first water suspension comprising sodium carbonate crystals is produced; the first water suspension is subjected to a separation, in order to produce crystals comprising sodium carbonate on the one hand, which are valorized, and a mother liquor on the other hand; and a part of the mother liquor is taken out of the crystallizer and put into contact in, a gas liquid contactor, with a gas comprising carbon dioxide, in order to produce a second water suspension comprising sodium bicarbonate crystals, which are separated and valorized. A reagent powder comprising sodium bicarbonate crystals made by such process.

1 - 20 . (canceled) 
     
     
         21 . A method for reducing the amount of alkali lost in evaporative ponds which are fed with a purge liquor containing such alkali, comprising:
 contacting said purge liquor with a gas comprising carbon dioxide.   
     
     
         22 . The method according to  claim 21 , wherein the purge liquor is a part of a mother liquor comprising sodium carbonate taken out of a sodium carbonate crystallizer. 
     
     
         23 . The method according to  claim 22 , wherein the sodium carbonate content in the mother liquor is at least 175 g/kg. 
     
     
         24 . The method according to  claim 22 , wherein the sodium carbonate content in the mother liquor is not more than 250 g/kg. 
     
     
         25 . The method according to  claim 22 , wherein the mother liquor does not contain more than 30 g/kg of sodium bicarbonate. 
     
     
         26 . The method according to  claim 21 , which produces a water suspension comprising sodium bicarbonate crystals. 
     
     
         27 . The method according to  claim 26 , wherein sodium bicarbonate crystals are separated from the water suspension to form a second mother liquor. 
     
     
         28 . The method according to  claim 27 , wherein the second mother liquor is debicarbonated with vapor and then sent to a pond. 
     
     
         29 . A method for treating a purge stream containing an inorganic salt, comprising:
 treating said purge stream with gaseous carbon dioxide.   
     
     
         30 . The method of  claim 29 , wherein said purge stream comprises sodium carbonate. 
     
     
         31 . A method for extending the life of tailings ponds produced from purge streams containing inorganic salts, which method comprises treating such purge stream with gaseous carbon dioxide. 
     
     
         32 . The method of  claim 31 , wherein the purge stream is treated prior to it being deposited in the tailings pond. 
     
     
         33 . The method of  claim 31 , wherein such purge stream is a soda ash purge stream. 
     
     
         34 . The method of  claim 31 , wherein such inorganic salt comprises sodium carbonate.