Using the solid waste-quicklime membrane swqm process for the production of sodium hydroxide

Abstract

The proposed invention uses ion exchange technology to produce dilute caustic soda liquor from calcium hydroxide liquor Ca(OH) 2 followed by the reaction of carbon dioxide CO 2 with caustic soda to produce dilute sodium carbonate solution. Multiple reverse osmosis and acidic CO 2 sparging can concentrate the Na 2 CO 3 liquor to 6-7%. The 6-7% liquor is treated with waste heat to produce 50% or solid Na2CO3. The 6-7% liquor can be treated with Ca(OH) 2 to produce 6-7% NaOH liquor then can be transformed to 50% or solid NaOH. The output of many industrial processes generates waste heat, brine water and CO2 and the present invention combines these components in the production of solid Na 2 CO3, NaOH or their high % liquors. Availability of waste heat sources can lead to higher efficiency in Na 2 CO 3 and NaOH production. The process is not electrochemical chloro alkali technology or Solvay process.

1 . The process by which ion exchange technology to produce dilute caustic soda liquor from calcium hydroxide liquor Ca(OH)2 followed by the reaction of carbon dioxide CO 2  with caustic soda to produce dilute sodium carbonate solution. Multiple reverse osmosis and acidic CO2 sparging can concentrate the Na2CO3 liquor to 6-7%. The 6-7% liquor is treated with waste heat to produce 50% or solid Na2CO3. The 6-7% liquor can be treated with Ca(OH) 2  to produce 6-7% NaOH liquor then can be transformed to 50% or solid NaOH. The invention requires three chemicals CO 2 , Ca(OH) 2 , and sodium chloride NaCl to produce NaOH. The output of many industrial processes generates waste heat, brine water, and CO 2  and the present invention combines these components in the production of solid Na2CO3, NaOH or their high % liquors. Availability of waste heat sources can lead to higher efficiency in Na2CO3 and NaOH production. The process is not electrochemical chloro-alkali technology or Solvay process. There are similarities in the hardware in patent # PCT/1B2008/002020 but the present patent differs in the mechanism of operation of the ion exchange reverse osmosis system and includes utilization of acidic flue gas. 
     
     
         2 . The present invention uses the SWQM process in patent# PCT/1B2008/002020 to eliminate the need for high consumption of electric power as in chloro-alkali technology. 
     
     
         3 . The use of brine and acidic water and advanced membrane and resin technology in solid waste processing and the production of soda ash Na2CO3 and caustic soda NaOH. 
     
     
         4 . The process by which this invention attempts to bring solid waste, brine water waste, acidic water waste extracted from acidic flue gas, and CO2 waste problems in one industrial process to bring about a green solution through large elimination of the various wastes stated above while making a financial benefit from selling the soda or caustic soda commodity chemical as byproduct of the combined processes. 
     
     
         5 . The process which essentially relies on advanced membrane technology systems to produce soda ash Na2CO3 and caustic soda NaOH we claim the following combined stages (i) to (iv) of the process:
 (i)- Sparger design: Acidic flue gas can be sparged under pressure to dissolve the acidic gas in sea water or river water to form acidic liquor that can be used in strong or weak ion exchange regeneration.   (ii)-Ion exchange system: Would receive the calcium hydroxide liquor Ca(OH)2 (e.g. ˜0.5 g/L) to produce a dilute caustic soda liquor at 1000 ppm concentration or higher depending on the type of ion-exchanger used.   (iii)-Reactors design: Carbon dioxide gas is sparged through caustic soda NaOH in a reactor to form a dilute sodium carbonate liquor Na2CO3 (e.g. 700 ppm Na2CO3 to 300 ppm NaOH). The latter is then subjected to further filtration to remove impurity particulates then passed to reverse osmosis system. The low % liquor needs to be converted and concentrated to higher % sodium carbonate Na2CO3 liquor (e.g. 2400 ppm Na2CO3 to 1000 ppm NaOH) by passing it to a reverse osmosis system under controlled pH conditions.   (iv)-Reverse osmosis (RO) unit contains RO cartridges cascaded with the CO2-NaOH reactors in between. The objective is to keep the NaOH concentration below 300 ppm as the concentration of Na2CO3 is increased.