Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/69—Sulfur trioxide; Sulfuric acid
  • C01B17/74—Preparation
  • C01B17/745—Preparation from sulfates
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
  • C01D1/04—Hydroxides
  • C01D1/28—Purification; Separation
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
  • C01D1/04—Hydroxides
  • C01D1/28—Purification; Separation
  • C01D1/38—Purification; Separation by dialysis
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
  • C01D5/06—Preparation of sulfates by double decomposition
  • C01D5/10—Preparation of sulfates by double decomposition with sulfates of magnesium, calcium, strontium, or barium

Definitions

• Tittle A combined reverse osmosis/ion exchange/electrodialysis (CROIED) process that uses gypsum as a raw material to produce sulfuric acid and sodium hydroxide.
• CROIED reverse osmosis/ion exchange/electrodialysis
• the said invention is highly useful when there is a source of gypsum or waste gypsum.
• gypsum or waste gypsum For example, in the phosphoric acid industry for every 1 .0 ton of phosphoric acid produced 5.0 tons of gypsum might go to waste. Coal fired power plants and similar releases large quantities of waste gypsum due to flue-gas desulfurization.
• a first major challenge is to reduce the impurities that stick to the gypsum particulates in order to get sodium sulfate product with acceptable purity. Therefore, first step in the CROIED process is to use ion exchange/filtration technology to convert waste gypsum to sodium sulfate.
• the CROIED process comprises an instrumental setup of ion exchange resin beds, reverse osmosis membranes, and an electrodialysis battery.
• the process starts with sedimentation/clarifier tanks that remove highly insoluble solids followed by microfiltration to remove micron size suspended solids.
• calcium sulfate (CaS0 4 ) gypsum powder of solubility ⁇ 2.1 -2.4 g/L gets processed with the desired volume of water to produce CaS0 4 slurry.
• the slurry is then passed through the microfiltration system to obtain CaS0 4 filtrate liquor such that,
• the filtrate is allowed to undergo an ion exchange process using a strong or weak acid cation (WAC) exchange bed to transform the liquor into sodium sulfate (Na 2 S0 4 ) such that,
• the bed is continually regenerated acting as a sodium pump for the production of Na 2 S0 4 .
• the Na 2 S0 4 concentration is set at 0.2% which can be concentrated to 7-8% using reverse osmosis technology typically applied in waste water treatment and brackish water technology ⁇ check supplemental flow chart).
• the 7-8% Na 2 S0 4 liquor is ready for processing by the electrodialysis bipolar membrane (EDBM) system where it gets converted to sulfuric acid (H 2 S0 4 ) and sodium hydroxide (NaOH), such that, 2Na + ( aq) + S0 4 2' ( aq) + H 2 0 ( i) + Energy ⁇ H 2 S0 4( a q ) + NaOH (aq )
• Mass Balance Starting with "gypsum" at 5.0 tons/hr. Using the 1E/RO section of the CROIED process the total Na 2 S0 4 that can be produced will be approximately 3.5-4.5 tons/hr in the 7% liquor. After processing the 7-8% Na 2 S0 4 liquor in the EDBM system sulfuric acid ( ⁇ 8%) and sodium hydroxide (-8%) streams are generated at the output.
• Block diagrams of ENGSL invention that uses gypsum to produce sulfuric acid and sodium hydroxide:
• the sulfuric acid stream -29 m3/hr with 8% TDS is evaporated up to 70-75% concentration which would contain 2.3-2.5 tons hr of sulfuric acid.
• the byproduct NaOH produced is 1 .92-1 .95 tons/hr that can be obtained as 3.8-4.0 nrVhr of 50% liquor using separate evaporator.
• the expected power consumption can vary between 2.75-2.85 MWH depending on the efficiency of the installed units in the CROIED process such as energy recovery devices, low energy membrane modules, latest advanced EDBM units, and most important efficient evaporators.
• 1 - Sulfuric acid can be produced using waste gypsum rather than harness the contact process that converts sulfur powder to sulfuric acid.
• the EDBM technology can be designed to produce only sulfuric acid if sodium hydroxide is not desired at lower energy consumption.
• Supply of sodium chloride can be from seawater using combined Nanofiltration/Reverese osmosis technology or rock salt from mining industry.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Urology & Nephrology (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=45888438

Family Applications (1)

Country Status (1)

Citations (2)

• 2012
  • 2012-02-09 WO PCT/IB2012/000276 patent/WO2013117950A1/fr not_active Ceased

Patent Citations (2)

Non-Patent Citations (3)

Similar Documents

Legal Events