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How to purify Na2SO4 ?

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metallurgy:
If Sodium sulphate waste product contains these materials:


--- Code: ---84 ~ % Na2SO4
--% Na2CO3
--% NaCl
--% NaF
pH=8.00 (in 5% solution)
--- End code ---

How to purify it to obtain pure Na2SO4 (99%)?

billnotgatez:
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metallurgy:

--- Quote from: billnotgatez on February 11, 2020, 11:48:46 AM ---You have to show your attempts or thoughts at solving the question to receive help.
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Click on the link near the top center of the forum page.
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--- End quote ---
Okay.
There are ways to purify Na2So4 like adding ferric sulphate into solution or fractional cristallization (very old default method), evaporation etc. etc.
https://patentimages.storage.googleapis.com/3a/cf/c9/8b7700c0c8da9a/US1673471.pdf
Removing impurities is important, but i dont know how to purify the industrial waste of sodium sulphate which has NaCL and NaF as these are high rate impurities...

AWK:
Your problem looks technological, I mean a large scale process. Besides, I can guess that you have solid impure sodium sulfate. In this case, the patent you cite may be useful if you adapt it to the composition of the impurities (the patent was intended for purifying the thenardite mineral without dissolving it). Therefore, you need to know the composition of the impurities quite accurately. According to this patent, anhydrous sodium sulfate is obtained. Decahydrate can be obtained by recrystallization. Carbonates and fluorides are relatively easy to remove, but you need to think about what to do with waste sodium chloride containing about half the sodium sulfate by mass.

metallurgy:

--- Quote from: AWK on February 12, 2020, 06:24:00 AM ---Your problem looks technological, I mean a large scale process. Besides, I can guess that you have solid impure sodium sulfate. In this case, the patent you cite may be useful if you adapt it to the composition of the impurities (the patent was intended for purifying the thenardite mineral without dissolving it). Therefore, you need to know the composition of the impurities quite accurately. According to this patent, anhydrous sodium sulfate is obtained. Decahydrate can be obtained by recrystallization. Carbonates and fluorides are relatively easy to remove, but you need to think about what to do with waste sodium chloride containing about half the sodium sulfate by mass.

--- End quote ---

Na2CO3 is 1-2% , NaCl 7-8%, NaF around 1%, the waste is solid yes, but the mentioned patent is from 1928, i've found another new patent:
https://patentimages.storage.googleapis.com/b7/72/43/3ff64f01856048/US20060163164A1.pdf

This says adding ferric sulphate into a solution to form suspension, plus they are adding peroxide to remove heavy metals which can be useful to clear impurities? I have no idea what kind of plant can do this as an industrial scale. For doing this may be this patent: https://patents.google.com/patent/US4246241A/en give an idea to separate NaCl from sodium sulphate...

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