RU_KLO
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Barium sulfate purification
Im purifying Barium Sulfate from Baryte rock.
Already have a procedure which I devised and am testing. (more later when all is done)
the question I have is:
"As barium sulfate is almost insoluble in water, digesting it with a concentrated NaOH solution (by digesting meaning: 1 hour, 70-80°C, 10M NaOH
solution), the NaOH will not attack it"
Is this statement true?
The idea of this procedure is to remove SiO2 contamination from baryte, but leaving BaSO4 behind. I dont want to use HF.
or how much time/concentration is needed to make SiO2 soluble with NaOH.
(water glass projects use 4 to 8 grams of sodium hydroxide in 10 milliliters of water. i.e 10M - 20M; Nurdrage uses 80gr NaOH/100 ml - 20M - for 60gr
SiO2)
[Edited on 1-7-2024 by RU_KLO]
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Sir_Gawain
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One industrial method of obtaining barium compounds from baryte is heating with carbon to reduce the sulfate to sulfide, dissolving the sulfide in
water, and precipitating barium carbonate or sulfate. The method you outlined should work, but will not provide as high purity. My best advice is to
just try it.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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Precipitates
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Barium sulphate still has some solubility (2.4 mg/litre), and may react under such harsh conditions i.e. hot, very concentrated NaOH (which seems fair
for dissolving silicon dioxide). But, if the loss in yield is small, it may be acceptable.
If the barium sulphate does react to a non-negligible extent, it may be worth just trying to dissolve all of it with the NaOH, and then adding
hydrochloric acid to precipitate out the silica.
Then you can add NaOH to the barium chloride filtrate to recover barium hydroxide again. Depending on the visual purity you may want to perform a
recrystallisation or two to remove iron (or/and alumina) impurities.
If you would then like barium sulphate, it can be obtained by reacting the hydroxide with calcium sulphate. Although barium hydroxide is a better
starting point for barium compounds.
[Edited on 2-7-2024 by Precipitates]
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RU_KLO
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Quote: Originally posted by Precipitates  | Barium sulphate still has some solubility (2.4 mg/litre)....
If the barium sulphate does react to a non-negligible extent, it may be worth just trying to dissolve all of it with the NaOH, and then adding
hydrochloric acid to precipitate out the silica.
Then you can add NaOH to the barium chloride filtrate to recover barium hydroxide again.
[Edited on 2-7-2024 by Precipitates] |
It more difficult than this. You cannot go from BaSO4 to chloride directly.
(you need to convert it first to carbonate by refluxing long time, molar ratio 2:1 to 4.8:1 - Na2CO3:BaSO4 - depends on the source of information)
this is from our wiki:
The trick is that barium carbonate is even less soluble than barium sulfate, and sulfate can be converted to carbonate by lengthy boiling in a
solution of sodium carbonate. This should be done under reflux, to prevent the solution in the pot from drying.
also BaSO4 solubility is 0.2448 mg/100 mL (20 °C) or 0.025 mg per liter...
the method for making/purifying BaSO4 soluble is in NaCl (840°C), up to 40% BaSO4 will dissolve in fused/molten NaCl.
Decant the impurities(in the molten NaCl) add Na2CO3 (4.8:1 ratio)
30 minutes and you have 95% convertion to BaCO3.
(the same procedure can be done with flourides (CaF2) to NaF/KF and gypsum to CaCO3 - but other alkaly earth halide should be used)
US2112903A
US2013401
Conversion of Barytes to Barium Carbonate
HAROLD SIMMONS BOOTH AND ELISHA FREDERICK POLLARD'
Western Reserve University, Cleveland 6, Ohio
[Edited on 2-7-2024 by RU_KLO]
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bnull
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Why not the other way around: dissolving BaSO4 and leaving silica as it is? A process is described in patent US1752244A, "Process for refining and purifying barium sulphate". I thought at first of EDTA or some other chelating agent but, inorganic salts
being cheaper and easier to handle, the latter seem to be a better idea.
Attachment: US1752244.pdf (457kB)
This file has been downloaded 94 times
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RU_KLO
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| Quote: Originally posted by bnull |
Why not the other way around: dissolving BaSO4 and leaving silica as it is? A process is described in patent
|
Just read it, it does not remove SiO2, it just make it easier to remove later "If silica or silicates are present in objection able amounts in the raw
material, a mixture of sulphuric acid, with a small amount of hydrofluoric acid, serves to decompose and render soluble both the iron and the silica
compounds.
Maybe I could add this procedure as starting procedure to make the baryte more "ready" to acid attack.
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Sulaiman
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'a small ammount of hydrofluoric acid' may passivate some contaminants making them difficult to remove later,
just guessing.
CAUTION : Hobby Chemist, not Professional or even Amateur
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EF2000
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If there are calcium compounds in baryte rock (and I guess there are), HF can turn them into CaF2, that is unfortunately insoluble and will be hard
to remove. Same problem with strontium sulphate, celestine, that is often found with baryte.
Wroom wroom
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bnull
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Did you consult the references given in page 2 of the patent (see figure)? I can't give you any directions since the majority of the papers are in
German, and my translations from it are sufferable at best. Perhaps you could adapt something from them.
Quod scripsi, scripsi.
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