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learner1112
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mnso4 industrial route
i am trying to figure out an economical industrial route of processing mnso4 from natural ore. essentially mno2. the first process is to burn sulphur
and inject the so2 formed into the crushed ore and water solution. the slurry thus obtained is kept at ph4-4.5 by adding lime. after the reaction the
slurry is filtered and the liquid which is pink in colour is obtained. now the problem is how to seperate the mnso4 present in the solution. can
anyone guide me, as when i try to heat the solution its ph goes down and it becomes acidic with evolution of so2 gas and probably the mnso4 is
converted baqck to mno2.
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acetatecorp
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Manganese Carbonate
Thanks for the detailed procedure Peach, I followed your instructions and got the same fabulous result. Just one question about the Manganese
carbonate:
It works great via the double displacement of the Manganese Sulphate and the Sodium Bicarbonate, but when done with Manganese Sulphate + Sodium
Carbonate I get a fluffy brown precipitate that dries to a light brown powder with a carbonate feel. I've researched and looked up many photos of
Manganese carbonate for sale and many of these are in fact brown. On other parts of the net the colour varies from white to light pink.
I've gone over the reaction equations also and I'm stumped as to why I get two very different results. Also, when making the acetate (II) from this
brown powder & AA, the reaction does not work and produces a small amount of dark brown precipitate.
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acetatecorp
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Sorry, this is my first post on here and my question probably wasnt clear:
Does anyone know why there is such a huge discrepancy between trying to make the carbonate from Sodium Carboante VS. Sodium Bicarbonate?
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blogfast25
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Quote: Originally posted by acetatecorp  | Sorry, this is my first post on here and my question probably wasnt clear:
Does anyone know why there is such a huge discrepancy between trying to make the carbonate from Sodium Carboante VS. Sodium Bicarbonate?
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There should be no discrepancy at all, assuming similar purities of the sodium carbonate and bicarbonate. Using carbonate will cause no
CO<sub>2</sub> fizz, of course.
Technical grade MnCO<sub>3</sub> varies in colour from white with a pink tinge (very pure) to beige to beige/brown (quite impure). The
contamination is almost always due to iron(III) oxide. Mn and Fe are often found together and are not so easy to separate. They will precipitate
together using carbonate/bicarbonate, the iron as Fe(OH)<sub>3</sub>.
[Edited on 22-4-2015 by blogfast25]
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UC235
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On leaving some freshly prepared, moist manganese carbonate outside a few years ago it became a light brown from a pink-tinged white. I assumed that
this was oxidation to MnO2, so the brown color of a commercial sample may not be entirely due to iron contamination.
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acetatecorp
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Thanks @blogfast25. I used cheap washing soda so probably very impure. I'll try getting AR grade sodium carbonate and test again or dehydrate some
baking soda.
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blogfast25
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| Quote: Originally posted by UC235 | | On leaving some freshly prepared, moist manganese carbonate outside a few years ago it became a light brown from a pink-tinged white. I assumed that
this was oxidation to MnO2, so the brown color of a commercial sample may not be entirely due to iron contamination. |
The samples that weren't very white that I've analysed all tested positive for Fe(III).
Of course moisture is a vector for air oxygen, so some oxidation to MnO2 is a possibility. Mn(II) carbonate has a general 'reputation' for being
stable though.
| Quote: Originally posted by acetatecorp | Thanks @blogfast25. I used cheap washing soda so probably very impure. I'll try getting AR grade sodium carbonate and test again or dehydrate some
baking soda.
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Or make a hot, saturated washing soda solution, hot filter carefully (sometimes it contains a bit of anti-caking MgO) and allow filtrate to cool and
chill. Collect quite pure Na2CO3.10H2O. Repeat for super purity, if needed. The decahydrate isn't very stable though (loses water) and for
stoichiometric work it's best dehydrated first.
Baking soda sometimes goes brown on heating because of rice powder as anti-caking agent. It's a test of purity: if it browns on heating it's not very
pure.
[Edited on 22-4-2015 by blogfast25]
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