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Author: Subject: Iron sulfide experiment
Jose
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[*] posted on 6-6-2020 at 18:29
Iron sulfide experiment


I am trying to produce Ferrous/Ferric sulfate from ferrous sulfide. The way I went about it was to first prepare CaS by thermal reduction of CaSO4 with aluminum:

CaSO4+Al=CaS+ Al2O3

Next, I mixed CaS with Ammonium Carbonate found in fermented urine to make ammonium sulfide. I then reacted the Ammonium sulfide with ferric Chloride and a black precipitate formed.

After left for several days the black precipitate dissapeared leaving a yellow slurry. I want to know if the dissapearance of the black precipitate was caused by slow oxidation or the ferrous sulfide turned back to ferric oxide.

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Jose
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[*] posted on 6-6-2020 at 18:49


Here is the picture of precipitated solid.

[Edited on 7-6-2020 by Jose]

20200606_225815.jpg - 278kB
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Jose
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[*] posted on 6-6-2020 at 19:01


Here's the solid after air oxidation.

[Edited on 7-6-2020 by Jose]

20200606_230347.jpg - 485kB
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Ubya
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[*] posted on 7-6-2020 at 02:08


ferrous sulfide is quite stable, I doubt it oxidizes that easily in air.

That yellow doesn't look like iron oxide, could it be an iron polysulfide? you didn't wash the precipitate and left it for many days in excess of sulfide ions





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Boffis
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[*] posted on 7-6-2020 at 06:52


Quote: Originally posted by Ubya  
ferrous sulfide is quite stable, I doubt it oxidizes that easily in air.


Oh yes it does! particularly precipitated iron sulphide with a composition close to FeS. Iron sulphides closer to pyrite/marcasite FeS2 are a little more stable but the grain size of precipitated iron sulphide is probably less than 1 micron so even FeS2 will oxidize rapidly. However the products of oxidation are many and varied according to the conditions. In the presence of large amounts of water yellow ferric hydrate, a ferric hydoxide sulphate phase and sulphur are usually the main products. In a restricted supply of water ferric sulphates and sulphuric acid are the main products. While with a restricted supply of oxygen and fairly acid condition ferrous sulphate and mixed ferrous ferric sulphates form.

Take a look at the iron sulphate minerals on Mindat.org there are dozens, particularly if you through in a trace of potassium, sodium etc.

Out of curiosity what are you trying to achieve? What is your aim?
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Jose
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[*] posted on 8-6-2020 at 03:49


I am trying to get ferrous sulfate from air oxidation of iron sulfide. Just figuring out what conditions are needed and what to look out for.
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