vano
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Arsenic compounds from ore
Hello. I had good ore of arsenic from the mountainous region of Caucasia and today I removed sulfide minerals from that rocks. to tell you truth I
removed small rocks from the sulfide mineral. every rock was almost sulfides. a major component was orpiment with a small amount of realgar. it isn't
soluble in hydrochloric acid but I dissolved it in conc. nitric acid very easily produces arsenic acid. the solution was clear, without any color.
photos of my mineral:
some rocks contain only orpiment, but when I mix orpiment-realgar finally powder was orange
https://en.wikipedia.org/wiki/Orpiment#/media/File:Orpiment....
 
[Edited on 4-10-2022 by vano]
[Edited on 4-10-2022 by vano]
[Edited on 4-10-2022 by vano]
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Fery
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vano you are lucky... woelen and me bought the ore from ebay in 2018 https://www.sciencemadness.org/whisper/viewthread.php?tid=85...
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Lionel Spanner
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Apparently, if you're after arsenic trioxide, there's a wet process that can produce it directly from the ore, using conc. sulphuric acid.
https://www.scientific.net/AMR.662.437
I've not tried it myself, so I can't comment on its effectiveness.
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vano
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good price for 250g if it was good quality ore.
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vano
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I use sulfuric acid also to dissolve sulfide but nothing happened, I use different concentrations also. I think conc. nitric acid is the best way,
also because of its fast reaction.
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Lionel Spanner
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Quote: Originally posted by vano  |
I use sulfuric acid also to dissolve sulfide but nothing happened, I use different concentrations also. I think conc. nitric acid is the best way,
also because of its fast reaction. |
It doesn't dissolve - it turns a slurry of the sulphide into the equally insoluble oxide. According to the paper, you also need to heat it at about
120 °C for two hours for this reaction to take place.
[Edited on 5-10-2022 by Lionel Spanner]
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vano
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yes, slow reaction. with nitric acid, it is way faster.
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vano
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I used 20 g of orpiment mineral. First i made arsenic acid, then ammonium arsenate trihydrate and 12-molybdoarsenic acid. Now I'm trying to make
amorphous arsenic(filter paper).
[Edited on 7-10-2022 by vano]
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vano
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Video of dissolving orpiment in conc. nitric acid.
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woelen
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Mood: interested
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Can you give some experimental details about how you made the ammonium arsenate and isolated this? Also interesting to see how you made the arsenic
powder. What yield did you have? Is the elemental arsenic reasonably pure?
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vano
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first, it was almost sulfide. solution of arsenic acid was clear and transparent. then I neutralized it with ammonium hydroxide and recrystallized it
twice the time. it is white and looks pure, but I want to make it much purer. also, I used exec nitric acid, so there is no As3+.
this time I just test how the process going. Tomorrow ill crystalize it a few times or try a different method. also, I use it in some test tube
reactions it is acceptable for me as a oremade reagent.
about arsenic. it formed a black-brownish amorphous powder very easily. but I am just interested if the reduction was easy for 5+, and it was, I just
use a crude solution of arsenic acid I can't give you details. the As powder was in small amounts so I didn't save it. it works but I prefer to make
useful compounds.
also, I tried reduction with zinc powder and also aluminum foil. both works.
[Edited on 8-10-2022 by vano]
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vano
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undissolved silicate mineral particles.
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vano
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I started to make much purer arsenate. here is MgNH4AsO4 which is insoluble arsenate. I precipitated this to separate it from the sulfate.
ill make this reaction, separating magnesium hydroxide from the solution, then I will heat the solution to remove ammonia.
MgNH4AsO4 + 3NaOH = Na3AsO4 + Mg(OH)2 + NH3 + H2O
ill wright details when ill make sodium arsenate finally.
[Edited on 12-10-2022 by vano]
[Edited on 12-10-2022 by vano]
[Edited on 12-10-2022 by vano]
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