Sciencemadness Discussion Board - Arsenic compounds from ore

Arsenic compounds from ore

vano - 4-10-2022 at 08:47

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]

Fery - 4-10-2022 at 10:06

vano you are lucky... woelen and me bought the ore from ebay in 2018 https://www.sciencemadness.org/whisper/viewthread.php?tid=85...

Lionel Spanner - 4-10-2022 at 11:11

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.

vano - 4-10-2022 at 11:40

Quote: Originally posted by Fery

vano you are lucky... woelen and me bought the ore from ebay in 2018 https://www.sciencemadness.org/whisper/viewthread.php?tid=85...

good price for 250g if it was good quality ore.

vano - 4-10-2022 at 11:45

Quote: Originally posted by Lionel Spanner

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.

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.

Lionel Spanner - 5-10-2022 at 08:09

Quote: Originally posted by vano

Quote: Originally posted by Lionel Spanner

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]

vano - 5-10-2022 at 08:49

yes, slow reaction. with nitric acid, it is way faster.

vano - 7-10-2022 at 03:55

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).

Picsart_22-10-07_15-54-50-895.jpg - 1.6MB

[Edited on 7-10-2022 by vano]

vano - 8-10-2022 at 03:46

Video of dissolving orpiment in conc. nitric acid.

woelen - 8-10-2022 at 12:18

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?

vano - 8-10-2022 at 12:40

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]

vano - 10-10-2022 at 00:03

undissolved silicate mineral particles.

311009068_793201071737391_6371388901590478161_n.jpg - 149kB

vano - 12-10-2022 at 08:03

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]