Cinnabar (HgS) digestion

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Cinnabar (HgS) digestion

Postby mj.mirazimi on October 24th, 2016, 9:16 pm 

Hi everyone,

I am looking for a procedure useful for cinnabar (HgS) digestion. I have searched and found that using aqua regia won't be helpful and I should use more powerful reagent to digest cinnabar.

Thanks for your help and time :)
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Re: Cinnabar (HgS) digestion

Postby Natural ChemE on October 25th, 2016, 9:02 pm 

mj.mirazimi » October 24th, 2016, 8:16 pm wrote:I am looking for a procedure useful for cinnabar (HgS) digestion.

Are you looking to separate the mercury and sulfur?

Wikipedia suggests
Cinnabar, Wikipedia wrote:To produce liquid mercury (quicksilver), crushed cinnabar ore is roasted in rotary furnaces. Pure mercury separates from sulfur in this process and easily evaporates. A condensing column is used to collect the liquid metal, which is most often shipped in iron flasks.
, so, I guess crush it and heat?

Mercury boils at 356.75°C while sulfur doesn't boil 'til 444.6°C, so it seems reasonable that heating crushed cinnabar around 400°C should result in a decent separation.

PS - Huh, YouTube'ing this thing's interesting. This guy actually does the separation on a kitchen stove in a clay pot:
    .
Probably not the best way if you're got a lab, especially given mercury's toxicity, but still interesting to see.
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Re: Cinnabar (HgS) digestion

Postby mj.mirazimi on October 25th, 2016, 9:33 pm 

Hi,
Thanks for your response.
However, I am looking a way to separate the Hg and S. I want to dissolve the cinnabar (HgS) rock completely (digest). However, I have searched and found that using aqua regia would not be effective and this mineral is too tough to be dissolved by aqua regia. Also, I have found a procedure to use a mixture of sulfuric acid, nitric acid, and potassium permanganate to dissolve the HgS but it is reported that this procedure can not dissolve it completely :(
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Re: Cinnabar (HgS) digestion

Postby Natural ChemE on November 6th, 2016, 6:52 am 

mj.mirazimi,

Hey, sorry for the slow reply!

Here's one separation process: How Products are Made: Mercury.

Looks like:
  1. Grind cinnabar into a fine powder.
    • Roast the cinnabar at high temperature (~600°C?) with oxygen, producing mercury vapor and sulfur oxide.
      • Condense the vapor stream with cooling water to recover liquid mercury.
        • Claus reaction, , to recover the elemental sulfur.
        Are you going for a separation process like this, or are you specifically interested in finding an acid that'd reliably dissolve cinnabar without the need for heating?
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        Re: Cinnabar (HgS) digestion

        Postby mj.mirazimi on November 6th, 2016, 12:24 pm 

        Hi,

        Thanks so much for your response.
        Actually, I have some rocks (seems that they are cinnabar minerals) and I want to dissolve them (digest) to have the mercury in the solution so I can do AAS or ICP to detect mercury ions in my solution.
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