## Cinnabar (HgS) digestion

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### Cinnabar (HgS) digestion

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 :)
mj.mirazimi
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### Re: Cinnabar (HgS) digestion

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.
Natural ChemE
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### Re: Cinnabar (HgS) digestion

Hi,
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 :(
mj.mirazimi
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### Re: Cinnabar (HgS) digestion

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, $2{{\text{H}}_{2}}{\text{S}}+{\text{S}}{{\text{O}}_{2}}{\rightarrow}3{\text{S}}+2{{\text{H}}_{2}}{\text{O}}$, 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?
Natural ChemE
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### Re: Cinnabar (HgS) digestion

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.
mj.mirazimi
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