I recently found a place with an insane amount of pyrite (we are talking about tons) already smashed into smaller pieces, and I'm wondering if there is any way of converting it into sulfuric acid.

I'm aware that this is possible:

$$\ce{4 FeS2 + 11 O2 -> 2 Fe2O3 + 8 SO2}$$ $$\ce{2 SO2 + 2 H2O + O2 -> 2 H2SO4}$$

but it requires to heat up pyrite to quite some temperature :/

Is there any chemical extraction method available?

  • $\begingroup$ What's wrong with heating? Yes, chemical methods without heating are technically possible, but insanely costly. $\endgroup$ – Ivan Neretin Jun 14 '17 at 15:10

There is a direct reaction to convert pyrite to sulfuric acid by treating it with nitric acid.

$$\ce{FeS2 + 18HNO3 → Fe(NO3)3 + 2H2SO4 + 15NO2 + 7H2O}$$

Iron(II) disulfide react with and nitric acid to produce iron(III) nitrate, sulfuric acid, nitrogen dioxide and water. Nitric acid - concentrated solution. The reaction takes place in a boiling solution.(source)

But the problem is that iron(III) nitrate is soluble and does not precipitate in the solution. You have to distill off the sulfuric acid.

So, in my opinion heating pyrite in oxygen and then hydro-oxidising sulfur dioxide produced to form sulfuric acid is the cheap and efficient way because it does not require any additional chemicals as @Ivan mentioned.

Also, if you have money/curiosity, try using a cheap, oxidizing agent like nitrous or nitric oxide. The advantage in this process is that the products beside sulfuric acid are gases which can leave easily but I recommend you to stick to the plan.


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