Collecting Sulfur Dioxide from a sulphide roast

[goldshark]

I am wondering if the Sulfur dioxide given off from roasting iron pyrite, could be captured for reuse in precipitating Au from AR. I hate to waste anything, so am wondering if the fumes could be bubbled through distilled water, for use later.

 

[Yggdrasil]

I am wondering if the Sulfur dioxide given off from roasting iron pyrite, could be captured for reuse in precipitating Au from AR. I hate to waste anything, so am wondering if the fumes could be bubbled through distilled water, for use later.

Hmm, maybe.
I'm not sure how well it will hold up though.
Maybe compress it into a cylinder, but without proper certificated gear it may not be safe.

 

[Ultrax]

This is not a very good idea due to the presence of arsenic in the gas phase during roasting.
The presence of arsenic in varying quantities is characteristic of most sulfides.

 

[goldshark]

This is not a very good idea due to the presence of arsenic in the gas phase during roasting.
The presence of arsenic in varying quantities is characteristic of most sulfides.

No Arsenic in this material, just Iron Pyrite. I thought maybe someone on the forum might have some ideas to convert it to SO2, instead of scrubbing it, with just the intent of neutralization. I only roast maybe 10 lbs. at a time, so like many small lots, maybe it isn't worth doing, but thought I would throw it out there. More for the science and environmental aspect, than the economics.

 

[Ultrax]

No Arsenic in this material, just Iron Pyrite. I thought maybe someone on the forum might have some ideas to convert it to SO2, instead of scrubbing it, with just the intent of neutralization. I only roast maybe 10 lbs. at a time, so like many small lots, maybe it isn't worth doing, but thought I would throw it out there. More for the science and environmental aspect, than the economics.

Unfortunately, you will have to build a full-fledged chemical plant
If you have at least 100 million dollars
Sulfide roasting is precisely an industrial method for producing sulfur oxide and sulfuric acid.

 

[Alondro]

It would be very hard to catch these gasses with a backyard setup.

You'd need to have a hot gas pumping set up or a scrubber-type capture system. It's VERY costly.

The only cost-effective way to capture gasses small scale is with wet chemistry. It's much simpler to vent NO2 or SO2 from a flask of reacting liquid and bubble them through up to 20% hydrogen peroxide, which regenerates some of the nitric and sulfuric acids, respectively and can then be distilled through a simple distillation apparatus. See NileRed videos on Youtube for examples of such acid distillation equipment and how to operate them.

A cleaned aquarium bubbler stone is very handy to help with the acid regeneration, as the tiny bubbles vastly increase the surface area for reaction. But you want to find a bubbler stone that won't react with the acid.

 

[eaglekeeper]

There is different types of gas dispersion tubes or gas wash bottles with a fritted disk on Amazon that might hold up to the acid. They cost significantly more that an air stone though.

Unfortunately I didn't find any gas dispersion tubes with a 24/40 joint, so you would have to come up with some type of stopper set up.

 

[Ultrax]

Chinese sulfur dioxide in a cylinders (1000 kg) costs 1.6 per kilogram.
Link to Alibaba seller
How much fuel will you need to burn when calcining sulfides to obtain this amount?
In addition to all the necessary equipment for gas capture and storage?

P. S. We also work with sulfide concentrates. Based on our experience, the gases released during roasting are primarily a significant problem for equipment and not a potential income.

 

[Alondro]

There is different types of gas dispersion tubes or gas wash bottles with a fritted disk on Amazon that might hold up to the acid. They cost significantly more that an air stone though.

Unfortunately I didn't find any gas dispersion tubes with a 24/40 joint, so you would have to come up with some type of stopper set up.

I have lab glassware, armed flasks, chemically-resistant tubing, etc. The stuff Sreetips has.

The connector to the airstone I bought just happens to perfectly fit into the end of the tubing. The airstone will hold up to the relatively weak acid generated in the general bubbling step. You're not going to regenerate concentrated acid via bubbling. That's what the distillation step is for.

Or, you can use the weak acid to strip base metals from e-scrap, and just keep cycling the gas released over and over until you deplete the anion groups.

Another interesting note: if you drop copper from your nitrate solution with iron, you'll have iron(III) nitrate solution (and perhaps some iron(II) nitrate), which will decompose to solid iron oxide and nitric acid vapor when heated to a mere 275F (125C). Here, you merely need to cool the vapor with a water-cooled distillation tube to regenerate nitric acid.

 

[goldshark]

I have purchased some Stainless oxygen stones for another of my businesses. For those in need of one, I used to purchase them from a welding fabricator who specializes in dairy and food processing equipment. A bigger facility will have them in stock, or have a good source. Price in 2012 was around $25.00 per inch for 1" material, plus the cost of the fitting and welding it on.
My original thought was to bubble the fumes through distilled water, making a weak solution of SO2/H2O, and not going all the way to Sulfuric via a catalyst. Evaporate the water to increase strength of solution. Since I am not a chemist obviously, would the dilute SO2/H2O mixture still drop the Au?

 

[Yggdrasil]

I have purchased some Stainless oxygen stones for another of my businesses. For those in need of one, I used to purchase them from a welding fabricator who specializes in dairy and food processing equipment. A bigger facility will have them in stock, or have a good source. Price in 2012 was around $25.00 per inch for 1" material, plus the cost of the fitting and welding it on.
My original thought was to bubble the fumes through distilled water, making a weak solution of SO2/H2O, and not going all the way to Sulfuric via a catalyst. Evaporate the water to increase strength of solution. Since I am not a chemist obviously, would the dilute SO2/H2O mixture still drop the Au?

I do not know the concentration needed.
But is it not easier to just have some SMB and drop some HCl into it and produce what you need when you need it.
Or just buy a cylinder?

 

[goldshark]

I do not know the concentration needed.
But is it not easier to just have some SMB and drop some HCl into it and produce what you need when you need it.
Or just buy a cylinder?

of course your recommendations are easier, but I also have a quest for knowledge. I hate to waste anything, so proposed this to the forum. It can be amazing sometimes to see somebody come up with a simple scheme to solve a problem. That is why I proposed bubbling the fumes through distilled water, instead of a caustic water solution to neutralize it. Just a crazy thought.

 

[Ultrax]

of course your recommendations are easier, but I also have a quest for knowledge. I hate to waste anything, so proposed this to the forum. It can be amazing sometimes to see somebody come up with a simple scheme to solve a problem. That is why I proposed bubbling the fumes through distilled water, instead of a caustic water solution to neutralize it. Just a crazy thought.

I think this is a quest for money and not for knowledge
This problem has long been solved in the most economical and correct way - at chemical plants Attempts to “reinvent the wheel” will only lead to irrational savings on your own safety.

Not all stainless steel is suitable for working with acids. And even the one that fits - cannot be welded without specific treatment to avoid further corrosion.

Sulfur dioxide in water produces unstable sulfurous acid: SO₂+ H₂O → H₂SO₃. If you have the ability to supply oxygen to the mixture under pressure and heat it with the presence of copper sulfate, you will get sulfuric acid 2H₂SO₃+ O₂+ CuSO₄→ 2H₂SO₄.

But in my humble opinion, most likely, at home you will end up with two problems instead of income - one with health, and the second with the law. Of course, we can theorize and discuss , but the practice of such reactions is VERY expensive and dangerous.

P. S. And no, it is not possible to evaporate water from the SO₂+ H₂0 mixture; the gas will evaporate.

 

[goldshark]

I think this is a quest for money and not for knowledge
This problem has long been solved in the most economical and correct way - at chemical plants Attempts to “reinvent the wheel” will only lead to irrational savings on your own safety.

Not all stainless steel is suitable for working with acids. And even the one that fits - cannot be welded without specific treatment to avoid further corrosion.

Sulfur dioxide in water produces unstable sulfurous acid: SO₂+ H₂O → H₂SO₃. If you have the ability to supply oxygen to the mixture under pressure and heat it with the presence of copper sulfate, you will get sulfuric acid 2H₂SO₃+ O₂+ CuSO₄→ 2H₂SO₄.

But in my humble opinion, most likely, at home you will end up with two problems instead of income - one with health, and the second with the law. Of course, we can theorize and discuss , but the practice of such reactions is VERY expensive and dangerous.

P. S. And no, it is not possible to evaporate water from the SO₂+ H₂0 mixture; the gas will evaporate.

Thank you for the replies. It was just a thought. That is what I enjoy about the forum. Great people responding courteously, in a prompt and scientific manner.

 

[D-dog]

No Arsenic in this material, just Iron Pyrite. I thought maybe someone on the forum might have some ideas to convert it to SO2, instead of scrubbing it, with just the intent of neutralization. I only roast maybe 10 lbs. at a time, so like many small lots, maybe it isn't worth doing, but thought I would throw it out there. More for the science and environmental aspect, than the economics.

Sounds like an interesting experiment to play with. I too sometimes enjoy doing things the hard way just to see if I can do it.

Have you thought of using a stainless steel pressure cooker as the roasting vessel? You could use standard SS threaded tubing connectors and an aquarium air pump. Pump fresh air into it on one side and have a second/output tube that goes to the bubbling chamber, on the other side.
I'm sure that you would have to replace the over pressure release device, as they are not acid resistant. But since you don't want any real pressure. You could just use a silicone stopper.
Basically it would be a boiler still with a flow through air supply.

 

[goldshark]

I could use this method, if I was trying to drop Au, while roasting. Bubble through pregnant AR solution. Roasting pyrite does require a good amount of air flow to oxidize it. I would imagine it would bubble quite vigorously with the volume of air pumped through the AR. Any input from members on the industrial side of processing SO2 into cylinders?

 

[Ultrax]

Please do not accumulate large quantities of SO₂ gas without careful precautions, especially if you don't have a gas sensor and reliable ventilation!

This gas is significantly heavier than air (2.2 times), so in case of leakage, if you accidentally breathe it in sufficiently dangerous concentration and lose consciousness, you can die with no chance of being saved. Even in moderate concentrations, you can get a severe lung burn.

The rubber seals of a kitchen stainless steel pressure cooker will fail very quickly under the influence of sulfur dioxide.

 

[Ultrax]

I could use this method, if I was trying to drop Au, while roasting. Bubble through pregnant AR solution. Roasting pyrite does require a good amount of air flow to oxidize it. I would imagine it would bubble quite vigorously with the volume of air pumped through the AR. Any input from members on the industrial side of processing SO2 into cylinders?

Check a very inexpensive Chinese solution: Sulfur dioxide blower

 

[goldshark]

Yeah, get it, not doable on a small scale. Will stick with SMB, or if I can find a bottle of SO2 gas, may try that some day. Next question, if I get a bottle of SO2 gas, where do you get a regulator for it?

 

[Ultrax]

Check here: GR5000, Gas Regulator, SGS600 , SO2