# Better step for remove iron with HCL



## j2000 (Nov 27, 2015)

Hi, iam sorry if this post already in other post...

I need to ask, I need to clean sample where is much Fe and S (sulfur)...
I wanna clean the Fe using HCL.
The question is:
Better i direct clean Fe include S with HCL ?
or 
Better i doing inceneration first around 700 deg celcius to boiling the sulfur?

Iam sorry if this question too newbie 

Regards

Joel


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## Barren Realms 007 (Nov 27, 2015)

What kind of material are you processing? Ore?


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## j2000 (Nov 27, 2015)

Yes, ore but form is powder...

Thanks


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## solar_plasma (Nov 27, 2015)

Only regarding iron, sulfur and gold (assuming there is nothing else):

You will want to completely roast off the sulfur first, otherwise you would have to deal with toxic H2S gas.

If there are other dangerous elements involved, this might not be an adequate answer.


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## j2000 (Nov 27, 2015)

Thanks Solar_Plasma,
There's also Gypsum in small qtt...


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## upcyclist (Nov 27, 2015)

j2000 said:


> Better i direct clean Fe include S with HCL ?
> or
> Better i doing inceneration first around 700 deg celcius to boiling the sulfur?



It's a little unclear: Are there sulfides/sulfates/sulfur in your ore, or are you talking about processing with sulfuric acid?

I understand you may not be a native English speaker, but precision in language is important on this forum. Since you said "boil", I question whether you are talking about roasting off sulfur compounds or heating an acid solution. "Roast" or "incinerate" are appropriate for solids, "boil" is for liquids. Even if you're talking about acids, you may want to heat, but be careful about boiling. It's dangerous, and often unnecessary.


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## Geo (Nov 27, 2015)

Roast the ore to a dull red heat and keep it there for about 20-30 minutes unless you are doing hundred pound lots at a time. I remember seeing the huge cast iron pots at mining camps and thinking they were cooking a lot of soup at one time. Later I found out what they were really being used for.


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## j2000 (Nov 28, 2015)

upcyclist said:


> j2000 said:
> 
> 
> > Better i direct clean Fe include S with HCL ?
> ...



Thanks upcyclist, i just knowing now, boil is just for liquid not for solid thing in chemical...
Its powder (solid) something like from ore, and i need to clean iron on this ore using HCL, but as i know this ore also have much sulfur, or fe sulfate (iam sorry is different).


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## j2000 (Nov 28, 2015)

Geo said:


> Roast the ore to a dull red heat and keep it there for about 20-30 minutes unless you are doing hundred pound lots at a time. I remember seeing the huge cast iron pots at mining camps and thinking they were cooking a lot of soup at one time. Later I found out what they were really being used for.



Thanks for your suggest....so its better to roast it first than clean with HCL...
Btw,as i know something like sulfur boiling point is 400 more celcius, i prefer using 800 deg celcius, it's ok?

Regards

Joel


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## solar_plasma (Nov 28, 2015)

about how to roast sulfide containing gold ores: Roserich, Metallurgy of gold, p. 237

http://ia700400.us.archive.org/35/items/metallurgyofgold00roserich/metallurgyofgold00roserich.pdf

Be aware of some nasty vapors and gasses under the roasting process. At least SO2 after oxidizing the sulfides with heat and air. Possibly arsene and selen compounds, zinc oxide vapors and probably other nasty stuff I can't think of right now.


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## j2000 (Nov 28, 2015)

solar_plasma said:


> about how to roast sulfide containing gold ores: Roserich, Metallurgy of gold, p. 237
> 
> http://ia700400.us.archive.org/35/items/metallurgyofgold00roserich/metallurgyofgold00roserich.pdf
> 
> Be aware of some nasty vapors and gasses under the roasting process. At least SO2 after oxidizing the sulfides with heat and air. Possibly arsene and selen compounds, zinc oxide vapors and probably other nasty stuff I can't think of right now.



Thanks Solar_Plasma, 
That is very sacred book, since 1899, cover included...hehehe

I already download now...
Thanks for sharing...

Regards

Joel


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## g_axelsson (Nov 28, 2015)

From the discussion I get the impression that more than one person thinks that sulfur and sulfides are the same thing, or iron can be treated just as iron sulfide (pyrite).

Molecules does not behave like their elements. For example sulfur boils at 444 °C while thermal decomposition of pyrite, FeS2, into FeS (iron(II) sulfide) and elemental sulfur starts at 540 °C and starts to pick up speed at around 700 °C.
FeS is a very stable compound ( melting point 1194 °C ) when heated but reacts easily with oxygen, giving iron oxides and sulfur dioxide.

So just heating pyrite to 500 °C doesn't remove any sulfur, you need to go higher and you need to add oxygen to remove all sulfur. Other sulfides are more or less sensitive to be heated up, so the composition of ore could affect how easy it is to remove sulfur and in the end decide how hot and for how long you need to roast it.

The same goes for believing that HCl would remove any iron from an ore. There are many compounds that is not affected by hydrochloric acid, pyrite is one I think.

Göran


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## NobleMetalWorks (Nov 28, 2015)

If you are not sure what the ore might contain in the way of elements and minerals, you might serve yourself well by having it assayed.

An elemental assay might show problematic metals in your concentrate, such as vanadium, zirconium, chromium, cadmium, etc. 

If you know there are values in your concentrates, and are having issues resolving them with only an elemental assay, you may wish to have a mineral assay done. If you are aware of what mineral forms of iron are in your material, you will then better know how to progress with ridding your concentrate of those issues. Or at the very least know the correct questions to ask on the forum.

Your material may require a pre-treatment or leach. It may require a smelting process prior to wet chemistry. It may require smelting, wet chemistry, melting, electrochemistry, etc. I am currently working with a material that requires roasting, washing, smelting, melting and then atomizing, and then wet chemistry. I would not have known to go about processing these concentrates in this way unless I first conducted a elemental and mineral assay.

Scott


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## j2000 (Nov 29, 2015)

g_axelsson said:


> From the discussion I get the impression that more than one person thinks that sulfur and sulfides are the same thing, or iron can be treated just as iron sulfide (pyrite).
> 
> Molecules does not behave like their elements. For example sulfur boils at 444 °C while thermal decomposition of pyrite, FeS2, into FeS (iron(II) sulfide) and elemental sulfur starts at 540 °C and starts to pick up speed at around 700 °C.
> FeS is a very stable compound ( melting point 1194 °C ) when heated but reacts easily with oxygen, giving iron oxides and sulfur dioxide.
> ...



Thanks for your explanation goran, i use 700 to 850 deg C, sometimes almost 1000.


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## j2000 (Nov 29, 2015)

NobleMetalWorks said:


> If you are not sure what the ore might contain in the way of elements and minerals, you might serve yourself well by having it assayed.
> 
> An elemental assay might show problematic metals in your concentrate, such as vanadium, zirconium, chromium, cadmium, etc.
> 
> ...



So far when i roasted, the powder ore contentrate lost weight for 1000 gram to be 800 gram, and then clean using HCL the weight will lost at least 400 gram, sometime over 500gram (not final).
So we still test and test, hope in this month we will have final result...
So far we got the gold but very low quantity...almost no profit...
I believe cleaning process too far from perfect...

But i hope someday i will find the best way...

Regards

Joel


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## solar_plasma (Nov 29, 2015)

If the yield was high or low depends on how much gold this ore is containing. Did you assay it? You should do it:


“The hardest thing of all is to find a black cat in a dark room, especially if there is no cat.”

― Confucius


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## dkbinco (Oct 7, 2022)

There is another post called Grinding your ore a second time that sugest a second grind will cause iron oxides to release the gold they still have encapulated. Still waiting to hear on method of second grind technique. I am questioning a ball mill...


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## Deano (Oct 7, 2022)

Iron is best removed from ores by simmering the ore in HCl, from 10 to 20% HCl is used in most cases. The HCl can be reused until the iron removal quality reduces significantly.
Unless you have high gold levels in the ore the cost of iron removal is prohibitive.
For complete iron removal you need to have a reducing agent present, unfortunately the best agent is stannous chloride which ups your costs considerably.
Deano


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## Ultrax (Oct 9, 2022)

Iron (without roasting) or iron oxide (after roasting) removal is not required in most cases of pyrite processing. The best way is to use direct smelting of pyrite concentrate with Na2CO3 and lead as a collector (in this case you don't need roasting at all - all iron will form iron-sodium slag). The second way is to use a high-temperature thiosulfate-ammonium-copper leaching process. Iron oxides will leave intact in the leaching wastes.


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## stampeden (Nov 4, 2022)

Roasting of arsenopyrite concentrates can be tricky and extractable values can and lost. If I remember, you need a two-stage roast. First at about 650 degree C - then after removing the sulfur and arsenic - raise the temp to 900 degree C to finish. If a direct high temp roast is used the values can lock-up and become refractive.


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## orvi (Nov 4, 2022)

Ultrax said:


> Iron (without roasting) or iron oxide (after roasting) removal is not required in most cases of pyrite processing. The best way is to use direct smelting of pyrite concentrate with Na2CO3 and lead as a collector (in this case you don't need roasting at all - all iron will form iron-sodium slag). The second way is to use a high-temperature thiosulfate-ammonium-copper leaching process. Iron oxides will leave intact in the leaching wastes.


Depends on quantity of the cons and richness. As for pyrite, you need to add whole lot of soda to break possible matte layer forming. All doable, but with poor quality cons, cost of the flux will be quite ramping. If leaching is applicable, it is a way to go. Slow roasting at lower temperatures with good scrubber (for SO2 and possible arsenic) will leave iron oxides, which are relatively easy to pulverize even more, and then leaching is relatively effective if setup is right.


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