# precipitating from sulfuric



## azdave35 (Jul 28, 2011)

i'm pre treating some ore in sulfuric acid in prep for leaching...i want to drop the metals from the sulfuric solution to see what base metals are in the ore....what do i use to drop them?...zinc maybe?...do i need to neutralize the acid before i drop the metals?..any help would be appreciated


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## Arrowood (Jul 28, 2011)

I dont know enough about this yet to help you,.. but I am very curious as to how you will test the precipitates you drop to learn what metals are present. I may try what you are doing to my ore next. I probably just add NaOH to a sample of the solution first to see if that precipitates anything however. Thanks for the idea! :lol:


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## azdave35 (Jul 28, 2011)

anytime you leach an ore you need to identify and eliminate the enemies (base metals...they will consume your leach and cause other problems) prior to leaching...once you know which base metals you are dealing with ...then you can come up with the proper pre treatment


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## Arrowood (Jul 28, 2011)

I was under the impression that removing base metals was the objective of the HCl / peroxide process,.. does sulfuric acid do the same thing? Are you adding peroxide to the sulfuric acid too?


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## azdave35 (Jul 28, 2011)

no...the suilfuric acid is just a pre treat that you do first before you leach...it gets rid of iron...lead..copper and a host of other nasties


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## Arrowood (Jul 28, 2011)

Ahh,. I see,.. I just got this info from wikipedia,.. "Sulfuric acid reacts with most metals via a single displacement reaction to produce hydrogen gas and the metal sulfate. Dilute H2SO4 attacks iron, aluminium, zinc, manganese, magnesium and nickel, but reactions with tin and copper require the acid to be hot and concentrated. Lead and tungsten, however, are resistant to sulfuric acid."

I assume you heated the sulfuric acid before you treated the ore? What about the lead however?,.. it is resistant to sulfuric acid. You wont know if the ore contains lead or not.


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## Geo (Jul 29, 2011)

lead can be dissolved with hcl acid which makes lead chloride which is water soluble.perhaps as a second step.


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## azdave35 (Jul 29, 2011)

thanks for the replies guys but i'd like some info on how to precip or drop the base metals (copper..lead iron ect ) after they are stripped from the ore and in solution


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## Geo (Jul 29, 2011)

azdave35 said:


> thanks for the replies guys but i'd like some info on how to precip or drop the base metals (copper..lead iron ect ) after they are stripped from the ore and in solution


zinc or aluminum will drop all base metals out of solution.first gather all your solution in one container and then add a large piece of copper which will drop all precious metals that may be present.after 24 hours remove the copper that's left and filter the solution,any sludge will contain any PM's that were missed in your refining.dilute your solution with equal amounts of water and place in a sturdy plastic container,i use a plastic 30 gallon drum with the top removed.add aluminum slowly (discarded beverage cans will work but need to be clean and dry, these will have a thin plastic liner that will need to be filtered out later) or any aluminum will work.zinc is more efficient but harder to come by.the reaction can be vigorous and will produce alot of heat so go slow.solution will become clear as base metals settle to the bottom.all base metals will be dropped when no more aluminum will react with the solution.decant used solution to a fresh container and neutralize with crushed limestone dust or baking soda (limestone is cheaper as it will take quite a bit to neutralize even a gallon) after adding more limestone doesnt produce any fizzing or reaction your spent solution is safe to discard.


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## azdave35 (Jul 30, 2011)

thanks geo


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## jeneje (Jul 30, 2011)

Geo said:


> azdave35 said:
> 
> 
> > thanks for the replies guys but i'd like some info on how to precip or drop the base metals (copper..lead iron ect ) after they are stripped from the ore and in solution
> ...



How do you seperate the pm's from the base metal after dropping if any are there?

Thanks
Ken


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## nickvc (Jul 30, 2011)

Ken that was covered in the first part by cementing with copper.


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## rusty (Jul 30, 2011)

azdave35 said:


> i'm pre treating some ore in sulfuric acid in prep for leaching...i want to drop the metals from the sulfuric solution to see what base metals are in the ore....what do i use to drop them?...zinc maybe?...do i need to neutralize the acid before i drop the metals?..any help would be appreciated



You could use a carbon as anode with a stainless steel cathode to strip the electrolyte ( sulfuric solution ) of metal. 

Regards
Rusty


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## Geo (Jul 30, 2011)

jeneje said:


> Geo said:
> 
> 
> > azdave35 said:
> ...


i assume you were asking how to separate the PM's from one another.i can give an answer based on this assumption but i may be wrong.take the sludge containing your PM's and rinse several times in boiling water then allow to dry.after your material is dry dissolve in 50/50 nitric acid and water.this will separate most PM's from your gold as gold will not dissolve in nitric alone.after digestion filter solution and rinse solids and place in a vessel that you can incinerate your solids,this will remove any nitric left.back to your nitric solution use NaCl or plain un-iodized table salt to drop any silver present in the form of silver chloride.back to the solids, dissolve your solids in the manner thats easier for you whether its aqua regia or hcl+chl.dont forget to test each solution with stannous chloride to be certain they contain PM's.after testing with a positive of Au double your volume of solution by adding to equal amounts of water then precipitate using sodium metabisulfite.


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