Copperas For Precipitating Gold

I have no experience using copperas, but I want to start using it in my refining.

Can someone tell me if this product I found on Ebay will work for refining?

http://www.ebay.com/itm/Copperas-4-lbs-/260937174071?pt=Fertilizer_Soil_Amendments&hash=item3cc1114c37

Thanks!

kadriver

Yes it will work. Fair price too. But you should be able to find it at your local garden supply.

No body here seems to carry it.

Thank you for reponding

kadriver

kadriver, I found it was hard for me to find it (in garden center shelf) were the ferrous sulfate was not oxidized brown, they should be green crystals, if oxidized brown it will not work to precipitate gold or test gold.

my feeling is if the crystals are partially oxidized (on the outside from exposure to air, but still green un-oxidized on the inside), they may precipitate some gold if enough crystals are added, but would also contaminate gold with the oxidized iron compound (probably not too much of a problem as Iron would possibly not melt into the gold, but I did not want to take a chance, of contaminating my gold, and found making the copperas i could make much better crystals, than what I could by locally at garden centers as garden supplements.

So I make my own, it is easy to make, I have posted a couple of different methods I use to make copperas (ferrous sulfate), and how I store the nice green crystals from oxidizing.

i agree. make your own and you know what you have.

What are the advantages/differences between SMB and Copperas? Why would you choose one over the other? I've only used SMB myself.

Jack:

SMB will drop other metals with your gold if you have some nitric left in your solution. This why it is essential to remove all free nitric before dropping with SMB.

Sometimes I will drop a nice caramel colored gold powder with SMB, then, at the end of the precipitation, a darker almost black cloud will form and turn my nicely colored precipitated gold a darker brown.

I beleive this is the non gold metal being precipitated and deposited in my clean gold powder.

I don't know if this happens with copperas or not. But I am convinced that is does happen with SMB in nitric solution.

kadriver

I know what your talking about and was wondering the same thing. I was thinking about doing a partial drop, filter off what dropped, then finish the drop, processing the two portions separately and testing at the end for purity.

Yes, my drops (with SMB) are always dirty. I'd be curious to know which does a cleaner drop out of SMB, Copperas or Oxi/acid.

when your working with dirty solutions (solutions with several different metals) drag down will occur with just about any precipitant used. as i understand it, its not the precipitant that causes the drag down but the metal precipitating that causes the effect. Harold can explain it much better than i can. that is one reason why its recomended that you re-refine metal precipitated from dirty solutions. the metal precipitating PULLS the base metal down with it and this occurs at or near the end of the process. if i can find the thread where Harold explained it to me i'll post the link.

here is a post by lazersteve that has a chart of precipitates from various solutions.

I am still trying to get a reading from it, but I can't seem to grasp the concepts of the information that the chart provides (I can't read the chart)!

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562

I am going to study it some more. An example description from the chart would be very helpful.

kadriver

Green boxes are the metals dropped alone with the chemical listed on the left, red boxes show multiple metals dropped with the chemicals from the left.

To drop Au alone from your AR (chloride) solution you should have used oxalic acid, by using copperas the gold you dropped likely has some portion of Pd in it still.

wouldnt that be from a hot solution? if the solution was room temperature the PT shouldnt have dropped.

The chart shows the reducing agents down the right side and the standard solution (chloride, nitrate, and sulfate) types across the top.

Here's a break down of what solution type a given solvent is:

Chloride Solutions: AP, HCl-Cl, HCl, Chlorine water, Salt water
Nitrate Solutions: Nitric Acid, Nitrates in water
Sulfate Solutions: Sulfuric Acid, Sulfates in water, Reduced Sulfites in solution, Sulfate Fusions
Mixed Nitrate/Chloride Solution : AR, Poorman's AR, SSN
Mixed Sulfate/Nitrate Solutions: Homemade Nitric Acid

A mixture of chloride (muriatic acid), sulfate (sulfuric acid), and nitrate (niter or nitric acid) solutions can give results from two or more categories across the page. This is why we denox solutions to narrow the items a particular reducing agent will precipitate.

As an example a purely chloride (eg: denoxxed AR, AP, or HCl-Cl) solution of gold and copper will precipitate gold and copper I chloride when SO2 (SMB, sodium sulfite, SO2 gas, etc.) is introduced. This is why we always want to eliminate the copper before using SO2 based precipitants. This is also why a good boil in HCl cleans your dark colored gold of the co-precipitated CuCl.

Another example is when Pt and Pd are dissovled together in AR (chloride and nitrate solution). Adding ammonium chloride without denoxxing will preciptate both Pd and Pt togehter as their ammonium chloride salts due to the presence of nitric acid. If you denox the solution properly you have a chloride solution now with Pd and Pt chlorides dissolved in it. Now when you add NH4Cl you will get the Pt to precpitate more cleanly and mostly free of Pd.

Reducing agents (precipitants) that cross index with a solution type on the chart in a green box will give you nearly clean metals as there will always be some drag down if impurites are dissolved in the solution. This is how dilution (to be avoided with Pt and Pd) and repeated precipitation cycles can help produce 'clean' precious metal when precipitated.

Reducing agents that list more than one product for a given solution type (in red) are more likely to yield impure metals if the other metal in the red box is present or if a mixtue of solution types are present.

Some entries on the chart include details about pH and temperature which are required for the given metal to precipitate in the solution.

I hope this helps explain the chart.

Steve

Absolutely, thank you that clear and concise explaination Steve.

Until now, for all the time I have been refining gold (a little over a year) I thought the reason to expel excess nitric was to prevent boil-overs and excess chemical usage when precipitating the gold.

While these are good reasons, the critical reason for getting the nitric out - completely - is to prevent co-precipitation of precious metals. I may have heard it before, but this time it gets to sink in - now the chart makes perfect sense to me.

kadriver