# Cementing Silver etc.



## MiltonFu (Mar 26, 2011)

I recently received an ore sample that supposedly contains silver and other precious metals. I added some of the ore to a dilute Aqua Regia and filtered the residue. A piece of copper was added to the AR and the following day it was covered in a grayish looking material as pictured.
Any suggestion as to what it might be from its appearance?

Secondly, I took another sample and added diluted Nitric acid and filtered it. I am yet to check the nitric, however, the residue ore from the nitric was washed and diluted AR was added. The subsequent AR solution was once again filtered and copper was added. The following day, the copper was covered in a black looking material. 
Any suggestion as to what this might be from appearance?.

Thanks.


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## shyknee (Mar 26, 2011)

test it and find out


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## MiltonFu (Mar 26, 2011)

I am not sure how to test it.
Besides, the coating maybe to thin for conventional test.


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## samuel-a (Mar 26, 2011)

MiltonFu said:


> I am not sure how to test it.
> Besides, the coating maybe to thin for conventional test.



it's quite easy actually.
rinse the cemented powders with a squeeze bottle to a flask, then rinse again to a test tube and wash with water several times.
siphon all water and dissolve with minimal amount of AR (3 drops HCL + one drop nitric acid). 

notice color. test with Stannous chloride. 
report back


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## MiltonFu (Apr 5, 2011)

Thank you Samuel.

I followed your suggestions and here are the results:

B2 is the black material in AR.
B3 after heat is applied.
B4 is the addition of stannous crystals.

G1 is grey material in AR
G2 is the addition of stannous crystals.

Comments anyone?.


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## samuel-a (Apr 5, 2011)

This looks like gold positive to me, But i can't tell for sure... 
I never had success testing properly over spot plate, so i just got used to the Q tips and filter papers instead.

From what i have learned, gold stain will not dissipate from the paper/cotton and can last months.
Once, i even found a Q tip that found it's way out of lab and ended up in the rain out side for few weeks, but the gold stain was still there.

Pt and Pd stains last only few hours before decomposition.


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## MiltonFu (Apr 6, 2011)

Thanks for your input Samuel.


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## MiltonFu (Apr 7, 2011)

I am looking forward to more opinions and comments on this thread.
What are the likely metals that will cement on copper?. I am still of the opinion that the results i am getting from the original product might be inconclusive, however, I am encouraged by the input from Samuel.

Thanks.


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## Barren Realms 007 (Apr 7, 2011)

MiltonFu said:


> I am looking forward to more opinions and comments on this thread.
> What are the likely metals that will cement on copper?. I am still of the opinion that the results i am getting from the original product might be inconclusive, however, I am encouraged by the input from Samuel.
> 
> Thanks.



Any thing _*below*_ it in this series.

Silver Ag
Palladium Pd
Mercury Hg
Platinum Pt
Gold Au


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## lazersteve (Apr 7, 2011)

Frank,

Anything *below* Cu in the activity series will be cemented by it. 

The higher up (K and Na at the top) the chart the more reactive. The lower down the chart (Au and Pt at the bottom) the least reactive.







Steve


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## Barren Realms 007 (Apr 7, 2011)

lazersteve said:


> Frank,
> 
> Anything *below* Cu in the activity series will be cemented by it.
> 
> ...



Yea I tried to copy that chart to post from another post of your's but it would not copy so I found another post with the list it in it. I think that list should be put in the general reactions thread. And I went back and fixed my post above yours. My mind must have been some where else. :| 

Thanks for catching that Steve.


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## MiltonFu (Apr 8, 2011)

Barren Realms and Steve, please look at the pictures in the original post. Can those colors cemented on the copper be associated with precious metals?


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## Barren Realms 007 (Apr 8, 2011)

On the picture of the copper tube with the black material on it, your answer would be poosibly yes.


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## butcher (Apr 12, 2011)

Here is something I would consider, cementing with copper seems to be a very good sign of values.
Unless you have high silver content in ore the platinum group is not too likely to dissolve in nitric acid (palladium will slowly).
Have you tried nitric acid alone and tried cementing on copper? Ag Pd.

Remember incineration can be used to rid previous acid that was used which may interfere with next process used. Like removing HCl when going to nitric and not wanting to make an aqua regia in situ from previous acid-metal salts.

Aqua regia will dissolve gold, some silver and palladium easily, platinum will not usually unless heated, so doing cold Aqua regia less likely to dissolve PGM's, ferrous sulfate to precipitate gold from solution. 

Hot aqua regia to get Platinum group into solution, denoxx solution ice to help ppt silver decant filter solution, ferrous sulfate to ppt gold, concentrate solution ammonium chloride for Platinum, sodium chlorate for Pd, (have read where rh may ppt after pt and solution oxidizes 24 hours).

For the most part Rh,Ru,,Ir, not attacked by aqua regia normally
Fusion in bisulfate will make Rh water soluble, (then fusion in alkali for Ru sorry I do not know details NaRuO4).

Ir still insoluble

A white spot plate or spoon some of these reactions can be used as tests for the metals, ferrous sulfate crystal will test for gold, and help to remove it for further testing of liquid,
Stannous chloride also for Au, Pt, Pd,
DMG for Pd,

The more experienced members can give better details, and have made some very good posts on the platinum group metals and testing for them.


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