# Mystery alloy



## kjavanb123 (Jun 11, 2017)

All,

We recieved 200 lbs of pulverized ores to be smelted.

The head ore assayed (xrf) for Platinum, which I let the customer know that is not reliable and should do a fire assay.

He insisted to proceed with smelting so we did our usual process, and final stage when we remove the silver with all PMs from the furnace, it is dissolved in nitric acid.

It left with no residue, so customer asked us to dilute the nitrate solution, then added lye which cleared the solution and grayish residue remained.

Here is some photos for better visual,

Precipitant from adding lye to nitrate solution,



We collected the above dried it then using an oxy torch melted that powder,
This was the first for me at least, as can be seen below, a gold color solid appeared on top of silvery white metal on the buttom of crucible, 



Upon more heat from torch it became like the following,



I made into a roll, cut a piece of it and tried with hot aqua regia, it was in a beaker in a bath, when nitric acid added reaction starts, avout 30 minutes into reaction still no signs of gold or platinum in solution by testing stannous,



Another thing it wont dissolve in nitric acid either, but when AR solution gets the room temperature, small white silver chloride precipitates.

I am going to try hcl and peroxide leach tommorow, at room temperature as suggested by Lou many years ago in one of my posts.

I wanted to share this with you all.

Thanks and regards
Kj


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## Lino1406 (Jun 11, 2017)

Do stannous chloride test. If it shows anything at all do NH4Cl precipitation


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## g_axelsson (Jun 12, 2017)

Let's see if I got this right...

You started with some unknown powder, to it you added silver... any lead? In short, what is your usual process?
How much silver was added and how much was recovered?

Then you dissolved the silver with any possible PGM:s and contaminants, no residues means no gold at least.
Palladium and platinum can be dissolved by nitric acid when alloyed with silver.

This dirty silver nitrate was mixed with NaOH, making silver oxide and various metal hydroxides. When melting the resulting powder the silver oxide would turn into silver again and would probably pick up some of the metal hydroxides as contamination. The golden area looks like metal oxides on top of the silver.
What is the weight of this silver button? What did you expect to happen?

The silver button is then treated with aqua regia, creating a thin layer of silver chloride, passivating the surface. When the solution cools down some of the silver chloride dissolved in aqua regia precipitates.
The button has a passivation layer so there is no surprise that straight nitric acid won't touch it after the aqua regia bath.

Hit the button with a hammer a couple of times to break the surface of silver chloride, then try nitric acid again.

Instead of adding lye to the silver nitrate solution you should have added HCl, this would precipitate the silver as chloride and leave any PGM:s in solution. The liquid could be evaporated and any excess nitric or hydrochloric acid would go off as gas, leaving a concentrated solution with PGM:s and other contaminants. 

Göran


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## kjavanb123 (Jun 12, 2017)

Thanks all.

I dissolved a piece of rolled sample picture below in hot sulfuric acid,



Acid dissolved it completely, I poured it on water, then added hcl which precipitated silver chloride which turned purple under the sun.

Conclusion, there was nothing but silver we add as collector.

G-axlsson
We did add lead oxide first in rotary followed by silver in cupel furnace.

I already tested the nitrate solution no signs of PGMs. 

Lye addition was by customer request. He probably got the gold fever well PGM version of it.

Thanks
Kj


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