Other Metals contamination in Silver Crystals

[JSRoeth]

I have processed 2 times an out put of Silver Crystals in an Electrolyte Silver Nitrate Cell.
I just had 50 ounces of crystals analyzed at a high end reputable gold / silver dealer in Houston recommend by the host of syndicated radio show of Michael Berry.

I understand that PGM metals can follow silver which I assume even in the elecgtrolysis process.
What I am uncertain how the other metals ended up in mu silver crystals.
Here is a breakdown of the XRF read out:
In - .671
Ag - 96.120
Ru - 1.262
Co - .638
Fe - .936
Mn - .310
Cr - .039

The Ru, I understand some PGM metal must have been in the feed stock I used to create the Silver Nitrate and is below in thee scale of metals that follow metals above.
The other metals as listed in The Metal Reactivity Series are a puzzle to me>
Fe & Mn are common to each other but above Ag. So thinking out loud here I am going to throw it out here that these metals might have been in the feed stock as well as the PGN contamination.

The In, Co, & Cr followed too I guess.

The question or uncertainty I have is, if any metal that is in the Silver Nitrate solution will they always follow the ion exchange from the anode to the cathode?

Next question is there a test I can conduct on the Silver Nitrate solution for other metals?
I know I can test for PGM and precipate with DMG but other metals I am unclear how to test and even remove before I start the cell.

On the bright side I did not have any Cu follow so I am pleased with that result.

My thought of how to proceed from this point is to start completely over.
re-Acid dissolution of the crystals, Silver shot, Anode bar and drop the silver out with copper in the 6 gallons of silver nitrate after I drop out any PGM metals it may contain.

last question or clarification is if I am correct with my deduction that the contamination is in the silver nitrate if these metals or similar metals listed are contained in the anode silver shot is is likely they will follow the ION exchange. I am of the opinion they would remain in the slimes filter basket yet at this point I am obviously uncertain.

Once again guidance is appreciated.

 

[anachronism]

That may well be because you are not keeping the slimes (which hold the impurities) separate.

 

[AshesoftheUniverse]

That may well be because you are not keeping the slimes (which hold the impurities) separate.

When you dissolve your silver feed stock, be sure to filter it well. The solution may look clear, but as Anachronism said, the slimes will contaminate your metal on the Cathode.
Using a 2 compartment electrowinning cell helps as well.
Even using a .25 micron filter will allow some to get through.
If it seems like too much work, let a commercial refiner coin-in on the impurities and take the hit.

 

[g_axelsson]

Just thinking out loud, haven't run into these problems in a cell so I'm not talking from experience.

The cell slimes in a working cell is mostly precious metals, silver, gold and pgm:s. Base metals are dissolved in the electrolyte.

The electrolyte should be slightly acidic to dissolve any base metals in the system. Have you checked the pH?

Too high voltage or too high current density might force out some contaminants.

Too low silver content in the electrolyte might also force out contaminants.

Göran

 

[butcher]

JSRoeth

I have more questions than I will have answers.

What was the silver feedstock and how was it prepared for the anode?

How is the electrolyte prepared?
What was the cathode (pure silver) stainless steel?
Note many of the metals indicated on the XRf reading are similar metals in the composition of stainless steel.

What type of silver cell design did you use Balbach Thumcell or the Moebius silver cell?
The design will in itself have an effect on the product.

How was anode bagged or slimes trapped?

Was the cell power supply turned off for the nights?

What parameters was the cell during operation voltage, current, temperature, current density, anode to cathode distance, pH, silver content and electrolyte density,(and even colors of the solution...)?


I find the mix of metals interesting in the XRF reading, and yet I find it also very strange, as some metals I would expect to see are not there, and other fairly reactive metals are also involved.

Manganese is more reactive than zinc, zinc more reactive than chromium, then we have iron, and cobalt, all metals that are much more reactive than copper, yet the results do not show copper here in the report.

Note with the exception of silver and Ru all of these metals are above hydrogen in the reactivity series, and would dissolve in acids, all Could be dissolved in acid and left in solution as silver was cemented out with copper...

Sorry I cannot think of answers only lots more questions.