Palladium in my Silver Cell Electrolyte

I harvested about 60 or 70 troy ounces of pure silver crystal from my silver cell.

The electrolyte starts out clear and colorless then gradually turns blue as the impure silver in the anode bag dissolves.

This last clean-out I had green electrolyte instead of the usual blue.

I guessed that some palladium must have gotten into the electrolyte.

To test my guess, I did a stannous test of the electrolyte and got a positive result.

What was your source of materials?

To verify the test, I drew a few ml of the green electrolyte and added some DMG and again got a positive test for palladium.

The reason i ask is because i ran a batch of sterling silver that i used for this video and i got the same results you did and an almost identical colored solution.

[youtube]http://www.youtube.com/watch?v=4ipu5dystW8[/youtube]

The source material came from Sterling/925 silver dishes, candle holders, and flatware - but I also added silver nitrate from gold inquartations.

I keep a heavy Pyrex coffee pot with a lid as my silver pot. I dissolve 925 jewelry and other sterling, plus I add the silver nitrate from gold inquartations and washings.

It holds about 2 liters. When it gets full I siphon off the clear, settled liquid and filter it. Then I add copper to the filtered liquid and cement out the precious metals.

The palladium probably came from some of the white gold that I recently processed.

Realistically, that probably isn't going to hurt anything.

If you want to get rid of it:
1. HCl to drop the chloride, rinse in nitric acid to remove Pd, convert the silver into anode bars or make it into silver nitrate
2. DMG works
3. Silver powder to cement Pd

Keep pH >3 and you'll run less risk of contamination in the silver.

Have you set up for Volhard yet?

I keep my cell voltage at 3.5v DC and it runs from 1.0 to 3.3 amps at that voltage depending on the electrolyte concentration.

I have been using 200 grams of silver per liter in my 3.5 liter silver cell.

I have heard from some pretty knowledgeable people on the forum that palladium can plate out with the pure silver crystal under certain conditions.

So I decided to run a test on the pure silver crystal - don't want to be giving away any palladium with my silver since palladium is about 37 times more valuable than silver at todays quotes on these metals.

I have also heard that the silver can contain as much as 10% palladium and you could not tell by looking at it - but I bet you could tell when you went to melt it.

To begin the test I took a sample of about 3 grams from the silver crystal that came out of the green electrolyte and put it in a small beaker.

Lou - thanks for the input. I have been slammed recently and have not made an opportunity to study the Volhard yet.

I added about 6ml distilled water and 2ml concentrated nitric acid.

Yep that would explain it. Mine was flatware and jewelry as well as i used some cemented powder from inquarting to make the shot.
I never worry about controlling the silver concentrations in my cell Lou. I run it as a batch process knowing that as long as i stay within parameters my solution should do X amount. At the end of a harvest i swap solutions and precipitate the silver from silver nitrate solution from the cell in cement form and the process just repeats over and over. It only takes me about 45 minutes to make up a fresh electrolyte solution and 10 minute to empty the cell and i'm back up and running. For me i'm not to swooft with the lab stuff like that so it's simpler for me. :mrgreen:

I then covered the beaker and added low heat to aid the reaction.

It took about 1.5 hours and the reaction was done - no more brown fumes and a few crystals of silver left in the bottom.

I then transferred the crystal clear silver nitrate solution to another beaker so I could retrieve the un-dissolved bits of silver.

After heating the DMG in the microwave for 10 seconds to dissolve the DMG crystals that had formed, I added about 2ml of DMG to the colorless silver nitrate sample.

There was absolutely no reaction. It stayed crystal clear and had the look of pure water.

I then did a stannous test just too see what would happen and got a surprising result.

I used a piece of filter paper as a test strip. After dipping the test strip in the clear silver nitrate solution, I added freshly made stannous chloride to the front of the test strip.

Pure white silver chloride formed instantly on the front of the test strip - but on the back side of the test strip a color formed.

I allowed the DMG test of the silver nitrate solution in the beaker to set for 10 minutes and it remained clear and colorless so I am fairly certain that there was no palladium in the silver crystal from the cell.

But the color on the back of the test strip baffled me - it looked faint purple which would be an indication of a trace of gold.

I don't see how gold could plate out - if there is any gold in the anode material it should get trapped in the filter bag - unless some ultra fine particles of gold passed through both filter bags (I use a double filter which is a filter bag inside a filter bag).

I use shot made from cement silver instead of anode bars. I do use a bamboo skewer to tamp down the shot inside the anode bag from time to time. This could cause a disturbance of the fine gold particles and cause some to be forced through the filter bags and into the silver crystal in the cell.

Since stannous chloride contains hydrochloric acid, and the silver nitrate sample may have some traces of residual nitric, they could combine to form a weak aqua regia that might cause ultra-fine particles of gold (if any are present) to dissolve and give a positive test for gold - but how likely is that?

The silver crystal is probably well within the three nines fine standard but I was thinking of making new electrolyte (from silver crystal saved from the last batch of silver) and running the whole lot back through the cell.

Any comments on this idea would be greatly appreciated.

kadriver

Silver nitrate + chloride -> silver chloride
Silver chloride + light -> purple metallic silver

Göran

Thanks g_axelsson, I have seen the AgCl turn purple after exposure to light, but I did not know that it was converted to "purple metallic silver". Learned something new - again!

This batch of silver made some of the nicest 5 Troy ounce bars I have seen - they will be for sale on eBay over the next few days - thanks!

kadriver

There were 78.6 Troy ounces of silver crystal in the corning ware dish pictured in this thread

kadriver