Silver Cell Capacity

[Palladium]

Do you heat your solution when you drop the silver with copper?

 

[Harold_V]

If any of your silver was used for inquartation, pretty good chance you picked up some palladium. When it's present, you'll find the solution leans towards green---and lightens to blue when all of the palladium has been cemented. The cemented palladium will discolor your silver, making it appear darker, even towards black, assuming you have enough present.

On that note, when ever you cement silver, if the barren solution is not blue, test with stannous chloride. The platinum metals are slow to cement, coming down only when all of the silver has been cemented. You can expect platinum in your silver nitrate solution, along with palladium, considering platinum will dissolve in nitric to some degree, when alloyed with silver.

The test with stannous chloride can resemble gold to some degree, depending on many variables, but you won't get a purple stain. The general reaction is anything from green through blue, however. It's a bit of a chameleon. That's why you should test with DMG-----it is conclusive, leaving you with no questions.

Don't be surprised by the presence of palladium in your silver. It's just a matter of time until you encounter some------as well as platinum. For that reason, you should concentrate your studying on those metals. They're a great retirement plan. Set them aside for that day.

Harold

 

[kadriver]

I checked on the silver that I dissolved last night. The silver had quit cementing, just as you described. There was a darker coating of material on the copper coils that I used to cement the silver with.

I took a drop of the solution and tested with stannous chloride. I was surprised to see a reaction. It has really got me thinking now.

I have been so focused on the gold and silver, that I have neglected to even consider that these other metals are present in some of these solutions.

I have seen green silver nitrate in the past, but it never sunk in to investigate what else might be in the solution besides silver.

This silver cell contamination event has opened my eyes.

I am now seeing other metals everywhere it seems!

I took down my copy of Hoke's book and literally wiped the dust off of it last night. I am going to devote my time to study of the other metals and how to get them out.

But for now, what should I do about this silver nitrate solution that I have now?

It appears that most of the silver has cememted out.

The copper coils that I use were still pretty beafy, and they were coated with the darker material.

Should I add some HCl to get the rest of the silver to precipitate out as silver chloride, then try to cement the platinum or palladium that is still in the solution.

Here I am, clueless all over again. Refining has a way of doing that to a newbie.

Thank you - kadriver

 

[kadriver]

Palladium:

I did not heat the solution. In fact, I was getting heat building up as the silver was cementing out.

I was even getting some fumes from the cementing.

I finally added some ice made from distilled water to get it to cool down.

I keep two or three trays of ice made from distilled water for dropping gold. I had a boil over while dropping gold a while back.

Now I add ice and place the container into a pyrex baking dish to catch any liquid if it does boil over.

kadriver

 

[HAuCl4]

You can forget about DMSO and spend your 18.2 Euro on different ways. DMG dissolves easily in aqueous NaOH. Use 2 moles of NaOH per mole of DMG and sufficient water to make up a solution of about 1 mole/lt NaOH. Adding this alkaline solution of DMG slowly to the nitrate solution will precipitate Pd selectively and quantitatively, without precipitation of Ni, provided the mixture will still remain acidic after addition of the alkaline precipitation agent. This can be assured by beforehand addition of an equimolar amount of nitric acid (2 moles per mole of DMG) to the nitrate
solution.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9058&hilit=freechemist+DMG+NaOH

I suggest you read this post and this thread and understand it well. 8)

If you already purchased DMG, then use it to recover very clean palladium from your solution, and then recycle the now clear silver nitrate into your silver cell. That's probably better than using zinc. All in all there isn't much palladium to recover, and DMG will get it all and in very pure form without further processing.IMHO. 8)

 

[kadriver]

HAuCl4:

Thanks. I will study it. I am not a chemist at all.

I have been reading Hoke's book on testing solutions for all metals in solution. I completely ignored this section because I was concentrating on gold & silver only.

The only one that I am familiar with is stannous chloride. And I have only used it to test for dissolved gold - until last night.

I am working on getting all the items needed for making the test and standard solutions talked about in Hoke. Then I will do the experiments as outlined in that section. I think it is Chapter IV.

I'm sure it will reveal how I need to go about getting the palladium out - if it is palladium.

I guess i will save the silver nitrate solution from last night and do some tests to see what is in there with the silver.

I chuckled when I read the part about beginners having worthless and useless unlabeled solutions sitting around. I am guilty.

Thank you - kadriver

 

[philddreamer]

Peter wrote:
"That yellow electrolyte had about 75 troy ounces through it.
I tested the solution with stannous chloride tonight and it was positive. But for what?
I have never seen stannous chloride react with anything other than AuCl.
I know there can't be any gold dissolved in the electrolyte..."

To me, it seems you ran too much material thru 1 litre of electrolyte; I undestood that as soon as the solution starts getting "dark", which is a sign of contamination, that it should be changed, but our experts will have the final word on that.

Also, the stannous test was +, but what was the color?

Palladium wrote:
"Do you heat your solution when you drop the silver with copper?"

I read the advised of the experts of heating the solution, but like Peter, my solution is loaded with silver & it gets hot fast when I start cementing. If I preheat the solution, wouldn't I run the risk off boil over? My question, the hotter the better for cementing?

Thanks Harold for the detailed explantion, excellent! I will be buying DMG, because like Peter, I want to master this silver refining process for the reasons you mentioned.

Thanks HAuCl4 for pointing the topic:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9058&hilit=freechemist+DMG+NaOH

Phil

 

[samuel-a]

I read the advised of the experts of heating the solution, but like Peter, my solution is loaded with silver & it gets hot fast when I start cementing. If I preheat the solution, wouldn't I run the risk off boil over? My question, the hotter the better for cementing?

Heat = time saver.

You would get same results after a week in a cold solution or a day in a hot one.
You can always fill the jug 1/2 way through so no spills occur.

I usually start the heat only after the majority of the silver had cemented.

 

[philddreamer]

Thanks Samuel, now I have a starting point for when I can start heating.

Phil

 

[Palladium]

I tried it both ways and believe heating before percipitaion is the way to go for me. It comes down fast and fine which makes for easy clean up.

 

[Harold_V]

Key to recovery of all of the silver and what ever platinum metals are included is to present a large surface area of copper to the solution. I don't recall ever heating for cementation, and that includes solutions that contained a rather generous portion of platinum and palladium. I processed a decent amount of dental gold, so my silver was almost always laden with them.

When your solution tests positive, simply allow it to stand longer. Once the silver is down, it, too, helps cement the higher values. In the end, you will achieve a full recovery, to the point where the solution is blue, and there are no detectable signs of other values. Also, after all has been cemented, stir the lot, to liberate silver nitrate that was dragged down and is isolated from contact with copper.

I generally allowed 24 hours for cementation and rarely needed more. I also had a large amount of copper in use at all times, so I could extract the values in what I considered a reasonable time. I used to melt copper and pour ingots that would be the equal of 100 ounce silver bars. I used the same mold for both purposes. I'd use two or more of those ingots, along with smaller pieces of copper that could be extracted after the silver was down. Any copper wire that I used was melted and poured as an ingot, to avoid the risk of residual copper being left behind.

On the subject of using DMG to extract palladium, I don't agree. It's costly, and creates a huge volume of palladium that will be difficult to handle. In fact, that's one of the reasons it's so useful as a testing solution. Small traces of palladium will yield a very visible precipitant, so the test is very sensitive. You're far better served to cement the palladium along with the silver and extract it from the slimes in the next parting. If you keep the palladium content low in your silver, it won't co-deposit with the crystals. Armed with that idea, don't reuse cemented silver for inquartation unless there is no palladium involved. If it accumulates too highly in your cement silver, parting will become troublesome, with co-deposition pretty much assured. Been there, done that.

Harold

 

[kadriver]

You're far better served to cement the palladium along with the silver and extract it from the slimes in the next parting.

Harold

I think I get it: the key to getting the other metals is to cement them all out with the silver. Wash the cemented silver as usual. Then dry and cast into anode bars. Then recover the other metals from the slimes in the anode basket.

I was wondering how I was going to get the other metals out of the spent electrolyte.

Should I just cement the silver from the dark yellow spent electrolyte with copper as usual? Will the other metals, if any, cement out with the silver?

The color of the solution in my cell did not get dark until this last batch. The previous batch of silver that I ran through the cell was processed in the same electrolyte but it was far lighter in color when I harvested the silver crystals.

That is why I posted it on the forum. I had never seen dark yellow contamination before. Sometimes green, but mostly blue.

I use copper wire coiled up and suspended in the silver nitrate with a string hung from a glass stirring rod. I monitor it closely to ensure that the copper wire does not get too thin and start dropping bits of copper into the silver. When the coil starts to get thin, I put in a new one. When I am sure that most of the silver is cemented, I put in a fresh coil or two and let it set overnight.

I have a 3 liter jar full of partially used copper wire coils. I have been melting them in a large dish to make a disk of copper that I can use to suspend in the silver nitrate.

I would like to get a nice furnace and melt the copper properly, then pour into bars like Harold talked about.

I will keep a close eye on this cell to see if I get any more contamination. So far it has turned a very pale yellow and the silver crystals are growing nicely.

The stannous test on that electrolyte produced a brownish color. I have no idea what that means.

Tomorrow I am going to make a fresh batch of stannous chloride and re-do the test. I will take some pictures and post them.

By the way, I processed some more silver last night. As I stated earlier, the silver nitrate was green. This batch was very unusual.

First, the cemeted silver was very fine - like pluff mud. It actually bonded together in the funnel in a large cake and I had to pry it out with a spoon.

Also, I used twice as much water than usual to get all the color out of the rinse. I tested the rinse water with HCl and there was silver chloride forming after about 1 and 1/2 gallons of distilled water had been through the silver. I use boiling distilled water to rinse the silver.

The resulting silver powder appeared darker than usual and much heavier per unit of volume than usual. It usually takes three spoons to get to 48 grams (the size of my anode bars). But this batch only took two spoons to get 48 grams.

The resulting anode bars looked a bit unusual. They were rouogh in appearance and frosty looking. My cemented silver anode bars usually look about as good as the fine silver bars.

I am thinking that I may have some other metals in the batch of silver. I did a stannous test on the silver nitrate last night and got a reaction - but I cannot remember the color. I have some of it left. I will do another test tomorrow with fresh stannous chloride.

If not for this forum, I would be making mistake after mistake. Learning by trial and error. Thanks to all for your input .

kadriver

 

[Harold_V]

I think I get it: the key to getting the other metals is to cement them all out with the silver. Wash the cemented silver as usual. Then dry and cast into anode bars. Then recover the other metals from the slimes in the anode basket.

Correct. That's the entire purpose of the silver cell---to remove traces of impurities---of all types. Some go in to solution, while others accumulate in the slimes.

I was wondering how I was going to get the other metals out of the spent electrolyte.

Should I just cement the silver from the dark yellow spent electrolyte with copper as usual? Will the other metals, if any, cement out with the silver?

That's exactly how I'd do it. At this point you don't have a lot of palladium in solution. That's obvious by the color. Palladium, when concentrated, will be dark coffee in color. The slight amount present won't create any issue for the next refining, and will, for the most part, report in the slimes. Expect traces to go in to solution, considering palladium readily dissolves in nitric. Traces won't be troublesome. Just keep watch on the color.

I'm curious. What have you done with your slimes up to this point? From your description of previous solutions, it sounds to me like you've recovered some platinum and/or palladium. If your electrolyte had turned green, fair chance that's why. My electrolyte was never blue---always tinted green when it was exchanged. That was due to my constantly handling palladium, and the fact that my silver always had traces of copper. I was impressed that yours did not.

Harold

 

[kadriver]

Harold:

Since I have been refining silver I have not been processing the slimes in the anode baskets for other metals.

The last couple of anode baskets are sitting at my shop still full of the material that was left from the refining. I have started making up a new basket and filter when ever I harvest the silver crystals. The cost is minimal and it gives me a little peace of mind.

I always double bag using one filter fit inside of another. I ensure that there are no seams or splits in the filter itself to guarantee none of the wastes in that filter bag make it into the cell with the pure silver.

Before that, I used to re-use the anode basket filter bags. I would remove the filter and place it on the inside of a 2 liter beaker. It would stick to the side of the beaker and then I used a squirt bottle to rinse all the slimes off the filter and into the bottom of the beaker - then re-use the filter.

Since I was only concerned with the silver, I would treat the slimes from the 2 liter beaker with nitric acid, then filter out the solids and save the remaining silver nitrate for cementing.

I think I just stuck the filter papers with the solids in my gold filter paper bag. I was quite unsure what to do with the solids that filtered out of the silver nitrate. I had tunnel vision - only gold & silver mattered to me.

I may have some values in those unprocessed filter baskets, and from the filter papers.

As a newcomer to refining, I was overwhelmed with just getting some good product out. Since I was learning, and still am, I wanted to try to keep it simple. Because of this (and I suppose a little lack of diligence) I completely ignored trying to recover any of the other metals.

But now things have changed for me. I have always said that the main ingredient in being good at ANYTHING, is the desire to do so. Before this contamination incident with my silver cell, I lacked that key ingredient.

I feel as though I am getting ready to open new doors in refining. I now have a strong desire to get at these other metals and start processing them. I can see where this could provide a big benefit - not only can I get the gold & silver, but I can start accumulating the other precious metals as well.

I am going over to my shop later today. I will re-test the yellow electrolyte with fresh stannous chloride. I will also test the remaining silver nitrate I spoke of in an earlier post. then I will add the two liquids together and begin cementing with copper.

I will post photos of these test results.

Thanks to all - kadriver

 

[Rodthrower18]

Kadriver,


I can't wait to see these photos! I am learning so much from so many of the exchanges that everyone has around here. Most of the questions that I THINK I'm coming up with are getting answered somewhere on the forum or with the help of my dear friend mr search bar.

Good luck to all

 

[goldenchild]

The resulting anode bars looked a bit unusual. They were rouogh in appearance and frosty looking. My cemented silver anode bars usually look about as good as the fine silver bars.

I am thinking that I may have some other metals in the batch of silver. I did a stannous test on the silver nitrate last night and got a reaction - but I cannot remember the color. I have some of it left. I will do another test tomorrow with fresh stannous chloride.

kadriver

Could be due somewhat to contanmination but it also looks like the metal was over heated causing boiling.

Key to recovery of all of the silver and what ever platinum metals are included is to present a large surface area of copper to the solution. I don't recall ever heating for cementation, and that includes solutions that contained a rather generous portion of platinum and palladium. I processed a decent amount of dental gold, so my silver was almost always laden with them.

Harold

This has me thinking. Just how common is it to get Pd contamination in silver and vice versa. I don't think it is very common at all unless you are processing dental scrap. Isn't Pd used in place of silver in karated jewelry which is rare in itself?

 

[kadriver]

I do not know how this contamination got in there.

Here is the test I did with fresh stannous chloride solution this evening.

The four photos are a series of pictures about 2 seconds apart as I dropped the stannous chloride onto the sample of spent electrolye (the dark yellow liquid from my silver cell).

It obviously tested positive for something. I do not know what this test indicates. It turned a brown color very rapidly in about 5 seconds.

Then it stopped and remained as pictured.

The silver nitrate showed a very faint yellow color.

I tested this same silver nitrate solution two night ago and it was much darker that the test result from tonight.

I do not know what it is. I am hoping that the forum members can tell what it might be from looking at the photos.

This is all very exciting - like starting all over again.

I feel a bit overwhelmed because i am not certain what I should do next.

I probably need to study some more and take a break from it for a while.

The nice thing about it is that it will still be there for me tomorrow. It isn't going anywhere.

Thanks for looking

kadriver

 

[kadriver]

Here is what the cell looks like tonight.

It is starting to get yellow again.

The crystals are growing nicely.

I may have to change the electrolyte when I take the silver out.

By the way, does anyone see a problem with leaving that glass rod in the cell when it is operating?

kadriver

 

[Harold_V]

I do not know what it is. I am hoping that the forum members can tell what it might be from looking at the photos.

Palladium tends to yield a green/blue color reaction, but that's testing a chloride solution. It's entirely possible the results you see are due to a nitrate solution, especially considering there's silver present. Dunno! One thing I'll mention, though---there may be times when you get a reaction from palladium that makes you question of you have gold present (there won't be a purple stain, in spite of a dark reaction, much like the one you got). I do not understand all the variables that cause the tests to vary as they do.

One thing to consider is that platinum can yield a dark brown reaction, but that's when it's highly concentrated. How you'd get platinum in solution with a silver cell I can't say. To my knowledge, that doesn't happen.

In my opinion, leaving the glass rod in the cell does no harm.

Harold

 

[Geo]

could you have mixed a white gold ring in with your silver rings? they use Pt in white gold,dont they? i dont know, just a thought.