Is there any thing to chase in these slimes

[Gsracer]

So I finally processed my anode slimes bucket from my silver cell. It has been a hair over 650 Troy ounces worth of silver that has gone through this batch.

Process so far is I have Incinerated the slimes and filter bags. After which I melted it all together and poured shot.

I was left with just over 700 grams of material. I decided to process this in two batches of 350 grams a piece.

First batch was today to get a feel for the process.

I parted everything in nitric acid till I was left with this green solution.



It took almost 3 hours to filter. I assume all PMs would be left in the filter paper which despite melting everything in to shot I was left with quite a bit of indigestes black residue.



I know some pms can go into solution in the presence of silver so I took a 50ml sample and dropped the silver with HCL so that I can get an accurate stannous test.



And here is my stannous test of the sample solution after dropping the silver.

Picture doesn’t really show it but it is a light tan brown color.



Question is.

I want the silver to feed into the cell. Given the very faint stannous test and the amount of residue in the filter I’m inclined to just drop the silver in solution with copper and run everything back through the cell.

I saved the filter paper for later processing.

But I’d like to have an opinion from the more experienced members.

Many thanks.

 

[nickvc]

The filter will contain any gold and as you stated any PGMs probably dissolved with the silver but it’s likely to be very little so I’d just cement the silver out for your cell and any PGMs will slowly build up , the color of the cement starts to discolor as the PGMs build up and contaminate your cement.

 

[Martijn]

Why melt it all together after having a perfect finely divided powder to incinerate, wash and leach? And then to part it all again with nitric. Try to keep it simple.

The silver content in your new alloyed shot may be just right (or wrong) to not fully leach with either nitric or AR.

Do you know why we inquart carat gold?

Pretty good chance you did not get all the silver out of the shot with the nitric leach. I expect the silver content in those slimes to be less then 75% but possibly still more than 25%

Any Pd present will be in the nitric leach if not all Pd allready dissolved in the cell
The other PGM's are less likely to follow silver, as far as i know.

But the stannous test does not show much anyway.

How long did you leave the paper laying to react with stannous? Give it a day and look again. An excess of HNO3 could hold a result back for some time or dissolve it again after showing.
When in doubt, cement it out.
Or test with DMG to be sure if you have a positive for Pd.

Now for your question,
Do you mean adding the dirty silver nitrate to the cell, or using the AgCl for feedstock to the cell? I assume the first.
If so:
Depends a bit on what you fed in the cell in the first place. Cleaned cemented silver or sterling or anodes melted from contact points or a whole bunch of different stuff melted together in anodes.
Trash in trash out.
I guess its the same compared to a final or a dirty AR dissolving step. For the latter, you could use a somewhat 'dirty' beaker. For the first option, go as clean as possible.

I would only let a bit of copper in as base metal contaminant in the electrolyte. If not sure whats in the digested slimes, cement and pour shot or anodes.

Martijn.

 

[Gsracer]

The filter will contain any gold and as you stated any PGMs probably dissolved with the silver but it’s likely to be very little so I’d just cement the silver out for your cell and any PGMs will slowly build up , the color of the cement starts to discolor as the PGMs build up and contaminate your cement.

Thank you nick, that was my suspicion as well.

 

[Gsracer]

Thank you for your detailed reply martin, all are valid points. Ill answer the points individually as i couldn't find a comprehensive thread regarding this subject outside of youtube which as we all know isn't the best source. Maybe this thread will help members in the future.

Why melt it all together after having a perfect finely divided powder to incinerate, wash and leach? And then to part it all again with nitric. Try to keep it simple.

There was a large volume of filter material mixed in with this as well as a BIT of undigested silver shot (from when i used silver shot) mixed in with the dried slimes. I have noted when i run my cells the filter bags wick up quite a bit of silver nitrate. Also the slimes are nasty to work with they get everywhere.

For my small scale setup, i needed to bring the volume down. Hence the reason why i shotted it. For me the goal is stacking silver and as relatively profitable as can be or at least under spot or close. My goal has been 100lbs for my son.

The silver content in your new alloyed shot may be just right (or wrong) to not fully leach with either nitric or AR.

Do you know why we inquart carat gold?

Pretty good chance you did not get all the silver out of the shot with the nitric leach. I expect the silver content in those slimes to be less then 75% but possibly still more than 25%

Any Pd present will be in the nitric leach if not all Pd allready dissolved in the cell
The other PGM's are less likely to follow silver, as far as i know.

You may be right regarding the alloyed shot. I know the reason for inquartation of gold but i haven't worked with gold to this point. As far as percentages, i converted the 50ml sample and the yield was around 13.5 grams of silver after conversion.

I hadn't thought about the last point regarding palladium, but your right, if any was present its probably been dissolved in the cell. And fed through several times.

But the stannous test does not show much anyway.

How long did you leave the paper laying to react with stannous? Give it a day and look again. An excess of HNO3 could hold a result back for some time or dissolve it again after showing.
When in doubt, cement it out.
Or test with DMG to be sure if you have a positive for Pd.

Regarding the stannous test, i checked it this morning and its hasnt changed, i would say very trace amount of anything present.

Now for your question,
Do you mean adding the dirty silver nitrate to the cell, or using the AgCl for feedstock to the cell? I assume the first.
If so:
Depends a bit on what you fed in the cell in the first place. Cleaned cemented silver or sterling or anodes melted from contact points or a whole bunch of different stuff melted together in anodes.
Trash in trash out.
I guess its the same compared to a final or a dirty AR dissolving step. For the latter, you could use a somewhat 'dirty' beaker. For the first option, go as clean as possible.

I would only let a bit of copper in as base metal contaminant in the electrolyte. If not sure whats in the digested slimes, cement and pour shot or anodes.

Martijn.

What i meant was the second point.

Being that the stannous test doesn't show much of anything, i think I'm just going to drop everything with copper and use that as anode material. For my electrolyte i only use silver pulled from the cell and never add any copper execept what builds up in the cell over time.

I should have mentioned the original feed stock was all marked sterling flatware. Most from 1920 on. All was parted with Nitric, cemented and poured into anodes. So very little if anything else should be present.

I will update as i proceed to help other members.

When i process the second batch today, i will save both of the black material filter papers and hit them with some AR and stannous test. I will post those results next week.

Thank you again.

 

[Gsracer]

So i processed the remaining half of the slimes and am just dropping everything with copper in order to have more anode bars for the cell. I’m pretty sure it’s all mostly silver in solution given the stannous test. I’ll post yield when I filter and dry.

The insolubles in the filter will be processed with some AR maybe next week.

 

[Gsracer]

So to update.

After two days of cementation and settling I pulled the material out.

Very interesting thing happened. Something that I haven’t experienced before. The cemented silver I guess it is. Was very finely divided. So much so that it took a whole day to settle.

As it settled it went into layers of different densities. Clear blue on top. Green in the middle.

Unfortunately I did not snap a pic of this.

Here as I was siphoning and filtering.


The material had the consistency of flour as opposed to regular cement silver consistency.

It was a nightmare to filter and rinse. Took almost 6 hours.

But I was left with relatively clean looking cement silver




Final yield was 581.31 grams

Which means I have a little over 100 grams of material missing. I suspect there’s some in the filter paper as the black insoluble solids. However I also suspect there was some copper in there. Very little as my feed stock was digested sterling cemented on copper.

I will update once I process the black powders.

Maybe it’s nothing. But maybe it’s something worthwhile.

My tentative plan is to hit the black material in the filter paper with 100ml nitric diluted with 100ml water just to make sure there’s no silver left.

Filter it then hit what’s left with AR and stannous test.