What do I have Here?

[Dreamer]

Over the last year, I've been dumping my waste onto copper without parting the silver. I cleaned out the bucket, removed the copper pieces, filtered and rinsed well. Incinerated the remains and treated with dilute nitric. The solute was negative for silver but I wound up with over a kilo of dirty dried silver chloride which is a complete nightmare discussed on another thread.

My question here today is " what do I have in my solution". I evaporated it down and added sulfamic at +90c to rid the Nitric. The Stannous test looks like Au and I don't see any PGM's. I took 2ml of solution and applied SMB, NH4Cl, and DMG (see pics).

SMB- black sludge precipitate
NH4Cl - has no precipitate
DMG- Gold crystals

Just strange why there would be Au. I did not use any Cl and I incinerated the starting material. If any Cl was liberated from the AgCl and survived, wouldn't the solute have had some AgNO3 in it?

- How should I proceed?
- Did I assay this in a logical way or am I missing something fundamentally?

Thank you for being here and for your remote mentorship.

 

[Martijn]

There should not be any precious metal left after cementing on copper. Except for palladium if there is a lot of cupric chloride in solution.
Where did this kilo of silver chloride come from? Not from this waste, right?
Gold crystals from a stockpot solution after cementing seems very unlikely, but filter, dissolve and test with stannous. I suspect palladium salts.

You say the stannous reaction looks like gold, what does it look like? Share a picture and show by adding a drop on filter paper and putting a drop of stannous next to it, just touching. This will show if there is copper( brown to black) or gold(purple to black) in solution. if too dark, dilute the drop before adding stannous.

 

[Dreamer]

Thanks for the reply. The stannous test is next to the test tubes. The material is from my waste bucket (copper treatment). The sediment was screened, incinerated and boiled in nitric. The solute was evaporated to 400ml. Treated with sulfamic and tested with those results. I've attached the photo of the remaining sediments for reference.

On a side note, this material was treated with AR and the remaining dirty AgCl was smelted in 40% borax(no collector metal or thinning agent) leaving me with a pile of slag with millions of fine beads of Ag mixed throughout..uhg! I seem to learn more from my own costly mistakes.

Anyways. Back to the nitric solute. I'm sure it is mostly Cuperic but the tests are leading me to believe there're PM's to recover. Copper wire dip comes out black.

Thank you for your attention. I appreciate your feedback.

 

[Martijn]

The stannous test is next to the test tubes.

That does look like gold. Strange. Did yo use a bubbler in the copper cementing step?

 

[kurtak]

the remaining dirty AgCl was smelted in 40% borax

For smelting AgCl you NEED to use soda ash for your flux - NOT borax

Soda ash is REQUIRED to make the reduction from AgCl to Ag

Borax (alone) will just cause the VAST majority of the AgCl to go off in the slag

Kurt

 

[Dreamer]

For smelting AgCl you NEED to use soda ash for your flux - NOT borax

Soda ash is REQUIRED to make the reduction from AgCl to Ag

Borax (alone) will just cause the VAST majority of the AgCl to go off in the slag

Kurt

Well I can attest to the truth of this. There was a post about using 40% Borax resulting in nearly 3N Ag so I gave it a try...big mistake. I wish there was a Hoke-like book on pyrometallurgy for step-wise learning.

 

[Dreamer]

That does look like gold. Strange. Did yo use a bubbler in the copper cementing step?

Yes I did, why?

I wound up cementing everything and processed the gold out, just under 2 grams and gave up chasing the PGMs, I put the waste back in my copper bucket. I'll go after them next time when I'm not dealing with a Silver chloride mess. Lesson Learned this year was to recover the silver as a nitrate first and keep the AgCl away from the Au.

I thought that throwing all the waste from gold recovery in a common copper bucket would make thing easy but I didn't realize having it mixed with a large quantity of AgCl would be so challenging.

 

[Yggdrasil]

Yes I did, why?

I wound up cementing everything and processed the gold out, just under 2 grams and gave up chasing the PGMs, I put the waste back in my copper bucket. I'll go after them next time when I'm not dealing with a Silver chloride mess. Lesson Learned this year was to recover the silver as a nitrate first and keep the AgCl away from the Au.

I thought that throwing all the waste from gold recovery in a common copper bucket would make thing easy but I didn't realize having it mixed with a large quantity of AgCl would be so challenging.

If you have cemented on Copper, the PGMs will be out too.

 

[Dreamer]

Thanks for the attention Ygg. After Cementing things out on copper, I recovered the Au via Nitric->rinse->AR-> Sulfamic-> Filter-> SMB. The waste was put back into my (copper containing) waste bucket. I realize I have a lot of studying to do and plan to venture into PGM's in the spring. I'm working on Silver recovery and refining now and have a bucket full of MLCC's to do next. These are of the late 90's-early 00's vintage so I don't expect much PGM's. I'd like to recover the Ag now and preserve any PGM's for later.

I'm planning on processing them with this plan in mind:

1) incinerate
2) Pulverize
3) Nitric leach the Ag
4) Filter sediment and leach with AR - to go into my copper waste bucket to recover any values, pitch the remaining MLCC's unaffected by the Nitric and AR
5) Cement the AgNO3
6) Convert the Cement to AgCl
7) Rinse to collect any PdCl -to go into my copper waste bucket to recover any values
8) Lye and Sugar convert the AgCl to Ag and "Corn flake" it for a silver cell

My goal is to collect and preserve the PGM's for later. Do any of my steps present any future complications or do you see any potential loss of values?

Am I wasting my time with the Cl conversion and instead just take the Silver cement and run it through a cell and deal with the filter sludge when I'm ready to venture into PGM recovery?

Very appreciative to have your input and remote mentorship.

Best Regards

 

[Martijn]

Yes I did, why?

Because no precious metals should be in solution if you let it react completely.

I thought that throwing all the waste from gold recovery in a common copper bucket would make thing easy but I didn't realize having it mixed with a large quantity of AgCl would be so challenging.

Waste should be stannous tested before adding to the stockpot, and once more to see if you can proceed to the iron pot.

All pm's should be with the silver chloride.
Excess oxidizer can keep pm's in solution, then just keep it longer in the stockpot.
If i had this mix of AgCl and cemented pm's, I would convert the AgCl with sulphuric and iron and then HNO3 to get the silver and any Pd out.

Have you read the dealing with waste thread?

I'm working on Silver recovery and refining now and have a bucket full of MLCC's to do next. These are of the late 90's-early 00's vintage so I don't expect much PGM's. I'd like to recover the Ag now and preserve any PGM's for later.

Look for posts from @kurtak, he reccommends smelting as the best method for processing mlcc's.

Am I wasting my time with the Cl conversion and instead just take the Silver cement and run it through a cell and deal with the filter sludge when I'm ready to venture into PGM recovery?

I advise you to look into the sulphuric iron process to convert AgCl. I like it.

Martijn.

 

[Dreamer]

Thank you kindly for the reply. When I cemented out the PM's from the solution in question, it emitted an appreciable amount of NO2 so it was not completely denox'd with the sulfamic even though it was help above 90c and significantly evaporated.

. There had to have been some Cl that was either liberated by the nitric boil or that survived the incineration, that's all I can think of.

If i had this mix of AgCl and cemented pm's, I would convert the AgCl with sulphuric and iron and then HNO3 to get the silver and any Pd out.

I haven't read anything on this process. Is there a link or a tag I could search with?

-and yes I have read the thread on dealing with waste. Being cocksure that my biochemistry degree was better than actual experience led to this Chlorific mess (sorry for the pun) and all the more reason to consult with this forum. It's far more complicated than most people realize. The more you know, the more you realize you don't know.

Look for posts from @kurtak, he reccommends smelting as the best method for processing mlcc's.

I kind've been forced into smelting and am reading up on the basics of it now. Inquartation and incineration is the extent of my knowledge/experience. Do you have any recommendations for introduction into pyrometallurgy?


Thank you so much for the guidance. Extremely Grateful.

 

[Martijn]

You can use the search function. Reading the older posts give a lot of additional info.
A search i did:
https://goldrefiningforum.com/search/80024/?q=Sulfuric+iron+silver+chloride&o=relevance
Im short it comes down to: washing the silver chloride clean of any salts and acid, covering in dilute sulfuric acid, adding iron nails and stir that, or stirring with a piece of iron.
This will convert the silver chloride into silver metal. Get the nails out with a magnet and wash clean until pH neutral. If you have rust forming during washing, wash again with warm water with a bit of sulfuric.

 

[FrugalRefiner]

It's far more complicated than most people realize. The more you know, the more you realize you don't know.

I've posted this several times before, but it seems to apply here. I call it the "Stages of Learning".

At first, you read a little and it seems to be simple and make sense.

As you read more, you start to see other processes, and conflicting information. There's so much new information, it can get very confusing.

As you continue, you're able to sort out the conflicting information, and it starts to make sense.

After much study you'll start to feel like you're really getting a handle on it all. You can answer most questions on the forum.

Then you read a post from Lou, and you realize how much you still don't know.

Dave

 

[4metals]

I thought that throwing all the waste from gold recovery in a common copper bucket would make thing easy but I didn't realize having it mixed with a large quantity of AgCl would be so challenging.

In an aqua regia refine the silver chlorides will be on your filter papers as they are largely insoluble in aqua regia.

Maybe I’ve never said this before but your insolubles from refining are never mixed with the liquors for cementation from aqua regia work. Because, well I guess now you see why. Those insolubles are typically either reduced dirty to make impure Silver metal or melted at a low temperature to melt the Silver Chloride into a bar form which can be processed separately. But you never want to add any insolubles to the stock pot liquids for cementation. It makes, as you now can see, a mess.

 

[kurtak]

Look for posts from @kurtak, he reccommends smelting as the best method for processing mlcc's.

Yes - smelting MLCCs is hands down better then leaching them

The BIG problem with leaching MLCCs is the ULTRA FINE ceramic MUD that results in the breakdown of the ceramic when leaching - when I say ultra fine MUD I am talking about mud that is like clay which makes it IMPOSSIBLE to get all the values (PMs) washed/filtered out of the MUD - you will most certainly loose values to being tied up in the MUD

The larger the batch = more mud = more values lost to being tied up in the mud

This is true with leaching any ceramics (such as crushed/ground/milled CATs etc.)

Whether you leach or smelt ceramics the ceramic needs to be ground/milled to fine powder - with leaching that is so the acid can get to the metals to dissolve them - BUT - then it is IMPOSSIBLE to get all the dissolved metal washed/filtered out of the mud

With smelting you want to use cryolite in your flux which actually dissolves the ceramic allowing the ceramic to go off in the slag allowing the molten metal to pool & settle in the bottom of your crucible & then as well to settle in the bottom of your cone mold --- you also want to use a collector metal in the smelt to help with the pooling/settling of the metals - silver or copper (NOT LEAD) are your best collector metals - I always used silver cemented from silver nitrate solutions because - (1) I processed "a lot" of silver in the first place & (2) you are processing the MLCCs for their Ag & Pd anyway --- meaning you have to "part" Ag & Pd whether you add more silver - or copper in place of silver

It does not take a lot of cryolite to dissolve the ceramic (so it goes off in the slag)

For the flux you want -------

The cryolite to make up 5 -10 % of the flux - the rest 50/50 borax (Anhydrous is preferred over 20 mule team) soda ash

Example; - for every 9 table spoons (or cups) of 50/50 borax/soda ash add 1 table spoon (or cup) cryolite = 10% cryolite

Keep in mind that this flux is hard on crucibles (because it dissolves ceramic) so use good quality crucibles not budget crucibles

The finer you grind/mill the ceramic the better as the finer the ceramic the better/quicker the ceramic dissolves (to go off in slag) = less time in the furnace = less hard on the crucible (as well as better pooling/collection of the metals)

You want the molten flux to run nice & fluid (for good circulation) if it is running to thick you can add "a bit" more cryolite &/or "a bit" of Fluorspar (which is also hard on crucibles)

I'm working on Silver recovery and refining now and have a bucket full of MLCC's to do next. These are of the late 90's-early 00's vintage so I don't expect much PGM's

Per the bold print - There "may" be a "fair" amount of Pd in the MLCCs from that time period - I say "fair" amount because ------

In the mid 90s is when they started to change from PM (Precious Metal) MLCCs to BM (Base Metal) MLCCs

So for a few years after (about 1995/1996) though they were starting to make BM MLCCs they were also still making PM MLCCs

now and have a bucket full of MLCC's

So a bucket full from that time period you could (or not) have a fair amount of Pd - I would look (test) for it

I kind've been forced into smelting and am reading up on the basics of it now. Inquartation and incineration is the extent of my knowledge/experience. Do you have any recommendations for introduction into pyrometallurgy?

Per the bold print - right here -------

https://goldrefiningforum.com/threads/smelting.23680/
Edit to add; - cryolite is used as a glaze for pottery so pottery shops are a place to look for it (it may be spelled kryolite - same thing just spelled different)

Here is where I got mine -----

Search Results

Kurt

 

[Dreamer]

In an aqua regia refine the silver chlorides will be on your filter papers as they are largely insoluble in aqua regia.

Maybe I’ve never said this before but your insolubles from refining are never mixed with the liquors for cementation from aqua regia work. Because, well I guess now you see why. Those insolubles are typically either reduced dirty to make impure Silver metal or melted at a low temperature to melt the Silver Chloride into a bar form which can be processed separately. But you never want to add any insolubles to the stock pot liquids for cementation. It makes, as you now can see, a mess.

I hope some beginners see this thread. Sharing my mistakes and consequences will at least benefit others.

Over the last year, I've just been throwing all my non-gold liquors onto copper in 2 waste buckets. One for waste which I expected would contain Ag and the second for Au. I DID NOT recover the Ag before I did this because I believed I would just get to it when I felt confident with my Au recovery and refining techniques and I'd have an abundant source of Ag to work with to develop those skills.

What I now realize (please correct me if I'm wrong) is that I should recover the Ag as a nitrate off copper as much as possible and minimize the dirty AgCl keeping both stocks wet for further recovery/refining AND never just dump these in my waste treatment stream believing it would easy to recover later.

I am hoping that I can gain some forward thinking insight as I move into Silver refining keeping in mind that I will have PGM's to learn about which will be concentrated from this last years Ag recovery. The waste stream came from scrap Karat/filled and a few hundred computers along with a couple Kg's of MLCC's I'm yet to process.

You guys have been AWESOME and I only hope I can contribute someday in a meaningful way.

Best Regards

 

[Dreamer]

Yes - smelting MLCCs is hands down better then leaching them

The BIG problem with leaching MLCCs is the ULTRA FINE ceramic MUD that results in the breakdown of the ceramic when leaching - when I say ultra fine MUD I am talking about mud that is like clay which makes it IMPOSSIBLE to get all the values (PMs) washed/filtered out of the MUD - you will most certainly loose values to being tied up in the MUD

The larger the batch = more mud = more values lost to being tied up in the mud

This is true with leaching any ceramics (such as crushed/ground/milled CATs etc.)

Whether you leach or smelt ceramics the ceramic needs to be ground/milled to fine powder - with leaching that is so the acid can get to the metals to dissolve them - BUT - then it is IMPOSSIBLE to get all the dissolved metal washed/filtered out of the mud

With smelting you want to use cryolite in your flux which actually dissolves the ceramic allowing the ceramic to go off in the slag allowing the molten metal to pool & settle in the bottom of your crucible & then as well to settle in the bottom of your cone mold --- you also want to use a collector metal in the smelt to help with the pooling/settling of the metals - silver or copper (NOT LEAD) are your best collector metals - I always used silver cemented from silver nitrate solutions because - (1) I processed "a lot" of silver in the first place & (2) you are processing the MLCCs for their Ag & Pd anyway --- meaning you have to "part" Ag & Pd whether you add more silver - or copper in place of silver

It does not take a lot of cryolite to dissolve the ceramic (so it goes off in the slag)

For the flux you want -------

The cryolite to make up 5 -10 % of the flux - the rest 50/50 borax (Anhydrous is preferred over 20 mule team) soda ash

Example; - for every 9 table spoons (or cups) of 50/50 borax/soda ash add 1 table spoon (or cup) cryolite = 10% cryolite

Keep in mind that this flux is hard on crucibles (because it dissolves ceramic) so use good quality crucibles not budget crucibles

The finer you grind/mill the ceramic the better as the finer the ceramic the better/quicker the ceramic dissolves (to go off in slag) = less time in the furnace = less hard on the crucible (as well as better pooling/collection of the metals)

You want the molten flux to run nice & fluid (for good circulation) if it is running to thick you can add "a bit" more cryolite &/or "a bit" of Fluorspar (which is also hard on crucibles)

Per the bold print - There "may" be a "fair" amount of Pd in the MLCCs from that time period - I say "fair" amount because ------

In the mid 90s is when they started to change from PM (Precious Metal) MLCCs to BM (Base Metal) MLCCs

So for a few years after (about 1995/1996) though they were starting to make BM MLCCs they were also still making PM MLCCs

So a bucket full from that time period you could (or not) have a fair amount of Pd - I would look (test) for it

Per the bold print - right here -------

https://goldrefiningforum.com/threads/smelting.23680/
Edit to add; - cryolite is used as a glaze for pottery so pottery shops are a place to look for it (it may be spelled kryolite - same thing just spelled different)

Here is where I got mine -----

Search Results

Kurt

Kurt, I cannot thank you enough for freely sharing your valuable knowledge. You've saved me a lot of agony.

I've been doing my smelting in a melt dish with an ox/ac torch and I am shopping for a furnace now. Keeping in mind that I am a small scale hobbyist, is there a size/brand you would recommend? I don't mind spending an extra hundred or so for something of useful quality but I don't need an oversized Rolls Royce to run up to the grocery store .

~Thom

 

[Martijn]

Kurt, I cannot thank you enough for freely sharing your valuable knowledge. You've saved me a lot of agony.

I've been doing my smelting in a melt dish with an ox/ac torch and I am shopping for a furnace now. Keeping in mind that I am a small scale hobbyist, is there a size/brand you would recommend? I don't mind spending an extra hundred or so for something of useful quality but I don't need an oversized Rolls Royce to run up to the grocery store .

~Thom

I built this small furnace from aerated concrete block. They cost 2 euro's a piece and are drilled and scraped out with ease.
I put a fire brick bottom underneath to have a flat bottom. The concrete wears in time but works great! Cold to the touch on the outside.
Thread 'Spending a weekend playing with part of the H2SO4 cell harvest.' Spending a weekend playing with part of the H2SO4 cell harvest.

 

[VK3NHL]

Being cocksure that my biochemistry degree was better than actual experience led to this Chlorific mess (sorry for the pun)

Your reference to “cocksure” reminds me of my early days in the lab where my boss’s favourite quote was:-

“The definition of education is man’s going forward from Cocksure ignorance to thoughtful uncertainty”

That was in the mid 1960’s
The things one remembers….

 

[Dreamer]

Yes - smelting MLCCs is hands down better then leaching them

The BIG problem with leaching MLCCs is the ULTRA FINE ceramic MUD that results in the breakdown of the ceramic when leaching - when I say ultra fine MUD I am talking about mud that is like clay which makes it IMPOSSIBLE to get all the values (PMs) washed/filtered out of the MUD - you will most certainly loose values to being tied up in the MUD

The larger the batch = more mud = more values lost to being tied up in the mud

This is true with leaching any ceramics (such as crushed/ground/milled CATs etc.)

Whether you leach or smelt ceramics the ceramic needs to be ground/milled to fine powder - with leaching that is so the acid can get to the metals to dissolve them - BUT - then it is IMPOSSIBLE to get all the dissolved metal washed/filtered out of the mud

With smelting you want to use cryolite in your flux which actually dissolves the ceramic allowing the ceramic to go off in the slag allowing the molten metal to pool & settle in the bottom of your crucible & then as well to settle in the bottom of your cone mold --- you also want to use a collector metal in the smelt to help with the pooling/settling of the metals - silver or copper (NOT LEAD) are your best collector metals - I always used silver cemented from silver nitrate solutions because - (1) I processed "a lot" of silver in the first place & (2) you are processing the MLCCs for their Ag & Pd anyway --- meaning you have to "part" Ag & Pd whether you add more silver - or copper in place of silver

It does not take a lot of cryolite to dissolve the ceramic (so it goes off in the slag)

For the flux you want -------

The cryolite to make up 5 -10 % of the flux - the rest 50/50 borax (Anhydrous is preferred over 20 mule team) soda ash

Example; - for every 9 table spoons (or cups) of 50/50 borax/soda ash add 1 table spoon (or cup) cryolite = 10% cryolite

Keep in mind that this flux is hard on crucibles (because it dissolves ceramic) so use good quality crucibles not budget crucibles

The finer you grind/mill the ceramic the better as the finer the ceramic the better/quicker the ceramic dissolves (to go off in slag) = less time in the furnace = less hard on the crucible (as well as better pooling/collection of the metals)

You want the molten flux to run nice & fluid (for good circulation) if it is running to thick you can add "a bit" more cryolite &/or "a bit" of Fluorspar (which is also hard on crucibles)

Per the bold print - There "may" be a "fair" amount of Pd in the MLCCs from that time period - I say "fair" amount because ------

In the mid 90s is when they started to change from PM (Precious Metal) MLCCs to BM (Base Metal) MLCCs

So for a few years after (about 1995/1996) though they were starting to make BM MLCCs they were also still making PM MLCCs

So a bucket full from that time period you could (or not) have a fair amount of Pd - I would look (test) for it

Per the bold print - right here -------

https://goldrefiningforum.com/threads/smelting.23680/
Edit to add; - cryolite is used as a glaze for pottery so pottery shops are a place to look for it (it may be spelled kryolite - same thing just spelled different)

Here is where I got mine -----

Search Results

Kurt

So after a few days of research and gathering materials. This is what I've got:

- 6kg high temp gas furnace kit
- Silicon Carbide Graphite crucible
- 10# Soda Ash
- 1# Cryolite
- Borax (Store bought)

My understanding is the pyrometallurgic process is basically conducting the redox reaction encouraged under heat while controlling the presence of O2. The use of cryolite appears to create HF insitu converting Si to SiF4 which is gasified taking care of the ceramic problem. The Soda Ash is the reducing agent allowing the desired metals to coagulate and stratify in the pour. The Borax prevents the oxidation of the collected metals and its weight provides a fragile transition layer( this I am deducting from what I've read).

The resulting gases are highly toxic- so proper PPE and precautions obviously cannot be overstated.

It's been 30 years since I worked with a furnace melting metals (aluminum in highschool) so I have a couple of questions if you'd be kind enough to help me with.

1) what should my first experiment be to gain some level of understanding of the process?
2) Is my basic understanding of the flux reaction and use correct?
3) Is there anything I should watch for?
4) How do you calculate the flux to material ratios?

Thank you for any guidance you can share.