Refining MLCC´s for Palladium and Silver !

[GoIdman]

My electric furnace burnt it's heating element within the first 2 to 3 months. So yes I know first hand that they are cheap.

Try to find a used calcination furnace used in dental labs something like in the link. https://www.linn-high-therm.de/products/details/lm-model.html .. The heating wire can be exchanged if broken, good quality kanthal wire can be bought from aliexpress for like 2-3 usd per 3kW. It lasts forever and goes up to 1350 C.

I rebuilt mine , i have 2 spare wires if it burns, changing the wire is max 30min.

If the funace is not operational you may even get it for free. Try dental labs if they have broken furnaces, you can refurb one yourself, its straightforward.

Those cheap chinese furnaces eat crucibles and heating elements like crazy, not economical at all.

I`ve never attempted smelting since i am not familiar with that process, but i presume i could use my furnace for that purpose too.

Be safe

Pete

 

[kurtak]

I`ve never attempted smelting since i am not familiar with that process, but i presume i could use my furnace for that purpose too.

If the heating elements in the (electric) furnace are exposed they (the furnace) is not a good option for smelting in

The fumes generated (which are high temp fumes & corrosive) during smelting will destroy the elements in "relatively" short time - so you will be replacing the elements "relatively" often --- relatively = more often when smelting compared to when just melting pure metals

The high temp corrosive fumes generated during smelting come primarily (but not exclusively) from the flux --- especially if oxidizing flux such a potassium nitrate (as one example) are used

If the heating elements go around all side of the furnace (including the floor) the first time you have a flux "boil over" (which IS going to happen) it is going to destroy the elements

Not saying an electric furnace can't be used for smelting - they just are not a good option for smelting

Kurt

 

[Alondro]

That is why I am advocating for permanent solution to much of the pyro-work. Reliable, robust, effective and able to melt anything you will likely encounter, even vaporize carbon if you feel like it

I built a wood-fired furnace long ago with just scrap brick and cinderblock. Only used about 12 fire bricks for the bottom and two sides. Since it was constructed like a chimney, with steel rebar between one lower layer of brick to elevate the fire and allow airflow to move swiftly through it, I could get that thing just hot enough to melt copper. But I needed to have a wheelbarrow full of very dry wood ready each time, and it burned it all in about an hour. With a cast iron crucible made from pipe and plugged at the bottom with refractory cement, it was fantastic for processing aluminum. I only tried to melt copper in the crucible once, but I didn't have enough good hardwood wood to hold temperature long enough to melt more than a fraction of the copper in the crucible. Pine wood doesn't burn long enough or hot enough.

I'll be building my Model 2 furnace of that type this spring, adapting what I learned from the limits of the first one. I believe I can hit 2200F with it and hold it there with enough hardwood. I'm also going to adapt it to use coal. I have a supply of old weathered coal from a long-abandoned rail track behind my development. The small chunks of PA-origin anthracite coal have been washed in rain and snow for 70 years, and now burns exceedingly clean, with no smoke at all. I'll be curious to see how high the temp will go with that.

 

[orvi]

I built a wood-fired furnace long ago with just scrap brick and cinderblock. Only used about 12 fire bricks for the bottom and two sides. Since it was constructed like a chimney, with steel rebar between one lower layer of brick to elevate the fire and allow airflow to move swiftly through it, I could get that thing just hot enough to melt copper. But I needed to have a wheelbarrow full of very dry wood ready each time, and it burned it all in about an hour. With a cast iron crucible made from pipe and plugged at the bottom with refractory cement, it was fantastic for processing aluminum. I only tried to melt copper in the crucible once, but I didn't have enough good hardwood wood to hold temperature long enough to melt more than a fraction of the copper in the crucible. Pine wood doesn't burn long enough or hot enough.

I'll be building my Model 2 furnace of that type this spring, adapting what I learned from the limits of the first one. I believe I can hit 2200F with it and hold it there with enough hardwood. I'm also going to adapt it to use coal. I have a supply of old weathered coal from a long-abandoned rail track behind my development. The small chunks of PA-origin anthracite coal have been washed in rain and snow for 70 years, and now burns exceedingly clean, with no smoke at all. I'll be curious to see how high the temp will go with that.

I would definitely stick to the whatever coal rather than wood. Much better energy density. I had charcoal powered small furnance back in my teenage years - which was allright to melt aluminium, but copper was too difficult. But with better insulation, I would melt copper easily in it.

But from practical point of view, this is completely out of scope for me now. It is always such a chore to get it hot in the first place, burn quantities of coal to get to like 1250°C to start doing something useful with it.
One of the best solid fuels is coke. Hard to ignite, but then when it kicks, that´s whole another story. With improper control of the blowing air, I once started to melt firebricks on the bottom of the furnance
All solid fuel furnances, altough DIY made are very sloppy for fine melting works, flying ashes or another things can mess up whole smelt, not speaking of inability to access temps for PGM working.

 

[GoIdman]

If the heating elements in the (electric) furnace are exposed they (the furnace) is not a good option for smelting in

The fumes generated (which are high temp fumes & corrosive) during smelting will destroy the elements in "relatively" short time - so you will be replacing the elements "relatively" often --- relatively = more often when smelting compared to when just melting pure metals

The high temp corrosive fumes generated during smelting come primarily (but not exclusively) from the flux --- especially if oxidizing flux such a potassium nitrate (as one example) are used

If the heating elements go around all side of the furnace (including the floor) the first time you have a flux "boil over" (which IS going to happen) it is going to destroy the elements

Not saying an electric furnace can't be used for smelting - they just are not a good option for smelting

Kurt

Thank you for the valuable info and insight, i will probably bild a gas operating furnace if i want to attempt smelting, the large crucibles are very expensive in my area.
Allthough my furnace has an evacuation pipe in the back, a 1 inch diameter with fan, i presume that is not enough for the large amount of toxic fumes.

Maybe i bild a gas operated furnace.

Pete

 

[Rreyes097]

It may not be necessary to mill them - BUT - if you don't run the leaching process to the point that the ceramic turns to an ultra fine ceramic mud you have NOT leached all the Ag/Pd out of the ceramic

The Ag/Pd is layered/sintered in the ceramic - as the leaching dissolves the Ag/Pd the ceramic falls apart into ultra fine ceramic particles - leaving you with an ultra fine clay like mud

That mud is impossible to filter !!!!

Therefore you have to wash it with water (to get the leach values out) let the ceramic settle (that can take a day or more) - decant the wash - AND - you have to do multiple washes (3 or MORE) & even then you will never get all the values washed out - there will always be at least "traces" left behind

This results in VERY diluted solutions which means lots of evaporation is needed before going to recovery of the values from the leach/washing process

At every step of trying to leach MLCCs you are likely to lose at least some values

LOTS of chem waste - time wasted & values lost in leaching MLCCs

Smelting = MUCH less time MUCH less chem waste & MUCH better recovery

For what it is worth

Kurt

Thanks guys. So just with this 20 gram batch I could see how difficult that ceramic was going to be. Because although I only had to deal with a little amount, it was plenty for it to stop up my filter. So I've been trying to research on the forum smelting but I haven't seen anything thus far for what I need. Which is day one, base knowledge first day on the job sort of stuff. I'm sure I know some things but I'd like to know everything I can before trying it. Anybody have any links that they know of?

 

[Yggdrasil]

Thanks guys. So just with this 20 gram batch I could see how difficult that ceramic was going to be. Because although I only had to deal with a little amount, it was plenty for it to stop up my filter. So I've been trying to research on the forum smelting but I haven't seen anything thus far for what I need. Which is day one, base knowledge first day on the job sort of stuff. I'm sure I know some things but I'd like to know everything I can before trying it. Anybody have any links that they know of?

The search function is your friend.
Search and read, the threads that have interesting stuff in them, has to be read completely. There is literally nuggets in here, you just have to find them.
As in real life, they don’t necessarily come easy

 

[Rreyes097]

So I filtered the 20g mlccs after letting it sit in nitric acid diluted with distilled water for 4 days. After many rinses with distilled water. I then evaporated some so it wasn't so much rinse liquid. I may have lost some values? I'm not sure. But then I used HCl to push out the silver chloride. I converted it and so here is a picture of it. Not sure how much it weighs but by the the looks of it not very much at all. But I don't myself going that route again with even materials. Before I dropped silver I tested it with stannous and it came up negative for pd and gold. So I got whatever silver I could since the mlccs weren't milled or even crushed to be honest. So I'll clean up that little bit of silver and put it with my other recovered silver. Then l suppose I'll go play with my best friend the "search button" thanks y'all for the input. I've got learning to do.

 

[Yggdrasil]

So I filtered the 20g mlccs after letting it sit in nitric acid diluted with distilled water for 4 days. After many rinses with distilled water. I then evaporated some so it wasn't so much rinse liquid. I may have lost some values? I'm not sure. But then I used HCl to push out the silver chloride. I converted it and so here is a picture of it. Not sure how much it weighs but by the the looks of it not very much at all. But I don't myself going that route again with even materials. Before I dropped silver I tested it with stannous and it came up negative for pd and gold. So I got whatever silver I could since the mlccs weren't milled or even crushed to be honest. So I'll clean up that little bit of silver and put it with my other recovered silver. Then l suppose I'll go play with my best friend the "search button" thanks y'all for the input. I've got learning to do.

How did you convert it?

 

[Rreyes097]

Sodium hydroxide and sugar

 

[Yggdrasil]

Sodium hydroxide and sugar

Then I think there might be something off with your process.
It is supposed to be a light grey heavy powder, not black.
Is it a light issue maybe?

 

[Rreyes097]

Well it's pretty dark but I guess u could call it dark dark brown but I'm not sure. Could I have not put enough in or either? Well I'll clean it up and maybe it will change to the proper color. Sorry about that

 

[Yggdrasil]

Well it's pretty dark but I guess u could call it dark dark brown but I'm not sure. Could I have not put enough in or either? Well I'll clean it up and maybe it willúmh will it 4u7ll

Can you try again, can’t understand the last part.

 

[Yggdrasil]

Well it's pretty dark but I guess u could call it dark dark brown but I'm not sure. Could I have not put enough in or either? Well I'll clean it up and maybe it willúmh will it 4u7ll

Anyway.
Can you describe in detail what you did and what happened?
There is definitely something off.
Edit for spelling

 

[eaglekeeper]

Unless the lighting is bad, I would say something is off. Did you use plain old table sugar or something else?. As Yggdrasil mentioned, It should be a bright gray/silvery color.

 

[Rreyes097]

Anyway.
Can you describe in datail what you did and what happened?
There us definitely something off.

All I did was follow the people name owl something. Owltech I think they are called. I simply put on my hot plate with magnetic mlccs and heated it up. While magnetic stirrer. Added about 2 maybe 3 tbsp sodium hydroxide. Until everything went from the to pretty much the same color it is now. Then I added regular sugar. This is where I wasn't sure how much sugar.

Unless the lighting is bad, I would say something is off. Did you use plain old table sugar or something else?. As Yggdrasil mentioned, It should be a bright gray/silvery color.

Just regular sugar.

 

[kurtak]

It is black/brown because it is still silver oxide

Just regular sugar.

You "should" use Kero syrup (corn syrup) regular sugar will work but corn syrup works better

That is because corn syrup is a reducing sugar (so better reduces silver oxide to actual silver) whereas regular sugar is not a reducing sugar

Also - though not absolutely necessary - you are better served if you wash all the hydroxide out of the AgO before using the sugar to convert the AgO to Ag

Kurt

 

[Rreyes097]

It is black/brown because it is still silver oxide

You "should" use Kero syrup (corn syrup) regular sugar will work but corn syrup works better

That is because corn syrup is a reducing sugar (so better reduces silver oxide to actual silver) whereas regular sugar is not a reducing sugar

Also - though not absolutely necessary - you are better served if you wash all the hydroxide out of the AgO before using the sugar to convert the AgO to Ag

Kurt

Oh thanks Kurt. I forgot about the washing after the sodium hydroxide. So what should I do now? More sugar? And next time I'll try and pick some of that kero syrup.

 

[Yggdrasil]

All I did was follow the people name owl something. Owltech I think they are called. I simply put on my hot plate with magnetic mlccs and heated it up. While magnetic stirrer. Added about 2 maybe 3 tbsp sodium hydroxide. Until everything went from the to pretty much the same color it is now. Then I added regular sugar. This is where I wasn't sure how much sugar.

Just regular sugar.

You confuse me. Did you try that procedure with the MLCCs directly?

If that is the case.
You REALLY need to study until you understand.
That precedure is for converting clean Silver Chloride to Silver Oxide and then to Silver.

So please do a step by step of what you did and what happened.

 

[Rreyes097]

You confuse me. Did you try that procedure with the MLCCs directly?

If that is the case.
You REALLY need to study until you understand.
That precedure is for converting clean Silver Chloride to Silver Oxide and then to Silver.

So please do a step by step of what you did and what happened.

What do you mean directly? Did i have the mlccs in there while I added the sodium hydroxide and then the sugar. So if you are asking if the mlccs were in the beaker will add that stuff then the answer is no.
After I put the mlccs into dilute nitric I then filtered out the mlccs. And many rinses with distilled water. Next I put the beaker back on the hot plate. Without lid, I tried to evaporate much of the liquid. Then i added sodium hydroxide and used my magnetic stirrer until all of the white chloride turned dark to even black. Next I added the sugar, regular sugar ( which I'm your I should used kero syrup and also should have rinsed that sugar before adding the sugar) so after adding that sugar I kept it in hot plate until it all looked dark and uniform color. Did I mess up? I guess I should have rinsed before sugar but all in all I followed instructions instructions according to my research.