Could this be rhodium plated??

[Bardboards]

I have a small box from 1979 with ~20lbs of PCBs bare. There was an original old order form ripped up in the box with the option to order rhodium plated. It’s cut off before I can see if it was checked off. However this sheen looks different than other sheen I have seen. Could it be rhodium? It’s matte with silver purple undertones.

 

[Bardboards]

And if it is rhodium plated, what do I do with it?

 

[4metals]

Nickel is a typical underplate, especially for mil spec plating. The two options on the sheet are for Nickel gold which would have been obvious, and Nickel rhodium which is silver in color and not necessarily mirror like depending on the finish of the underplate.

It can potentially be Rhodium plated. For sure. Until you get further along in the segregation process I would be keeping it separate with all other suspected rhodium plated boards.

 

[Soar2c]

Im absolutely lost... I have some similar high end communication boards. I pulled some metal to do a test smelt. I figured it would be pretty straight forward. I took bolt cutters to (2) gold pinned very dense gold in color transistors to fraction them down in size. Nothing was magnetic. When cutting through the metal (my thought was gold plated on silver) the metal was very soft and took a few times opening and closing the cutters for it snip off a piece. Along with these transitors I also removed this very pliable silvery metal circuit from the substrate board. And then I added all the gold plated pins I pulled from a connection board in the same electronics since this was a large showing of gold plated pins

In total my charge was very gold in color and had a lot of silver parts and colors intermixed. Again this seemed very straight forward. Charge was 68g of metallic gold and silver. Flux was 3x (68g) of Chapman flux and I added in 110g of borax powder and 29.4g of pure lead for collector in case there was some steel or copper intermixed as I figured they would oxidise and move to the slag and the lead collector would have a high affinity to attract the precious metals.

After the pour and cool down a lead + precious Metal Button was recovered at 89.4g

I broke this into two sections to further refine the lead out during magnesia cupellation in a muffle furnace.


So up until this point it seemed like I was gonna have a great pay day for my initial test since it was so straight forward, and then the tables turned.

I now have two magnesia cupells with a silvery blue tarnished metal with a copper undertone smeared in the cupell and as hard as rock bonded to the cupell.

Can someone offer some guidance and understanding please cause I'm lost.

Thanks.

Kyle

 

[Lino1406]

Im absolutely lost... I have some similar high end communication boards. I pulled some metal to do a test smelt. I figured it would be pretty straight forward. I took bolt cutters to (2) gold pinned very dense gold in color transistors to fraction them down in size. Nothing was magnetic. When cutting through the metal (my thought was gold plated on silver) the metal was very soft and took a few times opening and closing the cutters for it snip off a piece. Along with these transitors I also removed this very pliable silvery metal circuit from the substrate board. And then I added all the gold plated pins I pulled from a connection board in the same electronics since this was a large showing of gold plated pins

In total my charge was very gold in color and had a lot of silver parts and colors intermixed. Again this seemed very straight forward. Charge was 68g of metallic gold and silver. Flux was 3x (68g) of Chapman flux and I added in 110g of borax powder and 29.4g of pure lead for collector in case there was some steel or copper intermixed as I figured they would oxidise and move to the slag and the lead collector would have a high affinity to attract the precious metals.

After the pour and cool down a lead + precious Metal Button was recovered at 89.4g

I broke this into two sections to further refine the lead out during magnesia cupellation in a muffle furnace.


So up until this point it seemed like I was gonna have a great pay day for my initial test since it was so straight forward, and then the tables turned.

I now have two magnesia cupells with a silvery blue tarnished metal with a copper undertone smeared in the cupell and as hard as rock bonded to the cupell.

Can someone offer some guidance and understanding please cause I'm lost.

Thanks.

Kyle


View attachment 52167

Try to free the slags with hot water, NH4Cl, acid, you may need to destroy the crucibles

 

[orvi]

Im absolutely lost... I have some similar high end communication boards. I pulled some metal to do a test smelt. I figured it would be pretty straight forward. I took bolt cutters to (2) gold pinned very dense gold in color transistors to fraction them down in size. Nothing was magnetic. When cutting through the metal (my thought was gold plated on silver) the metal was very soft and took a few times opening and closing the cutters for it snip off a piece. Along with these transitors I also removed this very pliable silvery metal circuit from the substrate board. And then I added all the gold plated pins I pulled from a connection board in the same electronics since this was a large showing of gold plated pins

In total my charge was very gold in color and had a lot of silver parts and colors intermixed. Again this seemed very straight forward. Charge was 68g of metallic gold and silver. Flux was 3x (68g) of Chapman flux and I added in 110g of borax powder and 29.4g of pure lead for collector in case there was some steel or copper intermixed as I figured they would oxidise and move to the slag and the lead collector would have a high affinity to attract the precious metals.

After the pour and cool down a lead + precious Metal Button was recovered at 89.4g

I broke this into two sections to further refine the lead out during magnesia cupellation in a muffle furnace.


So up until this point it seemed like I was gonna have a great pay day for my initial test since it was so straight forward, and then the tables turned.

I now have two magnesia cupells with a silvery blue tarnished metal with a copper undertone smeared in the cupell and as hard as rock bonded to the cupell.

Can someone offer some guidance and understanding please cause I'm lost.

Thanks.

Kyle


View attachment 52167

It looks like you had too much base metals in your charge for ammount of lead you used. Iron or copper. So PbO formed does not liquified all of it and it stayed where it is expected to stay when not enough PbO "flux" is generated.
Either free the slags out of the cupels and smelt them as they are in a regular crucible, or add more lead (if cupel isn´t saturated yet) and continue. I would advise to free the slags to another crucible/cupel.

 

[orvi]

Nickel is a typical underplate, especially for mil spec plating. The two options on the sheet are for Nickel gold which would have been obvious, and Nickel rhodium which is silver in color and not necessarily mirror like depending on the finish of the underplate.

It can potentially be Rhodium plated. For sure. Until you get further along in the segregation process I would be keeping it separate with all other suspected rhodium plated boards.

Very interesting... Now I won´t sleep that much old boards which I tossed away...
I have seen Pd plated fingers on old boards, but it was distinct from the rest of the board. And as sane man does not have time to acid test all boards, I maybe did quite a bit of a mistake in the past

Did you ever encountered Rh plated PCBs ?

 

[4metals]

Did you ever encountered Rh plated PCBs ?

I never picked boards other than picking them up and throwing them into a shredder, and that was always without paying much attention to individual boards. But when I shipped copper based bullion made from shredding, pyrolyzing, melting and sparging the melt, there were occasions when Rhodium was in the assay. Usually not in payable quantities. We always shipped 1000 oz bars and the end refiner usually melted 6 to 10 of them and sampled them once.

Rhodium was never utilized in low end boards but military boards were a possibility as were telecom. And these boards are old. Back in 1975 Rhodium was under $300 an ounce so it wasn't crazy pricing that prevented its use.

Very interesting... Now I won´t sleep that much old boards which I tossed away...

In America there is an old expression, "don't cry over spilled milk". As a refiner I spilled a fair share of milk, but always learned from it.

I should point out that I refined long before the forum existed and much of a refiners experience was learned the hard way, by spilled milk!

 

[Alondro]

I never picked boards other than picking them up and throwing them into a shredder, and that was always without paying much attention to individual boards. But when I shipped copper based bullion made from shredding, pyrolyzing, melting and sparging the melt, there were occasions when Rhodium was in the assay. Usually not in payable quantities. We always shipped 1000 oz bars and the end refiner usually melted 6 to 10 of them and sampled them once.

Rhodium was never utilized in low end boards but military boards were a possibility as were telecom. And these boards are old. Back in 1975 Rhodium was under $300 an ounce so it wasn't crazy pricing that prevented its use.


In America there is an old expression, "don't cry over spilled milk". As a refiner I spilled a fair share of milk, but always learned from it.

I should point out that I refined long before the forum existed and much of a refiners experience was learned the hard way, by spilled milk!

I'd just do a couple tests on pieces of the metal to see what they dissolve in. A piece in conc. HCl and a piece in 50% nitric for the first tests. If the metal doesn't dissolve in either, then it gets very interesting.

If it dissolves in nitric, next thing is to see if the metal will cement out on copper. If it does, it's at least silver.

I've heard from some people that old traces like yours, especially from high-grade military, telecom and aerospace applications, can be a silver-palladium alloy. I have some old fingers that look to be made of that alloy, along with a handful of similar boards. They look very silvery when they've been kept in clean, dry conditions. But those exposed to the elements take on that purplish tone.

 

[orvi]

I never picked boards other than picking them up and throwing them into a shredder, and that was always without paying much attention to individual boards. But when I shipped copper based bullion made from shredding, pyrolyzing, melting and sparging the melt, there were occasions when Rhodium was in the assay. Usually not in payable quantities. We always shipped 1000 oz bars and the end refiner usually melted 6 to 10 of them and sampled them once.

Rhodium was never utilized in low end boards but military boards were a possibility as were telecom. And these boards are old. Back in 1975 Rhodium was under $300 an ounce so it wasn't crazy pricing that prevented its use.


In America there is an old expression, "don't cry over spilled milk". As a refiner I spilled a fair share of milk, but always learned from it.

I should point out that I refined long before the forum existed and much of a refiners experience was learned the hard way, by spilled milk!

To this day, I only knew about Rh in non-military e-scrap stuff from plating in reed relay tube contacts. And from testing pins for circuit boards testing. These are sometimes Rh plated.
Yeah, with spilled milk, it is the same saying here but I started refining when forum existed a healthy few years... nevermind... It´s time to grab vial of nitric we will see what is what

 

[orvi]

I'd just do a couple tests on pieces of the metal to see what they dissolve in. A piece in conc. HCl and a piece in 50% nitric for the first tests. If the metal doesn't dissolve in either, then it gets very interesting.

If it dissolves in nitric, next thing is to see if the metal will cement out on copper. If it does, it's at least silver.

I've heard from some people that old traces like yours, especially from high-grade military, telecom and aerospace applications, can be a silver-palladium alloy. I have some old fingers that look to be made of that alloy, along with a handful of similar boards. They look very silvery when they've been kept in clean, dry conditions. But those exposed to the elements take on that purplish tone.

I won´t take it so complicated. There aren´t that many possibilities what could be what.
Practically you are limited to Cu, Ag, Au (obvious), Ni, Sn, Pb, Pd and now - Rh. Nitric is all you need. Dilute nitric if you do not have experience with colours, concentrated nitric if you know what you see if you spot it.

AgSnPb - colourless, Sn with nice metastannic quark goo... obvious.
Au - obvious. No reaction with Au, just with copper underneath.
Cu, Ni - green/blue

Pd - REDDISH BROWN - and this is important. If you start to see very dirty green colour as drop of nitric start to react with the trace, you know you have Pd almost 100%. When copper/nickel colour mix with reddish brown Pd colour, final colour is very dirty brownish green colour. First time you spot this colouration, you will never forget how it should look like. Additionally, you can sprinkle some DMG onto the drop and stir with some piece of plastic.
Pd reacts significantly slower than copper. So that is another possibility how to spot the difference. If you drop dilute nitric, Pd foil will stay practically intact. Just copper will react vigorously. At room temp, concentrated acid just slowly catch some orange tinge (if pure Pd).

Rh - copper from underneath the Rh plate will be eaten by nitric, while Rh won´t do nothing

Anyway, everytime nitric does practically nothing to the metal on PCB, it is the reason to celebrate, as traces aren´t usually made from Al or Fe

 

[Lino1406]

Something from old days: In printed circuits manufacture, there was a stage of tinning, covering conductors with tin/lead as etch resist

 

[Findm-Keepm]

OP's board looks too "Hobbyish" to be anything other than a board with Electro-less tin plate on the copper vias. "Tinnit" was a well-known electro-less Tin-plate kit for circuit boards until the Urea in the package got poo-pooed by the EPA and others.

Off- center holes, hand drawn vias, and the board weight (high resin FR4, no mesh visible) leads me to think it was a kit board or some other low-end item. A quality CCA fab would have provided some identification, possible component polarity lands, and a larger ground plane. I can't fathom any use of Rhodium in CCA plating. Rhodium in electronics is most commonly found in older reed switches and relays as a contact material.

 

[Soar2c]

It looks like you had too much base metals in your charge for ammount of lead you used. Iron or copper. So PbO formed does not liquified all of it and it stayed where it is expected to stay when not enough PbO "flux" is generated.
Either free the slags out of the cupels and smelt them as they are in a regular crucible, or add more lead (if cupel isn´t saturated yet) and continue. I would advise to free the slags to another crucible/cupel.

Awesome, thanks for the help on this. I figured the electronics were very thick played in precious metals and I was assuming incorrectly for a low concentration of base metals. I had a local business scan the cupels with an XRF, and your assumption is spot on correct.

After the PbO froze the cupellation process, the XRF was reading something like 54% copper 0% Fe and only like 0.5% gold. Definitely no Rh, so the speculation of this original post based on the board you showed with the shiny strip of circuit, it is not Rh.

Ok so now back to my insanely hard metal frozen solid to the cupel, how would I break it free...just smash it? There's not much room left for the amount of copper and all the other junk thats in there.

Once it's removed I assume I take the weight and add equally the same amount of lead to resmelt into a button and then start the cupellation process over with new cupels?

Is there anyway to make a larger cupel for cheap, I heard Portland cement works to absorb the base metals and PbO, but I have no reference of the source of that.

Looks like these vintage high grade telecom boards from the 60s are really high end after all? And I was banking on several oz, I'm really bummed out.

 

[orvi]

Awesome, thanks for the help on this. I figured the electronics were very thick played in precious metals and I was assuming incorrectly for a low concentration of base metals. I had a local business scan the cupels with an XRF, and your assumption is spot on correct.

After the PbO froze the cupellation process, the XRF was reading something like 54% copper 0% Fe and only like 0.5% gold. Definitely no Rh, so the speculation of this original post based on the board you showed with the shiny strip of circuit, it is not Rh.

Ok so now back to my insanely hard metal frozen solid to the cupel, how would I break it free...just smash it? There's not much room left for the amount of copper and all the other junk thats in there.

Once it's removed I assume I take the weight and add equally the same amount of lead to resmelt into a button and then start the cupellation process over with new cupels?

Is there anyway to make a larger cupel for cheap, I heard Portland cement works to absorb the base metals and PbO, but I have no reference of the source of that.

Looks like these vintage high grade telecom boards from the 60s are really high end after all? And I was banking on several oz, I'm really bummed out.

Grab some catchpan, pliers and cut it out of the cupel. Not nice technique, but you get out what you want. Place it to the crucible, add similar ammount of borax and try to smelt it. If you are using graphite, be aware of the fact you recover all copper as it reduce to the metal.
Yeah, portland cement cupels work. But they tend to crack and adsorb some metal droplets into the cracks. Nothing extreme, but it is good to be aware of it. Owltech has few videos regarding preparation of cement cupels and using them - check them up

Yeah, they could be high grade, but maybe you have inflated views of what high grade is sobering to the reality is tough, but you get over it

 

[Soar2c]

could be high grade, but maybe you have inflated views of what high grade is sobering to the reality is tough, but you get over it

Orvi, you're not kidding! Ha ha ha I most definitely had inflated views of high grade boards. And you couldn't be more more correct, it was extremely tough to sober up. Much was the same when I discovered what the mining industry considers medium grade gold ore content. I dumped my life savings into a mineral prospecting start-up company thinking I was discovering something no one else had for my area. Truth is it's exactly the same as it is in Nevada's Carlin Trend with microscopic gold disseminated throughout the host. Having a grade a of 4g-5.5g/ton before concentration. I figured I would collect it, crush it, and concentrate it by a few cheap gravity concentration tools such as sluice boxes, clean up sluice, blue bowl, etc. Boy was I devastated to learn that the only way to concentrate is by froth flotation. :-( Unfortunately I have yet to see any way to make or mimic froth flotation for a 1 man artisanal operation. The operation setup in Nevada, USA cost around 3 billion USD, but they are extracting enough ore at an avg grade of 3.5g/ton to pour consistently 1000 oz/wk. I figured OK well its only a money situation that holding me back, so therefore I can get angel investors to push me along. Nope its not that simple, you need to invest in yourself to the tune of 100k-250k before any angel investor or venture capitalist will even consider. So sobering up was extremely difficult to understand that my measly $35k I invested was all that I had and that I invested it into the wrong type of equipment.

 

[Soar2c]

Place it (extracted metals from improper cupellation) into the crucible, add similar ammount of borax and try to smelt it.

Help me understand what you mean by the statement below. Since I am using a clay graphite crucible, I'm not following what you mean.

If you are using graphite, be aware of the fact you recover all copper as it reduce to the metal.

The metal in the cupel is already showing on the XRF that it is 50% Cu. What do you mean the about the graphite crucible? What is actually taking place in this process? I thought it was just a simple melting of the metals since these aren't sulfides or oxides. Sorry I'm new to the whole process. But I guess thinking back now to basic science is that this is a chemical reaction taking place and the matter is undergoing also physical phase changes from solid to liquid back to solid but the high heat is also performing chemical reactions which I assume this hardened alloy I am pulling from the cupel and mixing with (your recommended borax) in combination with the graphite, you're stating is performing some type of reduction on the base metals from an oxide back to the base of Cu?

*Be advised I am not crushing the entire cupel, I am just extracting the top metals that were not converted in the original cupellation attempt.

Thanks for you advice in helping me learn more and more about this awesome process. Nameste!

~ Kyle

 

[Yggdrasil]

Help me understand what you mean by the statement below. Since I am using a clay graphite crucible, I'm not following what you mean.

The metal in the cupel is already showing on the XRF that it is 50% Cu. What do you mean the about the graphite crucible? What is actually taking place in this process? I thought it was just a simple melting of the metals since these aren't sulfides or oxides. Sorry I'm new to the whole process. But I guess thinking back now to basic science is that this is a chemical reaction taking place and the matter is undergoing also physical phase changes from solid to liquid back to solid but the high heat is also performing chemical reactions which I assume this hardened alloy I am pulling from the cupel and mixing with (your recommended borax) in combination with the graphite, you're stating is performing some type of reduction on the base metals from an oxide back to the base of Cu?

*Be advised I am not crushing the entire cupel, I am just extracting the top metals that were not converted in the original cupellation attempt. View attachment 52273

Thanks for you advice in helping me learn more and more about this awesome process. Nameste!

~ Kyle

I guess he meant this:
If you are using graphite crucibles, strong reducing flames or add carbon in any way to the flux ut may reduce metal oxides to metal.

 

[orvi]

Orvi, you're not kidding! Ha ha ha I most definitely had inflated views of high grade boards. And you couldn't be more more correct, it was extremely tough to sober up. Much was the same when I discovered what the mining industry considers medium grade gold ore content. I dumped my life savings into a mineral prospecting start-up company thinking I was discovering something no one else had for my area. Truth is it's exactly the same as it is in Nevada's Carlin Trend with microscopic gold disseminated throughout the host. Having a grade a of 4g-5.5g/ton before concentration. I figured I would collect it, crush it, and concentrate it by a few cheap gravity concentration tools such as sluice boxes, clean up sluice, blue bowl, etc. Boy was I devastated to learn that the only way to concentrate is by froth flotation. :-( Unfortunately I have yet to see any way to make or mimic froth flotation for a 1 man artisanal operation. The operation setup in Nevada, USA cost around 3 billion USD, but they are extracting enough ore at an avg grade of 3.5g/ton to pour consistently 1000 oz/wk. I figured OK well its only a money situation that holding me back, so therefore I can get angel investors to push me along. Nope its not that simple, you need to invest in yourself to the tune of 100k-250k before any angel investor or venture capitalist will even consider. So sobering up was extremely difficult to understand that my measly $35k I invested was all that I had and that I invested it into the wrong type of equipment.

You need to consider all options. Do not take inspiration on Gold Rush on Discovery... It is very skewed view about mining in general. Carlin ore could be nice to proces, also some porphyry deposits, as sometimes you came across ore that is virtually only gold with less than 1% other metals (apart from iron etc) - so not very toxic waste, deposition of the processed mud is easier and not that hazardous. But with 3-4g/ton, you need to do volume. A lot of volume.
Froth flotation isn´t that hard to perform. But you have practically 3 options here - buy commercial setup (lots and lots of USD...), hire some experienced engineer and miner to design and build one for you (slightly less USD), or study hard and diligently and make one on your own. But it all takes a lot of time, evaluation and considerations. Most of the times, if you "underthink" the aimed plan, you will only focus on the things that SHOULD happen, not all of the little things that CAN happen. And these can make a striking difference in outcomes
If you show them blue bowls and shaker tables for extraction of superfine gold, I think this does not persuade them you are capable enough for investing into your starting business no offence

 

[Alondro]

Orvi, you're not kidding! Ha ha ha I most definitely had inflated views of high grade boards. And you couldn't be more more correct, it was extremely tough to sober up. Much was the same when I discovered what the mining industry considers medium grade gold ore content. I dumped my life savings into a mineral prospecting start-up company thinking I was discovering something no one else had for my area. Truth is it's exactly the same as it is in Nevada's Carlin Trend with microscopic gold disseminated throughout the host. Having a grade a of 4g-5.5g/ton before concentration. I figured I would collect it, crush it, and concentrate it by a few cheap gravity concentration tools such as sluice boxes, clean up sluice, blue bowl, etc. Boy was I devastated to learn that the only way to concentrate is by froth flotation. :-( Unfortunately I have yet to see any way to make or mimic froth flotation for a 1 man artisanal operation. The operation setup in Nevada, USA cost around 3 billion USD, but they are extracting enough ore at an avg grade of 3.5g/ton to pour consistently 1000 oz/wk. I figured OK well its only a money situation that holding me back, so therefore I can get angel investors to push me along. Nope its not that simple, you need to invest in yourself to the tune of 100k-250k before any angel investor or venture capitalist will even consider. So sobering up was extremely difficult to understand that my measly $35k I invested was all that I had and that I invested it into the wrong type of equipment.

Mount Baker Mining has a shaker table setup that seems quite efficient at recovering fine gold in rock.