# Old relay telephone exchange



## plamenppp (Feb 5, 2014)

I haven't written in a long, long time. There was reason for that I will not explain. 
Here is what I found - parts of old telephone relay exchange. I have never seen an assembled exchange. I've come across this kind of scrap over the last 4-5 years but the amount was not big. This time I got about 9 kg. The idea is simple - scrap yards do not buy it for brass or bronze. Some scrap yards know what i what and buy it. Others do not - my favorite type of scrap yards  So I bought it and started to work. The idea is the same as the idea in relays - get the contact points, refine and sell them with profit. The contact points here are made of silver - 999 purity (at least my data says so), the can be plated with Pd (in this case the have letter "A" written on the bronze, of they can be made of tungsten - letter "W", and I have heard legends about PtIr alloys. Here is what I did. First of all collect samples for pictures. After that get down to business - lost of time and efforts. Cutting edges can be boring and exhausting  In a relay telephone exchange man can find 5-6 types of contact points. 

After a couple of days of cutting edges I got about 940 cut edges with contact points. I will put them in AR and will get only silver as a result 

Enjoy some pictures 

Some pictures from the working process
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543663

Some cut edges
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543665

Best type edges ever. I call them horns. The % of yield is the highest!
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543666
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543667
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543668

Second type - small contact points on both sides - silver medal for worst type.
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543669
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543671

Third type - 4 good contact points - silver medal for best type
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543672
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543673

Fourth type - worst type ever - GOLD MEDAL! Each time I see one of these I frawn. Small contact points 
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543674
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543675
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543679

Fifth type - middle class contact points - most common
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543677
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543680

Sixth type - Almost the same as yield as the third type. Double contact points - front and back.
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543684
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543678

Seventh type - Almost the same as yield as the second type. 4 contact points on one side only. I found only one of these!!!!!
http://tgvtgv.snimka.bg/other/releina-centrala.802677.32543683


----------



## etack (Feb 5, 2014)

Why AR?

If you cant get nitric try dilute sulfuric to eat the Cu.

Eric


----------



## plamenppp (Feb 5, 2014)

The bronze is not exactly bronze  It contains Cu, Ni and Zn. AR will dissolve them but it will not touch the silver. This is the aim


----------



## etack (Feb 5, 2014)

Ar will attack the Ag in small amount. but it might be quicker than sulfuric.

Eric


----------



## plamenppp (Feb 5, 2014)

I may try sulfuric as well. I expect 50-60% yield from the cut edges. That means 350-400 gr bronze. It will not need much H2SO4.


----------



## goldsilverpro (Feb 5, 2014)

plamenppp said:


> I may try sulfuric as well. I expect 50-60% yield from the cut edges. That means 350-400 gr bronze. It will not need much H2SO4.


If my math is right, you can get about 285g of copper in 1 liter of 35% battery acid, theoretically speaking. In practice, it probably will take more acid. 

To dissolve copper in H2SO4, you must add an oxidizer, preferably hydrogen peroxide. When these 2 chemical are too strong, an explosion can occur. I read in one place (Wiki, I think) that an explosion can occur if you pour 50% H2O2 into concentrated 95% sulfuric. A 95% H2SO4/30% H2O2 mix (3 to 1, I think) is called Piranha solution. A common usage is to REALLY clean lab glassware. It replaced the old sulfuric/chromic mixture which, by the way, when hot, will dissolve copper but not palladium. I used it on trimmed pure rectangular palladium points on the copper base metal on the more common old wire relay type telephone switching stations. 

I saw a couple of recent videos linked on the forum that used H2SO4/H2O2 to dissolve copper. One mixed 35% battery acid directly with 12% beauty supply hydrogen peroxide and ran it at room temp. The reaction was vigorous and generated much heat. The guy advised that then container be at least 10 times the liquid volume. The other video was about 1/4 or 1/5 as strong and worked much more slowly (heat should have been applied to speed it up). 

To be safe, I wouldn't use anything stronger than the 35% battery acid/12% peroxide mixture above. I saw it work and believe it to be safe. Also, this mix is very vigorous and I don't think I would like it more so. Anything stronger might be hard to handle. Also, if what you are using is stronger than these numbers, dilute one or both before combining together.

If I had the need to dissolve a bunch of copper I would definitely experiment with the H2SO4 method. If it works smoothly, it may be the best way yet for things like pins or fingers. The best thing about it is the reduction in fumes as compared to AP or nitric, but you still need good exhaust. Every little bubble floating up into the air has a skin of sulfuric acid on it.

You could probably control the reaction by adding the peroxide in increments, not unlike my nitric addition method. On a larger scale the peroxide could probably be slowly metered in with an adjustable peristaltic metering pump.

A small amount of silver might dissolve - silver sulfate is not very soluble. This can be eventually recovered as silver chloride or cement silver. Palladium might also dissolve but could probably be cemented with copper. The Ni and Zn should dissolve.

There are 2 or 3 other recent, decent threads concerned with using sulfuric on copper. I think I've commented on one or two of them. The 2 videos I spoke of are on those threads.


----------



## Irons (Feb 5, 2014)

I've used Sodium Bisulfate with dilute H2O2 with good results. It's a little slow, but little safety issues.


----------



## Harold_V (Feb 6, 2014)

etack said:


> Why AR?
> 
> If you cant get nitric try dilute sulfuric to eat the Cu.
> 
> Eric


Dilute sulfuric will not dissolve copper. It WILL dissolve copper oxide. 
Dilute sulfuric is commonly used to pickle copper for that reason. 

Harold


----------



## solar_plasma (Feb 6, 2014)

I am confused: Once I read that in the sulfuric cell the acid must not become too dilluted, because it would dissolve copper then....maybe I do not remember this correctly? I did a quick search and found only what Harold already said and that sulfuric needs an oxidizer to dissolve copper or has to be concentrated and very hot.

On the other side once I stored copper powders in dilluted sulfuric, which slowly over weeks produced CuSO4....according to those facts above only because O2 from the air dissolved and acted as an oxidizer?

Maybe someone could clear up, what on the first sight looks paradox to me.


----------



## Anonymous (Feb 6, 2014)

I like GSP's advice a lot as it's practical and reasonable here. 

Use weaker solutions and learn to control the reaction before moving any further and trying it with the concentrated products.


----------



## solar_plasma (Feb 6, 2014)

> Use weaker solutions and learn to control the reaction before moving any further and trying it with the concentrated products.



Amen, brother! Old discussion and finally we agree. :lol:


----------



## butcher (Feb 6, 2014)

solar, 
With electrolysis at the anode we can force electrons to be removed from atoms (oxidized by the power supply in the electrolyte solution),electrolysis forces a reaction or electron movement that would not ordinarily occur, making electrons move easily in a solution or chemical reaction that would not occur in the solution without the force of electrolysis.
The copper is oxidized at the anode and form copper sulfate ions in the more dilute sulfate electrolyte solution, where the concentrated sulfuric electrolyte would tend to passivate the copper at the anode.

Sodium nitrate can be used as an oxidizer with sulfuric acid, to oxidize the copper, with copper being dissolved in solution, using heat, with this method we can distill off the gases of the reaction and make nitric acid, the copper dissolves (and helps to form the NOx gases used to form the nitric acid, NOx gases dissolved in water or dilute H2O2) the reaction leaves a solution of copper sulfate, gold will not be attacked or dissolve, and gold foils can be separated from the copper sulfate solution, I have done this with cut gold plated pins, the nitric acid and the copper sulfate can both be used in other recovery processes which gives us useful products, and virtually no waste from the process.
A process I call killing two birds with one stone.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=6199&hilit=killing+two+birds+one+stone

If silver is involved in a solution of sulfuric acid with an oxidizer, I suspect we would have some silver sulfate to deal with later.


----------



## Geo (Feb 7, 2014)

Too, like any other acidic solution, the warmer it is, the more reactive it is. Heat plays a large part in when and how sulfuric acid reacts to certain metals. I've made copper sulfate by dissolving copper in dilute sulfuric acid but the acid was near boiling.


----------



## solar_plasma (Feb 7, 2014)

butcher,

thank you, it took from early in the morning till after work, but now I know what you meaned. I cannot compare the cell situation to sulfuric without any extra charge. Dillution of the sulfuric in the sulfuric cell causes dissolving of basemetal just because we force them by the charge. Without this charge dill. sulfuric will not attack copper readily without much time, much heat and/or oxidizers. Got it. Thank you all!


----------



## goldsilverpro (Feb 7, 2014)

The more I delve into the H2SO4/H2O2 copper dissolving system, the more complicated I see it is. The big problem with just using those 2 chemicals alone is that the H2O2 decomposes very quickly. I noticed on one of the videos that there seemed to be too much gassing for the amount of copper being dissolved. This gassing is the oxygen released from the breakdown of the H2O2. In the patent literature, this problem is solved by the addition of various organic compounds that act as stabilizers. There are many listed but some of the more common ones are ethylene glycol (common antifreeze) or glycerin, either of which are added at 20ml/l. Another listed is sulfamic acid - 5g/l. The use of urea was also mentioned as a possibility in one patent. Formic or propianic acids are also mentioned.

The addition of a stabilizer can reduce the rate of H2O2 decomposition to as little as 1/500 of what it would be without a stabilizer.

https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3537895.pdf
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3597290.pdf
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3649194.pdf
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US3801512.pdf

Temperature is another factor in the decomposition rate of H2O2. In these patents, the temperature is held to a max of about 140F.

In one patent, in a chart, they say that a solution containing 20ml/l of either ethylene glycol or glycerin would eat through the copper layer on a 1oz copper/ft2 circuit board in from 135 to 175 seconds (about 2 to 3 minutes).


----------



## butcher (Feb 7, 2014)

Reusing old copper chloride solution to attack copper or Iron chloride solution to dissolve copper, this will work for gold or silver, the silver will form chloride so some of the silver makes silver chloride, some of the thicker pieces of silver are left protected by the chloride crust.

With any recovery methods the more of the base metal you can remove mechanically (like cutting the silver contacts off of the large copper bus bar), the less base metal you will have to dissolve.

Collection of some older posts I made on this subject:

Old used Copper II chloride solution (reusing the waste), or making and using the ferric chloride leach...

Ferrous chloride FeCl2 can be made dissolving Iron in HCl and water approximate equal volumes of water and acid, (steel wool or transformer laminates).
Fe (s) + 2HCl (aq) + H2O (l) --> FeCl2 (aq) + H2 (g)

Ferrous chloride FeCl2 with excess HCl will oxidize with air to form Ferric chloride, but the reaction can take a long time.
FeCl2 (aq) + 1/4 O2 (g) + HCl (aq) --> FeCl3 (aq) + 1/2 H2O

Now from the ferrous chloride FeCl2, we can make ferric chloride FeCl3, with about equal volume of 3% Hydrogen peroxide H2O2. Heat is generated in the reaction of oxidation of the iron chloride.
FeCl2 (aq) + H2O2 (aq) + HCl (aq) --> FeCl3 + H2O + H + O

Ferric chloride (FeCl3) can etch copper (Cu) or iron (Fe), oxidizing the copper or iron into solution and reducing the ferric chloride (FeCl3) back to ferrous chloride (FeCl2).
2FeCl3 (aq) + Fe (s) --> 3FeCl2 (aq)
Etching copper a two step process.
FeCl3 (aq) + Cu (s) --> FeCl2 (aq) + CuCl
Then 
FeCl3 (aq) + CuCl --> FeCl2 (aq) + CuCl2 (aq)

Now we have discussed the normal leach for copper used to etch copper.
Let add some things to this discussions where we can continue to use this solution.
(This discussion also applies to the old used copper II chloride leach we can no longer use because it has been contaminated with iron or Kovar.)

We can heat this solution (ferrous chloride and cupric chloride (FeCl2 + CuCl2) with more copper, (this copper could be copper we need to dissolve from other metals like silver or gold plating like pins or pieces of copper with silver contact points...), the solution when heated being still acidic eats at the copper with a vengeance, especially as it gets concentrated, heating it to a fairly thick dark brown solution.
FeCl2 + CuCl2 + Cu (s) --> FeCl2 (aq) + 2 CuCl (aq)
Here we have both ferrous chloride and cuprous chloride dissolved in solution.

This leaves us with ferrous chloride and cuprous chloride in solution, If we decant a portion of this solution into a jar and let it cool, Most of the CuCl will settle out as a dark powder (along with any gold flakes, silver chloride, lead chloride if involve...).

Now once cooled and settled we can we can decant the mostly ferrous chloride back to the main solution (we will discuss it more later).

The copper I chloride (cuprous chloride) (CuCl), can be rinsed with Hot boiling water (this will dissolve some salts of the iron and copper chlorides, and lead (this rinse water decanted hot can also be returned to the main solution.
This leaves us with white powders of copper I chloride, silver chloride and gold flakes, now we can save these powders for reuse later.
Or dissolve the CuCl in HCl.
CuCl + HCl --> CuCl2
So now after we let the silver chloride and gold foils settle, we can decant the CuCl2 solution, Which is clean enough to use as a new batch of copper II chloride leach (CuCl2) (miss-named acid peroxide leach, or AP on the forum).

Now back to or FeCl2 ferrous chloride solution if you reread this post from the beginning you can see where the ferrous chloride solution (FeCl2) can be oxidized back to the ferric chloride FeCl3 to leach more copper or iron...

____
Now we can get some other iron products, or byproducts, from these iron solutions with the methods above, iron solutions can hydrolyze and with oxygen can form some insoluble iron oxides or hydroxides in solution, or precipitate from solution. Strong heat can accelerate this. One of these can be a red Iron powder (red rouge powder) (a form of rust), that will not dissolve in acids (even aqua regia)...

4 FeCl2 + 4 H2O + O2 <-- --> 2 Fe2O3 + HCl
Or
heated too strongly
FeCl2 +H2O +1/4 O2 --> 1/2 FeCl2 + 2HCl

6 HCl + Fe2O3 + Fe --> 3 FeCl3 + 3H2O

6 FeCl2 +3/2 O2 + H2O --> 2 FeO.OH + 12 HCl
Then
4 FeCl3 + 8H2O --> FeO.OH +12 HCl
FeCl3 + 3H2O --> Fe(OH)3 + HCl

These iron oxides or hydroxides normally do not cause a problem with the gold recovery processes, the red iron powders do not dissolve easily and even gold can be dissolved from the red powder...

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=19816&p=203499&hilit=ferric+chloride#p203499

Here is another place you can use that waste solution, you have been waiting to deal with.

You can use the old waste solution, that old jug of copper chloride that has become more of an Iron chloride (from seeing to much iron in its use)

FeCL3 ferric chloride can etch copper in a two-step process:
FeCl3 + Cu --> FeCl2 + CuCl
Then 
FeCl3 + CuCl --> CuCl2 + FeCl2

Silver normally will not dissolve in an acidic Chloride solution, as it oxidizes easily and forms a crust of silver chloride AgCl, which coats the silver protecting it from further oxidation.

But we can put some silver into a solution if we have a very High chloride content:
Silver chloride AgCl is fairly insoluble in water but if we heated it strongly in salt water NaCl (concentrating the solution) we can put some of the silver into the salt solution as silver dichloride soluble in the concentrated brine solution, upon dilution we would again get the insoluble white silver chloride {AgCl2 + H2O --> AgCl + Cl- + H2O} this is the similar to how we get a little silver in our aqua regia solutions.
AgCl + Cl- --> AgCl2



Ferric chloride heated with silver will etch the silver, this iron III chloride solution is aggressive when heated and concentrated, it etches silver plate slowly but effectively, and with plated silver it become very aggressive to the copper under the silver, the concentrated ferric chloride will hold some silver as AgCl2 and precipitate the rest as AgCl, it will also hold a lot of copper into solution as CuCl2 and CuCl, by dilution we can precipitate the CuCl and the little AgCl.

Ag + FeCl3 --> AgCl + FeCl2
Thin plated silver converts to silver chloride fairly easily, thicker pieces of silver can become coated with a protective crust of silver chloride, with this used Iron/ copper chloride solution being heated and concentrated strongly with agitation the silver crust on the silver can become broken loose by the mechanical agitation of the solution (process of the heat and stirring), this can expose fresh silver as the crust is removed converting more silver to AgCl as the fresh silver is exposed, in this many the thicker silver can be converted to silver chloride fairly effectively is one wishes to, it just takes a little longer in the process.

The CuCl white powders can be stored wet, and re acidified in HCl to make an etching solution of copper II Chloride later, leaving the little bit of silver as white powder 
4CuCl + 4HCl + O2 --> 4CuCl2 + 2H2O

For the little bit of silver on buss bars or contact arms (silver contact removed) you can dissolve the silver with copper, the heavy bar will still have a lot of copper metal left you could sell as copper metal (you will dissolve a good portion of the copper weight though), for thin silver plate it will dissolve all of the copper. 

Ferric chloride will also dissolve iron into solution if needed.

Do not expect to get much silver from buss bars, or from plated silver.

When your done with your waste solution, treat it and dispose of it properly, for those who have not studied how see dealing with waste in our safety section.
Butcher

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=11890&hilit=ferric+chloride

Kovar, An iron compound with about 54% Fe, 29% nickel, 17% cobalt, and traces of silicone, carbon, and manganese, usually used where they need strength or a springy metal.

Beryllium copper is another alloy used, where they need a spring metal or where strength or stress may prove a problem for the softer copper metal, where non sparking may be needed, or a non ferrous metal is needed, beryllium copper can have about 0.5% to 3% beryllium, and many time cobalt and nickel are part of the alloy.

Kovar with all of that iron is much more magnetic than beryllium copper, or the copper pins with a tiny bit of the weakly magnetic nickel plating under the layer of gold.

A strong magnet may attract the nickel, where a weaker magnet would not, and where the weaker magnet would only attract the iron in the Kovar.

If the copper is hard and springy, I would suspect beryllium, pure copper is fairly soft (will cut easy with a knife), and bends easily
In electronic scrap you will find these metals used where they are needed to better perform a function, or are needed to insure reliability, pins that may bend easy may use the stronger Kovar, contact may use beryllium to insure good contact, or for its springy nature, or to strengthen the pins from being bent out of shape by plugging in or unplugging connections…


This is a hard subject to explain but I will try.
Reuse of old copper II chloride leach that has become loaded with iron, and can actually become an iron chloride or and iron/copper chloride solution.

First lets look at what happens when we use our (AP) copper II chloride to dissolve Iron, we convert the copper II chloride CuCl2 (cupric chloride), to FeCl2 (ferrous chloride) and copper metal powders.

CuCl2 + Fe --> FeCl2 +Cu

Our solution during this reaction may actually have several copper and iron chloride salts involved before the above reaction is driven to completion.

Now once we end up with iron II Chloride FeCl2 (ferrous chloride) we normally think of our (AP) or copper II chloride as spent or waste, because FeCl2 is just about useless to attack copper.

But we can use this old spent leach solution to dissolve base metals, and actually we can reuse it to dissolve a heck of a lot more copper (not as FeCl2 but we can get FeCl3 from this solution).

Lets look at some iron chemistry to set up this discussion.

If we dissolve Iron (Fe) in HCl we can make ferrous chloride.
Fe + 2HCl --> FeCl2 + H2

This FeCl2 ferrous chloride will not readily attack copper.
But if let the acidic FeCl2 (ferrous chloride) set exposed in air for a long period of time it will absorb oxygen and oxidize to ferric chloride FeCL3.
4FeCl2 + O2 + HCl --> 4FeCl3 + 2H2O
we can speed this oxidation of ferrous chloride (FeCl2) to FeCl3 (ferric chloride) by adding about equal volumes of 3% H2O2 solution.
2FeCl2 + H2O2 (3%) + 2HCl --> 2FeCl3 + 2H2O

I have also found just strongly heating the solution also help it to absorb oxygen especially when the solution is concentrated.

Now Ferric chloride FeCl3 is a great etch for copper metals, hot concentrated solutions heated to a thicker solution, help to convert silver to silver chloride the heavy brine solution helps to remove the silver chloride crust that forms, gold is not attacked but plated gold will flake off as copper underneath is attacked.

Ferric chloride is used to etch copper circuit boards, just the same way the copper II chloride leach we call acid peroxide is used, the main reason to use CuCl2 cupric chloride leach over the ferric chloride leach to dissolve copper is the ease of which we can rejuvenate the cupric leach for reuse, in a copper cycle.
we can also rejuvenate the Iron chloride leach, but it is not as easy to get the copper back out of the leach.

I have stumbled on a way to use the ferric chloride leach (our old spent copper chloride leaches), by reusing my waste solution to dissolve base metals.
And actually make a copper II chloride leach from the copper I chloride powders in the process.

First we need to look at the two-step process of using ferric chloride FeCl3 to etch copper.
FeCl3 + Cu --> FeCl2 + CuCl
then
FeCl3 + CuCl --> FeCl2 + CuCl2
notice in the first part of reaction we can form CuCl, and later in the reaction the CuCl is oxidized to CuCl2, as the FeCl3 is reduced to FeCl2.
And in the second part of the reaction we end up with both iron and copper chlorides in solution as FeCl2 and CuCl2.

If we stop this above reaction in the middle we can separate most of the CuCl and let the concentrated solution cool and settle to powders of CuCl, AgCl and Au foils.
Returning most of the FeCl2 to the main reaction to help dissolve more copper as it picks up air (or we can add a little H2O2 to convert the FeCl2 back to FeCl3...

This is what I tried to explain in the post above.
Where I said:
I reuse this solution to dissolve copper and base metals.

Actually it become more of an iron chloride, if strongly heated you will be amazed at how much copper you can dissolve with this old used (AP leach), the iron chloride will dissolve pounds of copper in a corning dish on a hot plate when the solution get thick brown, decant a portion of the leach into a cooling jar there most of the copper will settle out as copper I chloride (a brown powder, unless diluted with water which will turn it white as acids are diluted) after settling you can return iron chloride liquid back to the corning dish to dissolve more copper,

The copper I chloride powder washed with a little water will give a white powder of copper I chloride this rinse liquid you can add back to the heated corning dish above to dissolve more copper.

This leaves you with the white copper I chloride powders, with some HCl add this dissolves and becomes copper II chloride, which can be used, as you know to dissolve copper, and if you had silver or gold on the copper you were dissolving above, you will be left with gold foils or silver chloride powders after adding the HCl.

So here we get our CuCl back to make a new CuCl2 leach solution (acid peroxide leach), we concentrate our old iron chloride solution (to treat for waste) giving us less waste to deal with.
And dissolve pounds of copper from things like contact points with chunks of copper that were cut from the relay or motor contactors, or gold foils from copper brass or iron pins...

Reusing a solution that was once considered a waste solution, to do more work dissolving pounds of copper, collecting a useful copper I chloride we can make into a fresh copper II chloride leach, and collect silver and gold, while reducing the left over waste solution to deal with.


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=19838&hilit=ferric+chloride

Edited 5-30-2014 to update some information


----------



## plamenppp (Feb 7, 2014)

Wow, wow, wow, this has become an university lecture. All I wanted was to post some pictures


----------



## kurtak (Feb 8, 2014)

Last year I bought 2300 lb of this type phone relay points from a scrap yard - that was the relays still mounted on the mounting rails - paid 35 cents a lb

after removing the relays from the mounting rail I used my tile saw with diamond blade to cut the points off the bus bars - using the tile saw allowed me to cut the points off close (to the points) with the bus bars still attached to the coil assembly so 90% of the bus bar stayed with the relay assembly which meant I only needed to dissolve 10% of the bus bar

That of coarse reduced the amount of acid needed - about 10% of the points were pure palladium - used nitric to dissolve brass & silver which left the pure Pd points in the bottom of my bucket

Got right at 1.5 ozt Pd & about 1 lb Ag & the Ag also contained Pd (which was recovered in silver cell)

of course sold iron (from mounting rails) back to scrap yard & when I sold the relays (with most of the bus bar still attached) I got 45 cents a lb (different buyer) plus I ended up with a fair amount of #2 insulated wire @ $1.35/lb 

All in all the iron - relays, & wire paid me back what I paid plus a about $150 (due to getting higher price for relays & wire) so Pd & Ag was my real profit --- took me a week to do whole process 

It was the Pd that made it worth it - if the points had been all Ag there still would have been a small profit - but not enough for the time & effort - I knew about the Pd before buying the 2300 lb because I first bought 100 lb & did a test run

Kurt


----------



## Geo (Feb 8, 2014)

i scrapped tons of those steel racks that still had the copper coils and points. at the time, i didnt know about precious metals and sold the contacts with the copper coils as #2 copper. some of the coils were wire wound and some were just solid copper with no wire. each coil was held in place with a brass screw through the rack and into the steel shaft in the middle. my wife and i used drills to take out the screws and we worked all day, 6 days a week for a month before we removed all the coils and points from the racks. hindsight is 20/20.


----------



## goldsilverpro (Feb 8, 2014)

kurtak said:


> Last year I bought 2300 lb of this type phone relay points from a scrap yard - that was the relays still mounted on the mounting rails - paid 35 cents a lb
> 
> after removing the relays from the mounting rail I used my tile saw with diamond blade to cut the points off the bus bars - using the tile saw allowed me to cut the points off close (to the points) with the bus bars still attached to the coil assembly so 90% of the bus bar stayed with the relay assembly which meant I only needed to dissolve 10% of the bus bar
> 
> ...



Surely you must have dissolved some of the Pd in the nitric.


----------



## kurtak (Feb 8, 2014)

goldsilverpro said:


> kurtak said:
> 
> 
> > Got right at 1.5 ozt Pd & about 1 lb Ag & the Ag also contained Pd (which was recovered in silver cell)
> ...



Yes of course - note that I mention recovering that Pd in the silver cell --- in fact I am at this very moment working on recovering the Au, Pt, Pd & Rh from all my saved up anode slims - so that Pd will finally be coming back out in the wash --- the 1.5 ozt Pd I got back in the original process was the Pd that didn't go into solution at that time

Kurt


----------



## goldsilverpro (Feb 8, 2014)

My initial education on Pd points occurred in the early 70's when we got in about 50,000# of wire relays. That weight included the steel racks and the wiring bundles. All the tiny rectangular shaped points were pure Pd. The value overall ended up to be about $1/pound, with Pd at about $60/oz. We cut off the blades as close as possible with a small reciprocating alligator shear.

I did a lot of experiments looking for something that would dissolve the copper without touching the Pd. The only thing I could find was a solution containing 4# of chromic acid and 2900ml of conc. sulfuric acid. A nasty mix. I don't remember the total volume this was diluted to but I'm thinking it was 2-4 gallons (I'm thinking it was 2 gal). I also don't remember if the solution was heated or not - maybe not, since the copper dissolving generated much heat. After this treatment, there was still a thin layer of nickel on the back of all the points. If the nickel was still there, you could pick up the points with a magnet. The nickel was removed selectively with hot conc. HCl, leaving the pure Pd. I assume the Pd was pure because that's what we sold it for on a continual basis to the same large buyer. However, Lou and I talked about this once and he didn't think they were pure.

The last Pd relay banks I processed, about 5000# gross weight, were found in a small forgotten room about 10 years ago on the empty 3rd floor of a place I worked. The building (about 750,000 ft2) was originally built and used by a large metal fabricating company. When the phone companies started to convert to electronic switching in the 70's, this scrap was everywhere and was readily snapped up by the refiners. Now, about the only place you can find it is in old buildings (maybe, abandoned buildings) that had switching rooms to operate the 100's of phones in the plant.

There are many different Pd relay configurations. The most common good ones were long and skinny. The plastic boxes were about 1" x 3/4" x 3 or 4" tall. Instead of flat blades, the points were mounted on long wires, probably phosphor bronze . The photo is about the closest thing I could find in appearance, although it seems to be a later version. It was on eBay - 1st link. The 2nd link shows banks of relays.
http://www.ebay.com/itm/Western-Electric-Telephone-Relay-Vintage-Wire-Spring-/280512060964?pt=LH_DefaultDomain_0&hash=item414fd25e24
https://encrypted.google.com/search?as_st=y&tbm=isch&as_q=vintage+telephone+switching+relay&as_epq=&as_oq=&as_eq=&imgsz=&imgar=&imgc=&imgcolor=&imgtype=&cr=&as_sitesearch=&safe=images&as_filetype=&as_rights=#facrc=_&imgdii=_&imgrc=hGRMA1blpI07DM%253A%3BQQyDF5clYO800M%3Bhttp%253A%252F%252Fthumbs1.ebaystatic.com%252Fd%252Fl225%252Fm%252FmwzQOTXlR3C_HcQpE6okMiA.jpg%3Bhttp%253A%252F%252Fwww.ebay.com%252Fsch%252Fi.html%253F_kw%253DWestern%252BElectric%252BRELAY%3B224%3B165


----------



## plamenppp (Feb 8, 2014)

I used AR.

350 gr net 

I expected more. That means around 40% of the cut edges or 40 grams per kg gross.


----------

