# gold in microphones



## Andy (Mar 7, 2007)

Finally i have found a place where I can find the info I have been searching for ! Did you guys know that in old (pre 97) pabx office teleephones there is a ring of solid gold in the hands free microphones. I came accross 110 phones at a demolition site NEC make. Each ring weighs in at .1 gram. Cheers - Andy


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## lazersteve (Mar 7, 2007)

Welcome to the Forum Andy,

How about posting the model number of the phones and a pic of the gold rings?


Steve


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## Andy (Mar 7, 2007)

Hi steve,
I will take a pic when i get into work and post it up today. I am keenly waiting your next post so i can get my own bath happening. Ive tried ferric chloride and ammonium persulfate with few good results. My gear is ready just looking for the liquid recipe. I actually found out about the microphones from one of the world gold sites. There is actually gold rings or plates in most old microphones in old mobile phones too. I just use a pair of wire cutters and gently squeeze about 2mm down from the top and they just split open. 
Cheers - Andy


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## lazersteve (Mar 7, 2007)

Andy,

I've had excellent results using ferric chloride to strip pins. It works fast and is very simple to use. It's a little messy for my tastes however (lots of rust stains!). It's somewhat harder to rinse from the gold flakes also. That's why I switched to the acid-peroxide method.

The persulfate just didn't meet my needs at all. It takes too much of it to do the job. Expensive too.

Steve


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## PRECIOUS METALS (Mar 8, 2007)

im susing acid whats the mix of the peroxide

whats the mix of the acid and peroxide


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## jmelson (Mar 8, 2007)

Andy said:


> Finally i have found a place where I can find the info I have been searching for ! Did you guys know that in old (pre 97) pabx office teleephones there is a ring of solid gold in the hands free microphones. I came accross 110 phones at a demolition site NEC make. Each ring weighs in at .1 gram. Cheers - Andy


I have NEC Electra phones both at work and at home (we wanted intercoms both places, a well-used phone system was way cheaper). While working on
these phones, I also noticed a big ring in the microphones of SOME of them that was gold plated. These are in the regular handset. Not all the handsets have the gold ring, some look like silver, maybe.

Anyway, .1 g per unit is a HELL of a lot of gold. I do a whole pot of gold-bearing scrap and get .2 g or so out. Of course, 110 units at .1 g is 11 g, or roughly $200. Are you SURE this thing is SOLID gold? First, it would be awfully flimsy, as pure gold is a soft metal. If it is stiff, or brittle, it isn't 24 Kt gold. Most likely, it is gold-plated brass or phosphor bronze, great for electrical contacts, and the color of the base metal is awfully close to gold.

Thanks,


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## lazersteve (Mar 8, 2007)

Here's how to settle it:

Cut one on the rings into quater rings.
Toss the pieces into a pyrex measuring cup.
Add 1/4 cup HCL
Add 1/8 cup H2O2 3%
Swirl gently and wait 5-15 minutes

If the solution begins to turn any shade of blue or green then it's definitely not solid 24kt.

Post the pix of the test here!


Steve


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## Harold_V (Mar 9, 2007)

A simple file mark, followed by a drop of nitric acid on the piece will reveal everything you need to know. If it's solid gold, you will get no reaction. If you get a quick response of foaming, along with a greenish blue color, it's copper, likely gold plated.

Harold


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## Fever (Mar 31, 2007)

It's quite true. I get some very nice gold-plated items from phone microphones. Pictured below are two of the most common finds for me. These are from the "pay phone" type headset. There is also a silicon chip with gold traces in most cell phone microphones. 

Fever


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## solar_plasma (Jun 11, 2013)

lazersteve:


> I've had excellent results using ferric chloride to strip pins. It works fast and is very simple to use. It's a little messy for my tastes however (lots of rust stains!). It's somewhat harder to rinse from the gold flakes also. That's why I switched to the acid-peroxide method.



I think I have searched all threads about ferric chloride and did not find a better answer to my question than lazersteves post above. So, before I just try and end up frustrated, here my question:

Since I have some pounds of ferric chloride I don't use,* would it be advisable to use it on the kovar of my +/- 300 g of TO-5 transistors*, which have gold plated legs, gold on the inside bottom under the die and ofcourse some goldwires? From lazersteve's post I understand, that there is no absolute answer to this, but maybe someone likes to give his two cent.


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## Geo (Jun 11, 2013)

ferric chloride will dissolve iron and works better warm. im not sure that adding O2 even effects the rate of dissolution the same way it does in copper chloride.i make small batches of ferric chloride using steel wool dissolved in hcl and peroxide using heat.it really chews threw copper and other base metals much faster than copper chloride.i use it when i need speed. while not as fast as nitric acid, it will do a batch of fingers in a days time.


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## solar_plasma (Jun 11, 2013)

Thanks for reply. Sounds like it's worth to have tried.

I have just looked quickly on the mol relations. Since I have ferric chloride hexahydrate, it would take about 500 g of it to dissolve round about 60g basemetals :shock: . I bid myself welcome to reality :roll:


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## butcher (Jun 11, 2013)

When I end up with a batch of Iron chloride, usually old copper chloride leach contaminated with iron, I will use it in a corning ceramic dish on a hot plate to dissolve low grade scrap copper or iron, I use heat and let the solution concentrate, adding more Iron chloride solution as the water vapors off, and solution thickens and becomes more acidic, letting solution concentrate strengthens its acid property's, and it will dissolve copper and iron with a vengeance, when solution is highly concentrated I will decant thicker solution to a jar, on cooling some copper chloride precipitates out.


This recovery process helps me reduce my large volume waste copper/iron chloride solution, and gives me a way to dissolve large volume of thick copper or thin iron from scrap at the same time.

After solution cools and as much copper I chloride settles out that will in my settling jar, I can return liquid back to the ceramic dish to dissolve more copper with additions of more of my old copper chloride/iron chloride solution, and keep repeating this process, reducing the volume of my used solution of copper chloride/Iron chloride, and forming copper salts of the copper and iron I am working on to dissolve. (I can have two of or more of these cooling jars going at one time).

Using a suction tool to transfer liquids, I will not remove the solid metals or insoluble powders at the bottom of the ceramic dish, or the cooling settling jars.

My goal here is forming copper chloride salts out of the copper metal, and dissolving iron into solution.
This is continued till I have dissolved the metals (most of the gold, will remain as powders in the bottom of the casserole dish, but some will be carried over to the settling and cooling jar with the copper salts, most of the iron tends to stay in solution, any silver will normally get carried over in decanting as silver chloride is fluffy and takes time to settle.

in this settling jar I will have a dark brown powder of copper, and an dark brown almost black thick solution, this thick concentrated solution will also hold a lot of copper, diluting the solution with water will precipitate the copper from the iron chloride, the water will also dissolve acid from the dark brown copper powders making them white, ( if much silver in these white copper powders it will normally darken again in sunlight later) now this lighter green iron chloride solution can be decanted, the powders washed in more water, after stirred powers are settled, a few more water washes are done, leaving me with copper I chloride salts, with some gold or silver in the jar, I can keep these powders stored under a layer of water, to use to make copper chloride solution later, or I can use these copper powders in a type of sludge for a stock pot collector of values where the copper chloride powders go into solution when acidic waste is added to this stock pot, the copper chloride powders replace more noble metals from solution in this stock pot leaving me with more valuable powders in my stock pot over time.

I do not add hydrogen peroxide to the iron chloride (old copper chloride) solution when I use it to dissolve copper or iron, with strong heat the oxygen makes the iron in solution form hydroxides of iron, the iron hydroxides will be in the form of a red rouge powder.

This red rouge iron powder when formed will not dissolve in acids, to much of any extent at all, even in aqua regia, I have dissolved gold from a batch of the red rouge iron hydroxide powder and most of this red iron hydroxide stays insoluble.

I have also used this to dissolve copper pipe pieces where they were silver soldered to recover the silver.


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## FrugalRefiner (Jun 11, 2013)

butcher,

You continue to amaze me.

Some people try to use everything but the squeal. You seem to find ways to use the squeal as well as the echo of the squeal!

You are the master of finding a use for waste!

Dave


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## solar_plasma (Jun 11, 2013)

@butcher

I have to read and chew on this some more times and work with it before I fully understand it. It sounds like there is a lifetime of experience weaved into your ingenious re-usage of the waste and could be the solution to the biggest problems in recovering - cost of chemicals and amounts of waste. I will set my focus on this field now. Thank you!


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## CBentre (Jun 12, 2013)

solar_plasma said:


> lazersteve:
> 
> 
> > I've had excellent results using ferric chloride to strip pins. It works fast and is very simple to use. It's a little messy for my tastes however (lots of rust stains!). It's somewhat harder to rinse from the gold flakes also. That's why I switched to the acid-peroxide method.
> ...



Hey Solar thanks for bringing this post up, I purchased a few skids of phones last week.I think I'm going to have to have a second look now.


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## solar_plasma (Jul 11, 2013)

butcher


> When I end up with a batch of Iron chloride, usually old copper chloride leach contaminated with iron, I will use it in a corning ceramic dish on a hot plate to dissolve low grade scrap copper or iron, I use heat and let the solution concentrate, adding more Iron chloride solution as the water vapors off, and solution thickens and becomes more acidic, letting solution concentrate strengthens its acid property's, and it will dissolve copper and iron with a vengeance, when solution is highly concentrated I will decant thicker solution to a jar, on cooling some copper chloride precipitates out.
> 
> 
> This recovery process helps me reduce my large volume waste copper/iron chloride solution, and gives me a way to dissolve large volume of thick copper or thin iron from scrap at the same time.
> ...



My used ferric chloride solutions looks more and more like a used AP (dark green, in bad light almost black) and it seems, that it works equal to AP when I add some fresh HCl. After butchers post and after my first experiences, I believe a used ferric chloride solution is pretty the same as an iron contaminated AP/CuCl2. 

Please correct or confirm.


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## butcher (Jul 11, 2013)

The iron/copper chloride solution and the Iron chloride are fairly similar, and work very similar dissolving base metals and copper, depending on how you keep reusing the solution, they look and act similar, but there are some differences in how they act also, very concentrated copper II chloride will precipitate copper I chloride, Iron chloride at this stage of concentration and heat is actually more aggressive at dissolving copper into solution, but if left concentrated and allowed to cool will then precipitate out the copper i chloride, the iron chloride after a time, heat and H2O2 or air can make an insoluble iron oxide hydroxide red powder, this iron compound will end up with any of your other insolubles, even any gold you may have, but luckily the other metals are soluble in one solution or the other, this red iron hydroxide is so resistant to acids you can dissolve the gold from this red rouge powder, even with acids as strong as aqua regia.

The iron chloride is not as easily to regenerate as the copper II chloride, but (at this stage we do not really need to keep the solution growing in volume either), by the time we have reused the copper II chloride so much to dissolve copper and base metals, we have pretty much got our use out of the solution. 

The copper chloride solution seems to grow in volume as we use it, so using the iron chloride/copper chloride or iron chloride for a little bit more before treating it for waste helps us to get a little more work done with the solution and can help to reduce the volume of our waste solution somewhat, so using our used pre-waste solution to dissolve base metals is helpful, and we can also use it for materials that would normally contaminate our nice clean re-useable copper II chloride without feeling guilty, .


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## Geo (Jul 12, 2013)

the one metal you cant avoid is the one that will foul either solution to the point they will stop working, and that is nickel. its beneath all gold plate and in many iron alloys. since you cant avoid the nickel under the gold, you can minimize the stainless steel and iron alloys you dissolve.


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