# Need some help with Generator Brushes



## gecox22 (Nov 28, 2016)

Good afternoon,

I have about 200 lb's worth of silver carbon generator brushes. I know I can recycle them for a profit, but thought I would look into if it would be better to refine the silver myself. Even though I have read countless posts and watch numerous videos on silver refining, I just can't seem to find anything on silver carbon brushes and silver removal. 

So first question, would it be worth it?

Second question is if it is worth it, how would I go about doing it? would it be by crushing them up into a powered or could I do chunks? Then add in the nitric acid and distilled water to get silver nitrate and then use copper to pull out the silver from the nitrate? 

I have never tried anything like this before so any help would be greatly appreciated.

Thanks


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## Lou (Nov 28, 2016)

Nitric acid will do the job quite well but lots of rinsing with distilled water will be required.
That's also a LOT of fume to make. You may even be able to do them somewhat by silver cell and finishing it off with small amounts of nitric acid. 

Depending on manufacturer, they usually are about 50% by weight Ag, so that's a nice 20K+ find!

If you get bored or toss in the towel, shoot me a PM.

I like to grind them up into powder and then burn them for a LONG time to remove the carbon.


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## gecox22 (Nov 29, 2016)

Would you happen to know how much Nitric acid I would need to get started? 

How could I found out how much Brush materiel I could use per milliliter of Nitric acid, or do I just keep re using some material till it no longer become silver nitrate?

What is Fume? 

I guess I need to look up silver cell because I don't know what that it.

Would it just be easier to burn them for a long time as you stated. And at what temp? I am surely willing to send you some just for helping out thus far. Feel free to reply here or contact me through pm.

Sorry for all the questions, I have never done anything like this just figured it would be something to look into because I can get alot more in the future. 

Thanks


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## jimdoc (Nov 29, 2016)

Sounds like you might be better off selling them.


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## snoman701 (Nov 29, 2016)

What kind of generators are these from and how are they identified in comparison to just a standard large carbon brush?


Sent from my iPhone using Tapatalk


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## gecox22 (Nov 29, 2016)

I dont just wanna sell them if I could make more of a profit refining them myself. I priced with a company that buys these types of brushes and if what lou said is true the profit from refining them my self outrageously makes it better to refine them myself 

As for the Generator, These are big generators for wind turbines, The brushes are specially design for these types of generator. As for the grade for the brushes the chart I am reading shows a 67% metal content.


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## Lou (Nov 29, 2016)

That would be a great score at 200 lbs at 67% content. I agree, do it yourself. I'd love to make honest money off you but this is a doable project. 

Usually they make them by pressurizing the molten silver into porous graphite. Kind of the same way they do with Elkonite for EDM or contacts. You can't melt them as is because of the carbon--it won't coalesce. Thankfully, carbon burns and silver doesn't. 

In this case, your best friend is thermal oxidation and then melting. Ideally you'd want a rotating stainless tube with posts to lift the material as it oxidizes (I have one such). Sure a tube furnace would be great but you could always get by with a box oven. Just roast them at a red heat with air until the weight does not change.

You can go to the restaurant supply and get one of these:

http://www.webstaurantstore.com/stainless-steel-steam-table-spillage-water-pan/92299765.html


Get a second one as they make a great silver cell and act as the cathode on which very pure silver will grow, should you take the material and want to make it even better. You can use a 30 g/L electrolyte made of silver nitrate with a few grams per liter of copper nitrate. Use distilled water. Regular muslin cloth will be great as an anode bag. If you didn't melt into anode blocks and just dumped the brushes in, they'll slowly dissolve electrolytically and what little carbon that might remain in the inside will stay in the bag. 

Get one of the plastic covers to use as the anode basket. They nest nicely in those stainless pans because they're supposed to; some Dremel work and you're off to the races. 

http://www.webstaurantstore.com/3121/plastic-food-pans-drain-trays-and-lids.html

Hope that solves your problems. Finer points of all of this are all over the forum. Congrats on the score! If you find this helpful, consider donating to the forum


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## Platdigger (Nov 29, 2016)

Have you tried to crush one or just brake one up with a hammer?


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## justinhcase (Nov 29, 2016)

I did process a few kilos of 50%graphite 50%Ag.
tried elector winning smelting and acid digestion.
Very messy.the carbon holds a good value very well and filters at a glacial rate.
(A) as part of it's designee it is used because the point at which the Graphite transits to it's gaseous compounds is above the vaporizing temperature for silver. This means that trying to simply smelt resulted in about 20% loss. Though you may be able to reduce that with a good flux mixture.
(B) all carbon's are very good at retaining other elements and compounds, which is why it is one of the most effective filter we know of.so normal digestion to silver nitrate and cementation is inefficient as well as there is always a good deal of value locked up in the graphite residue.
The best option would be gasification under high-pressure H2O and O2,there are a number of company's with specialist reactors you could approach if you had a high enough turnover.
I did run a trial of a silver cell which did not work for very long,So in order to run your brush straight you would have to build a specialist cell with ultrasonic agitation ,full time powered filtration and tie up about 3-4 kilos of silver in electrolyte.
But that was as far as I got before the client went else where.
Still have a little slop left I am going to just put in with my waste.


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## Lou (Nov 29, 2016)

Justin, it was gold?! I've never seen that before.


The silver ones you have to roast!


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## justinhcase (Nov 29, 2016)

Lou said:


> Justin, it was gold?! I've never seen that before.
> 
> 
> The silver ones you have to roast!


Sorry type O.Ag.
How did you roast?
I ground down and mixed with a high nitrate flux to help things along.
A more controlled decomposition would have been good.
It came down to quantity's as investing in the new kit necessary was more expensive than any lightly return for processing.
Don't you have a lot of company's in the U.S. specializing in carbon decomposition to process the residual carbon filters from cyanide recovery?


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## gecox22 (Nov 29, 2016)

Have I broke one up yet with a hammer, Nope I haven't tried anything yet. Thus why I am asking questions first and reading up on what to do and what not to do. Never even tried anything like this before

So Justin your saying your cant just put them into a furnace as Lou describes and using Nitric Acid wont work as well? 

I am sure there are company's that will do it at a cost. The one company I talked with said they would offer 8 dollars a pounds with the cables cut off and 3 dollars a lb if the cables where left on. Just running rough math if I have 200 lb's of brushes that is only 1600 bucks versus a 67% metal rating minus the 20% you stated I am still looking at over 20k in silver minus chemicals and equipment to get started. So 20% loss isn't that bad in the short term if I am sitting on that much right?

I am just trying to find the best way if possible to refine the silver from the brushes. I cant thank every one enough for all the help this far.


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## justinhcase (Nov 29, 2016)

"So Justin your saying your cant just put them into a furnace as Lou describes and using Nitric Acid wont work as well? "
It may depend on the kind of furnace you run.My electric assay furnace is tiny and I would not want to leave it running over night.Safety and the cost.I am a skin flint and the 30p an hour can add up.
So I used my gas furnace to test if a slow heat up to melt would do the trick.
Lou will have a better muffle furnace than I do ,I have heard of people running them with the door a crack to burn off carbon but never tried this my self.
Graphite would take a long time.
It will take you a bit to refine a working method,a lot will be to do with the volume and the amount you can invest verses what is needed.
There are no easy and clean methods ,the dust is a particular hazard when crushed. .


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## Smack (Nov 30, 2016)

I like this story :mrgreen: :G


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## justinhcase (Nov 30, 2016)

May be 4metals can help.
He was the one who suggested the Ultrasonically agitated and filtered silver cell.
May have worked if given more time to develop.
But Graphite brakes up into Graphene quite easaly and small particle's like that are a bugger to filter.
Mucked up my main cell quite well,and never got enough to warrant the modified cell.
Would like to hear of better options because I know of good source.


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## Lou (Nov 30, 2016)

Let me clarify:

You can not melt them as is without blowing oxygen into the melt. You only want to process the part that is the silver. Leave the connectors and base metals off. They must be silver.

You can "burn" the graphite out at 1400 F until your silver weighs the same. If you're worried about them not burning, heat one up to an orange glow with a cutting torch and then blow only oxygen on it. Your patient end result will be a button of silver.

You can take that largely carbon material and then (s)melt. You might need a flux, you might not. Or, you can dump the brushes into a cell after incineration. 

You can make a silver cell using the pieces I linked to, some jump start cables, a piece of bus for the cathode to sit on, and a power supply. The cell side of things has been beaten to death.


And to answer your question Justin...I am set up to do these in a small rotary calciner.


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## justinhcase (Dec 1, 2016)

Lou said:


> And to answer your question Justin...I am set up to do these in a small rotary calciner.



I have seen large industrial unit's but never one that would fit inside .
You have a unit suited to small job's?
Was it you who had the rotary furnace as well?
A Short tour would be very informative.


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## Lou (Dec 1, 2016)

We don't have any rotary smelting furnaces like what 4metals posted. 

But yes the small one is like a 6 or 8" bore that's about 6' long. Tilts, spins, goes up to 1100 C. Tube is alloy 625


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## gecox22 (Dec 1, 2016)

Lou said:


> Let me clarify:
> 
> You can not melt them as is without blowing oxygen into the melt. You only want to process the part that is the silver. Leave the connectors and base metals off. They must be silver.
> 
> ...



I got a torch at work and think I try will this first just to see the results. I will let you know how it goes. Also sent you a pm as well asking some questions. 

and as for this which I missed a while back


Lou said:


> Hope that solves your problems. Finer points of all of this are all over the forum. Congrats on the score! If you find this helpful, *consider donating to the forum *



If this comes out to the amount we hope it does I will certainly like to donate to show my gratitude.


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## justinhcase (Mar 6, 2017)

Now after looking at all the alternatives.Electro-cell, furnace and such.
A client sent me a sample which some one had just dunked the hole lot in nitric.
No milling just straight leach on intact chunks..
When i tested the material I got about 55%,after intact leaching by this chap there is left 1.59%Ag
The question is if all the extra farting around is in any way economical?
All the junk did confuse me ,I could not work out what that cocktail was.


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## rickbb (Mar 7, 2017)

If it's already been leached in nitric it won't have much silver left in it. Which is what that analysis shows. Their leach was successful.


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## g_axelsson (Mar 7, 2017)

When doing an analyze on a sample, it is first put into an oven. It is heated to above the boiling point of water and the weight is compared to the original sample. That way they find out the moisture content. Next step is to heat it up to glowing in an oxygen atmosphere until it doesn't loose any more weight. This burns off any organic matter and carbon. Then the weight is compared with the original, so the water content is included in the ignition loss. Anything remaining then goes for analyze. The first list of elements was detected but in very small amounts, the larger list is elements that are below detecting limits.

The sample analyzed was wet, it contained 28.75% of moisture, most of it was carbon and other volatile substances and it burned, 95.65% of the sample went up in smoke, so 95.65-28.75 = 66.9% was probably carbon.
Left after ignition is 4.35% and 1.59% of the original mass was silver. That leaves 2.76% of unknown components. The elements I'm missing from their list is silicon, calcium and oxygen so I guess most of the unspecified mass is calcium or silicon oxides from contaminants in the graphite.

As Rickbb said, the leach with nitric was quite successful.

For each kilo of leached carbon brushes you still got 16g of silver. If you want to extract that last part too you can burn them and leach the ash. A kilo of leached brushes would give 43g of ash and it would contain 16g of silver.
So from 200 pounds of carbon brushes you can extract 110 pounds of silver by straight leaching in nitric. Of the remaining 90 pounds of carbon you would get 3.9 pounds of ash with 1.44 pounds of silver.

Göran


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## justinhcase (Mar 7, 2017)

Yes I understand the content.
What surprised me was how effective such a primitive method has been.
I have been going all around the houses and have even started the construction of a rotary calciner/incinerator.
I did not take the contract because I was not certain about the effectiveness of my recovery.
Turns out I needent have worried.
I have been asked to clean up now but the cream of the easaly recovered metal has been had.
I think it is much like the case of VHS and Beta-max.
It is not about having the best system that our economical system rewards,It is about having the technology that is just good enough to do the job that makes the money. 
Over engineer and die.It is a luxury I have only every known through governmental contract.
Which is a pity.I love over engineering!!
Exerting an obscene amount of force upon a problem.Yumm EEEE :lol:


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## Aaronfv (Feb 15, 2022)

gecox22 said:


> Good afternoon,
> 
> I have about 200 lb's worth of silver carbon generator brushes. I know I can recycle them for a profit, but thought I would look into if it would be better to refine the silver myself. Even though I have read countless posts and watch numerous videos on silver refining, I just can't seem to find anything on silver carbon brushes and silver removal.
> 
> ...


I find myself in a similar situation and really enjoyed reading this thread. I found a video on YouTube that might be really helpful.


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