# Mechanical Stripping



## goldsilverpro (May 13, 2007)

A lot of you have been around long enough to realize that one of the most important things would to be able to strip gold off without dissolving the base metal. That way, it would be faster, cheaper, and would produce less waste. You would not only have gold to sell, you also would have copper. If you ever come up with a new, cheap, safe method for doing this, don't tell anybody and quickly get a patent on it. 

About the only things that have been found to do this are cyanide/oxidizer, iodine/iodide, and bromine/bromide. It's also maybe possible to use hypo (sodium thiosulfate). As Sue suggested, somebody should experiment with hypo. I used cyanide every day for about 20 years. Sometimes, I worked around 5000 gallon tanks. It is cheap, efficient, safe, fast and, most important of all, it can be completely destroyed. It's formula is CN and it can be broken down to CO2 and N2.

The following is a secret, never told, so don't tell anybody :lol: . I'll probably never do anything with it. 

One day, in L.A., I got the idea of using abrasives to remove the gold. I put some pins in a rock tumbler along with some silicon carbide powder. All the pins got was dirty. I did no more work on this. I think it will work with the right abrasive. The problem is in separating the gold from the abrasive. Probably something like a separating table or a spiral wheel.

*The Wheelabrader*. I think that's what they call them. This is a vertically rotating, cage like, wheel with small holes in it to prevent the parts from falling out and to let the sand fall through. It is designed for small parts. Inside of the wheel is a sandblasting nozzle. The wheel is inside of a sandblasting booth. The parts are put into the wheel, the nozzle is turned on, and the wheel is rotated. The metal wheel is coated with a rubbery plastic to prevent the sand from eroding the wheel. Eventually, every part is completely sandblasted. It gets in all the holes and the cracks. There's really not much to them and they could be made.

I spent about 4 hours, one day, doing experiments in a company that sold Wheelabraders. I had lots of bags of different types of parts, including rhodium plated jewelry. I tried several abrasives that worked so-so. However, the problem of getting the gold out was always on my mind.

I finally tried some glass shot and steel shot peening media. This stuff worked great and fast on everything. Instead of abrading the gold off, the shot peens it off. During peening, the plating layers are peened thinner. This stretches the gold sideways and it just pops off (along with the nickel).

Some of the steel shot Wheelabraders have built in magnetic separators to clean the shot from the garbage. Gold flake collection should be easy with one of those.

EDIT: Since this post, I found out that there is a piece of equipment called a Wheelabrader but it is much different than what I described. I don't know what the machine I used is called.


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## lazersteve (May 13, 2007)

Chris,

The idea sounds pretty solid. I have a few questions and comments.

What would stop the nickel layer from being peened off with the gold layer?

What would stop the copper layer from being partially peened into the mix?

I think the steel peening balls are the way to go. This would make separation easy. Any peened metals besides gold would have to be removed by the standard dissolving techniques.

I have a friend that had a metal shop and he had some sort of machine similar to your description that used ceramic cones as the 'peening'. I think he told me the purpose of the device was to polish or smooth the burrs off of tooled metals, I can't really remember what it was for. Harold probably knows since he was a machinist by trade. I also saw an episode of Dirty Jobs last year where Mike Rowe cast some drain covers out of nickle and they put the raw casts into a similar machine to polish the drain covers and deburr them. That machine had very fine particles for the peening, I think they called it shotting.

This definitely has some promise.

Steve


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## Paige (May 14, 2007)

Chris,

I have heard that the easiest way to destroy cyanide for disposition is to add bleach. It renders it into two or three harmless substances. Is this correct?

Paige


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## goldsilverpro (May 14, 2007)

You need bleach and lye. You end up with cyanates, which still have a degree of toxicity. There are other ways of breaking it down further - strong peroxide, for example. One of the best is to heat the solution under pressure.


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## aflacglobal (May 18, 2007)

Hey ! This is a story i think might help.

I had the opportunity to help liquidate a plant located here in Alabama 
a couple of years ago. It was another one of those Get a phone call
deals, and almost played out like the story of my first gold find. Except in this one i made off like a bandit. :shock: 

I had a phone call one day. ( as a buying agent for a scrap processor. )
They had a bunch of (quote) : scrap metal dust to get rid of. I ask , are you talking about turnings ? 

No they said it's like slag and little beads of slag or metal. It's in sealed 55 gallon drums. I thought , what the hell are these people talking about ? We have a building full of it. 
I thought, maybe waste product from a manufacturing process ? I have to go see this.

OK i set up an appointment with this little old lady. No shit , she had to be in her 70"s . But Grand ma wasn't no fool either. She was wise , but didn't play no games. Seems her husband had died about 10 years before.
The daughter and son tried to run the business, and that they did. 

Straight into the ground. The books were still there and if you have any sense you can figure it out. Think about what we all have in our offices that could tell the general story of the outline of our life. What's in your wallet ?  LOL

Anyway Daddies little girl had a two year degree from the yahoo university, and J.R. was a peter puffer. I swear to god it's true.
J.R. wanted to manage the crews and sis wanted to run the office. Oh Hell no ! What's wrong with this picture.

After the plant shut down. Grand ma kicked their ass out into the real world. Now she wanted to get rid of this trash as she called it. LOL
And clean the building up and market it for sale. She said if you will help me get this place ready, i will give you all the metal and split the equipment profit with you. Then what's left they ( J.R. and sis ) can split.
This place has been here to long and the memories need to go. I'll get them to answer your questions and you just Handel it. If you have any problem , you just call me. It was all in Grand ma's name. I ask do you want the money. No she said, I'm tired of the dickering. Give it to them.

Shittttttt ! Yes Mam .  
OK, at this point i guess i need to go ahead and tell you what it is, or should i. OK ! It was a warehouse full of shot and grit. ( shot is round and
grit is jagged ) It is used in the process of cleaning, polishing, DE burring,peening, if you use it as a shot you can also peen a surface to stress harden the alloy. Etc.

These range from small to large in scope and have grit values like that of sand paper, blasting media,sand, glass, walnut shells, almond pits, Plastic,
metal, and even talc powder can be used as a blasting, etching, or polishing compound. Let's not all forget the The Mohs scale of hardness .
Oh my god where is this going ???

Now follow me. The year was 1990 something ( early ) The old man was alive and the company was doing fine. What were they doing ? well
the old man actually started a business based on the principle of trash is free. Here the deal. He bought 2 vacuum trucks. They things would suck a man up a hose ( 6 in ). No shit they were dangerous. he would go down to the ship ports in Mississippi, up in Boston. He would go to these mfg plants and such. 
They use this grit in all kind of industry, and they all have different ways of using it to exact a certain process. 

The Wheelabrator http://www.wheelabratorgroup.com/ Is just one method.
They had this stuff piled up in massive quantities. A 55 gallon drum can weigh between 1600 and 2300 lbs. When you use it in these processes you also get the by product of what the grit was used to clean. Aluminum,Steel, copper. Etc.

For them it is HAZ waste. Well here comes Grand pa and offers to haul it off for free. Hey. No problem. Steel was cheap then and we didn't have a high tariff on it. Scrap steel was going for about 7 cents a lb. this stuff was worth about $ 500 drum ( when i found it ) So what they did was use it one time and discard it. Once the old man got it back to his factory he would run it Thur a process where the material is run Thur a long , fire heated tube to burn off any oils. Then it was sent over mesh screens to separate the various grit sizes. Then run Thur a magnetic separator. Then it dropped down a set of spirals where the round shot would roll on Thur but the grit not being round would vibrate down a flat surface. Like a shaker table for gold. After that it was put in a drum inside a sealed plastic bag. Strapped, places on pallets, labeled, weighted and stacked.

Well the kids knew how to get it but they could not sell it quick enough.
So it was shall we say back logged. bad !

I think i wound up with about 683 drums, You do the math. Even though i didn't get market value, it was still nice for me and the buyer.

Now what in the world does this have to do with chickens and puppies ?
Well i was just reading and thought of the discussion about the Wheelabrator And thought, yes ! it might work.

Later Gentlemen,

Ralph


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## austexjwlry (Jun 10, 2007)

In our jewelry shop we use large & small vibratory tumblers which should be more effective than silicon carbide in a rotary tumbler. We use green plastisized pyramid shaped pellets for the most aggressive cutdown stage after casting & deburring rings. The white ones are less aggressive ,would definitely clean pins of mil. coated gold in probably one or two days!

They would be a lot less messy than silicon carbide grit or aluminun oxide grit but still have either plastic & zircon or plastic & quartz residue. The longer you run them the thicker the slurry would be. Pyramids are easily rinsed through a strainer.We buy them from rio grande jewelry supplies.
You could allow your gold particles to settle in vessel then siphon lighter suspended plastic, then burn remaining plastic, melt, refine as usual.
Might be a real acid saver. I'll have to try a batch!

Wayne


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## mike.fortin (Jun 10, 2007)

Wayne--I'm interested in the results of your test. Have you decided electronic scrap to try it on? Pins? Fingers? Chips? I hope you take picutres.
This could be profitable fun. Mike.


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## lazersteve (Jun 10, 2007)

Wayne,

A friend of mine has a metal fabrication shop and they use a large one of the same type of machine with the cone type pellets. They use it to debur medium sized metal objects. He's in China right now, but when he returns I'm going to ask him about doing some tests of my own.

Exciting Stuff!

Steve


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## austexjwlry (Jun 12, 2007)

I'm sure it would work on loose pins but not on inside of groups of 2 or 3 rows etc. that have been sawed off or sheared, because the pyramid shape is too large,1/4" across at the base new. Mine are avg. 3/16" used. Still way too large to get between rows. The cones we have available to order are 3/8" new.

Would also work on trimmed fingers! You could check your work often and when you see only copper rinse well. Having ground off diamond burs for quite some time, I'm can eye visibly tell the difference gold and copper layer.

I only have about 1 oz of loose pins at the moment. I process everything as fast as I get it; it does me no good in boxes.The absolute best return for us is to alloy our metal, cast it or roll it into wire! Then sell jewelry!

I'm trying to learn from Steve and everyone else by going after manu. scrap. We have Dell computer here, they throw away bags & bags of new caps. etc. We used to clean up in their dumpsters until security guards ran us off! I'll try again by asking permission or offer to buy.Actively looking for more sourses.
I'll pull or clip some pins or buy some a.s.a.p. to try tumblers. 

Wayne


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## austexjwlry (Jun 13, 2007)

Steve

I'm only going to use 68 gms of mixed low grade pins. All the pins off 4 motherboards & a few modems for the test. I'm running them in white (the less agressive) pyramids I have because they were already in 1 1/2 gallon tumbler. When I first poured them in a few immediately stuck to the stem in the middle of tumbler; I wiped them down into barrel. Some of the pyramids creep up the outside of tumbler barrel while tumbling and may stay there along with some pins and not get scoured.

I'll also try the green pyramids in vibratory, and both green & white in rotary Lortone 12lb tumbler (ball mill). I put them in white pyramids tonight at 11:00 p.m. C.S.T., will check in the morning.

I have pictures but was wondering what you consider best size? These are 640Xvaries. I only added one picture to a different post then added a second one as reply which requires more verbiage to post, etc. This time I'll try to add more pictures to the post. In the future I'll try to limit unnecessary photos.

Thanks,
Wayne


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## austexjwlry (Jun 13, 2007)

1 1/2 gallon vibratory , 12 lb Lortone barrel


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## lazersteve (Jun 13, 2007)

Wayne,

Looks like you have access to some nice equipment there. The larger mill seems like it should be able to handle ceramic cpus and plastic pack ic's very well. Have you tried it with any of these?


Steve


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## austexjwlry (Jun 13, 2007)

Steve

Ran tumbler for 12hrs. Over all I'd say results were great, all of the pins that were lightly plated appear completely stripped. Heavy plating on modem type (phone plug) wire looks very light. The small pins from the square socket the processors plug into seem to have held their coating the best.
In the picture of the pins in sauser below, the two at the bottom were the only type showing any gold still.
I dumped tumbler contents in bucket then tried magnet to seperate pins. Most don't seem magnetic. Will have to devize better method to seperate pins & pyramids. 
Had I used green (the more aggressive) pyramids would probably have been completely finished by now. Will dump back into tumbler as is, foam & all..Will run another 12 hrs and let you know results.

Wayne


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## austexjwlry (Jun 13, 2007)

Steve

I got two hexagonal barrels with this tumbler at a garage sale for $15. Are you thinking of running already broken ceramic cpus to mill the pieces smaller or with abrasive pyramids to remove metals for further refining?
I use a 6" wheel diamond grinder made by Diamond Pacific called a Genie.If I removed most flatpacs & large chips, the course wheel 180 grit I believe would remove soldered on palladium chips etc., pretty fast.
Problem is, its like a Baldor motor with 3 diamond wheels on each side. Would need a motor with just one wheel ,the course one on it. These are wet grinders with water for the lubricant to keep dust down. Cuts agate (quartz) like butter with new wheel.These wheels are only 1 1/2"wide.
We also have an expandable rubber wheel 2 1/2" wide x 6",that you slip abrasive diamond belts onto then centrifical forse holds tight on wheels. These are good since your only paying for the belts when they wear out, not the wheel.
Harbon Freight sells a diamond cut off wheel set with arbor to mount in dremel or foredom tool. I make coils of stainless steel welding rod for chainmail links. They cut with ease, will try on various parts! They are like the aluminum oxide cut off wheels you get with a dremel set, but are much more aggressive, do'nt shatter and last a lot longer.

Wayne


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## austexjwlry (Jun 13, 2007)

Mike.fortin

I'll be glad to run some fingers a.s.a.p. I'm very grateful for ideas! 

Thank you

Wayne


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## mike.fortin (Jun 14, 2007)

Wayne--glad to hear you be trying gold fingers soon. What is it that is wet stiff you use making that head of foam. Cheap beer? LOL.
I don't think you'll find a better method for seperating pins and pyramids than gold panning. Do you know how? Use a big pan. I bet the plastic floats eventually. Like your picutres. Real good ones. Mike.


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## lazersteve (Jun 14, 2007)

Wayne said:


> I make coils of stainless steel welding rod for chainmail links.



It seems you and I have more in common than meets the eye. I also make chainmail. I picked it up from a close friend 20 years ago. I've been hooked (pun intended) ever since!
:lol: 
Steve


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## austexjwlry (Jun 14, 2007)

Steve

The first time I ran pins in white pyramids for 12hrs, still showed some gold.

This time I ran the same pins,water, pyramids for 19 hrs. We separated some pins, with almost the same results still showing some gold on pins. Will run again tonight.

It's really a mess - plastic pyramids, tin, lead,and very little gold in a slurry. It's a pain to separate pins & pyramids. I already don't consider this a successful techinique because of the mess. But physically its working.

I believe goldsilverpro had the right idea, just wrong abrasive media. In lapidary rock tumbling for instance the books say break quartz into chunks then tumble in rotary tumbler to shape with 60/90 silicon carbide (coarse grit); after about 1 week, the corners are nicely shaped and rounded, etc. I've done this many times. It works. Then you move to next finer grit, 600 grit or better in vibratory or rotary tumbler. The vibratory works better for smoothing rocks after initial shaping. But the rotary is most aggressive for shaping and material removal in every stage. Which is what we want, except it takes longer!

It is my belief we need as non-contaminating a media as possible. My suggestion would be make our own out of bottle glass (soda lime) for instance. No other abrasive grit, just crushed bottle glass grit & pins with just water to cover. No soap or anything else to contaminate.

We use small glass beads in sandblaster in sandblasting cabinet to etch or put a matte finish on silver and gold jewelry. This helps lead me to believe glass would work as abrasive even without air pressure. Primitive man used flint and obsidian knives etc... When you crush it, it will have lots of microscopic sharp edges. Quartz & glass have a conchoidial (curved) fracture. Should be pretty abrasive.

In a 12lb rotary tumbler you could run from 4 to 6lbs of pins and remainder being grit & water. I'd say fill the barrel 1/2 full of pins maybe a little less. Add crushed ( almost powdered glass) to almost 3/4 full, cover with water and run until pins are clean, possibly as long as a week. I'd check daily, adding more water to keep slurry from getting too thick which would slow down sliding action in barrel and/or add grit as necessary. After pins are cleaned of gold separate pins with kitchen sieve or screen, remove lead with hydrochloric, tin with sulfuric acid on hot plate. Rinse well, dissolve gold in AR, precipitate as usual. I'm sure you would go at refining differently, would like to hear how!

What do you think?

Wayne


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## lazersteve (Jun 14, 2007)

Wayne,

Sounds like you've got some good ideas. The problems with separation concern me. It would be great if the abrasive material were magnetic. I've started looking into fine steel peening shot back when GSP brought this topic up. This idea needs some serious thought to work out the details, but it certainly shows some promise.

Great work.

Steve


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## austexjwlry (Jun 15, 2007)

Steve 

We use stainless steel shot in 12lb rotary tumbler for the final polish stage only. We start with green pyramids (coarse) grit 1st. Then white pyramids (fine) grit. Then stainless steel shot peens or burnishes the surface of silver rings etc. almost perfectly. It does surface harden the silver somewhat but not properly.

Plain steel shot is a lot cheaper but rusts & corrodes badly when not in use even if dried before storage. Stainless steel shot is almost maintanance free. It comes as ellipse, diagonal, pin, ballcone & oval shape.

We also use porcelain balls in vibratory tumbler for finished jewelry except that set with soft stones.We use 409 or windex glass cleaner in both , can be diluted with water to suit.

To achieve almost spring hardness in silver put it (ring etc.) in kiln or oven at 600 degrees F for 3 hrs to allow maximum silver crystal growth to occur within metal. Do not quench in water, allow to air cool.

Annealing is the opposite; you heat to dull orange in dim lit room then quench in water. The absolute best way to anneal silver is in an electric kiln at 1200 degrees F for 1/2hr for say 8ga round wire to 1hr or 1 1/2 hr for small ingots or rods to be rolled. Few people have the patience to stay on metal long enough with a torch to properly anneal it. Most people overheat which can be worse.

Flame chemistry is very important also oxidizing versus reducing to achieve different results. Like when initially beginning to melt brown powder in crucible I use very reducing flame (light & flowing) very little oxygen to blow brown powder out of burno crucible. As metal starts to pull and sinter together add a little more oxygen to increase heat. As it pulls together a little more add more oxygen again etc. until your metal is melted. If you go from very little oxygen to sharply defined points on flame but no more your flame in considered neutral. This is the hottest flame and what you want. As you add more oxygen the flame starts to cool more and more. Add a little more oxygen you flame starts to hiss as it becomes more oxidizing. A lot more oxygen your flame will start to kind of roar; this is a very oxidizing flame.

Wayne


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## aflacglobal (Jun 15, 2007)

This gentleman Is great.


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## Photobacterium (Dec 7, 2011)

lazersteve said:


> I have a friend that had a metal shop and he had some sort of machine similar to your description that used ceramic cones as the 'peening'. I think he told me the purpose of the device was to polish or smooth the burrs off of tooled metals, I can't really remember what it was for. Harold probably knows since he was a machinist by trade. I also saw an episode of Dirty Jobs last year where Mike Rowe cast some drain covers out of nickle and they put the raw casts into a similar machine to polish the drain covers and deburr them. That machine had very fine particles for the peening, I think they called it shotting.



i worked at one place in the mid-80's that had a large CNC shop (several larger mills & lathes) and the typical accessories ... tool room, metrology lab, fixture making area, proto machine shop for us engineers, etc.

there, the call-out was "tumble deburr". most of our parts were aluminum, often with copper plating and 50 microinches of gold.

i always liked that finish - both the tumble deburr alum, AND the .000050 gold.


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## solar_plasma (Apr 1, 2014)

gsp wrote:


> One day, in L.A., I got the idea of using abrasives to remove the gold. I put some pins in a rock tumbler along with some silicon carbide powder.



wayne wrote:


> In a 12lb rotary tumbler you could run from 4 to 6lbs of pins and remainder being grit & water. I'd say fill the barrel 1/2 full of pins maybe a little less. Add crushed ( almost powdered glass) to almost 3/4 full, cover with water and run until pins are clean,



Just got that idea and found again, there is no good idea, anyone hasn't had before  did anyone have succes with that method on pins since?


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