# Few questions about gold cell



## patnor1011 (Feb 14, 2010)

I am in process of constructing firewalkers tumbler cell. Amazing piece of equipment I must say. I have few questions and will appreciate help from any of you with experiences in this field.
1. I will be running pins from motherboards in there. Some of them are pretty small say 2-3 mm. I want to ask if holes in plastic cup where they will be "rotating" can be very small say needle size. As far as I know gold is dissolved and while "traveling" to cathode they form powder falling to bottom. Are needle size holes sufficient enough? 

2. While I know that AP with HCl and fumes produced are corrosive to any metals near and is recommended to do it outdoors or under fume hood is running sulfuric based gold cell and fumes involved damaging metals in the same way or no?

3. Is sulfuric eating/dissolving copper? I was thinking of that rotating plastic cup holding pins - I am thinking of making bottom part of it from very fine copper mesh to run very small pins. Setup in firewalkers pictures has bigger holes but he is running bigger pieces in it.

Thanks. Pat.


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## Barren Realms 007 (Feb 14, 2010)

There are fumes created, look at Steves video again.

Copper will be disolved in your solution, listen to Steves video again.


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## leavemealone (Feb 14, 2010)

> I am in process of constructing firewalkers tumbler cell. Amazing piece of equipment I must say. I have few questions and will appreciate help from any of you with experiences in this field.


Jack created the "tumbler" to process pins,and found out quick it doesnt do small pins very well.It works great on larger pins that have a lower surface to mass ratio.Pins that are smaller and have a really high surface to mass ratio do well in the "basket" that steve shows in one of his cell videos,or can be processed using plain AP.
The tumbler is great,but it still takes the same amount of time to strip the pins as steves basket method.However,the tumbler is hands free......but dissolves an incredible amount of base metals before all of the pins are stripped.Before he got sick we had been batting around the idea of using a stationary container and having a rotating anode.I've had the idea on the back burner primarily because of his health.I would feel guilty continuing with it until we can do it together.
Johnny


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## goldsilverpro (Feb 14, 2010)

Patnor,



> 1. I will be running pins from motherboards in there. Some of them are pretty small say 2-3 mm. I want to ask if holes in plastic cup where they will be "rotating" can be very small say needle size. As far as I know gold is dissolved and while "traveling" to cathode they form powder falling to bottom. Are needle size holes sufficient enough?



The main thing, or course, is to make the holes of such a size that the pins don't fall through. I would make them as large as possible, in order for the sludge to fall through. The plating barrels, which this thing is patterned after, don't generally have straight through holes. They are made of sheets where the holes are drilled in a "herringbone pattern". The holes are made like this: |^| This way, it's impossible for any size pins to fall through. You may be able to buy this herringbone sheet and then cut it and plastic weld it into a hexagonal basket shape. Plastic welding is cheap to set up and very simple to do.



> 2. While I know that AP with HCl and fumes produced are corrosive to any metals near and is recommended to do it outdoors or under fume hood is running sulfuric based gold cell and fumes involved damaging metals in the same way or no?


The amount of fumes are proportional to the total amperage and the temp. of the solution. The fumes themselves are not bad. However, the bubbles coming off are incased in liquid sulfuric.



> 3. Is sulfuric eating/dissolving copper? I was thinking of that rotating plastic cup holding pins - I am thinking of making bottom part of it from very fine copper mesh to run very small pins. Setup in firewalkers pictures has bigger holes but he is running bigger pieces in it.


If you keep the temperature of the solution below about 110 - 120F (43 - 49C) by adjusting the amperage, you should have no attack on the copper. I had a 50 gal tank and ran parts clipped onto bare brass racks. I ran each rack several times per day for a couple of years and had no noticeable attack to the brass. The temperature is very important in this respect. If you want to run a lot of parts, get a large tank to absorb the heat.


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## leavemealone (Feb 14, 2010)

I believe lou said he was running a 150 gallon stainless setup.It may not have been that big,but I know it was huge.I just can't find the email now.
Johnny


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## goldsilverpro (Feb 14, 2010)

> I believe lou said he was running a 150 gallon stainless setup.It may not have been that big,but I know it was huge.I just can't find the email now.



Are we still talking about a concentrated sulfuric gold stripping cell? I read most every post, especially those made by someone who really knows what they are doing, like Lou, Harold, 4metals, fournines, lazersteve, etc. I recall no mention of Lou running a sulfuric cell of any size, and I'm sure that a 150 gallon one would have grabbed my attention. Even if he did, I can't imagine him constructing it of stainless steel, although he may have. Please correct me if I'm wrong. If I am wrong, pass the crow. Maybe you're thinking of some other type of system.


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## leavemealone (Feb 15, 2010)

No you are not wrong chris.....we had been talking through emails when we were talking about it.I think it was a couple of years ago,but it may have been sooner.And like I said in the post,it may not have been that big,but I do remember it was huge.He had a contract with intel many years ago,and I think he "rebuilt" eproms.Anyways, they extracted several pounds of gold a week.And yes,it was a stainless cell,and it was being used as the cathode.
Johnny


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## goldsilverpro (Feb 15, 2010)

> No you are not wrong chris.....we had been talking through emails when we were talking about it.I think it was a couple of years ago,but it may have been sooner.And like I said in the post,it may not have been that big,but I do remember it was huge.He had a contract with intel many years ago,and I think he "rebuilt" eproms.Anyways, they extracted several pounds of gold a week.And yes,it was a stainless cell,and it was being used as the cathode.



Are you sure it wasn't me you are talking about? In the 70s, I co-owned two different companies in L.A. that rebuilt eprom packages and other side-braze packages, using a process that I came up with. Our largest customer was Intel. We also did a lot of work for AMD and AMI. They sent us their in-house rejects and we removed the chip and lid, stripped the packages in a modified H2SO4 stripper, replated the gold, and shipped them back to Intel, or whoever, for re-use. Later on, we rebuilt reject hybrid packages used mainly in the fiber optics industry. I did not use SS tanks. They were 50 gallons and were made from mild steel.

If Lou also did this, I would definitely be interested in talking to him - I'll ask him about it. I've mentioned that I did this several times on the forum and, had Lou done the same exact thing, with the same exact customers, I would have thought he surely would have said something.


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## leavemealone (Feb 15, 2010)

Can I blame it on me not having my coffee yet?!?!?!?
Yes I remember now.I remember discussing the hangers and everything so clearly.Crap,sorry chris.
I hope lou is not reading this......lol.
I even started going through old emails from members looking for lous emails....lmao.
Well I need to get ready for work,so I'll see you guys in a few hours.
Johnny


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## goldsilverpro (Feb 15, 2010)

No problem. I constantly get people mixed up. It's easy to do with 10,000 members.


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## leavemealone (Feb 15, 2010)

Too funny.It was easy to remember everyone back when there was about 100 or so members.Now it seems like we get over 100 new ones a day.
Johnny


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## patnor1011 (Feb 15, 2010)

Thank you for responses. Now I think that I will go AP route with smaller pins but I surely construct filewalkers tumbler cell I might use it later when I will have enough bigger items to run in it. I want to do it becouse I have lots of time now just hanging around in home like lion in cage as I am off work now recovering after some surgeries so I need to do something otherwise I will go mad...
Heh maybe it will be good idea to make one extra to find out how much will folks on ebay pay for it.... :twisted:


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## aflacglobal (Feb 15, 2010)

A long true story. 

In about '72, I invented a method and formed a company, with a money partner, for the service of recycling all-gold plated, old type CPU, side-braze packages (mainly 40 lead) for reuse. These were rejected parts, in various stages of production. Most were rejected on final testing, after sealing. 

I went to the Silicon Valley to hustle business. I hit about 10 huge electronics concerns, cold, and showed them before and after samples. Every company I went to was very eager to talk to me and they all gave me samples of their rejects. 

I also found out that Fairchild Semiconductor had spent a lot of money trying to do this same thing and had failed miserably. There were also a couple of smaller companies that had worked on this, but their methods were Mickey Mouse and they produced unacceptable parts. I think they were the ones who got the patents that are mentioned below. 

Purple plague was one of the reasons for rejection. 

My biggest customers were Intel, AMD, and AMI. At the end, we were doing about 100,000 packages per week. We (1) Removed the lid and chip with heat and a vacuum probe and removed the bonding wires; (2) Chemically stripped (electrolytically) the gold plate and gold alloy brazes selectively without attacking the base metals (the crux of my invention). These base metals were Kovar legs and sealing ring, plus moly-manganese chip pad, internal traces, bonding fingers, and pads to braze the legs to. Also, silver/copper braze was used to attach the legs. There was also nickel plating under all the gold plating. I should mention that cyanide (the first thing I tried) wouldn't work because it attacked the copper and silver; (3) Replated the gold; and (4) Returned them to the companies for new chip attachment and reuse. Our recycled packages had a higher yield than new packages. We charged half the price of a new package. The new price of these same packages now is about $4 or $5, although there are far fewer of them used today. The extra gold we removed from the gold brazes (80/20, Au/Sn for the lid; about 96/4, Au/Si for the chip) nearly paid for our processing. At that time, when the companies put out a new chip, the early manufacturing reject rates were as high as 98% 

The business ended in '74 (I think) when Nixon devalued (10%) the dollar twice and there was a 6 month dock strike. The electronics industry died. No parts could then be shipped to or from the overseas assembly facilities. Right before the strike, a company in Texas promised us 100,000 parts per day. When the strike hit, they went down to 5,000 per week. We shut our doors. Oh well. 

The same process can be used for high dollar ($10 to $1,000), all-gold, hybrid packages, which are used widely today in specialized applications. The process costs are about the same as on the cheaper packages and the 50% charge still applies. Lower volumes, lower setup costs, much higher profits, on the hybrids. I set up a small hybrid process in '80. We rented a booth in a ISHM show (International Society of Hybrid Microelectronics). We laid out about 20 different before and after packages on black velvet and got over 100 electronic companies that were interested in our wares. However, at that time, my main business was gold and silver refining. 1980 was also the year that the PM prices went through the roof. We sometimes had 20 people waiting in line, when we opened the door, to sell us gold and silver scrap. There just wasn't any time to concentrate on the packages. 

As far as I know, no one else has ever come up with viable process to rework these packages. There are a couple of patents out, but they require a lot of hand work and are far slower, much more expensive, and inferior to mine. I didn't patent my process but it's still in my head (and in my head only, I think). My process is still very viable. 

About once a year, I feel a need to rant about this. If only that frigging dock strike hadn't happened! Oh well.
GSP.

viewtopic.php?f=39&t=1080&hilit=corners

Oh, and this is a classic to http://onepocket.org/Corners.htm



I ran the same solution for several years, 10 hours a day. I collected the gold (about 50 - 100 oz) every week, or so, and put the same solution back in the tank. It was a 50 gal steel tank and I made the tank the cathode. It was run at 250 amps (5 A/gallon) and, even then, it would normally heat up to about 10 F above ambient. If it got much hotter, it started attacking things that I didn't want it to attack and creating other problems.

The boiling point of your H2SO4 is about 500 F. That means that, if you continue pouring the amps to it, it will keep getting hotter and hotter. Have you checked the temperature? I think that is your main problem, considering that little dinky quart of acid you're using and the huge amount of amps you're applying.

Here's how I would do it. Before putting the parts in, turn the rectifier knob to zero. After the parts are in, adjust the amps to about 10 max (from 2 to 5 would probably be better for your little tank). The voltage will be about 2, or so. When the amps start dropping, increase them back to 10 (or, from 2 to 5). Continue this until the voltage is about 12 - 15 and stop adjusting. You have to stay with it. The amps will soon go to zero. Using this method, average gold plating will take about 2 or 3 minutes. I was stripping 1 mil thick gold/tin braze (that's 30 times thicker that the gold on fingers) and that took 15 minutes. Don't overload the tank with parts. Run fewer parts and more batches. If the temperature reaches about 130 F, let it cool off. Either that or lower the maximum amps. When you reach a point where the amps won't go to zero, that means that there is so much metal powder floating around in there that you have a partial short - it's time to harvest the gold. If you do what I'm suggesting, I think that things will go faster, things will be safer, and you'll be able to re-use the solution. Just be patient and try it once my way.

I know of no 55 gallon plastic drum that will go to 400 F, unless it is made from something like teflon. I would figure about 170 F before it starts to get soft. Also, hot concentrated H2SO4 tends to remove the plasticizers from plastic and it starts cracking.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=5069#p43570


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## leavemealone (Feb 15, 2010)

I talked to firewalker this morning but forgot to ask if he wanted to sell his tumbler.He was going to give it to me a while back,but I already have one and I never really used the one I have.He usually calls every morning around 9 and every night around 7 or 8 .So I'll ask him tonight when he calls.
Johnny


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## leavemealone (Feb 16, 2010)

Ok just got off the phone with him.$100 plus shipping for the whole thing.
If you want it let me know and I'll give you his paypal address.
Johnny


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