# Suggested Modifications Comments



## lazersteve (Apr 4, 2007)

Chris,

Thank you for the great tips, it seems you have lots of tricks which will greatly improve upon all the methods that I currently use. It just goes to show how big of a role years of hands on experience plays in these matters. My hat is off to you and Harold for taking the time to guide us new guys.

Thanks again for all you are adding to this forum.

Steve


----------



## goldsilverpro (Apr 4, 2007)

Thanks for the kind words. I might mention that the suggested modifications are here:

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=223


----------



## Fever (Apr 4, 2007)

This is good stuff! Can you elaborate on why you selected mild steel for the tank (cathode) rather than something like a stainless steel vessel that would stand up better to corrosion? Also, did you isolate the tank in some sort of non-conductive framework so as to minimize any possible stray current? 

Thanks for the info....

Fever


----------



## goldsilverpro (Apr 4, 2007)

In this case, it's reversed. The mild steel suffered no attack over several years except for very slight etching at the top of the solution where the sulfuric, iron, and oxygen, from the air, all contact each other. The welds weren't affected either. Use welding rod that contains no nickel. Nickel is the one bad actor in this whole system. Although slow, the sulfuric will attack nickel or nickel alloys. Also, much nickel will make the solution stop stripping. I have thought, over the years, that a small addition of chromic acid or potassium dichromate would prevent nickel attack but, I haven't tried it. There is no problem with stray currents. If I remember right, the tank sat on the concrete floor. It was made of 1/4" steel, since 50 gallons of sulfuric weighs about 800#.

When I first experimented with this solution, I was using a standard, thin, 4 liter stainless lab beaker. In a few days, the solution ate a hole in the beaker. The stainless was magnetic. Probably 400 series with no nickel. But, 300 series, with nickel, would probably have been eaten sooner. Maybe, the chromium, in both SS series, is attacked also.

There's one thing I should mention. Strong sulfuric is a desiccant. In other words, it absorbs moisture out of the air and gets weaker. People in high humidity areas may notice this. Probably not, though, since the absorption slows down considerably as it gets weaker. Good to know, though.

When I ran the 50 gallon system, I used bare brass racks to hold the parts. Here again, I got no attack except for slight etching where the top of the solution, the brass, and the air all met. Also, due to water absorption, the solution was probably weaker at the surface. And, weak electrolytic sulfuric will attack most base metals.


----------



## Fever (Apr 4, 2007)

Thanks for the details GSP!

The main reason I was interested in learning more is because I have an entire fab shop at my disposal, and I'm a Journeyman Welder, so I have built all sorts of interesting trinkets through the years, most of which were used in oceanographic experiments. I'm just beginning to apply my fabbing knowledge to the whole precious metal recovery/refining world, which is now fully consuming me as my new hobby, and I plan on building some great items to aid me in this adventure.

Thanks again for your sharing your knowledge!!

Fever


----------



## lazersteve (Apr 4, 2007)

Chris,

Your description of the operation of the modified cell is very good. I live in Florida and hence have experienced the problem you discussed with water absorption. This is why in my tutorials I suggest the use of a cover for the cell when it is not in use. I've discussed the technique of using the container for the anode with the gentleman that I got my cell plans from. He told me had been using a cell constructed in this arrangement for some time. His plans did not mention the use of mild steel or brass and the setup was geared towards stripping 10-20#'s of pins at one time with high current densities. It required stirring to maintain the stripping action. What is the operating voltage and current draw of your setup?

Steve


----------



## goldsilverpro (Apr 5, 2007)

I used to run a lot of gold plated IC lids with Gold/Tin braze on them using this stripper (not exactly - see below). When you try to strip a bunch of small parts, like these lids or pins, in a pile, in a basket, only the surface of the pile strips. The pins in the center don't receive current and remain unstripped unless you stir them up quite often. This problem was solved by using a "plating barrel". Here's a good shot of a plating barrel:
http://www.singletoncorp.com/portable_barrels.html

This will give you an idea of prices:
http://www.luster-on.com/home.html?lang=en-us&target=d8.html

Notice the black cable going inside the barrel. There's one on each side. On the ends of these cables, there's a lead slug that flops around on the inside of the barrel, as it rotates, making eventual contact with every part. The lead slug is called a dangler. It's hard to see in the photo but, the barrel is finely perforated to allow the passage of solution and current. The speed is variable but is best run about 3 rpm. In short order, everything is stripped. They are expensive and come in various sizes. Our barrel was about 8" in dia. and 12" in length. Also, they are made of various materials. The mfgr. can suggest the best material that will stand up to conc. sulfuric. You could probably made a barrel out of finely perforated steel or, steel with large holes lined with a spot welded heavy screen, using solid teflon bearings. The holes would have to be small enough to prevent the pins from falling out.

I must warn you that the standard solution formula won't work on gold alloys, such as Gold/Tin. I doubt that it will work on most karat golds. It took me a year to come up with modifications to the solution to make it eat alloy. I've been tempted to give you the info but, I can't do it. It's too valuable. I formed two very profitable businesses using the process. I made enough to live on the beach in Malibu for 5 years. My son's best friend in high school was Charlie Sheen. It's still viable. The parts are still there and I'm the only one that can process them. No BS.

Your present system works great on plated gold, like pins, however.

The volt/amp relationship is tricky. You can't use a battery charger, like yours, on larger batches. You need a power supply that can be adjusted. If you tried running a much larger batch using your uncontrolled power supply, at a constant 6 or 12 volts, you would peg the meter, blow the fuse and, if there is no fuse, you could blow the power supply. It's hard to see, only running a pin or two, what really happens. Here's the way it works, assuming a larger batch:

When you first turn it on, at 6V, the amps go sky high. As the gold strips, the amps go down and the volts go up. When the gold is gone, there is zero amps. It tells you when it is finished.

I used a 12V, 200A rectifier for the 50 gallon tank. Here's the way I ran it. I started with the volts at zero. I slowly turned up the voltage and watched the amperage. At first, it may only take 2 or 3 volts to get, say, 175 amps. As the gold strips, the amps steadily go down and you can steadily increase the volts to maintain the 175 amps. At some point, you will have 6 volts and 175 amps. At this point, you stop adjusting. The amps go down and the voltage climbs. Soon, the amps will be zero and the volts will probably be max. If you think about it, any adjustment gives constant power - volts times amps, even if they are both changing. Also, if you think about it, any size power supply would work, no matter how large the batch. The time it took to strip the gold would depend on the available power output. A very small power supply would strip all of the gold but, it would take more time.

You could control your power supply by plugging it in to a Variac, a variable transformer. Variacs work on most devices. I think they will work fine on a battery charger. On the left in the photo.
http://variac.com/


----------



## lazersteve (Apr 5, 2007)

Extending your suggestions to be controlled via an electronic device, you could automatically control the power (volts x amps) to be at a constant level so you wouldn't need to manually perform the task. Monitor the voltage across the anode and cathode via a feedback circuit and have the electronics (a triac or scr in place of your variac on the AC input side) control the load current and voltage (dc power) ratio on the output side. 

Chris I have to say that you have been a very valuable resource to this forum with the level of knowledge that you bring. Thank you again. 

Steve


----------



## Anonymous (Apr 5, 2007)

Hi, Chris.

Been following this discussion with interest. Since the OEM dangler appears to be copper in composition, are you indicating you created replacement danglers of Pb? If so, the abraiding must be considerable, even at the slow rate of 3rpm. 

2 Questions:
Assuming you fabricated your own dangler contacts, how often did you replace them in your larger unit? 

Assuming reduction in current density due to abraiding, did you consider this loss as a contributory factor in the current fluctuations you described? Thanks.

a man named Sue


----------



## sandhog (Apr 5, 2007)

Sue,

If I read his post correctly he uses the steel tank as the cathode and then he used the baskets as the anode.


-Bill


----------



## goldsilverpro (Apr 5, 2007)

Bill,

The barrel was plastic. Polypropylene, I think. The danglers were, therefore, the anode.

Sue,

The barrel I was using was scrounged but, it was like new. It came with the lead danglers. If I remember right, the lead was harder than normal so, it probably was an alloy. To be honest, it always worked great so, I didn't pay much attention to the danglers. They never seemed to change. I don't remember any fluctuations in anything. Recently, on the Web, I noticed that a lot of the danglers were steel balls. There are other types of contacts. Center bar contacts are just that, a center bar at the axle position. There are also button contacts, which are rows of metal buttons, about 1" in dia., mounted and wired, somehow, on the insides of the barrel. They also sell a self contained barrel. It looks like a cement mixer pointed up at a slight angle. You put the solution and the parts together in the tumbler. I've only seen it in photos so, I don't how the contacts work. 

To all, I would like to suggest a book. It is called the, "Metal Finishing Guidebook and Directory" and is about 900 pages. You can't buy it. It's a trade book. You only get it with a subscription to Metal Finishing Magazine, which is free to plating people. It is upgraded each year and is sent, in the spring, as the mags 12th issue. If you've just barely missed the date, you'll have to wait a year to get it. To get a subscription, on the online form, you'll have to type in the right things to convince them that you're in the plating business. I doubt if they check on you.

http://www.metalfinishing.com/magazine/index.html

Of the many books I own, I have used this book the most, even more than Hoke. Plating and refining are very closely knit, especially electrolytic refining. I spent about 10 years in the gold plating business and I still have a 1968 issue, my first one. Here are some handy chapters with refining applications, all in good detail: Ultrasonics; Barrel Plating; Gold, Silver, Platinum, Palladium, Rhodium, Ruthenium Plating (separate chapters); Stripping Metallic Coatings; Chemical Analysis; Thickness Testing; Identification of Deposits; DC Power Supplies; Rack Design; Pumps; Mixing; Industrial Ventilation; Wastewater Treatment.


----------



## Fever (Apr 5, 2007)

Fascinating stuff GSP.

I envy your knowledge! As far as hardened lead is concerned, I think they alloy Lead with Antimony in most modern abrasive/concussive applications, as the addition of Antimony significantly increases the resiliency of the Lead. Not 100% sure about that, but I think you can buy Lead/Antimony grinding media (balls) for modern ball mills.

Please continue to enlighten us with your knowledge. This is some great stuff indeed.....

Fever


----------



## austexjwlry (Jun 17, 2007)

Goldsilverpro

In Small Scale Refining of Jewelers Wastes by Ronald Loewen, they use a rotary cement mixer as a ball mill for grinding / reprocessing of slag. Lowes has one with a plastic barrel you can replace. 
If you added a mercury slipring connector or slip ring setup like on wind generators,screen,and danglers it might work.I'm not sure if their plastic barrels would hold up to acid.
Might work with 12lb lortone tumbler barrel with slipring connecter, screen,and dangler.You would have to gear down r.p.m.s and possibly use plastic bottle instead for barrel.
Would R.V. 10 gallon hot water tank or larger with the top cut off work as possible alternative for your mild steel tank ?

Thanks
Wayne


----------



## Harold_V (Jun 17, 2007)

austexjwlry said:


> Goldsilverpro
> 
> In Small Scale Refining of Jewelers Wastes by Ronald Loewen, they use a rotary cement mixer as a ball mill for grinding / reprocessing of slag.



I'd be very cautious about that idea. You may recover prills, but everything that has not agglomerated would likely be discarded. Virtually all of it can be recovered by further melting in the appropriate furnace, using the proper reducing fluxes. The resulting slag from that operation can be too low in value to warrant any further processing. 

Harold


----------



## austexjwlry (Jun 17, 2007)

Harold

Thank you sir!
Did you see the picture of sweeps burner with ceramic lined secondary burner? I have oilfield casing barbeque pit/ sweeps burner thinking of adding ribbon burner from home depot with possibly refractory material and perforated stainless plates for scrubbers like in alcohol distillation stills or other steel rods or bars, just something for particles to run into on way out.Possibly use almost passive blower just to keep things going in right direction.
Not sure if improvement would warrant time & expense.

Thanks again
Wayne


----------



## Harold_V (Jun 18, 2007)

I have no clue where I'd have seen the picture in question, but I'll gladly take a look if you can direct me to its location.

My experience with a filtered fume hood taught me a great deal about the value of working with the exhaust from refining and incinerating. Even after a furnace type filter being employed, values still accumulated on the paddles of the blower, and in the stack, albeit at very low rates. From that you can conclude that anything you do to slow the movement of the air, or any surface you can provide that will capture the values, will be an asset. The only caution I'd throw out is to insure that when it comes time to recover the values, it's not an arduous task-------and can be accomplished without totally dismantling the hood/exhaust system. Otherwise, it may not happen. 

My fume hood had what could be considered an exponential horn design, which slowed the moving column of air before it reached the filter, and provided an accumulation chamber in the process. By removing the lower panel support brackets, it was possible to access the interior of the hood for removal of values. The top of the hood was also removable, which permitted access to the balance of the hood. The only problem was that it was quite tall, and near the ceiling, so there wasn't much working room. The hood contained a 20" x 25" filter, which was accessed by simply removing a front cover, held in place with two stainless wing nuts. 

Incineration of polishing wastes tends to be one of the more wasteful operations in refining bench materials-----which you appear to understand. I'd encourage you to explore your idea-------there are other methods to the same end----one need not duplicate the hood I made. My design evolved, in part, because of the materials I had on hand. Even when I built my last hood ('84), one had few options where asbestos was concerned. I accumulated any and every possible piece of asbestos board I could locate and put all of it in storage, then worked accordingly. 

Here's a picture of the hood, taken just prior to selling the refining business. The hood had been in use for ten years and was really showing it's age. Note some rust on what used to be plated steel items. A refining environment is quite corrosive, even when a hood is in operation!

Harold


----------



## postmako (Jul 8, 2007)

lazersteve said:


> Extending your suggestions to be controlled via an electronic device, you could automatically control the power (volts x amps) to be at a constant level so you wouldn't need to manually perform the task.



Actually has anyone considered using this method to get the total power that goes into stripping off the gold as an indication of the amount of gold?

In other words, can we reliably use the power consumed in order to determine what gold content to expect and as a means of testing purity?

Just an idea (I was a physicist in my former life, graduated Summa Cum Laude from Washington University in St. Louis), hopefully I can start to make some contributions. 

Cheers,
Kory


----------



## goldsilverpro (Jul 15, 2007)

In the plating industry, they use amp-hour or amp-minute meters to control the amount of metal being deposited. You could use these for de-plating but, I would think that the variables would have to be held constant. Also, variations in the types of gold plating could make a difference.

As I mentioned before, physics was also my field, at least as far as my education was concerned. Looking back, I never really liked it. It was a pure ego trip, since I considered it the most difficult field of study. If I could do it all over, I would study electrochemistry, separation science, chemical engineering, extractive metallurgy, or something similar. I still have enough feel for physics to know that the 3 WTC buildings couldn't come down at free fall speed without a little help from something, no matter what BS Popular Mechanics came out with.


----------



## goldsilverpro (Jul 15, 2007)

I've noticed a trend, on this forum, to shy away from the sulfuric cell as a method of running pins. In my opinion, the stationary copper mesh basket isn't the best way to go about this. Also. I feel that the sulfuric cell is far superior to any copper dissolving method, if it were engineered right. I think if someone were to come up with a rotating basket, all would be well.

I've been thinking of maybe using a slow turning BBQ rotisserie setup for this. A plastic container, with holes in it, could be mounted (centered) on the axle. The container would be filled a little over half full with pins. The container would only be about 1/3 submerged and the axle would be kept out of the solution. Most rotisserie axles are square and this would make it easy to turn the container, if the plastic were thick enough. One section of the axle, near one end. would be ground round and a springy metal anode contact could be used to constantly apply current to the axle. Something like a brush on a slip ring. I see the rotisserie being mounted on a board under the tank. The tank would have two cathodes connected together, one on each side of the basket container. As the container turned, pins would touch the axle and provide current to the whole mass of pins.

Hard to explain.


----------



## lazersteve (Jul 15, 2007)

GSP,

I agree with you 100%. I had this item on my things to do list, but it keeps getting pushed down the list. My idea uses an electric ice cream churn.

Nothing has made it to paper yet, as usual it's still all in my head.

I think the cell is an excellent gold recovery tool and I will put some effort into making it better soon. 

The copper basket was a successful test of something Harold had proposed, but like so many of these methods there is still plenty of room for improvement.

Steve


----------



## Harold_V (Jul 15, 2007)

goldsilverpro said:


> the sulfuric cell is far superior to any copper dissolving method, if it were engineered right.



That's true to the point where pins have no solder covering. Gold under solder can not be recovered by stripping, as we both know. 



> I think if someone were to come up with a rotating basket, all would be well.



Not really much of a challenge so long as some basic machine tools are at one's disposal. A person could explore a barrel plating setup and build something similar on a scale in keeping with predicted flow of material. 



> Hard to explain.



But easy to follow. You did fine, at least for me, with the perspective of a machinist. 

The copper basket works fine, but the operator should dump and reinstall the pins at least once during stripping, so covered surfaces are uncovered and exposed for stripping. I dare say that less than 1% of the plating would be left behind by this method, unless the pins are flat (wire wrap pins, for example). They might stick together under difficult circumstances, although a barrel device would likely change that. Good idea, the barrel.

Harold


----------



## postmako (Jul 15, 2007)

goldsilverpro said:


> I still have enough feel for physics to know that the 3 WTC buildings couldn't come down at free fall speed without a little help from our friends, no matter what BS Popular Mechanics came out with.



Physics seemed like a waste a time and an ego trip for me as well. I then went into Computer Science in order to get a decent job.

Regarding the 3 WTC buildings, most physicists and civil engineers feel the same way, myself included. Check out http://www.infowars.com for a decent syndicated radio show that will keep you informed on the happenings of the world, recent news, etc...

Cheers,
Kory

Ron Paul for 2008!


----------



## aflacglobal (Jul 15, 2007)

Physics seemed like a waste a time and an ego trip for me as well. I then went into Computer Science in order to get a decent job.  :shock: :shock: :shock: 

I'll take physics. :wink: 

Regarding the 3 WTC buildings, most physicists and civil engineers feel the same way, myself included :arrow: I'm neither one, But it don't take a whiz to figure it out. :wink:


----------



## goldsilverpro (Jul 15, 2007)

Bless you, Ralph, and postmako.


----------



## GeeDub (Feb 14, 2009)

Harold_V said:


> austexjwlry said:
> 
> 
> > Goldsilverpro
> ...


Okay, you lost me on this one. 
I used to ball mill the slag, screen the oversize out and then leach the powder.


----------



## GeeDub (Feb 14, 2009)

goldsilverpro said:


> I feel that the sulfuric cell is far superior to any copper dissolving method, if it were engineered right. I think if someone were to come up with a rotating basket, all would be well.


How about a vibratory polisher type setup? Put the whole thing on springs with a vibrator and the pieces will keep shifting. Ordinarily in a vibrating polisher, you must keep the liquid amount low so the parts develop a roiling action, however, using it in a solution as in your cell, will still have the parts move about and expose all of themselves. They just sort of wiggle around endlessly.

Here's a guy who details how he built one. Not how I would design it, but if it jerks, it works:

http://www.cnczone.com/forums/archive/index.php/t-14464.html


----------



## Harold_V (Feb 15, 2009)

GeeDub said:


> Harold_V said:
> 
> 
> > austexjwlry said:
> ...


Use the proper flux and collector and there's no need to leach the powder. Given adequate furnace time and a fluid slag, all of the values, at least for practical purposes, will have been collected. 

Harold


----------



## GeeDub (Feb 22, 2009)

Harold_V said:


> Use the proper flux and collector and there's no need to leach the powder. Given adequate furnace time and a fluid slag, all of the values, at least for practical purposes, will have been collected.


Quite true. But I had decided to stop using Litharge. The final low grade sweeps were sent to the big smelter at Amax in Carteret, NJ, so I could just do a low labor let-it-sit leach, wash, and not kill myself for the little bit that was left. This was as opposed to sitting there watching a furnace for a looong time.


----------



## Harold_V (Feb 22, 2009)

GeeDub said:


> Quite true. But I had decided to stop using Litharge.


No litharge was used, nor was it desirable. I used silver chloride and traces of other metals (from the stock pot) to act as the collector. A generous soak time and an excellent flux formula insured good extraction. It's amazing what you can do with proper heating and soaking. 

I am not claiming that I achieved total extraction----only that the remaining values were so low that it was not cost effective to process with litharge, which was the process used by the smelter that would have accepted the material for processing. They are the ones that did the assay. 

Harold


----------



## GeeDub (Feb 22, 2009)

Harold_V said:


> No litharge was used, nor was it desirable. I used silver chloride and traces of other metals (from the stock pot) to act as the collector. A generous soak time and an excellent flux formula insured good extraction.


Nah, wouldn't have worked for me. 
I can't stand the smoke from a silver chloride melt. The only powdered metal I had was from my ironed out solutions. Too many things in that, such as nickel strike from plating wires.

My AgCl was metallized and run through my silver cells. Also the generous soak time would use lots of fuel and I would have to stand watch (don't believe in unattended furnaces). In NY fuel is not all that cheap, and my time was better spent elsewhere. A leach can sit unattended while I do other things.

The message to all you newbies is: There is no universal "best way". Your circumstances may direct the methods you use. Space available (even the physical shape of the space) local regulations and zoning, fuel costs, labor costs, metals processed, how much money you have for capitalization, all these things affect your decisions.

BTW Harold, Cool Furnace.

-Gee


----------



## Harold_V (Feb 22, 2009)

GeeDub said:


> My AgCl was metallized and run through my silver cells. Also the generous soak time would use lots of fuel and I would have to stand watch (don't believe in unattended furnaces). In NY fuel is not all that cheap, and my time was better spent elsewhere. A leach can sit unattended while I do other things.


I didn't consider the recovery of over 200 troy ounces of gold, along with platinum, palladium and a serious amount of silver, a waste of my time. I couldn't imagine spending it anywhere where it would have provided a greater return. I had a furnace room that was ventilated by a 1 horse blower, attached to the hood, under which sat the furnace. Because of the nature of the operation, there was little in the way of fumes, so they were a non-issue. 



> The message to all you newbies is: There is no universal "best way". Your circumstances may direct the methods you use. Space available (even the physical shape of the space) local regulations and zoning, fuel costs, labor costs, metals processed, how much money you have for capitalization, all these things affect your decisions.



Exactly right, and the reason I followed the procedure I outlined. Leaching my waste material would have been a waste of time. 



> BTW Harold, Cool Furnace.



Thanks. My design, and home built. Didn't hurt that I am a machinist by trade, and that I have the required machinery. 

Harold


----------



## GeeDub (Feb 22, 2009)

Harold_V said:


> I didn't consider the recovery of over 200 troy ounces of gold, along with platinum, palladium and a serious amount of silver, a waste of my time. I couldn't imagine spending it anywhere where it would have provided a greater return.


You missed my point on that one. 
An unattended leach would give you the time you spent on the smelt, to apply to *another* 200 ounce job, thereby yielding 400 oz for the same amount of time. Of course, this presumes you have loads of other scrap waiting in line to be processed.


----------



## Harold_V (Feb 23, 2009)

GeeDub said:


> Harold_V said:
> 
> 
> > I didn't consider the recovery of over 200 troy ounces of gold, along with platinum, palladium and a serious amount of silver, a waste of my time. I couldn't imagine spending it anywhere where it would have provided a greater return.
> ...


No, I didn't miss your point. You don't understand the problem, therefore your comments are not appropriate. 



> An unattended leach would give you the time you spent on the smelt, to apply to *another* 200 ounce job, thereby yielding 400 oz for the same amount of time. Of course, this presumes you have loads of other scrap waiting in line to be processed.



And just what "magical" leach are you proposing that would extract gold, silver, platinum and palladium? Better yet, how is it you know so much about what I was doing when you have no clue _what _I was doing?

I used the best possible leach-----I used my furnace. The results I achieved spoke volumes about the veracity of the decision I made--- which was perfectly appropriate for the task at hand, unlike leaching. 

Harold


----------



## goldsilverpro (Feb 23, 2009)

> The message to all you newbies is: There is no universal "best way". Your circumstances may direct the methods you use. Space available (even the physical shape of the space) local regulations and zoning, fuel costs, labor costs, metals processed, how much money you have for capitalization, all these things affect your decisions.



I certainly agree with that. The trick is to gain enough knowledge so that you know all of your options that would enable you to adapt your process to your circumstances. 

Also, prove your ideas on a small scale before you run the whole batch. There's nothing worse than getting gold tied up with a bunch of other metals or materials that you can't process. 

Also, when you dream up a process, first make up a list of the negatives that are possible when doing that particular process. If you can't live with these negatives, figure out another way of doing it.



> I can't stand the smoke from a silver chloride melt.



Here again, I agree. I had a friend that died from this. He liked to stand over the furnace and watch the AgCl to Ag conversion.


----------



## lysdexic (May 28, 2014)

goldsilverpro said:


> I've noticed a trend, on this forum, to shy away from the sulfuric cell as a method of running pins. In my opinion, the stationary copper mesh basket isn't the best way to go about this. Also. I feel that the sulfuric cell is far superior to any copper dissolving method, if it were engineered right. I think if someone were to come up with a rotating basket, all would be well.
> 
> I've been thinking of maybe using a slow turning BBQ rotisserie setup for this. A plastic container, with holes in it, could be mounted (centered) on the axle. The container would be filled a little over half full with pins. The container would only be about 1/3 submerged and the axle would be kept out of the solution. Most rotisserie axles are square and this would make it easy to turn the container, if the plastic were thick enough. One section of the axle, near one end. would be ground round and a springy metal anode contact could be used to constantly apply current to the axle. Something like a brush on a slip ring. I see the rotisserie being mounted on a board under the tank. The tank would have two cathodes connected together, one on each side of the basket container. As the container turned, pins would touch the axle and provide current to the whole mass of pins.
> 
> Hard to explain.



Old topic I know and not sure if you ever did anything with this. I'm no where near ready for sulfuric stripping cells (or a lot of other things) but I can't stop the wheels from turning. I can't count how many times something like this has got my attention while researching/reading for the heck of it, and I just keep my mouth shut and move on. I'll risk comment, if nothing else I'll remember this way and be able to revisit it in the future...

If copper mesh baskets are what most use in their cells and the "drum" in your idea had large perforations or slats... copper mesh could be used to line the drum and be the anode. The drum could be a bit larger and filled about 1/3 full to allow more "turnover" of the pins ...or at least keep them under the solution more, "1/2 round" plastic "bumps" could be run parallel to the axle spaced around the circumference to aid in mixing . ...and why not use your steel tank as the cathode. I imagine drum size and spacing would be somewhat critical, but I'm sure a crafty person could design tank and drum for optimal performance.

Doug


----------



## goldsilverpro (May 28, 2014)

lysdexic said:


> goldsilverpro said:
> 
> 
> > I've noticed a trend, on this forum, to shy away from the sulfuric cell as a method of running pins. In my opinion, the stationary copper mesh basket isn't the best way to go about this. Also. I feel that the sulfuric cell is far superior to any copper dissolving method, if it were engineered right. I think if someone were to come up with a rotating basket, all would be well.
> ...



I may be wrong, but I don't think lining the drum with a metal mesh will work very well. I think most of the current will be drawn to the mesh. Sort of like a "Faraday Cage". Stuff might eventually strip, but it would take longer than it would without the mesh liner.
https://en.wikipedia.org/wiki/Faraday_cage

I would think you could make the center bar the anode and fill the drum a little more than half. You could also hand 2 or 3 short lengths of heavy chain on the anodic center bar (axle) with spacers to keep them in position. The chain links would dangle and make contact to the parts.


----------



## lysdexic (May 29, 2014)

GSP (Chris is it?),

I was actually thinking of putting a Faraday cage around my house once upon a time... long story, no relevance. 

I have to agree then, I'm probably missing something. From my little understanding from reading on sulfuric stripping cells... the currant flow turns sulfuric to persulfuric acid near the anode (A Steve and Harold discussion I believe was one source for that) and persulfuric acid dissolves gold, the persulfuric decomposes back into sulfuric dropping the gold (no sources I can credit, just the picture I've drawn from reading). I haven't done an exhaustive study on the process, but from what I can gather most use a copper mesh as the anode. I would think that currant would follow the path from mesh to cathode and not involve the pins/parts at all unless I missed where the mesh basket is suspended below the cathode and currant would have to flow through the material. The copper mesh drum is just a notion hatched under ignorance then I'd say.

The wheels still keep spinning however. My thoughts were based somewhat on the fact that I will probably never see enough pins/plated material to more than half fill a drum much larger than a soup can... if I could however I think I'd try your idea and make a steel cathode tank (something that would look like a 1/2 cylindrical shape that would accommodate the "drum" with whatever clearance was deemed best suited... putting all parts of the drum equidistant from the tank cathode (probably need more clearance where values would accumulate?). I know I should keep it simple, the more complicated, the more likely it will not get the job done. I'm still stuck on the idea of less than 1/2 full though on the drum. Supporting and turning the drum on hubs that would allow a stationary (not really an axle) support for say bar shaped anodes that would extend down into the material and perhaps some plastic "plow" or "cultivator" shaped agitators. If having a open hole in the drum was an issue a teflon bushing between a stationary "plug" and rotating drum might work.

Okay, I'll shut up now. This is the kind of cr... crud that goes through my pea brain with everything I study. No wonder I don't get a lot done.

Doug

(edit to correct spelling/punctuation)


----------



## g_axelsson (May 29, 2014)

This is an old but good topic from early 2009. Later that year, in the summer, Firewalker made a tumbler for the sulfuric cell.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=5092

Sadly, some of the early pictures are gone, but the photobucket links are still working.

Lysdexic, when the anode basket is contacting the gold plated scrap, everything it makes electric contact with is part of the anode, both the basket and the scrap.
For optimal stripping you want your gold scrap between the anode basket and the cathode, then the persulfuric acid would be created just where the gold is. The acid is very unstable and only migrates a small distance from the anode (basket or scrap) before turning back into sulfuric acid. If the gold isn't very close it won't be affected.

Göran


----------



## lysdexic (May 29, 2014)

Göran,

Thank you for the link to firewalker's tumbler. A much more efficient design than what I was envisioning here. 



g_axelsson said:


> Lysdexic, when the anode basket is contacting the gold plated scrap, everything it makes electric contact with is part of the anode, both the basket and the scrap.
> For optimal stripping you want your gold scrap between the anode basket and the cathode, then the persulfuric acid would be created just where the gold is. The acid is very unstable and only migrates a small distance from the anode (basket or scrap) before turning back into sulfuric acid. If the gold isn't very close it won't be affected.
> 
> Göran



Thank you, sometimes I can be as "sharp as a cannon ball". I have no idea why I didn't see all of the scrap as being electrically part of the anode. I appreciate you taking time to help me on my way.

I came to this forum seeking PM's... of course I still seek them, however it has become knowledge fever I have instead of gold fever. It's been so long since I used my "learning muscles" to any real extent. Everyone here has given me a gift no amount of PM's could ever buy. Thank You!

Doug


----------

