Taking a great idea and applying modern techniques

[4metals]

OK, I misunderstood when you said,

This was actually altered so that the inflow pump was fitted to the top pipe, making the lower left hand pipe the overflow back to the tank.

I thought you meant the top pipe as in the top of the inner section. So the inflow and return of unprocessed solution are both on the outside pipe section not the inside. And by keeping that full of gold containing solution, more solution is drawn through the carbon felt proportional to the quantity of liquid pumped out from inside the carbon felt. Is there any significant flow restriction from the density of the felt fabric? Or does more flow restriction develop as the felt loads up with metal?

I am familiar with the copper expanded mesh cathodes where there is never enough flow restriction to be an issue but, as you pointed out, the surface area of the copper mesh is significantly less than that of the carbon felt.

You have two self regulating reservoirs- the one that is the header tank and the one around the cathode. A simple switch that works on current detection will turn the cell off if it runs dry.

So the outside reservoir, which you are calling a header tank has a feed pump and an overflow and it maintains level as long as the pump functions. The other reservoir which you call the one around the cathode can run dry if the flow through the cathode carbon felt is less than the flow rate of the inner peristaltic pump or if the pump filling the header tank craps out and the inner pump sucks the reservoir dry. So I guess it can slow significantly by clogging with deposited metal. Damn gold clogging things up! Either way if the cell goes dry it shuts down, nice.

 

[anachronism]

I thought you meant the top pipe as in the top of the inner section. So the inflow and return of unprocessed solution are both on the outside pipe section not the inside. And by keeping that full of gold containing solution, more solution is drawn through the carbon felt proportional to the quantity of liquid pumped out from inside the carbon felt. Is there any significant flow restriction from the density of the felt fabric? Or does more flow restriction develop as the felt loads up with metal?

Flow restriction isn't initially a factor as you would be drawing from as little as a litre per hour up to 2 litres per hour through the cell at this size. In larger cells with more flow rate, you have an increase in cathode surface area albeit not necessarily in direct proportion. Yes as metal is deposited on the carbon the flow rate will diminish and that is one of the key indicators as to how close your carbon is to becoming fully loaded because it would in time end up completely clogged. Now that is a good place to be simply because due to the enormous surface area the sheer amount of gold you can fit on even a small cathode before clogging it is way more than the average home user is likely to be processing. Put it this way- 50g is hardly even visible as much more than a discolouration. So for the smaller batch guy flow rate won't present an issue.

I am familiar with the copper expanded mesh cathodes where there is never enough flow restriction to be an issue but, as you pointed out, the surface area of the copper mesh is significantly less than that of the carbon felt. Yes the difference in surface area is enormous.

You have two self regulating reservoirs- the one that is the header tank and the one around the cathode. A simple switch that works on current detection will turn the cell off if it runs dry.

So the outside reservoir, which you are calling a header tank has a feed pump and an overflow and it maintains level as long as the pump functions.

Entirely correct.

The other reservoir which you call the one around the cathode can run dry if the flow through the cathode carbon felt is less than the flow rate of the inner peristaltic pump or if the pump filling the header tank craps out and the inner pump sucks the reservoir dry.

Not quite. The reservoir around the exterior of the cathode is not dependant upon the outflow from the return pump that's between the cathode and anode unless the feed from the header tank ceases.

So I guess it can slow significantly by clogging with deposited metal. Damn gold clogging things up! True and see above. Either way if the cell goes dry it shuts down, nice.

 

[nickvc]

I have to say well covered and answered Jon, if the members follow this thread with input from our experts then they can learn a lot, but they need to fully understand what is been discussed and the science behind it.

 

[4metals]

The real appeal is what hasn't really been discussed on this thread. That is the low concentrations (in PPM) of cyanide required to strip the gold. Maintaining lower levels of cyanide leaves the majority of the copper on the scrap but collects the gold and silver.

This is not really refining and it isn't even the material preparation before leaching, but it is a major step forward which combined with the material preparation and the post cell ashing and acid refining, can go a long way in processing e-scrap and make previously unprofitable operations turn the corner with a process that is both scalable and relatively straightforward.

This cell deserves the attention of all those who recover gold and silver from e-scrap.

 

[4metals]

Any new progress on the build? I would hate to see this thread dry up and be forgotten, this process has the potential to put a lot of the other e-scrap methods into the old and forgotten files.

Surely there must be some interest out there!!!!!

 

[anachronism]

The update from my end is as follows 4metals:

We've received the final material that we selected for the print because of the chemical resistance and overall balance between flexibility and rigidity. It's a material which isn't as widely used as others yet so there has been a lot of experimentation with regards to print temperatures and base sheet material to avoid deformation and de-lamination. That's now sorted out and the picture below shows some of the new material in it's correct dimensions although merely half a print. It's still a rough print at this stage but we should be moving towards final prints this weekend, rolling into early next week.

The plan is to have 2 working cells for the Christmas break to fully trial using the leach system which is also in fabrication.

 

[4metals]

Thanks for the update. With the cell you are printing, what is the area of the fabric that will be exposed to the leach solution. I know the actual surface area is exponentially higher than the physical piece of felt you use, but what size piece of felt will this accommodate? And what volume of solution will the entire cell contain when operating?


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[Lou]

Looks a lot to me like a carbon version of that gold bug system.

I always used steel wool to do this process, not carbon felt.

Where do you get the felt state side and what is the solution concentration you operate at (before/after the felt, in g/L CN- and Au)?

 

[rickbb]

Appears to be 2 kinds of carbon felt, PAN and Rayon. Amazon lists lots of PAN carbon felt for use as a welding or soldering heat shielding blanket. The specs for it say it's not a good conductor of current, so I'm guessing that Rayon is?

https://www.amazon.com/HIGH-TEMP-FELT-WELDING-BLANKET/dp/B00S1R9B22/ref=sr_1_5?ie=UTF8&qid=1481907237&sr=8-5&keywords=carbon+felt

"However, please note it is not electrically conductive."

More info and sources here;

http://ceramaterials.com/graphitecarbonfelt.html

http://www.hpmsgraphite.com/activatedcarbonfiber.html

 

[anachronism]

You are not using activated carbon of any type in this cell Rick. Having said that your other link is great- thanks for that.

 

[anachronism]

Thanks for the update. With the cell you are printing, what is the area of the fabric that will be exposed to the leach solution. I know the actual surface area is exponentially higher than the physical piece of felt you use, but what size piece of felt will this accommodate? And what volume of solution will the entire cell contain when operating?

For the smaller cell approx 140 sq cm of cathode, and as mentioned before this scales depending upon the height of the cell used. Volume of liquid approx 310 cubic cm in this version.


Sent from my iPhone using Tapatalk

 

[anachronism]

Looks a lot to me like a carbon version of that gold bug system.

I'd not looked at that before Lou and even from a brief scan of the documents there are certainly some similarities in function if not construction and design.

I always used steel wool to do this process, not carbon felt.

Yeah we've touched on this before - the sheer surface area if the major difference coupled with the inert carbon vs steel in the metal deposited.

Where do you get the felt state side and what is the solution concentration you operate at (before/after the felt, in g/L CN- and Au)?

Stateside I would not have had a clue until Rick kindly posted a link. The premise of the cell is to attach to a leach circuit where the leach is low strength and kept at low tenors by the stripping action of the cell. Sub .5g per litre gold prior to cathode and substantially less per litre afterwards for the return into the leach tank to keep the average circuit load as low as possible.

Cyanide strengths depend on the type of product being leached, the speed of leach required, and the contaminants present in the raw material. So your range of strengths would begin at as low as 0.05g per litre and progress upwards.

 

[4metals]

Wow, that i s less than 22 square inches of fabric and 11 fluid ounces of strip in the cell. (I converted these numbers to help those of us who live in countries that do not recognize the wisdom of the metric system)

That is one pint sized (literally) cell. From the lack of response to this thread from others, I can only assume they do not recognize the amazing potential of this system for a small time collector.

So let's do an imaginary refine so members can get a feel for the versatility of this system as well as the investment in space for the setup.

If we were to start simple, say with gold plated pins. Like sulfuric stripping is used for by many members as a mechanism to get the gold and leave behind the base metals. So a leach tank for, lets say, a 4 liter beaker filled with gold plated pins. What size leaching system would be required to strip and hold the gold in solution. I am guessing a 5 gallon (20 liter) bucket? What concentration of CN^-would be required to strip this metal? And how long from start to finish for the leach?

So with an investment of X grams of Cyanide and Y hours of time stripping, the material is ready for stripping in the 3D printed cell. How long will it take to completely strip the solution of gold in the cell?

I happen to know the answers to these questions but I am trying to put this into a perspective where our members can see the value of this system and start asking some questions and maybe see the true potential of this system. I am sure some are put off by the fact that the majority of the stripping is done by cyanide. But there are alternatives that are legal and the treatment of the parts per million levels of cyanide you will encounter when you eventually discard your leach is likely easier than treatment of acid wastes.

And this cell can help in the treatment of waste too! The versatility of this system can have serious implications on refining. The fact that many of our members have yet to realize its value has me scratching my already hairless head!

 

[anachronism]

So with an investment of X grams of Cyanide and Y hours of time stripping, the material is ready for stripping in the 3D printed cell. How long will it take to completely strip the solution of gold in the cell?

I've pulled this particular question out as it merits an explanation as to the workings of the system for clarity. You are not going to be waiting Y hours to begin stripping the gold into the cell. You are going to be stripping through the cell right from the get go, and continuously throughout the leach process. How long it takes to fully strip the gold from the leach circuit on completion of the leach depends upon the volume of liquid in the circuit and the chosen rate of flow through the cell. As an example at 1 litre per hour you can completely strip a 20 litre circuit in 20 hours. With the analogy you used for a pile of pins I believe (but have yet to prove via a working model,) you could theoretically have a full circuit of less than 8 litres.

And this cell can help in the treatment of waste too! The versatility of this system can have serious implications on refining. The fact that many of our members have yet to realize its value has me scratching my already hairless head!

Reverse the polarity of the cell by literally flipping a switch, pop a fresh cathode in and you'll be able to destroy your CN bearing waste solution at a rate of 1 litre per hour in this little cell. Obviously the cell scales, so take this as a mere starting point.

 

[FrugalRefiner]

From the lack of response to this thread from others, I can only assume they do not recognize the amazing potential of this system for a small time collector.

The fact that many of our members have yet to realize its value has me scratching my already hairless head!

I can only speak for myself, but I don't deal with much escrap or other gold plated material. While the idea of cyanide stripping of plated material is interesting, and I may experiment with it at some time in the future, I will probably never deal with quantities that would justify the time and expense to create CAD drawings, buy a 3D printer, experiment with different kinds of plastics, etc. If I decided to experiment with a cell like this, it would be a frugal version as described by Deano similar to the one Jon made first. If I wanted a more durable version I might spend a few hours drilling some carefully placed holes in some PVC pipe. I'm not trying to take anything away from Jon's work. It's just beyond my needs.

Another factor that may be keeping the thread from getting many responses is that until very recently, the use of cyanide has been discouraged on the forum. Obviously the professional refiners here have used it, but I would guess the vast majority of our members have never touched the stuff. Even in the Eco-Goldex thread, we've cautioned members to wait until there are some comprehensive threads created on the subject. Those threads have been mentioned, but they still don't exist.

So I don't know that members don't recognize the potential or realize its value, but I would guess it is likely beyond the needs or means of most members at this time.

Dave

 

[4metals]

When this type of cell is running, the cyanide concentrations are very low and the recovery is excellent for stripping gold from pins headers or any exposed gold. But it doesn't end there, if it can be leached it can be concentrated in this type cell. Think silver plated flatware, think film, anything you can strip off chemically, you can process in this to concentrate your values on the carbon felt. From there on out, it is just a roast and acid refining.

That is why I think this warrants a discussion, and even your explanation of why it isn't for you Dave helps to explain some of the benefits and can help allay some of the fears members may have in dealing with this technology. If a full blown discussion can evolve here there are a lot of members who can realize its potential. But if we don't discuss it it will be just another lost pearl buried in pages of babble that most will miss out on.

 

[FrugalRefiner]

4metals, I wasn't trying to discourage discussion. I apologize if the intent of my post wasn't clear. You commented about wondering why the thread wasn't getting more responses. I simply responded to that by giving my opinion as to why that might be.

I'll be happy to see cyanide discussed. I've encouraged it in the past. If I could write a comprehensive thread on the subject, I'd do so, but I have never used it so it is beyond my experience.

Dave

 

[nickvc]

I feel that perhaps when the prototypes are ready then a video showing how to use it with different materials and solutions may well get more conversation going, this to many is a new process, I posted about the same cell some years ago but that was prohibitively expensive for general use, as 4merals has pointed out this can strip all metals from solution so using it for waste treatment will make disposal safe and easy, this is a brilliant idea that Jon is trying show to all the members, it's now up to the members to see its potential and ask the questions which will show how many could benefit from its use.

 

[Yggdrasil]

Hi!
The cell caught my interest the moment Deano informed about it.

It's use seem to be mostly "limited by imagination" though especially well suited for constant/long lasting leeching which benefits from low concentrations of leech liquor and/or dissolved metals.
My reluctance to comment so far has been that I haven't come to a point where I have accumulated any information to share :wink: In fact my graphite electrode disappeared on route from Beijing to Europe and my felt has just arrived in town.
I do not have access to a 3D printer as Jon has so my initial construction will not be as nice as his.

Kudos to Jon for pushing his research forward and sharing :!: :!:

But I think it is fully possible to design a system that is only dependent of one pump and is scalable to multiple cells.
If gravity fed from the leech system with a adjustable valve into the outer chamber with overflow as current design to a collector tank. A new gravitation fed system from the inner cell with its own adjustable valve into same collector tank. Then the only pump you need is a pump to re introduce the leech liquor back to the system.
Obviously the pump must have sufficient capacity to do so. Additionally with this design one can have backups and aeration or what ever treatment one feels suitable to the leech system prior to pumping it back.

Please correct me if I there are issues that I have overlooked.

Lets get some drive to further evolve this promising technology :lol:

 

[kurtak]

That is one pint sized (literally) cell. From the lack of response to this thread from others, I can only assume they do not recognize the amazing potential of this system for a small time collector.

I can't speak for anyone else BUT I certainly recognize the potential of this system - I simply have not responded (posted) because right now I am reading & hanging on "every word" to soak up the "awesome" info being presented by those of you taking center stage to present this thread with such fine & great detail :!: :!: :!:

This thread is :G :G :G IMO 8)

And this cell can help in the treatment of waste too! The versatility of this system can have serious implications on refining. The fact that many of our members have yet to realize its value has me scratching my already hairless head!

I agree - & per the underlined - I resemble that remark :lol: (told you I was hanging on every word) :mrgreen:

Kurt