Self scraping silver cells

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4metals

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I'm working with a refiner in Michigan who wanted to run silver cells. I got him up and running with 6, 45 gallon Moebius cells and we're making fine silver to beat the band. Now he wants to change the rules. Originally it was fine to run 3 shifts and shut down on Sunday but now he wants to only staff it for 1 shift. The crystals grow too fast to go un-scraped for that long without shorting out. At 200 amps per cell we're making 18 kilo's of fine silver from each cell per day and 5 cells are always running and 1 waiting to run. Every cell has to be broken down after 5 days running due to the copper buildup.

My thought was a slow ( 1 rpm) rotating stainless cylinder with a permanently mounted scraper which will dislodge the silver into a funnel below the cathode to collect what falls. A funnel will allow the fine crystals to collect at one central point where I figure we could build an archemedes screw to constantly empty the funnel over the side of the bath.

We seem to have quite a collection of mechanical minds on this forum, has anyone done this? I'm fishing for opinions here.
 
Here is a patent for a similar device.

http://www.freepatentsonline.com/5100528.html

This seems much like the operation of this coolant sump oil skimmer.

http://www.coolantconsultants.com/Zebra%20GS4H300.jpg
 
These cells seem to have a respectable percentage of the silver crystal fall off and lay on the bottom, which also requires cleaning it out. I figured knocking the silver down into a funnel and then pulling it out with the screw would solve both issues at once.

I think the cell in the patent is a monster, very big piece. Round cathode rotating above and below the solution, possible. Thanks
 
I have never operated a silver cell.
However I did read a lot about it here in this forum and I was wondering why cant you use Junkman jim silver cell instead of a mobeius cell
 
See if anything in this PDF gives you any help with ideas.

http://www.intec.com.au/uploaded_files/document_uploads/Cobre_2003_Intec_Ltd_Paper.pdf
 
Many times, I've slept with Thum silver cells that had to be tended to every 4 hours.

There are quite a few patents for continuous operation of silver cells. Don't have the numbers in front of me. Check the ones by Adalbert Prior. If I remember right, 1 or 2 of his involved continuous operation
 
GSP

And I've spent many a night babysitting a roaring incinerator, if it's your own refinery, it's what you do. This guy needed to produce 15000 ounces a week of fine silver and now that he sees the relatively slim margins, he wants to produce the same and pay for less. Looks like a serious investment in engineering some self emptying cells is in order.

The PDF from palladium has similarities to what I'm thinking but it again is for a huge cell. I'm thinking of a unit that will fit into a cell the size of a 55 gallon drum. a rotating cylindrical cathode and an octagonal buss configuration to surround the cathode with anodes. We've been fortunate that titanium anode baskets (1 per cell) have eliminated the melting of the anode stubs which saves in both accounting work and melt time.

I need to find a good stainless welder to weld up some 316 stainless prototypes.
 
4metals try RFQWORK.COM a website dedicated to small job shops, anything from machining, welding to water jet. You may get lucky and find someone close to you, eliminating shipping costs.

Post an add someone will reply with a quote.

Best Regards
G
 
As an example lets take Junkman jims cell.
For this project make the hight longer
2 or 3 times longer or more
Where the bottom of the cell is make it so that it is like a tray and that it can slip in and out threw a narrow massage
The narrow hole has to be very tight and when it is full of silver it is pulled back and the silver will fall to the bottom
This can be done with a stepper motor and it will cost about 200 dollars
I wonder if I can get a patent on this idea
 
I know you're concerned with modifying a Moebius cell, so what I'm saying is worthless to you.

With a standard 30 gallon Thum cell, however, I've always though that all one would need is a horizontal rod (rigid plastic), about an inch above the cathode, moving back and forth, between the basket and the cathode, the length of the cell. That should be fairly easy to set up. The plating industry sells the same type mechanism to move the parts back and forth - called cathode rod agitators. These are shown on page 736 of this large book download. I just wrote a blurb on this book, here:
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=6481&p=57415#p57415

The spacing between anode(s) and cathode is about 4.5". The crystal tends to pile up on the cathode sheet, right underneath the center of the anode basket, and, in about 4 hours, the peak of the pile will almost be high enough to reach and short out to the anode. The rod would tend to level this pile out so that, maybe, one could go about 12 hours (instead of 4), or more, between pushings. Instead of starting with the basket at one end, I would put it in the middle. In a Thum cell, there's no need to have automatic collection of the crystal, since it only takes about 10 minutes to do it manually.
 
GSP,

First off I don't think anything you've ever said to me is worthless. Knocking off the crystals with a cathode rocker is a good simple fix, a Bodine motor from a plating barrel and a few gears will make a nice drive motor for a continuous wiper of the existing plate cathodes. I'm not so sure that an expanded metal cathode would cause all of the crystal to sheet off without some help as Irons suggested, possible but I haven't experienced it.

A relatively narrow conveyor like in Palladium's post would fit the bill to bring the dislodged crystals up and out of the cell.
 
4metals,

I just re-read your 1st post. You're getting 92% cathode efficiency, which is excellent.

I guess my only questions are (1) how much space do you have below the bottoms of the anodes/cathodes and (2) how much space between the anodes and cathodes?

I don't think you could get much simpler than removing the crystal with a screw, from a funnel shaped catcher. Also, it wouldn't take up much space. The rocker type mechanism could surely be used to dislodge the crystals or to at least continually clear the crystal in the space between anode and cathode. I did just find an old reference which used wooden scrapers to continuously knock the crystal off - scroll down about 1/2 page.
http://books.google.com/books?id=1YJPAAAAMAAJ&pg=PA267&dq=moebius+silver+cell+scraper&lr=&as_brr=1&cd=23#v=onepage&q=moebius%20silver%20cell%20scraper&f=false
 
The tanks presently have about 6" beneath the cathode and the distance between the anodes and the cathode is 5" on each side. The anode bags are large enough so they allow all 5 anodes per side to fit in the same rectangular bag, they are held open and firm with a pvc frame. Because of the anode bag frame the anode bag to cathode is 4". Along the bottom of the bags is where the crystal growth comes sneaking into the bag if we wait too long to scrape.

If we can come up with a screw design we'll probably use round tanks around 55 gallon size. The extra volume will give us more time before the copper levels grow to 8 oz/gal. That's the point where we take it out of service and cement the silver to start over.

Gotta love those old reference books!
 
From the link to the book you posted GSP, could this be the answer Peter was looking for on growing the large silver crystals? Clipped from page 269.


http://books.google.com/books?id=1YJPAAAAMAAJ&pg=PA269&img=1&zoom=3&hl=en&sig=ACfU3U0zze7OuSWQi8fZbW5vWG86htolKA&ci=42%2C441%2C832%2C466&edge=0
 
4metals,

How much copper do you start out with in the solution?

Since you are redesigning the tank, I guess the present dimensions are moot. I was just trying to think of ways to fit all this stuff into the existing tank. With only 6" of space at the bottom, I doubt if that's enough slope to collect the crystal at a single point in the funnel. Maybe, some nozzles all around to push the crystal to the center might work. Instead of something funnel shaped with the low spot at the center, maybe the collection tray should totally slope to one end, with the sides at the low point sloped to bring the crystal to the center, side-wise.

I have a small aquarium with gravel on the bottom. Once a week, I use a siphon to clean the crap from the gravel. The siphon is a plastic tube about 1.5" dia x 7" long, with a length of 3/8" tubing attached to it. Just from the small amount of vacuum produced by this, the large tube totally fills up with the gravel. What I'm wondering is: With air or vacuum, could you somehow suck (or, push) the crystal (and some solution) up in a tube, into a container with a screen on the bottom of it, and then drain the solution back into the tank and hold the crystal in the container? If you could do that, I think it might be simpler than a screw. It might be bad if a hose broke loose, however.

Just thinking.

Chris
 
GSP

I really appreciate your insight, you are right the bottom clearance isn't enough too do much down there. I have them make up the cells at 1/2 oz/gal as copper. Any less and the start up collecting is too difficult as the silver is too adherent to the cathode.

Since I'm basically starting a new in Michigan, I also could switch to Thums. A slightly sloped "v" shaped cathode with a valley for a long screw to crank the crystal up and out. The tanks are shallow anyway so lift isn't high to get it out. Then I could sweep the crystal towards the screw with a cathode rocker motor setup on each side. Since we're having little or no anode end remelts by using titanium baskets, I wonder if the benefits of Thum vs Moebius really will be substantial. I can foresee benefits of both approaches.

I really love this kind of work!
 
qst42know said:
From the link to the book you posted GSP, could this be the answer Peter was looking for on growing the large silver crystals? Clipped from page 269.


http://books.google.com/books?id=1YJPAAAAMAAJ&pg=PA269&img=1&zoom=3&hl=en&sig=ACfU3U0zze7OuSWQi8fZbW5vWG86htolKA&ci=42%2C441%2C832%2C466&edge=0

It might be, but due to some quirk in the Danish copyright laws, I'm only allowed to see this:
:cry:Danish copyright.JPG
 
4metals,

In thinking about using the Thum cell, I have some questions. What is the average silver purity of the material being processed? What is the initial silver concentration makeup of the solution you're now using?

I wonder if there is any sort of small inert pump that would lift the crystal (and some solution, of course) out? Along the lines of a very small trash pump or a very small dredge? I visualize the crystal slurry being pumped into a reservoir at the top and the solution draining back into the tank from an overflow pipe.

In considering a screw, do you think it could bind due to the hard crystal?

Most probably, this idea is too complicated. What if the tank were elevated and the bottom were sloped toward the center. No tray. Underneath the bottom center would be a double valve arrangement with a length of, say, 4" plastic pipe between the valves. The opening and closing of the valves would be programmed to cycle electrically (the complicated part). To start, both valves would be closed. The top valve would then open and the crystal would dump into the pipe. A vibrator could be mounted to the bottom of the tank to make all the crystal go into the pipe. The top valve would close. The capacity of the pipe would have to be large enough to make sure all the crystal went into it. Otherwise, some would catch in the valve and prevent it from completely closing (that could be a big problem). The bottom valve would then open and dump the silver into a container. A little distilled water would enter the pipe to flush all the crystal out. The bottom valve would close and the cycle would repeat.

A simpler version would be to use a smaller shorter pipe (say, 1" dia.) and have no valves. The crystals and solution would constantly dump into a reservoir, aided by the vibrator (or, two). The reservoir would have an overflow into another tank and the solution would be pumped from there back into the cell.

Just thinking out loud.

Chris
 
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