I just bought a caswell 25amp rectifier( same as sold on Ishor.com) to run a small silver refining cell. There is only 1 knob to adjust voltage and amp. If I set the power supply at 3v the current is only 3-4amp, is there a way to get 3volt at 25amp? so I can get the best productivity from my cell? At 3amp I'll only be producing a few gram per hour..
Silver cell question
- Thread starter elfixx
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here some more info that might be usefull to solve this problem;
Anode is about 98% pure silver 4cmx 8cm x0,75cm
Cathode is a titanium plate 6cmx12cmx0,3cm
The cell is about 15cm tall by 10cm large
Anode and cathode are about 8cm from one another
The electrolite is made of 90g of silver disolved is 100ml of 70% nitric then dilluted with water to 1.6L
The alligator clip are hooked on 1/4 inch welding rod
Anode and cathode are suspended to the rods by steel S shape hook
Anode is about 98% pure silver 4cmx 8cm x0,75cm
Cathode is a titanium plate 6cmx12cmx0,3cm
The cell is about 15cm tall by 10cm large
Anode and cathode are about 8cm from one another
The electrolite is made of 90g of silver disolved is 100ml of 70% nitric then dilluted with water to 1.6L
The alligator clip are hooked on 1/4 inch welding rod
Anode and cathode are suspended to the rods by steel S shape hook
machiavelli976
Well-known member
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- Mar 25, 2010
- Messages
- 263
from Ohm law you have I=U/R. to raise I you have to increase U or decrease R. if you want to keep U constant you must decrease the resistivity of the cell. that means larger surface for anods and cathods. increase their number and alternate them.
Sorry, but I can't think in centimeters. The anode is about 5 sq.in. on the one face that is facing the cathode. In the Thum cell, the most current used is about .35 amps per sq.in. (50 A/sq.ft.) of anode area. For 5 sq.in., this would be about a max of about 1.75 amps. If you go much higher that this, it will take more voltage. A voltage of 4 should be OK, but I wouldn't go much higher. It sounds like the anode size might be the biggest part of your problem. If you do increase the anode size, don't exceed the surface area of your cathode.
If the tank is round with a 10 cm diameter, it contains about .25 gallons. If it is square, it holds about .3 gallons. A Thum cell runs about 6 to 7 amps per gallon. Therefore, at the top end, you shouldn't run more than about 2 amps. If you exceed this, the solution will probably get too hot and this could cause problems.
Everything else seems OK, except, I don't like the s-hooks. They move around and can continually semi-break the connection. Also, it only takes a speck of corrosion to lose contact. It might help to take a file and carefully file a knife edge on the hook where it contacts the rod.
Considering your solution volume and anode area, I am not surprised at the A/V ratio you're getting. If you want to run more amps, I would get a bigger tank and use more anode area.
BTW, at 2 amps, you should dissolve and deposit about 8 grams of silver per hour.
Here's something else I just thought of, although it might not be a problem for you. In my cell (a horizontal Thum cell), I used unbleached muslin, under the anodes, to trap the anode insolubles and keep them from contaminating the crystal. Due to the sizing in the muslin, it was often several hours before I got the full amount of amperage. The sizing sealed the cloth and blocked the current flow. I just started the voltage between 3 and 4 volts. At first, there was very little current flow. After a short period of time, I got some amperage. As the amps increased, the voltage decreased. Every once in awhile, I turned the voltage back up to 3 or 4. After 3 or 4 hours, the system stabilized.
In the same line of thinking, if the anode cloth you're using is too tightly woven, it will impede the current flow. As far as muslin is concerned, I'm thinking 100 threads per inch is recommended. Your cloth should be of a mesh size that prevents the flow of any garbage through it, yet allows the unimpeded flow of current.
Something else I just thought of. When calculating the anode surface area, you only figure the side that is facing the cathode. If you were to place a cathode on each side of the anode, your effective anode area would double. However, you may not have enough room in the tank. That would put the anode/spacing at 2", or less. If you get too close, there's a greater danger of the crystal growing between the electrodes and shorting them out. If so, I would hope there's an ammeter fuse on your rectifier.
Noxx
Well-known member
Here we have to work with both metric and imperial. When I go to home depot, I ask for x feet of tubing.But when calculating heat of vaporization, it's KJ/Kg.
We still work with imperial units because you guys still lead the way in North America.
I'm more familiar with centimeter, but still, I designed my furnace in inches...
Barren Realms 007
In Remembrance
Noxx said:
But when calculating heat of vaporization, it's KJ/Kg.
We still work with imperial units because you guys still lead the way in North America.
I'm more familiar with centimeter, but still, I designed my furnace in inches...
You are makeing the chane away from the metric system, you are moving closer to the US. Next thing we hear you will apply for citizenship to the US. 8) 8)
Noxx
Well-known member
Lol 8)
qst42know
Well-known member
Filter bags on eBay in the business/industrial section. I don't know what micron size you would need.
Find a lady that will sew one up. Try polyester cloth and polyester thread.
I have yet to build my silver cell but I called around to several filter manufacturers and got a 1 square foot sample of the 13oz polynap free. It should make 4 filters for a horizontal thum cell. It may be possible to wash the filter into a beaker and reuse it a few times:?: of this I am not sure. If the 13oz polynap works well it can be purchased by the square yard.
Mark
Mark
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Not a good idea. Use a filter repeatedly until it isn't functioning well, but do not wash. Instead, replace the filter when necessary, incinerate, and process the ash for values.seawolf said:
Reason?
Especially if it has a nap, when you wash the filter, you're going to cover both faces with what is, for all practical purposes, contamination. That tends to undo the hard work you do in parting the silver.
Try the filter material to see if it functions to your satisfaction. If it does, buy enough to replace as required. It won't be expensive, and will save you considerable trouble in the long haul.
My filter required about 1/3 yard of material. I followed my own advice. Because my anodes contained a fair percentage of platinum and palladium, I'd lift the anode from the basket and scoop up the slimes occasionally, using an acid dipper. I could part several hundred ounces of silver before changing the filter.
Harold
elfixx said:
Hi
According to this post I calculate anode area is about 7 inch but GSP calculated 5 inch.
Do we must just calculate surface area of the bottom of the silver? Even if all of the silver submerges in electrolyte? ( Assuming cathode is a steel bowl )
Thanks
Only the surface area facing the cathode - 4.96 in2. It makes no difference how much is submerged. It's impossible to calculate the exact effective surface area.saadat68 said:
