Info on sulphuric deplating/stripping cell

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darinventions

Well-known member
Joined
Jan 10, 2015
Messages
98
Ok ill start off with please only comment if you have good knowledge & or experience with this type on cell..i am working on a new design of a stripping cell...i have a working cell an have been writing all of my info in a log book ...i need outside info to cross reference others experience with my own...my first question is how much run time do you generally get before it gets to hot....question 2 do you find any advantage using sulfuric with or without glycerine... question 3has anyone experimented with different voltages such as 8v/14v /6v&andwhat amperage did you use if you can remember ...i thank you very much for all your info and if anyone has any other good info to share that i didnot cover please post and explain...keep in mind that I'm using all info collected here for a new more efficient design of this cell
 
1. Depends on amps, cell size and distance between anode and cathode. The higher the amps, the more heat is produced.The smaller a cell is, the faster heat builds.The greater the distance between anode and cathode, the less current will pass through the electrolyte.
2. Glycerin is not needed and can be dangerous if nitric acid is accidentally introduced. Glycerin and nitric acid in sulfuric acid makes nitro glycerin when heated. It was believed that the glycerin helped the gold precipitate which is not the case as it will precipitate as soon as the gold leaves the vicinity of the anode.
3. Voltage and amperage is determined by the size of the anode and cathode and distance between them. 12v at 10 amps will heat a 1 liter cell in about 15 minutes of continuous use if you are using an anode basket.
 
Thank you for the info GEO..the info on glycerine is very important for beginners or the experienced refiner that just didn't find any info about it during his or her search...ill admit i did not know that could happen an I've spent hours researching different random stuff that applies...as for the cell i think most all of them will be of the same size rather if it is a 1liter. or greater....but with my design that I'm working on there will be no need to have a cell that is larger than. 1 liter.... an the run time should increase to one hour +or-...
 
U=I•R

P=U•I

1 Watt over a time of 1 second ist equal to 1 Joule

1 Joule will heat 1g gramm of water 0,239 Kelvin

the heat capacity of water is 4,186 kJ/(kg K)

the heat capacity of H2SO4 is 1,386 kJ/(kg K)

So it will take about 3 times as much energy to warm up H2O compared to H2SO4 (for H2SO4 ~0,72 Kelvin per gramm per Joule)

If we use the cell (1 kg H2SO4) at let us say 40 Watts, it will get 0,0288 K warmer every second, 1,728 K every minute, 51,84 K in a half hour.

this is without calculating the loss of warmth, just as if we would use a thermal isolated container

Quite seldom I have to calculate anything else but water and I wasn't sure, if I could find out, but when I do the plausibility check and compare this result to what I have experienced, it seems to be just fine.


One advice: everyone who wants to basically understand his cell, should have a look on Ohm's law! Just as Geo already said: The Ampere is always given by the setting of voltage and resistance. The resistance is given by the electrode areal, distance and composition of electrolyte.
 
solar_plasma said:
One advice: everyone who wants to basically understand his cell, should have a look on Ohm's law! Just as Geo already said: The Ampere is always given by the setting of voltage and resistance. The resistance is given by the electrode areal, distance and composition of electrolyte.
And in the case of a sulfuric cell also of the electrode composition. When the gold is gone the passivation of the electrode surface increases the surface polarization that reduces the current. It can also be seen as the passivisation is decreasing the electrode area.

Göran
 
Göran, I am quite happy, that the severe look of the physicist didn't find any bigger mistakes, than this! :lol: Thank you for adding this important point!
 
Ok sorry for not posting on this sooner ..I've been waiting on a copper screen to come in that i ordered on ebay ..the dude forgot to ship it an it took twice as long to get it..anyway i did get to run it an it ran for 45 minutes an held a steady temperature of 57°F...i put all kinds of different gold plated items in with different types of base metals including steel ,bronze ,atonamy,bismuth,tin,an even a little ingot of solder that had some gold on the bottom of it... if you where wondering ..yes this unit is water cooled. an sealed ..i use a small water pump an have a little thermometer mounted on it to monitor the temp..i will be posting pictures of it later in the week ..i thank everyone that shared information pertaining to this ..
 
I forgot to mention that it only dissolved gold..all the base metals came out looking like new minus the gold plating
 
darinventions said:
Ok sorry for not posting on this sooner ..I've been waiting on a copper screen to come in that i ordered on ebay ..the dude forgot to ship it an it took twice as long to get it..anyway i did get to run it an it ran for 45 minutes an held a steady temperature of 57°F...i put all kinds of different gold plated items in with different types of base metals including steel ,bronze ,atonamy,bismuth,tin,an even a little ingot of solder that had some gold on the bottom of it... if you where wondering ..yes this unit is water cooled. an sealed ..i use a small water pump an have a little thermometer mounted on it to monitor the temp..i will be posting pictures of it later in the week ..i thank everyone that shared information pertaining to this ..

Water cooled and sealed? This type of cell produces hydrogen gas, which is highly explosive (refer to the Hindenburg accident). I hope you mean the water cooling is sealed and not the electrolytic cell. If the electrolytic cell is sealed, and close to any water source, you could not only create an explosion, but that same explosion might cause sulfuric acid to come into contact with water, and that I don't imagine would be a good day for anyone close by.

You are using concentrated sulfuric acid in a sulfuric gold deplating cell. If concentrated sulfuric acid comes into contact with water, it will spatter all over the place. The sulfuric acid evaporates the water so fast, that it will splatter far if it comes into contact. Personally, I would never use any sulfuric acid anywhere near water, regardless of how safe you think it might be. It reacts far too violently with water to take that kind of risk.

This is what happens at the anode when you put an electrical current through concentrated sulfuric acid. You are creating persulfuric-acid, Also called Caro's acid, permonosulfuric acid, etc. Under these conditions gold is soluble and the gold ions migrate into solution, as soon as the gold ions go into solution, the persulfuric acid immediately turns back into sulfuric acid and the gold drops back out of solution, finely divided. Once the gold has been stripped, the persulfuric acid attacks the base metals, creating an oxidizing layer and resistance to electrical current. This is the reason when using a car battery charger, you see a drop in the readings. Under these conditions you should never see base metal that looks like new. Not ever. Not unless you are doing something totally outside inorganic chemistry as we know it.

I have made several sulfuric cells. When I am using them, I will stop using one if it becomes hot, and use another. Switching off like this, I feel, is better than attempting to cool with water. I do use material that strips heat from the sulfuric electrolytic cell however. Jewelers use broken up pumice to quickly strip heat from metal. I took this idea and simply bedded the cells in the pumice to strip heat from the cell so I can run each longer, this also cools the cells down faster after use. In this way I not only can run the cell for longer periods of time, but also am not putting myself at risk.

One last note, I know I am repeating myself but I feel this must be included for those who might be new, reading this post, and wish to create a water cooled sulfuric electrolytic cell. Don't. There is no reason to use water to cool an eletrolytic cell. You can always use more than one cell, it's not worth putting your health at risk, or those near you. If sulfuric acid comes into contact with your eyes, it could blind you for life, or cause other damage as well. And never, ever, seal a sulfuric electrolytic cell, the hydrogen gas that builds up is highly explosive.

Scott
 
While the problems of introducing water to sulfuric acid are well known, water cooled stripping cells are not unknown. I personally witnessed one in the mid 70's, operated by the US Government (in New Mexico). Published information of the time indicates that the government had recovered more than 35,000 ounces of gold by this method. The storage yard supported the claim, as there was a huge number of 55 gallon barrels of stripped components stored in the yard.

The water jacket was open, as was the stripping cell proper, but the height of the water jacket was below that of the stripping portion of the cell. I can see how enclosing the water portion would be safer, but I certainly endorse the idea of a water cooled cell, in particular, if one has access to a respectable amount of material in need of stripping, as the cell can be operated non-stop, until it has accumulated a large volume of value. The cell in question was built accordingly.

Harold
 
Sorry i should have been more discriptive...The cell has a water reservoir that is sealed..the actual cell is set into an sealed to the top of the reservoir...Now i pressure checked it with a water pump that put out twice the volume an pressure than the one that will be used..i let it run for 48 hours straight an had no leaks. then it set for about 10 days full of water an didnot bleed off..meaning it didnot draw air ...As i said eairlier in my post i have a thermometer mounted in it to check temperature regularly ...I COMPLETELY understand the dangers of sulfuric an water..i went through a lot of trial & error to find what would properly bond everthing together .
 
I was gonna post pictures but they're no good..i will take more an post tomarrow...until then what you will see is a mini fume hood i made that the cell sits in..the platform is set at 5° angle going back to the wall in case of spills , there are two holes in the platform with hoses glued in to drain off any kind of spill into a 5gal. bucket...you'll see two clear hoses coming up from the water bucket into the cooling reservoir...next to the water bucket you'll see a glass jar with two lines..this is to siphon out the cell of all acid ...mounted on the side of the fumehood is a vacuum that operates the siphon...then of coarse no cell would be complete without a 12V-10Amp battery charger
 
Pics of the cell and fumehood...other items are a measuring cup an plastic tweeser
 

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Well these are all the pictures..the only upgrades i plan to add would be a triple gang box for light switches..one for exhaust fan/one for siphon vacuum /an one for battery charger... I'm gonna get a little LED light to place behind the cell in the hope to be able to monitor saturation of solution
 

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That is a nice compact fume hood you have there. Do you happen to have a diagram of it, or is it on the site? I should make one, but never have the room for it. This size would be perfect after moving a few things around.
 
Anyone interested in making anything I've made will be able to find it on( build your own equipment ) after the first of the year. I've got lots of NEAT STUFF that will save a lot of money an the best part is it all works very well..i use this stuff all the time ...so keep a watch on that portion of the forum after the first ...
 
I feel as though i should comment on the exhaust fan. this is a BRUSHLESS FAN from an old computer tower..why brushless? because while using anystripping cell hydrogen gas is created,and hydrogen gas is EXTREMELY FLAMMABLE..while a electric motor that has brushes will make a spark which could ignite this hydrogen gas..a BRUSHLESS MOTOR does not make any spark
 
Though I can hardly imagine that you will reach the LEL of hydrogen (4vol%) in a well ventliated room, this might become possible in your case (as far as I understand your setup). If so, the hazmat squadleader in me is alarmed as your construction is far from beeing explosion prevented. You have a lot of areals that might get charged with static electricity, all the more there are rotating plastic parts (the pc fan). And you have a wonderful ground/earth in your cell. So, there is in fact everything needed to blast this construction - I hope you're wearing ear- and faceprotection :lol: 20% of that volume would be enough to give you a hearing damage.

Well, you might be lucky all the time, but I would not feel very safe with it.

https://en.wikipedia.org/wiki/Flammability_limit
 
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