GRF Search!

deplating silver plate with sulfuric acid

<<

rbramsey

Active Member

Posts: 55

Joined: October 26th, 2010, 1:56 pm

Location: NE Alabama

Post January 5th, 2011, 5:09 pm

Re: deplating silver plate with sulfuric acid

I have been busy on another project with silver. I rigged a computer P/S so I it can be used. This will give me 3.3V@25A, 5v@30A, and 12V@20A. I had a hard time locating 97% sulfuric acid. So, I started by evaporating battery acid down. I need to find out the profitability of recovering the silver from plating so I can move forward on this project. If it is not profitable yet, then at what price does silver need to be.

Goldfinger4 wrote:Still waiting for your report :)
I am also currently experimenting around with a sulfuric acid cell. I use plated spoons, 37% sulfuric acid and a stainless steel electrode.
Up to now is did nor notice any AgSO4 crystals at the bottom of the container. I don't understand why this should happen - silver permanently dissolves at the steel electrode.


When I used 37% sulfuric acid, the silver went into the solution. I would see it immediately. I was using a 12v@80A. The cell ran a constant ~50A. The cathode was lead. The copper was plating out to the cathode. It would take 10 minutes to deplate a bowl. After about an hour or so it would seem to stop working. The electrolyte was full. I cemented out the silver with a copper bar. I was able to start up the cell after that, but it wouldn't work as well. This is when GSP told me I would have problems trying this way. Since then I have been getting supplies together to doing right.

I also tried to melt the silver of from plated brass. The melting temperature of brass is above 1000°C. With a temperature of 985°C all silver flows to the bottom of the melting pot. This is clearly visible as the brass is covered by red copper oxide. Be careful not to inhale zinc fumes.
The purity of the silver is about 40-50%, mainly polluted by zinc and brass material because the furnace is always hotter at the bottom and there some brass will be melted. I let the spoons in the pot for around 15 min. Maybe less than 15 min would be possible. My furnace runs on 700W.


How clean is the brass when it comes out? Is it clean enough to sell as brass? The few pieces of brass plated silver was yellow brass, and there is some other white metal on it. It couldn't be sold sold as brass.

With some finagling, I got the copper pieces are clean enough to sell as #1 copper. It is not practical to do on a larger scale. There is too much labor involved.
Richard
<<

rbramsey

Active Member

Posts: 55

Joined: October 26th, 2010, 1:56 pm

Location: NE Alabama

Post January 5th, 2011, 5:21 pm

Re: deplating silver plate with sulfuric acid

joem wrote:using a brush in water to manually remove the silver
http://www.youtube.com/watch?v=I2igGhOjfcg at about the 51 second mark
Then filter the silver out , dry and run through a crystal silver cell


This is similar to what I thinking as another approach, but better. I was looking at using an enclosed bead blaster to blast off the silver. After a while, mix the beads with nitric to remove the silver and copper. Another Idea, was to use an air scaler or wire wheel to scratch off the silver. These approaches used a lot of labor. The last approach would be to smelt the plated copper to cast anode bars and electrofine the copper, and catch the silver as slime.

Richard
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post January 5th, 2011, 8:29 pm

Re: deplating silver plate with sulfuric acid

I tried the copper electrolysis with plated stuff. It did not work, silver also dissolved though my voltmeter only displayed 0,4V.

Maybe the melting method can be improved. From one fork and two spoons I recovered 8g silver.
I will try heating to 920°C. Maybe the gaseous zinc breaks up the silver plating and it can be easily removed.
I report on weekend.

I found someone to buy brass metal. I don't know if he would buy it covered with copper oxide. But it would be no problem to melt nice ingots for selling.
CuO has a high melting point and can easily be removed from the molten metal.
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post January 7th, 2011, 9:51 pm

Re: deplating silver plate with sulfuric acid

Heating plated brass to the boiling point of zinc did not remove the silver plating.. it somehow went through the hot silver and covered it with an oxide coating.

Any news about your deplating project?
<<

goldsilverpro

User avatar

Active Member

Posts: 6181

Joined: March 30th, 2007, 3:45 pm

Location: Nevada, Missouri

Post January 7th, 2011, 10:06 pm

Re: deplating silver plate with sulfuric acid

With time, the copper will migrate up through the silver. This is greatly accelerated with heat.
GoldSilverPro's eBook For Sale. viewtopic.php?f=84&t=5810
________________________
"The refiner is always the last liar." Louis Labash, 1979
________________________
A pocketful of theory and $3 will buy you a cup of coffee almost anywhere.
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post February 5th, 2011, 4:09 pm

Re: deplating silver plate with sulfuric acid

So this is my new silver deplating cell.
The anodes are 6 plated forks, the kathode is stainless steal. In the big bowl you can see fresh silver, dried silver is in the smaller bowl.
The electrolyte is 2l of 37% sulfuric acid and a little bit nitric acid. It runs on about 2,2 V and 23-26 A. I tried it on 5V (4,2V at the electrodes) but it produced acrid smelling colorless gas (maybe SO2) so that I can not use this higher voltage, although the 50-60A could have speeded up the reaction.

I don't want to produce pure silver, 50% purity would be enough. I found a metal refinary nearby that offers to refine 30kg of raw material for 550EUR and gives me nice stamped silver bars back.

Did you make any new experiences? What voltage do you use now?
You do not have the required permissions to view the files attached to this post.
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post February 8th, 2011, 12:07 pm

Re: deplating silver plate with sulfuric acid

After 9h: 16g raw / 12g silver measured by AgCl-method
<<

Lonnie

Active Member

Posts: 56

Joined: February 13th, 2011, 10:20 am

Post February 13th, 2011, 6:32 pm

Re: deplating silver plate with sulfuric acid

Harold wrote

"" Is anyone willing to conduct some experiments for the good of all readers? ""

I certainly am willing and ready . I'm new to doing this so I'm not to sure of how much help I could be but willing to try if it might help me reach my goals . L et me give you some back ground on myself . My names Lonnie and I'm residing in Middle Tennessee . I happen to have quite a bit of silver alloyed contacts and about a 100 pounds of copper with a heavy coat of silver plate .

So I've been trying to come up with a way of removing the silver from the contacts as well as from the plated copper . I bought instructions on ebay LOl using sulfuric acid and sodium nitrate to plate the silver out into solution . It's suppost to turn the electrolyte red and when done you drop the stuff with common table salt .

I started with some electrical items I have with a heavy silver plating on them . Using a battery charger it was blasting the silver coating off in tiny flakes and white junk was forming on the plated piece blocking the DC current and it would stop working .

So I pulled out a toy I bought at another auction and when I put the current to it this time it started turning the electrolyte white about like milk . I let it go and in a few minutes stripped the silver from a few pieces . Then it started precipitating into white chunks that soon turned purple .

Could this purple stuff be AgCl ? From reading in here I see the people with more experience advise staying away from AgCl if that is in fact what I have . btw I'm completley new to this so If trying to help I need things explained a tad bit better than most . I am trying to learn as I go and use terms like AgCl and not Silver Chloride . So dont assume I have a back ground in chemistry just because I do that . I just figure I'll learn these things if I use them as I advance my knowledge in this area .

Things I'm using and facts I've observed so far .

I get my sulfuric acid from old car batteries ( it's free ) . Trying to cut cost as I'm aware theys not much money in removing silver plating . I figure lead could be in this so I cook my AgCl ( if thats what the purple stuff is ) in a crock pot for 4 hours , filter while hot and repete this again . I did get about 1/8 inch of a white substance that settled in my first wash water I'm assuming is lead . Plus my first wash had a slight blue tint to it . My second wash came out crystal clear with no white substance settling in the bottom .

Sodiun Nitrate I have to purchase on ebay . The electrolyte plays out rather fast but filtering seems to make it work good as new again . It is becoming contaminated with copper that I hope I can figure a way of removing so I can keep using the stuff .

Per the ebay instructions I use a lead fishing sinker as my cathode . Another reason I figured a little lead in the sulfuric acid shouldn't be a problem . Copper does collect at the cathode but I'm able to collect most of this with a snipper bottle .

If this white milky stuff that turns purple is the silver then it's easy to remove from my electrolyte . It falls out by itself simply filter the stuff and the electrolyte is ready to use again . However if it is the silver it's in the form of AgCl that the most experienced in here advise staying away from .

Plus I'm getting a silver looking substance also . I haven't tried melting any but it appears to be little chunks of silver metal . Oddly enough I only get this in my wash water . What I do is sumerge the plated piece and hit it with DC current . After a few minutes I remove it and dip in water and use a brush on it . If all silver is gone I'm done with that piece if not I give it more DC juice . I'm assuming the silver looking chunks are plating that was loosened up by the current and knocked off by the brushing .

A little information on my DC power supply .

I'm using a toy I bought at another auction . It's called a

EBERBACH Electro-Analyzer 1000

Electro-Analyzer 1000
Eberbachs Electro-Analyzer 1000 apparatus is the laboratory standard for determinations of lead, nickel, copper, zinc, antimony, cadmium and other metals by the electro-deposition process.
Unit has a finished steel case (30 high) with stainless steel front surface and occupies a table space of 15 x 17. The front panel protects the apparatus from corrosive spillage and fumes. No electrically corrodible components are positioned where material may fall into the cell and alter results.
The unit delivers up to 10 volts, 10 amperes DC at each of two positions for simultaneous determinations. Separate ammeters (0-10A) and center-zero voltmeters (10-0-10V) indicate amount and direction of current flow at each position. Polarity reversing switches change the polarity of the electrodes. Current to each position is supplied by individual power transistors controlled by potentiometers. In line fuses protect AC and DC circuits.
Stirrers are driven at a constant speed of 620 rpm by a split-phase induction motor. Hollow spindles permit easy vertical adjustment of the glass stirring rods. Power to each stirrer and entire unit is controlled by individual switches with pilot lamps.
Heavy-duty platinum electrodes (45 mesh) are recommended for this unit. However, lighter weight electrodes may be used. Spring loaded electrode holders grip the electrodes without deforming the stem and may be moved horizontally for centering nested electrodes. For rotating anode techniques a stainless steel rotating anode holder may be substituted for glass stirring rod


My goals

I seriously doubt I get rich or make any money doing this . Thats one reason for my need to do cheaply as possable . I'f I could just say I refined and purified this bar to 99.999 fine silver it would be payment enough .

So my thoughts were to get it pure enough the first time to run it through a thumb cell and clean it on up . Any help reaching this goal is greatly appreachated . If I can conduct experiments that may help all the readers that would be great also . So you know who I am and what I'm trying to do . If you have an idea you would like for me to try just run it by me . If I'm able to I'd be happy to give it a try .

Thanks

Lonnie
<<

lazersteve

User avatar

Active Member

Posts: 6865

Joined: February 27th, 2007, 11:20 pm

Location: Florida

Post February 13th, 2011, 7:16 pm

Re: deplating silver plate with sulfuric acid

Lonnie,

The white stuff that turns purple is AgCl= Silver chloride.

Your cell electrolyte is a crude form of nitric acid.

You should check out the Guided Tour Link below for several useful links to terminology used here, General Reactions, Safety, Forum rules, etc.

The copper colored stuff at the cathode is copper metal. The silver colored stuff at the cathode is silver metal.

The real problem with your cell is the electrolyte. It's an impure form of nitric acid which leads to salts like sodium sulfate, copper sulfate, silver sulfate, and a mix of other stuff. It would be best if you take a break from running any cell or experiments until you get a handle on what methods work best for the scrap you want to process.

Take some time and read Hokes book and the links in the Guided Tour.

Steve
The proof is in the pudding.
Purchase refining supplies and DVDs --> Lazersteve's Store
Click Here for the -->Guided Tour Link
Find anything on the Forum FAST!!!---> Click Here
Click Here for -->Stannous Chloride Recipe and Testing Results
What is in Lazersteves DVD's ?
<<

Lonnie

Active Member

Posts: 56

Joined: February 13th, 2011, 10:20 am

Post February 13th, 2011, 9:33 pm

Re: deplating silver plate with sulfuric acid

Steve

Thanks for the reply it's good to at least be certain the purple stuff is indeed AgCl . The silver metal like substance never came from the cathode it was brushed from the anode in my wash water . I have took a break running it with the exceptions of small experiments on other material I have removed over the years . My motto has been if you do not know what it is then DO NOT sell the stuff . The real reason for the break is simply that I nered to do other things plus after reading yesterday that I should avoid AgCl if at all possable put an end to me producing that .

Speaking of safty I do like the fact that my process doesn't appear to gas off any silver dioxide ( I think ) thats the name of the red / brown deadly gas produced when silver is digested in nitric acid . It may be making small amounts but when covered with a sheet of glass I see no red/brown gas building up .

I kinda like that idea as my work station is outside in my mill house ( no lab ) type facillity to safly do this in . I do train a fan on the cell and approach it from the fan side always making sure any fumes produced are blown away from me . Still if I could come up with a process that doesn't actually digest the silver producing the silver dioxide gas I'd prefer that process . However I dont want a form of silver thats trouble to melt or just as toxic . I've been reading a little on silver oxide as I think it gets on the anode if I let it set running to long . Sometype of brownish black looking film starts building on it .

So yes I agree it's time to stop running the cell and learn a few things . I worked on a kiln and a thumb cell today . I have everything needed to build a small kiln and will concentrate on this while reading . Plus gathering up things to make a good cell from once I get it all ironed out a little better . Thinking I'll use a scrap coffee maker I have . The sides arn't sloped like the material I've read suggest for easy removal but it is made in such a way the removal of crystals should be fairly easy anyhow . It's about 20 inch long and maybe 12 inch wide . It's not as tall as I invisioned I'd like but still I think it's a good quality start for the price ( free ) . Too good of a start not to take advantage of the professional welding and construction .

Sure it has it's pros and cons but already constructed of food grade stainless and it doesn't leak . It has one hole in it where the electrolyte could easily be drained for cleaning of Ag crystals via a chemical resistant valve . It's a little bigger than I'd like it to be but not so big I couldn't make due with it .

I will take the tour and read the material you suggested . Will probably be Tuesday before I can get back on line to begine this . Again thanks for the reply and all help is appreachated .
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post February 20th, 2011, 1:37 pm

Re: deplating silver plate with sulfuric acid

Hi Lonnie!

The main principle in dissolving silver is a redox reaction. That means, you either need a material that is more attractive to electrones than silver and steals them (like the nitrate ion from nitric acid) or you steel electrones by connecting the silver to the positive pole of a power supply.

I don't understand you method.. it looks like a mix of both.. you are using a power supply, so silver should be the positive pole and move to the negative pole where you can recover it as a mass looking like a sponge or small crystals. Of course, some silver remains in the sollution but that's no problem because you use this sollution for a longer time. There is no need to recover it whith table salt because afterwards you can throw you sollution away. When the electrolyte is contaminated with chloride ions a silver chloride layer will form on your plated material and hinder further reactions (or did you make other experiences?).

Table salt is only needed when you dissolve silver in nitric acid (sulfuric acid + nitrate salts = nitric acid).

A useful method for producing 999 pure silver is:
1. deplating in sulfuric acid cell
2. dissolving the relatively impure silver sponge in nitric acid and use the table salt method, making raw silver bars als electrodes
3. running a silver cell with silver nitrate electrolyte

I decided for myself that I stop after step 1 and sell the raw silver to a raffinery. Steps 2 and 3 pruduce toxic gases and waste and cause costs, nitric acid is expensive. And it is working time expensive..
<<

colibri

Member

Posts: 12

Joined: February 17th, 2011, 3:23 pm

Post February 24th, 2011, 9:35 am

Re: deplating silver plate with sulfuric acid

Regarding the removing silver plating in 37% sulphuric acid, I have been reading the posts with interest and thought Id have a go. Ive got a lot of old electronics bits that are silver plated and always wondered if it was possible to recover the plating.

So using a stainless cathode I have managed to de plate a few items, I found that the cell current was very low until it removed the silver and when it hit the copper underneath the current shot up. Now I have a cathode covered in a dark brown sludge and the sulphuric is a cloudy light green colour. Am I doing it right?

Im thinking I should now be able to cement out some of the silver using a copper bar. I guess there is a large quantity of copper in the sulphuric, would it be possible to cement this out using iron?

cheers

Anthony
<<

Goldfinger4

Active Member

Posts: 51

Joined: January 4th, 2011, 9:29 pm

Post February 25th, 2011, 12:10 pm

Re: deplating silver plate with sulfuric acid

Electrolysis is a continous method. There is no reason for cementing out copper or silver. Simply use the electrolyte for the rest of your stuff and collect the dark sludge. When there is nothing left, you can cement out the silver by using copper or the silver chloride method, then you can cement out copper and nickel with iron because they pollute the environment. After that you can throw it somewhere in the landscape :)

I think your current rised because the electrolyte filled with metal ions. I do not recognize a much different current when the silver plating is removed.
<<

Amature

Member

Posts: 8

Joined: April 3rd, 2011, 2:00 pm

Post April 20th, 2011, 7:09 pm

Re: deplating silver plate with sulfuric acid

I found through some research that if you take four cups of sulfuric and 50cc of nitric acid elevated to a temp somewhere around 179 degrees Fahrenheit the silver strips off and no base metal is lost. I have tried this and it works extremely well and it is quick. I will have to find the info again to give you more info but I am stripping all kinds of silver pieces and it does not take long to make a troy ounce of silver using this method.
<<

goldsilverpro

User avatar

Active Member

Posts: 6181

Joined: March 30th, 2007, 3:45 pm

Location: Nevada, Missouri

Post April 20th, 2011, 7:57 pm

Re: deplating silver plate with sulfuric acid

Amature wrote:I found through some research that if you take four cups of sulfuric and 50cc of nitric acid elevated to a temp somewhere around 179 degrees Fahrenheit the silver strips off and no base metal is lost. I have tried this and it works extremely well and it is quick. I will have to find the info again to give you more info but I am stripping all kinds of silver pieces and it does not take long to make a troy ounce of silver using this method.


We've discussed that solution many times on the forum. It also works pretty well at room temp (a helluva lot safer), but it is slower, especially on thick deposits. How do you plan on recovering the silver from the solution?
GoldSilverPro's eBook For Sale. viewtopic.php?f=84&t=5810
________________________
"The refiner is always the last liar." Louis Labash, 1979
________________________
A pocketful of theory and $3 will buy you a cup of coffee almost anywhere.
<<

Amature

Member

Posts: 8

Joined: April 3rd, 2011, 2:00 pm

Post April 20th, 2011, 8:54 pm

Re: deplating silver plate with sulfuric acid

As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
http://www.ehow.com/how_7617322_remove- ... -bath.html
http://www.finishing.com/225/07.shtml
<<

Drewbie

Active Member

Posts: 157

Joined: January 12th, 2011, 10:35 pm

Post April 21st, 2011, 2:05 pm

Re: deplating silver plate with sulfuric acid

Amature wrote:if you take four cups of sulfuric and 50cc of nitric acid...


What strengths?

Regards,
<<

Amature

Member

Posts: 8

Joined: April 3rd, 2011, 2:00 pm

Post April 21st, 2011, 4:58 pm

Re: deplating silver plate with sulfuric acid

I use Rooto for the Sulfuric acid and I use 70% nitric acid
<<

teclu

User avatar

Active Member

Posts: 156

Joined: May 24th, 2009, 3:58 am

Post April 22nd, 2011, 10:39 pm

Re: deplating silver plate with sulfuric acid

Amature wrote:As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
http://www.ehow.com/how_7617322_remove- ... -bath.html
http://www.finishing.com/225/07.shtml



Hello Amature,
Nice and interesting work! But now, please confirm me if I understood correctly:1000 ml distiled water+950 ml h2so4(93%) + 50 ml hno3(70%)= 2000ml deplating solution+ 80 degrees Celsius. For what amount of silver use this 2 liters?
...and, what kind of salt used for cementing? purity of silver?
teclu
<<

goldsilverpro

User avatar

Active Member

Posts: 6181

Joined: March 30th, 2007, 3:45 pm

Location: Nevada, Missouri

Post April 23rd, 2011, 8:24 am

Re: deplating silver plate with sulfuric acid

teclu wrote:
Amature wrote:As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
http://www.ehow.com/how_7617322_remove- ... -bath.html
http://www.finishing.com/225/07.shtml



Hello Amature,
Nice and interesting work! But now, please confirm me if I understood correctly:1000 ml distiled water+950 ml h2so4(93%) + 50 ml hno3(70%)= 2000ml deplating solution+ 80 degrees Celsius. For what amount of silver use this 2 liters?
...and, what kind of salt used for cementing? purity of silver?
teclu



Use no water at all. Just 950 ml sulfuric + 50 ml nitric.
GoldSilverPro's eBook For Sale. viewtopic.php?f=84&t=5810
________________________
"The refiner is always the last liar." Louis Labash, 1979
________________________
A pocketful of theory and $3 will buy you a cup of coffee almost anywhere.
PreviousNext

Return to Silver

Who is online

Users browsing this forum: No registered users and 1 guest

[Most Recent Quotes from www.kitco.com]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by Vjacheslav Trushkin for Free Forums/DivisionCore.