How to turn waste into reusable materials

[Barren Realms 007]

That sounds like a post that I did in another area of the forum a few days ago. If I my memory is serving me correctly, it seems like I was told that he was using dilute sulphuric acid with silver nitrate salt added. I will try to contact the guy in person and eliminate the grapevine of confusion and get him to tell me for sure the details of his set up.

That is a diffrent thread than what I am thinking of, I think the thread I saw was with AP solution. I'll see if I can find it and eliminate the confusion on my part as well. But you might be right. When you find yours would you please post it.

 

[butcher]

Hi Richard
I assume you connect your silverware to the anode with
metal clips

What do you have on the cathode side

Also how much power to you supply for anode and cathode
Thanks

silver plated article is anode, the anode dissolves, the silver and plates out as powders to the cathode,
the cathode can be another silver plated article, copper,
stainless steel, as it does not dissolve, what I used for the cathode was a circle with a long tab, to get the idea draw a circle and a real long rectangle attached, this long rectangle is bent up from circle, the circle will fit in bottom of jar, the long rectangle bent up along inside edge of jar and out of acid electrolyte, the voltage is from a 12 volt battery being charged by a 12 volt battery charger, the series wired lamp, in anode wire, a automobile tail lamp bulb. limits current to cell, it also gives indication to cells current and operation, if cell is dead short the lamp just lights full bright, if the cell is an open circuit no current flow the lamp is off, the filiment of the lamp is also a small resistance in series with the cell, so it will drop a portion of the 12volts the cell will see. the electrolyte and cell condition will determine current draw from power source, as its resistance changes, so will the current.
this is really much more simple than it sounds

 

[goldsilverpro]

silver plated article is anode, the anode dissolves, the silver and plates out as powders to the cathode,
the cathode can be another silver plated article, copper,
stainless steel, as it does not dissolve, what I used for the cathode was a circle with a long tab, to get the idea draw a circle and a real long rectangle attached, this long rectangle is bent up from circle, the circle will fit in bottom of jar, the long rectangle bent up along inside edge of jar and out of acid electrolyte, the voltage is from a 12 volt battery being charged by a 12 volt battery charger, the series wired lamp, in anode wire, a automobile tail lamp bulb. limits current to cell, it also gives indication to cells current and operation, if cell is dead short the lamp just lights full bright, if the cell is an open circuit no current flow the lamp is off, the filiment of the lamp is also a small resistance in series with the cell, so it will drop a portion of the 12volts the cell will see. the electrolyte and cell condition will determine current draw from power source, as its resistance changes, so will the current.
this is really much more simple than it sounds

I'm confused. Can you explain again exactly what the electrolyte is composed of?

 

[dick b]

GSP:

This is from butcher-
"I have done some expierimenting with the copper sulfate electrolyte, sometimes I get a mix that will deplate the silver, and not dissolve much brass or copper, problem is I am not sure of the exact mix yet, but it contains mostly copper sulfate, a tiny bit of nitric and the HCL wash from a previous batch of silver chloride, basically a very dilute tiny bit of aqua regia in my copper sulfate, this while deplating the silver plate some comes off as the copper under the silver plate is attacked, and some of the silver turns to a white silver chloride powder, which after deplating for around an hour I will brush off into the jar cell. if you try this study about the gases formed from electrolytic solutions, even these if a feller built a cell to collect them could prove useful, or dangerous if a feller did not do his homework.

I have also tried using a dilute HNO3 electrolyte, but I seem to like the copper sulfate better."

I think he is trying to make a silver cell using waste chemicals for the elecrtolyte.

dickb

 

[butcher]

usually I just use copper sulfate as electolyte (this is a byproduct of another process.
I have tried nitrate's for electrolyte but they cost me more than its worth.

I have expierimented with other ingredients like copper sulfate with some nitrate and a little chloride,

Gsp my goal is not to plate or seperate metals, just to break them down to powder metals less surface area so my acids and oxidizers will dissolve them easily.

Acid peroxide (also a byproduct I have alot of) helps cleanup the copper powder, little additions of new chemicals and heat.

Although if I could just remove silver in the cell that would be gravy, but have not found a way yet,
have read where platers would remove silverplate to replate articles, seems I remember they used concentrated sulfuric and a little nitric Hot, that sounds a little dangerous as hot concentrated sulfuric would give a feller a good burn.

I have been recovering silver from plated object using byproducts from other processes, and having to use very little new acids, this is giving me impure silver (after removing most of the copper) which I can use to inquart with. or I can run it through another cell,use nitric, or whatever.

basically working around using nitric acid as it is too costly for me even homeade for this silver plated junk.

 

[dick b]

Butcher:

I've been following this thread because I think that a cheap way to deplate silver plate to recover it for inquarting gold would be a great way to go.

It's easy to pick up silverplate because most places don't want it and you get to recycle the copper after recovering the silver.

Thats a win win for me, and reusing old acids and chemicals instead of throwing them away is even better. Zero waste to dispose of!

dick b

 

[butcher]

So far my copper from this process is mostly recovered powders, some undisolved strips.

my goal was not copper, but if we could get the silver off cheaply and safely that would help, and give us more copper whole to sell.

one feller on the forum said he pressed his copper powder to a puck, and sintered it with a torch and scrap yard bought it.

 

[Barren Realms 007]

That sounds like a post that I did in another area of the forum a few days ago. If I my memory is serving me correctly, it seems like I was told that he was using dilute sulphuric acid with silver nitrate salt added. I will try to contact the guy in person and eliminate the grapevine of confusion and get him to tell me for sure the details of his set up.

You are correct it was a post of yours. Here is a link to the thread.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=46&t=5587&p=55422#p55422

Here is the post.

I know of a freind of mine told me of his retired former employer who has built a silver stripping cell in a 30 gallon plastic drum. He is buying old silverplated items from the thrift stores and yardsales and stripping them in the cell. He is then taking the stripped copper items and buffing them on a polishing wheel with jeweler's rouge and reselling the polished copper items at the flea market for several times what he paid for them and is planning on recoverying the silver from the cell once it is saturated.

 

[goldsilverpro]

Everything I can think of about stripping silver from copper.

About the best source for stripping most any metal from any other metal is the plating industry literature. Platers often need to strip faulty plating from a part and then re-plate it. Silver on copper is a problem because most chemicals that dissolve silver will also dissolve copper. In most plating books, the same three methods are listed. Please realize that platers are mainly interested in recovering the parts and not recovering the metal that is stripped.

(1) 95% concentrated sulfuric, by volume, plus 5% nitric by volume. Although the books tell you to run this at 175F-190F, I have found it will work at room temperature, although a lot slower. Moving the parts around helps. Any water in the solution will increase the attack on the copper. Cover the solution when not in use - concentrated sulfuric is an excellent desiccant and will suck moisture out of the air. The books also tell you to add a little nitric when it slows down. It might help to increase the nitric a few percentage points when making a fresh solution. Getting the silver out is a problem. The best way is probably to dilute the solution and then drop out the silver as silver chloride. I don't know how much dilution is required to do this, but I would guess at least 3 parts water to 1 part acid. To reuse this solution, the water would have to be removed by evaporation.

(2) Another standard solution is to add 30 g/l of sodium nitrate to concentrated sulfuric acid. The silver plated copper parts are made the anode at 3 volts. The temp is from 70F to 110F. I have never tried this. I don't know whether the silver plates out or if it stays in solution.

(3) A solution of 200 g/l (1.7#/gal) sodium thiosulfate, run anodically. They don't give the operating conditions, but I would try about 4 volts to start. Recovering the silver is another problem. You could zinc it out, although I would guess it would have to be diluted first. I tried this solution once and it worked quite well, as I remember, but I didn't try to recover the silver.

You can also strip the silver in a standard, concentrated sulfuric, gold stripping cell. This is mentioned in the original patent (2185858), but it doesn't tell you how to recover the silver.

I once discovered that silver can be stripped in about a 4-6oz/gal sodium cyanide solution that contains a lot of sodium hydroxide. I can't remember how much NaOH, but I think it was between 12-16 oz/gal. This is run at 6 volts and the silver plates out on a stainless cathode. This works very well. For large parts, I used 2 cathode sheets, one on each side of the tank, and put the part in between. For small parts, you need a tumbler. The large amount of NaOH somehow prevents attack on the copper.

It might be interesting to experiment with a solution of about 4-6 oz/gal sodium nitrate and about 8-16 oz/gal NaOH at about 4-6 volts. This is just an educated guess. It may not work at all. If it does work, it may be the best one of all.

BTW, when I experiment, I always start with the chemicals on the low side and then slowly add more if things look promising - the reason for this should be obvious. The primary rule of experimentation is to NEVER change more than one variable (chemical concentration of only one of the chemicals, temperature, pH, voltage, amperage, stir or not stir, etc.) at a time, for each subsequent experiment. Otherwise, you don't know which of the things you did changed the results. When I experiment, I always make a crude chart and list all the possible variables at the top of the columns, from left to right, and put the experiments (trials) in the rows. The results of each experiment are in the last column (a wide column) on the right - if possible, try to quantitize the results. As you run the experiments, you will start to see trends in the results and then you make adjustments to try and maximize the desired results.

I haven't looked, but you might search Google Patents for this, using various keywords. There may be proprietary chemicals for stripping silver from copper. It so, they would likely be patented. Also, they are likely to be cyanide based.

 

[butcher]

Thank You Gold Silver Pro, that is a great bit of information. As always you seem to have the answer's.
One thing I have noticed with some electrolytes, they will change from acidic to basic, and others just seem to become more acidic, depending on the starting solutions, sulfuric based solution seem to become more acidic and nitrate base seem to go toward hydroxide.
some solutions seem to even smell of hydroxide, and acid and base will dissolve anode metals, I have tried to find a good source of information that can explain the chemical reactions in a cell, and have read some, but have yet to find a good source that explains it either well enough or to where I can get a good hold on it.
as the gas from the elctrodes can be a big part as to the chemistry,
as I can guess PH or current for just dissolveing anode, does not seem to be as important, as it would with plating or stripping one metal from a base metal would be, these both seem to become varible as cell chemistry seems to change.

The sodium nitrate/sodium hydroxide does sound very interesting.
since Hydrogen and oxygen seem easily to evolve as gas, and if anode metal is disolving then should not produce much hydrogen, so would then just the loss of oxygen here, start to make an acidic sodium nitrate solution? any chance of NOx gas evolving? I do need to study this more, I am good with electricity and electronics, and just started studying chemistry, but when you start mixing chemistry and electricity in my brain, I think my brain cell's start shorting out.

P.S. On the silver ware or flatware I have notice silver plated on copper, and what seems to be yellow brass, but there also seems to be a white or silver colored metal they also plate to I would like to know what it is, could it just be white brass?

 

[Anonymous]

Plating removal tooth paste,
calcium nitrate, battery acid, make a calcium sulfate/nitrate acid paste, apply rinse off when silver is dissolved, filter under vacuum.

I did not try large parts, just a small test, when I was getting some silver plated scrap.

jim

 

[goldsilverpro]

One thing I have noticed with some electrolytes, they will change from acidic to basic, and others just seem to become more acidic, depending on the starting solutions, sulfuric based solution seem to become more acidic and nitrate base seem to go toward hydroxide.

A little electrolytic systems 101.

Assume you are plating nickel from a standard Watts nickel plating bath using nickel anodes. This bath contains nickel sulfate, boric acid, and other things and an ideal pH for this bath is 4.3. As you apply current, nickel plates at the cathode and dissolves at the anode. Under perfect conditions, 1.095 grams (I got this number from a plating book) of nickel will dissolve per amp per hour and the same amount will plate out. Electrolytically, this number will never be higher. It is based on Faraday's laws of electrolysis and is determined by the element involved and it's valence in the particular electrolyte.
http://en.wikipedia.org/wiki/Faraday%27s_laws_of_electrolysis
When 1.095 grams of nickel per amp-hr dissolve at the anode, the anode reaction is said to be operating at 100% efficiency. The same with the plating of nickel at the cathode. At 100% efficiency of both electrodes, the system is in perfect balance and the pH will always remain at 4.3.

In practice, these dissolving and plating electrode reactions rarely operate at 100% efficiency. To utilize the entire amount of amperage applied (which must happen), other electrode reactions will occur. The exact blend of these reactions depends on many different variables. The most common of these electrode side reactions is the splitting of water. When water splits at the cathode, H2 gas escapes the solution and OH- ion enters the solution. In this case, since the OH- ion is alkaline, the pH will increase. Water splitting at the anode generates O2 gas, which escapes, and H+ ion, which enters the solution, The H+ ion is acidic and lowers the pH. The amount of water splitting at the 2 electrodes is rarely the same. Therefore, depending on many variables, the pH will usually go up or down - note that if the same amount of water splitting occurs at both electrodes, all of the H+ will combine with all of the OH-, to form water, and the pH won't change. If you use an inert anode (one that doesn't dissolve in the particular electrolyte you're using), 100% of the current applied will split water and the pH will rise. Water splitting is explained pretty well in this link.
http://www.green-planet-solar-energy.com/hydrogen-electrolysis.html

Often, there are other reactions that occur. These usually depend on the electrolyte composition and the relative affinities for various reactions to occur. For example, in solutions that contain Cl- ion, Cl2 gas will usually be generated at the anode instead of O2.

This was quite wordy and, in practice, you just need to be aware that these things can happen. It's very hard to predict exactly what will happen in a particular setup. You can only experiment and measure the results. When experimenting, consider these things I've mentioned and start out with your best guess.

Here are a few of the things that can alter the electrode reactions.

(1) The electrolyte makeup. This includes both the chemicals involved and their concentrations. Low concentrations will certainly alter the electrode reactions, especially at the cathode.
(2) The ratio of the anode surface area to the cathode surface area. In most plating applications, they recommend that the anode surface area be at least twice the cathode surface area.
(3) The temperature.
(4) In certain solutions using certain types of anodes under certain conditions, a chemical film can coat the anode. If the anode is of the soluble type, this film can impede the dissolving of the anode.
(5) The current density. This is defined as the number of amps applied per square inch (or square foot, or square decimeter, or whatever). Most electrode reactions operate most efficiently within a certain current density range.
(6) The voltage. Every metal has a certain minimum threshold voltage required in order for it to plate. The electrolyte has something to do with this also. In most cases, the voltage will be high enough so you don't have to worry about it.

This is only the tip of the iceberg.

P.S. On the silver ware or flatware I have notice silver plated on copper, and what seems to be yellow brass, but there also seems to be a white or silver colored metal they also plate to I would like to know what it is, could it just be white brass?

The white metal is usually German silver (also called nickel silver and other names), an alloy of copper and nickel that looks like silver but contains no silver.

 

[butcher]

Thanks again for the help,
I knew water can split to hydrogen and OH and oxygen and hydrogen can gas off, also know chlorine can from a chloride solution,
are these the only things normally to leave the cell as gas? I have not heard of other cations gassing off , can they loose an oxygen (like water), and change from like a sulfate to a sulfide?

one thing where I have been breaking the silver plated ware down to powder's, the voltage and current are most likely higher than Ideal, and I have not worried about PH and my solutions vary radically in acid to water concentration, and so the driving of gasses and chemistry also a little different than a plating setup, where all these varibles would be setup to more Ideal conditions and monitored.

another stupid question say I have two different cations in solution like sulfate and nitrate, would there be a potiential difference between these? and would they possibly migrate to different electrodes accordingly? or maybe I just start trying to over think something I have not a grasp on yet?
I do know if over charging a lead acid battery you will drive off gases that normally would stay in solution much better, mostly water splitting but they can also carry some acids with them, maybe from popping gas bubbles, as sulfuric I dont believe should leave as gas.

 

[goldsilverpro]

Richard,

None of your questions are easily answered.

I knew water can split to hydrogen and OH and oxygen and hydrogen can gas off, also know chlorine can from a chloride solution,
are these the only things normally to leave the cell as gas?

I know I have read that there are other things that can form gases at the electrodes. I just can't remember what they are.

can they loose an oxygen (like water), and change from like a sulfate to a sulfide?

I would consider these as chemical changes produced by electrolytic forces. These things can happen. For example, a thiosulfate solution can break down and form a sulfide at the cathode. This happens when trying to deposit silver from photo fixer solutions, especially with poor cathode agitation and/or a low silver concentration.

so the driving of gasses and chemistry also a little different than a plating setup, where all these varibles would be setup to more Ideal conditions and monitored.

The reactions aren't different, they are just much more complex and unpredictable when you have a mix of many different things. For example, it is very simple to plate copper or zinc, individually. When you combine the 2 in the same bath to plate brass, the exact alloy you produce is very difficult to control. Small changes in things like the various concentrations of the 4 or 5 ingredients, temperature, or agitation can produce great differences in the deposit. There have been many people that have attempted to plate a stainless steel deposit from a solution containing iron, chromium, and nickel - 3 metals. Although they have been trying to do this for at least 50 years, no one has ever come up with a commercially feasible system. And all these things are done under ideal conditions using ideal electrolytes. When you have a haphazard mix of several anions and cations of mixed concentrations, which is different every time you do it, the predictability and control problems could increase 1000 fold, with no exaggeration.

another stupid question say I have two different cations in solution like sulfate and nitrate, would there be a potiential difference between these? and would they possibly migrate to different electrodes accordingly? or maybe I just start trying to over think something I have not a grasp on yet?

How would you set this up?

I do know if over charging a lead acid battery you will drive off gases that normally would stay in solution much better, mostly water splitting but they can also carry some acids with them, maybe from popping gas bubbles, as sulfuric I dont believe should leave as gas.

Think about what the gas bubbles are. Every bubble I have seen is made up of a gas on the inside being held together by a thin film of liquid on the outside. The liquid is the sulfuric electrolyte. Is it possible for gas to escape the solution without being inside of a bubble? I'd have to think about that. I guess I have seen bubbles break at the solution surface and release only the gas into the air.

Sorry I didn't do better.

When you add a lot of things to the mix, there are a lot of possible things than can occur, each with a certain affinity. The possibility of some certain thing occurring is dependent on many variables, such as the individual ratios of the concentrations of the constituents. Also, all of these charged things can interact with each other electrically. It's truly a bucket of worms.

Chris

 

[butcher]

Chris, I think you did an exellent job, of answering my questions. I have a hard time stating a question that someone might understand.
Alot of times when I see something happen, my mind is not satisfied by just seeing. I have to try to find out why, what if, and most any detail I can, sometimes when just seeing should be enough.
thanks again GSP it truly is a bucket of worms.

 

[philddreamer]

Thank you guys!

I enjoyed all the information. I also like to know the "why"; & I just learned the why of few more things.

phil

 

[golddie]

I have silver nitrate and I have droped the silver with table salt
I seperate the liquid from the silver chloride.

What is this remaining solution
what metals are in it.
Can I throw it away in the sink or do I have to neutrlize it
also neutrlize it with what
Thanks

 

[lazersteve]

It's a mixture of nitric acid, water, and base metal nitrates.

Do not dump it in your drain!

Search the forum for copper nitrate and you will find disposal instructions and alternate uses.

Steve

 

[usbfreak]

Respected Chemists,
How can i recover usable and saleable materials (like sulphates and others) from spent sulfuric acid solution(98% H2SO4 diluted with water in the ratio of 1:50 approx) used for pickling iron (containing impurities like sand etc. ) ?
:?:

 

[solar seeker]

well given the vagueness of your question I would suggest filtering the sulfuric acid soluiton then boiling it down untill the solution reaches the point where the metal salts precipitate out. If the sulfuric acid isn't reasonably usable begin focusing on removing one type of contamanant at a time. The stuff in the filter will doubtlessly include the sand that you mentioned and likely iron compounds. The stuff that precipitated out may include many different metal sulfates or sulfites that dissolve in water but not sulfuric acid.

Knowing exactly what went into a solution is the key to knowing how to get it out.