Melting A Copper Disk with Melt Dish and Torch

[kadriver]

Hello:

I have a 3 liter jar full of used copper wire coils in distilled water.

I use relatively thin 12 gauge copper wire rolled into nice neat coils to cement silver out of my silver nitrate solutions.

The used copper coils in the 3 liter jar mentioned above are the remnants from that process.

I use 12 gauge copper wire instead of buss bars, tubing, or sheet copper because I was able to get a couple of hundred feet of it (3-strand solid copper wire) at a yard sale for under $5 bucks.

As the silver cements, the copper wire gets smaller in diameter. If the copper wire is allowed to stay in the silver nitrate too long, then it will get too thin and little pieces of copper wire will break off from the main coil and possibly contaminate the cemented silver.

I watch the coils closely and just before the copper wire starts to get too thin, I remove the coil(s) and rinse all the silver and silver nitrate off with a squirt bottle.

Once the used coil of copper wire has been removed from the silver nitrate solution, and the silver has been rinsed off, I place the too-thin used copper coil in a 3 liter container full of distilled water.

I then suspend a fresh clean coil of copper wire back into the silver nitrate to continue cementing all the silver out of the solution.

I have several pounds of these used, too-thin copper wire coils. I want to reuse them for cementing silver but they are not suitable because they are too-thin and they may end up contaminating the silver.

I have been toying with the idea of building or buying a furnace so that I could melt & pour some nice copper bars out of these too-thin copper coils and use them for cementing silver.

But I can't seem to justify a furnace, other than to have a new toy.

I have made some fairly decent solid copper disks out of the too-thin copper coils using only an insulated melting dish and an oxy/acet torch.

Once I have accumulated a bunch of the too-thin copper coils, I placed them into a large insulated melting dish and cranked up the oxy/acet torch and melt them into a nice disk of copper.

The dish is insulated with a type of white fleece high temp wool material that I got from a friend of mine who works in the molten metal industry. I form the insulation around the bottom of the dish to keep in as much heat as possible.

My friend also gave me two light weight refractory bricks. They are almost as light as styrofoam but they are high temp. These can be hewn out to form a cavity that a melting dish can fit into. But I have not used these yet.

During the melt, I use lots of borax as a kind of flux. I can't get the entire disk molten all at once so I kind of run a molten pool around the entire disk surface until all the holes are filled in. It takes a lot of heat and time to do it.

Once it is fully formed into a solid disk, I turn the torch off and quickly pry the copper disk out of the melting dish using pliers and a screwdriver while it is still cherry red and the flux is still somewhat molten.

If the borax cools off and sets up, then I believe that the dish would probably have to be broken to get the copper disk out, or the dish would have to be reheated - but I have never had this happen. I have had the dish break from squeezing it too hard with the pliers.

I can reuse the melting dish a couple of times if I don't break it during the pry out.

The disks that I have made actually came out looking pretty good. About 3.75 to 4 inches in diameter and 3/8 inch thick in the middle. They were bright and shiny after I gave them a bath in warm dilute sulfuric acid.

The top of the disk looked relatively uniform, but the bottom next to the melting dish was irregular with pockets and depressions.

I drilled a hole in the disk, put a string through it and suspend it in silver nitrate to cement out silver.

I have a full jar of too-thin copper wire. I will make a disk of copper out of the too-thin copper coils I have. Then I will take some pictures and post them on the forum.

Comments and critique on this process would be welcomed and appreciated.

kadriver

 

[butcher]

I would not waste the fuel on the old wire, use that wire in dropping values from your waste solutions like stock pots, or add it to your copper scrap bin.

You can get buss bar from an old breaker panel, or copper bars from large breakers when your getting the silver contacts off them, or take a say six inch long piece of 1 1/2" inch copper pipe some large tin snips or hack saw cut long ways and fold open hammer flat, punch hole in one end to put piece of copper wire in to hang on the side of your cementing vessel.

For as much silver as your dealing with get some buss bar.

If you do melt copper use carbon source (charcoal) (flour) (sodium carbonate) in your flux copper oxidizes easily and burns off in gas, have you noticed the blue green flame anytime copper is in a fire.

 

[nickvc]

Butchers advice is as usual excellent. The use of the bits of wire for your stock pot is a win win situation and just adding it to your clean scrap copper pile could be good too if you can get one of your local scrap yards to swap your copper wire for bar or sheet, with a little profit for them,for cementation.

 

[Harold_V]

There is an avenue you can pursue that will cost you nothing, and you'll be able to fully consume the thin copper wire. It's simple----start with a small amount of the thin wire, less than is required to cement the silver in solution. When it has been totally consumed, add large pieces to finish the cementing process. Give it plenty of time to do it's work, and agitate the solution occasionally. I used to do that with a gloved hand. Takes but seconds to accomplish the task. When you see no signs of the added wire, you'll know it's time to add larger pieces.

Unless you have good reason to do so, don't melt the stuff. The cost makes it a less than good investment, especially when you can get full use without doing so.

Harold

 

[dtectr]

As I recall, when I was in high school (yeah, in caveman days ;-p ) my metals teacher, Mr. Nelson, strongly cautioned us re: melting/welding the copper family without proper ventilation due to fumes. I do not remember which fumes were involved, however.

 

[kadriver]

As usual the least complicated answer is found to the best answer.

Adding the too-thin coils to a fresh batch of silver nitrate and waiting until they are completely consumed seems like the way to go.

I won't have to use any resources, and the product gets completely used without any waste.

Plus I don't have to wash the coils anymore - it was time consuming and added to the volume of waste I was generating. Another beneficial short-cut.

It is amazing how the simplest answer to a problem can be so elusive due to lack of experience.

The forum has just solved another problem for me.

Thanks to all for your responses. Thanks for sharing your experience Harold.

kadriver

 

[notch]

As I recall, when I was in high school (yeah, in caveman days ;-p ) my metals teacher, Mr. Nelson, strongly cautioned us re: melting/welding the copper family without proper ventilation due to fumes. I do not remember which fumes were involved, however.

My thinking that it's the Zinc in Brass.

 

[kadriver]

I had a couple problems when I tried to cement some silver tonight. I got then worked out but I am curious as to the cause.

First, and this is not one of the problems, I was able to dissolve 854 grams of clean sterling silver in only 800 ml distilled water and 850 ml 68% nitric acid.

I cooked it for a few hours (about 3) until all the metal had dissolved into solution without a trace of metal left in the container.

Here is my first question: If it takes 1.22 ml nitric to dissolve 1 gram of sterling, as I have read elsewhere on this forum, then how can it be that I was able to dissolve 854 grams of steriling plates using only 850 ml nitric acid?

In past experience, I was getting some brown gas from my silver nitrate solutions when I added the copper wire to cement out the silver, plus the container would heat up.

When this happened, I would add urea to neutralize the excess nitric, and the gassing stopped. The silver then cemented out with no problem.

This was happening on every batch of silver however - excess nitric and brown gas - so I decided to cut the amount of acid back to see what would happen.

I reasoned that if some of the silver was left undissolved because not enough acid was added, then I could just put the undissolved bits in with the next batch. This, I thought, would garantee that all the nitric would be used and none wasted. I still beleive this to be true.

I have cut back the amount of nitric acid I use to dissolve incinerated 925 and sterling silver. I only use 1 ml nitric and a little less than 1 ml distilled water and the result is this - The silver gets digested with very little solid silver left over - if any.

Maybe there is something I am overlooking, but I am glad that I no longer have to deal with brown gas, urea, and a hot beaker.

Here is one of the problems I spoke of at the beginning of this post; After filtering the solutions using the process, weights, and volumes described above, I suspended a coil of copper wire in the silver nitrate. Normally the silver begins to cement right away and starts falling off the copper to the bottom of the beaker.

But in this case the copper coil quickly became covered with a tough coating of silver and then the cementing action stopped - no silver was forming and falling to the bottom of the container like I am used to seeing.

It looked like I had a silver plated coil of copper hanging in a clean blue solution of silver nitrate. I even let it hang there and walked away. When I returned hours later, nothing. Just the same coil with a hard coating of silver on it. No silver in the bottom of the beaker.

To solve the problem, I grabbed the coil with a gloved hand (something I would have never dreamed of doing before Harold suggested it in his post above) and bent the wire to break the silver coating that had encrusted over the copper wire. I then put the copper coil back into the solution.

After breaking the crust off the copper coil, I added about 300 ml or so of distilled water to the solution. the cementing action began. I concluded that the solution might have been too concentrated. Not too sure though.

I am not used to working with this large amount of silver, usually only about 400 to 600 grams at a time.

But this time I had 850 grams of metal in about 1650 ml of liquid. I think that it was much more concentrated than I am used to working with.

Here is the second problem that I was able to solve; the nitric acid was so depleted in one batch of silver nitrate that the exact opposite happened. When I put the copper coil in the solution, it just sat there and no silver formed on the coil! Eventually some tiny particles of silver began to form.

I was baffeled. I solved this problem by adding about 6 or 8 ml of nitric acid to that container. The silver began cementing out but it was was very slow to start.

Just when I was starting to think I was getting the hang of all this I experience two totally different problems that baffeled me - at first.

Once the cementing was underway and everything was looking good, I actually took some of the too-thin coils I had stored and added them to the container of silver nitrate. The too-thin coils were quickly and completely dissolved, just as Harold had described earlier in this post.

I added some more too-thin copper coils to the liquid and stood there and stirred it until it was completely dissolved. It was kind of satisfying to be able to use those pieces of too-thin wire and have them dissolve into silver right in front of my eyes.

I am used to keeping those tiyn bits of copper wire out of the silver nitrate at all costs. So it was a bit uncomfortable putting them into the solution.

But in the end all the small pieces of copper were completely dissolved and turned into silver.

Can anyone explain why I got a hard crust of silver to form on the copper wire? I suspect that it was due to high concentration of silver and low amount of nitric acid. I know that the hard crust probably encased the copper and prevented the silver nitrate from getting to the copper which is why it did not cement out any more silver.

thank you - kadriver

 

[Harold_V]

Your assumption is correct. A heavily concentrated silver nitrate solution does not cement well, nor does a solution devoid of free nitric. Adding water to dilute, and a few drops of nitric would be the right thing to do.

On the subject of concentrated solutions, I had that experience more times than I care to relate. Because I used large chunks of copper for cementation, there were times when the silver had adhered so tightly that I was unable to dislodge the plated surface entirely. On such an occasion, I'd bare a portion of one side, so it could cement, then allow it to work from there. There were occasions where the balance of the plating remained, and was liberated only after the copper had been dissolved from the opposite side.

Harold

 

[Grassbur]

I had a couple problems when I tried to cement some silver tonight. I got then worked out but I am curious as to the cause.

First, and this is not one of the problems, I was able to dissolve 854 grams of clean sterling silver in only 800 ml distilled water and 850 ml 68% nitric acid.

I cooked it for a few hours (about 3) until all the metal had dissolved into solution without a trace of metal left in the container.

Here is my first question: If it takes 1.22 ml nitric to dissolve 1 gram of sterling, as I have read elsewhere on this forum, then how can it be that I was able to dissolve 854 grams of steriling plates using only 850 ml nitric acid?

In past experience, I was getting some brown gas from my silver nitrate solutions when I added the copper wire to cement out the silver, plus the container would heat up.

When this happened, I would add urea to neutralize the excess nitric, and the gassing stopped. The silver then cemented out with no problem.

This was happening on every batch of silver however - excess nitric and brown gas - so I decided to cut the amount of acid back to see what would happen.

I reasoned that if some of the silver was left undissolved because not enough acid was added, then I could just put the undissolved bits in with the next batch. This, I thought, would garantee that all the nitric would be used and none wasted. I still beleive this to be true.

I have cut back the amount of nitric acid I use to dissolve incinerated 925 and sterling silver. I only use 1 ml nitric and a little less than 1 ml distilled water and the result is this - The silver gets digested with very little solid silver left over - if any.

Maybe there is something I am overlooking, but I am glad that I no longer have to deal with brown gas, urea, and a hot beaker.

Here is one of the problems I spoke of at the beginning of this post; After filtering the solutions using the process, weights, and volumes described above, I suspended a coil of copper wire in the silver nitrate. Normally the silver begins to cement right away and starts falling off the copper to the bottom of the beaker.

But in this case the copper coil quickly became covered with a tough coating of silver and then the cementing action stopped - no silver was forming and falling to the bottom of the container like I am used to seeing.

It looked like I had a silver plated coil of copper hanging in a clean blue solution of silver nitrate. I even let it hang there and walked away. When I returned hours later, nothing. Just the same coil with a hard coating of silver on it. No silver in the bottom of the beaker.

To solve the problem, I grabbed the coil with a gloved hand (something I would have never dreamed of doing before Harold suggested it in his post above) and bent the wire to break the silver coating that had encrusted over the copper wire. I then put the copper coil back into the solution.

After breaking the crust off the copper coil, I added about 300 ml or so of distilled water to the solution. the cementing action began. I concluded that the solution might have been too concentrated. Not too sure though.

I am not used to working with this large amount of silver, usually only about 400 to 600 grams at a time.

But this time I had 850 grams of metal in about 1650 ml of liquid. I think that it was much more concentrated than I am used to working with.

Here is the second problem that I was able to solve; the nitric acid was so depleted in one batch of silver nitrate that the exact opposite happened. When I put the copper coil in the solution, it just sat there and no silver formed on the coil! Eventually some tiny particles of silver began to form.

I was baffeled. I solved this problem by adding about 6 or 8 ml of nitric acid to that container. The silver began cementing out but it was was very slow to start.

Just when I was starting to think I was getting the hang of all this I experience two totally different problems that baffeled me - at first.

Once the cementing was underway and everything was looking good, I actually took some of the too-thin coils I had stored and added them to the container of silver nitrate. The too-thin coils were quickly and completely dissolved, just as Harold had described earlier in this post.

I added some more too-thin copper coils to the liquid and stood there and stirred it until it was completely dissolved. It was kind of satisfying to be able to use those pieces of too-thin wire and have them dissolve into silver right in front of my eyes.

I am used to keeping those tiyn bits of copper wire out of the silver nitrate at all costs. So it was a bit uncomfortable putting them into the solution.

But in the end all the small pieces of copper were completely dissolved and turned into silver.

Can anyone explain why I got a hard crust of silver to form on the copper wire? I suspect that it was due to high concentration of silver and low amount of nitric acid. I know that the hard crust probably encased the copper and prevented the silver nitrate from getting to the copper which is why it did not cement out any more silver.

thank you - kadriver

We refined (Partially, our anodes are all poured) 100 ozt this past weekend.

We had 4-3l beakers, 2 contained 200ml 68% nitric/200Ml water, 10 ozt .925 over a hotplate on low.

I know that this is about 180ml shy of the required amount of nitric and we would usually have about 4 ozt remaining out of each run.

We did not want to add more nitric because with every 50ml of nitric, you have to dilute it with 500ml of water. (before cementing)

So with the 200ml nitirc, 200ml water, and 10ozt, you beaker was 500ml full. Add in the required 2000ml water after the reaction dies and your 3000ml beaker is 2500ml full.

The other 2 Beakers where Cementing with Buss bar. So at all times we had 2 beakers dissolving and 2 beakers cementing.

I had a question though through this process.

The first 10 or so minutes of cementing, all the silver was shiny in color, after 20 minutes (And a sizable pile of cement) the coating on the Buss started to become darker gray and some began to float. Why is this?

Is the Darker color actually copper eating off with the silver?

Is the stuff floating because the nitric is to strong??

Thanks,
Grassbur

 

[Barren Realms 007]

I had a couple problems when I tried to cement some silver tonight. I got then worked out but I am curious as to the cause.

First, and this is not one of the problems, I was able to dissolve 854 grams of clean sterling silver in only 800 ml distilled water and 850 ml 68% nitric acid.

I cooked it for a few hours (about 3) until all the metal had dissolved into solution without a trace of metal left in the container.

Here is my first question: If it takes 1.22 ml nitric to dissolve 1 gram of sterling, as I have read elsewhere on this forum, then how can it be that I was able to dissolve 854 grams of steriling plates using only 850 ml nitric acid?

In past experience, I was getting some brown gas from my silver nitrate solutions when I added the copper wire to cement out the silver, plus the container would heat up.

When this happened, I would add urea to neutralize the excess nitric, and the gassing stopped. The silver then cemented out with no problem.

This was happening on every batch of silver however - excess nitric and brown gas - so I decided to cut the amount of acid back to see what would happen.

I reasoned that if some of the silver was left undissolved because not enough acid was added, then I could just put the undissolved bits in with the next batch. This, I thought, would garantee that all the nitric would be used and none wasted. I still beleive this to be true.

I have cut back the amount of nitric acid I use to dissolve incinerated 925 and sterling silver. I only use 1 ml nitric and a little less than 1 ml distilled water and the result is this - The silver gets digested with very little solid silver left over - if any.

Maybe there is something I am overlooking, but I am glad that I no longer have to deal with brown gas, urea, and a hot beaker.

Here is one of the problems I spoke of at the beginning of this post; After filtering the solutions using the process, weights, and volumes described above, I suspended a coil of copper wire in the silver nitrate. Normally the silver begins to cement right away and starts falling off the copper to the bottom of the beaker.

But in this case the copper coil quickly became covered with a tough coating of silver and then the cementing action stopped - no silver was forming and falling to the bottom of the container like I am used to seeing.

It looked like I had a silver plated coil of copper hanging in a clean blue solution of silver nitrate. I even let it hang there and walked away. When I returned hours later, nothing. Just the same coil with a hard coating of silver on it. No silver in the bottom of the beaker.

To solve the problem, I grabbed the coil with a gloved hand (something I would have never dreamed of doing before Harold suggested it in his post above) and bent the wire to break the silver coating that had encrusted over the copper wire. I then put the copper coil back into the solution.

After breaking the crust off the copper coil, I added about 300 ml or so of distilled water to the solution. the cementing action began. I concluded that the solution might have been too concentrated. Not too sure though.

I am not used to working with this large amount of silver, usually only about 400 to 600 grams at a time.

But this time I had 850 grams of metal in about 1650 ml of liquid. I think that it was much more concentrated than I am used to working with.

Here is the second problem that I was able to solve; the nitric acid was so depleted in one batch of silver nitrate that the exact opposite happened. When I put the copper coil in the solution, it just sat there and no silver formed on the coil! Eventually some tiny particles of silver began to form.

I was baffeled. I solved this problem by adding about 6 or 8 ml of nitric acid to that container. The silver began cementing out but it was was very slow to start.

Just when I was starting to think I was getting the hang of all this I experience two totally different problems that baffeled me - at first.

Once the cementing was underway and everything was looking good, I actually took some of the too-thin coils I had stored and added them to the container of silver nitrate. The too-thin coils were quickly and completely dissolved, just as Harold had described earlier in this post.

I added some more too-thin copper coils to the liquid and stood there and stirred it until it was completely dissolved. It was kind of satisfying to be able to use those pieces of too-thin wire and have them dissolve into silver right in front of my eyes.

I am used to keeping those tiyn bits of copper wire out of the silver nitrate at all costs. So it was a bit uncomfortable putting them into the solution.

But in the end all the small pieces of copper were completely dissolved and turned into silver.

Can anyone explain why I got a hard crust of silver to form on the copper wire? I suspect that it was due to high concentration of silver and low amount of nitric acid. I know that the hard crust probably encased the copper and prevented the silver nitrate from getting to the copper which is why it did not cement out any more silver.

thank you - kadriver

We refined (Partially, our anodes are all poured) 100 ozt this past weekend.

We had 4-3l beakers, 2 contained 200ml 68% nitric/200Ml water, 10 ozt .925 over a hotplate on low.

I know that this is about 180ml shy of the required amount of nitric and we would usually have about 4 ozt remaining out of each run.

We did not want to add more nitric because with every 50ml of nitric, you have to dilute it with 500ml of water. (before cementing)

So with the 200ml nitirc, 200ml water, and 10ozt, you beaker was 500ml full. Add in the required 2000ml water after the reaction dies and your 3000ml beaker is 2500ml full.

The other 2 Beakers where Cementing with Buss bar. So at all times we had 2 beakers dissolving and 2 beakers cementing.

I had a question though through this process.

The first 10 or so minutes of cementing, all the silver was shiny in color, after 20 minutes (And a sizable pile of cement) the coating on the Buss started to become darker gray and some began to float. Why is this?

Is the Darker color actually copper eating off with the silver?

Is the stuff floating because the nitric is to strong??

Thanks,
Grassbur

You can cement out your silver with out diluting your solution 10x with water.

 

[Harold_V]

The first 10 or so minutes of cementing, all the silver was shiny in color, after 20 minutes (And a sizable pile of cement) the coating on the Buss started to become darker gray and some began to float. Why is this?

It's hard to say with certainty, but I'd expect that's the results of the silver content lowering, so the deposit is growing slower and finer. Large surfaces reflect light much better than do small surfaces---evidence of which we see when we precipitate gold.

Is the Darker color actually copper eating off with the silver?

Not sure what you mean by your question---but you should understand that there's an electron exchanged between the copper and silver, which results in the silver coming out of solution, and the copper going in to solution (it's being dissolved, for lack of better terminology). Copper has no reason to be "eaten off" without yielding silver in the process, although if you have excessive nitric acid present, that may not be the case. That condition will generally result in copper dissolving, along with silver, until a state of equilibrium is achieved. You'll know when that's happening because it will be gassing off that familiar brown cloud.

Is the stuff floating because the nitric is to strong??

It can be. Do you see any of that brown cloud we're talking about? Can you smell it? I found that to be a positive test, although I generally did my cementing in the mouth of the fume hood. It's a good idea to vent the hydrogen that is liberated instead of allowing it to build up in the room.

Harold

 

[Grassbur]

Do you see any of that brown cloud we're talking about? Can you smell it? I found that to be a positive test, although I generally did my cementing in the mouth of the fume hood. It's a good idea to vent the hydrogen that is liberated instead of allowing it to build up in the room.

Harold

Yes, I will see a small brown puff when I give the floating pieces a good stir. I came to the conclusion that the Nitric was too strong because on some dissolving batches, the Nitric seemed to get used up and nothing would float, all the cement would just drop to the bottom.

If I where to take 10 ozt of silver, 300ml of 68-70% nitric, and 300ml of water then how much water would i need to dilute it with after the reaction? I would have thought 3000ml (10x Nitric content) is needed. You are saying that you don't need that much. Is there a different ratio that you use? Or is it a case by case using an eye test?

I don't recall Hoke talking about cementing with Copper, only the Chloride Method.

 

[Harold_V]

If I where to take 10 ozt of silver, 300ml of 68-70% nitric, and 300ml of water then how much water would i need to dilute it with after the reaction? I would have thought 3000ml (10x Nitric content) is needed. You are saying that you don't need that much. Is there a different ratio that you use? Or is it a case by case using an eye test?

I may not be the best person to answer these questions. I was never overly concerned about ratios---no more than I was concerned about the use of distilled water. I used it only for making my electrolyte---otherwise I used tap water for all of my dilutions. The traces of silver chloride weren't a concern for me, in particular when you consider that silver was selling for well under $4/ounce for the majority of time when I was refining.

Back to the question, I'd dilute my acid (68%---tech grade) roughly 50%, by volume, when it was applied. I heated, and drove the temperature to boiling, which accelerates the reactions, and shows a positive indicator that all nitric has been consumed. When I was satisfied that I had either consumed all of the silver and base metals, or the nitric, I then filled the vessel (always a beaker, in my case) with tap water, to cool the solution, then after allowing a few moments for the values to settle, I'd pour off the solution. It was immediately set for cementation, so if I had to venture a guess as to the dilution rate, I'd suggest it was likely more like one part nitric to three parts water.

It's easy enough to know if you have the solution too concentrated---it plates out a solid film instead of the cement silver you hope to achieve. If you find that's happening, dilute more. If you find you don't have enough free nitric (just a little is required), dribble in a few drops and stir well. While there may be an optimum ratio, it will work through a wide range---so keep it simple. No need to lose any sleep, for in the end, you'll recover the silver and that's the objective.

I don't recall Hoke talking about cementing with Copper, only the Chloride Method.

It has been many years since I last looked at her book. I retired from refining in '94. However, that she discusses the use of copper, or not, I can't say, but make that your routine. Avoid working with silver chloride unless you have a good reason to do so. Beyond that, if you cement with silver, you'll also cement traces of greater values, which commonly find themselves dissolved along with silver, in particular if it has been used for inquartation. Silver becomes the carrier, assuring you do not lose them. They are recovered in the silver cell, reporting in the slimes.

Hoke treated silver with considerable contempt. As I recall, she recommended silver by sent to major refiners. That may have made sense for the benchman that was a goldsmith, and was concerned with the recovery of his gold for reuse, but as a home refiner, you should pay strict attention to four metals. They will make their presence known to you almost routinely. They are silver, gold, palladium and platinum.

Harold

 

[Grassbur]

"I was never overly concerned about ratios---no more than I was concerned about the use of distilled water. I used it only for making my electrolyte---otherwise I used tap water for all of my dilutions."

I agree with this whole heatedly. It stands to reason that the minerals/metals that might come from the tap water would be easily removed in the cell.

"It's easy enough to know if you have the solution too concentrated---it plates out a solid film instead of the cement silver you hope to achieve."

I believe that this is the gray "cement" I was referring to earlier in this thread so that makes sense.

I had one more question. I was reading the PDF you wrote awhile back, this is the thread that i found it in

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=5398

While reading about the silver cell and it's construction, I got the impression that the cell was purchased with all the required materials by the reader. Did you, at one time sell manufactured silver cells? Maybe I am misinterpreting the reading, but I am still curious!

Thanks again for sharing your wisdom. I have always said there is no such thing as a free lunch. That may hold true, but this "Free Forum" has provided me with knowledge to acquire many lunches

 

[Harold_V]

It stands to reason that the minerals/metals that might come from the tap water would be easily removed in the cell.

Assuming they made it that far. Minerals should be easily removed in the melting process, when the anodes are cast. I always used borax in melting the cemented silver, which was poured to a cone mold, cleaned, then re-melted to pour anodes.

Key concern with using tap water is the conversion of silver to silver chloride, which is lost when the silver is melted. I had to weigh the minor loss (my water was chlorinated) against the cost of distilled water, but I couldn't justify the cost or the inconvenience of using distilled. In addition, much of the silver chloride I developed ended up in my waste materials, where I expected it to function as a collector for greater values. I had gone out on a limb on that decision, not knowing if it would function as hoped, but was rewarded with a huge recovery of gold, platinum and palladium when my waste materials were processed by furnace just prior to my retirement. I now pronounce it a resounding success.

While reading about the silver cell and it's construction, I got the impression that the cell was purchased with all the required materials by the reader. Did you, at one time sell manufactured silver cells? Maybe I am misinterpreting the reading, but I am still curious![/quote]
When I retired, I sold my entire operation, including the silver cell. I question if, maybe, that's what you read. I was never in the business of providing equipment. I built my own cell, as well as a large sulfuric stripping cell, but for my own use. The only exception was the twin to the sulfuric stripping cell. I was flown to New Mexico (from Utah) by a customer, so I could see a cell in operation. I then designed and built a cell for him (along with one for myself). It was one of those strange circumstances where my hobby spilled over to my machine shop. I was machining full time when this occurred.

I have always said there is no such thing as a free lunch. That may hold true, but this "Free Forum" has provided me with knowledge to acquire many lunches

True enough, but only through the generosity of those of us that are willing to spend our time here, attempting to help other so they, too, may achieve success.

The point about a free lunch is only half of the statement. While it's true that some receive the "free lunch" in question, it is free only because others are willing to donate our time. That's the point, one that many lose track of. Anything free costs someone, somewhere, something. They shoulder the cost so others can benefit. That's been my philosophy as long as I've moderated, which has been a long time. I do what I do because I firmly believe that knowledge should be shared, and that we repay our debt to mankind by passing on the things we learned from others. Rarely does one *own* knowledge----it generally comes from others. I know mine did. Considering it was *gifted* to me, I have an obligation to pass it forward.

Harold

 

[Photobacterium]

Hello:

I have a 3 liter jar full of used copper wire coils in distilled water.

I use relatively thin 12 gauge copper wire rolled into nice neat coils to cement silver out of my silver nitrate solutions.

i had some copper wire from an old Monster Cable all ready for a cementation. (of silver from copper/silver nitrate mixture).

then i had second thoughts about using a copper source so finely stranded. i was concerned that small pieces might fall of and get "lost" in the silver metal powder. since Lazer Steve used solid copper pipe in the tutorial, i went back to that.

but i still have that copper wire laid out, twisted, bent to hang over the edge of the beaker - ready to go.

since your silver bars are beautiful, i gather it's not a problem.

does the stranded wire work better for cementation than solid copper pieces ?

anyway, i'm encouraged to hear that you use stranded copper wire - since i got a bunch of it ! and i wanted to save the copper tubing for more productive purposes 8)

 

[Geo]

if you use copper pipe, slice the pipe length wise on one side (i use my dremmel) then spread the pipe open and beat flat with a hammer. it gives you a nice copper sheet to work with.

 

[Harold_V]

then i had second thoughts about using a copper source so finely stranded. i was concerned that small pieces might fall of and get "lost" in the silver metal powder.

Bingo!
There's nothing wrong with using fine wire, so long as you KNOW it will all be digested. Otherwise you end up contaminating your silver, which drastically shortens the useful life of your electrolyte in a parting cell. If you must use fine wire, use it sparingly, then finish off with a piece of copper that can be retrieved. In the long run, you'll use all of the fine wire and not have paid a price for doing so.

Harold

 

[kadriver]

I started using thin wire to cement silver, but I began to get tiny bits of the copper wire in my cemented silver.

I decided to melt the copper wire in a melt dish. I got some soft light weight refractory brick from a friend who is in the molten metal industry - he sells refractory to metal plants.

I carved a cavity out of two of these bricks to insulate the melt dish so I could make a copper disk.

The refractory brick worked so well that the copper melted completely.

As I melted the copper wire I noticed that the metal was liquid, just like I am used to seeing when I pour silver bars.

Using an old graphite mold, I attempted to pour a copper bar - it worked perfectly!

I now have an open face furnace for melting and pouring copper bars.

I kept a mapp torch on the dish and used the oxy/acct to do the melt.

It melted completely and I was able to pout 16 bars each weighing 150 grams or so.

This was an unexpected and pleasant surprise as I thought the copper would never get hot enough with a torch, let alone be able to pour bars!

kadriver