# Lessons learned...



## AuMINIMayhem (May 3, 2007)

Hey guys, ok so I've finished with the cell and began the task of trying to "smelt".. uhhh. yeah.. not working out so well..

Here's a couple things I learned..

2000f.. hot. very VERY hot! :shock: :lol: 

The Paragon Q11a kiln does not like it when you drop (spill, overflow, whatever) either Boric Acid, Sodium Nitrate or Glass on the floor.. the tiles will melt into a gooey mess at any temp over about 1800..  

graphite crucibles are pourous.. the glass in your flux will bleed through, if you don't pay attention (not to mention the crucible degraged to an unusable condition after one firing.. :evil: )

Those gold flakes... not gold.. not even close..  don't waste your time..

Nitric acid is insanely hard to come by (I know, I know.. there's a recipe to make your own... I'm just not equipped to do that at the moment)

The fumes from Sodium nitrate burning off in the kiln are fairly corrossive to the paint of your kiln (watch that steam!).. they're also fairly irritating even in the open air.. very good at aggravating the sinuses.. 

but I do have a button to show off.. pretty sure that it's rediculously unpure, but hey.. it's my first attempt! cut me some slack will ya? :lol: 


*more updates to follow.. you may comment and laugh at my expense as you see fit.. *


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## lazersteve (May 3, 2007)

Mayhem,

I'm glad to see the misses let you come out and play with us... I was starting to worry about you. :lol: 

I'm sorry to hear about your mishaps with the kiln and all.

I know you think nitric is out of your grasp, but you mentioned one of the two ingredients in your post: sodium nitrate. All you need now to make it is to stop into a Napa auto parts store and grab a $5 bag-in-a-box of battery electrolyte and a few good glass vessels, a scale, table salt, and ice. Don't forget the safety equipment too.

I noticed you mentioned Boric Acid, I'm not sure if you can substitute boric for* borax*, they are not the same thing. The borax is just plain laundry detergent, 20 Mule Team, found at Wal Mart on the cleaning supplies isle.

Great to hear from you!

Steve


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## goldsilverpro (May 3, 2007)

I'm not laughing.

I found your furnace on the net. Did you buy this one or the one with the more expensive controller?
http://www.bigceramicstore.com/Supplies/kilns/KNPGQ11A.gif

If you bought the one pictured, you'll really have to keep an eagle eye on the temperature, as it's heating up, and remember the settings you need and don't exceed these settings except to fine adjust. If you turn it on high and walk away, you could have a total meltdown, and then you'll have to replace the element and the tiles - a big job. The name of the controller on this cheaper model contains the word "infinite". If you think about it, that's a scary word. It took me a couple of meltdowns before I learned to spend more money for a better controller. The cheaper controllers work but, you really have to keep an eye on them.

*Don't use niter (sodium nitrate)*. This is what is destroying the carbon crucible. All you need to melt gold is a little borax. The niter also may be weakening the tiles. You could get a few inexpensive clay fire assay crucibles to melt in, but still, don't use niter.

If the tiles soften at 1800 F., something is wrong. The literature says the furnace goes to 2300. If the tiles are softening at that temperature, contact the mfgr. It could also be the niter or, it may be hotter than you think. What color is the hot chamber? Light yellow is about where you want to be. If it's white hot, it's too hot.

Actually, in the picture, it looks like a pretty good little furnace. You could even run fire assays in it.

As you discovered, you need some pretty long tongs (about 18"). You'll also need welder's leather gloves, at least. 

*NO NITER!*


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## AuMINIMayhem (May 3, 2007)

yep.. that's the kiln. Yeah, it looks like what would happen if I spilled some of that green "blood" from the Alien movies in there..LOL!.. actually I called the manufacturer and I can replace the tiles fairly cheaply.. so no harm no foul on that..

as far as the Soda of Nitrate whoooops! too late.. it's mixed in with my powders.. can't think of a way of removing it short of heavy heavy rinsing (no way.. that took wayyy too long, I don't have a vaccuum chamber.. had to let it percolate..)

Borax isn't boric acid?.. sheesh! I'm batting a million here aren't I?..    

crap..  :roll: 

Thanks guys.. oh, Steve.. I noticed you're in FL.. what part?.. I actually was born and raised in Orlando.. I'm actually trying to move back down there... perhaps if I get down there you might take on an apprentice?.. :wink: 

goldsilver.. yeah it was yellow/slightly orange hot inside .. right at 2000 maybe a little less (hard to read the pyrometer)..


well, back to the drawing board.. but I will post the picture of the "sacred lump of the unknown" later.. it's good for a :lol: anyways  

Thanks again!
Derek


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## goldsilverpro (May 3, 2007)

It's not too late. Rinse it out with hot water. If you don't, you'll just destroy more crucibles and tiles. You have to get rid of the boric acid anyway. Put it in a few (if you're using coffee filters) filter papers and start pouring hot water through it. If a lot of gold powder gets hung up in the paper, burn it to ash, with no black carbon remaining. You can then put the ash into aqua regia or melt it with a little borax. You've learned something and I guarantee it will go smoother the second time. You're doing fine. Patience.


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## AuMINIMayhem (May 3, 2007)

ahhhhhh... I'm so glad you said that, I wasn't going to admit to trying this, but... 

I was already working on pouring hot water through the powders to remove the boric acid.. plus.. I had kinda planned on burning the coffee filters past the black carbon stage.. sounds like I'm on the right track (for once..LOL!) Only thing I won't be able to wash out is the silica (#20 silica sand, already formed into glass particles.. I had ground up the whole mess with a mortar and pestle in frustration to start over again..

Thanks again, man!

Derek


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## goldsilverpro (May 3, 2007)

The silica won't hurt but, you'll need a little extra borax. Silica melts thick and the borax should thin it out a bit.

When you burn the papers, you have to get rid of all the black carbon. Carbon needs air or oxygen to burn. You can blow on the embers gently through a straw or turn on the oxygen only, very very low, on the torch. Carbon doesn't melt and it floats on top of the slag and carries gold with it.


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## goldsilverpro (May 3, 2007)

I didn't realize until I reread your post that this stuff had already been in the furnace. I thought it was another batch. I hope it rinses out. Might be iffy. If it doesn't, let me know and we'll figure something else out. If you have a melting dish or a cupel, you might be better off melting this batch with a torch.

At this point, your goals are to get all the gold and don't damage the furnace any further.


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## lazersteve (May 3, 2007)

Mayhem said:


> Steve.. I noticed you're in FL.. what part?..



I'm up in the panhandle, right outside of Pensacola.

Steve


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## goldsilverpro (May 3, 2007)

I was stationed at Eglin for awhile. My son lived in Ft. Walton Beach and owned a donut shop there. I really like that part of Florida. Getting crowded though.


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## lazersteve (May 3, 2007)

I just returned home from having dinner in Fort Walton less than an hour ago.


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## goldsilverpro (May 3, 2007)

What's the name of the island, right next to Fort Walton? When I was at Eglin, the only thing on the island was a Tiki style beer bar, white sand, and sand crabs. The last time I saw it, it was wall to wall hotels. I was shocked when I looked down on it from the bridge.


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## lazersteve (May 3, 2007)

Okaloosa Island, Navarre, or Destin, which one? Destin is the most beautiful I think, emerald green waters.. breathtaking.


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## catfish (May 3, 2007)

I can’t help but be amused at your problems with the Kiln... Take my word, it is not the kiln. I have one just like it and have melted many ounces of gold in it with out any problems. I had this oven for about a year and half, never had any problems.

My only concerns are how much flux did you use and what formula of mix with the sodium nitrate and other things you mentioned. I learned that good Anhydrous Borax works great at about 1 to 1 ratio of gold to flux. I run my oven about 45 minutes on high to really get a good flowing mix of my gold for pouring. I also use good grade clay crucibles.

I like your attitude, hang in there.

Catfish

Good luck on getting it repaired. And by the way, I have a daughter in Panama City and also a son stationed there in the Air Force.


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## AuMINIMayhem (May 4, 2007)

Catfish.. thanks.  yeah I know it's definately not the kiln.. it's absolutely a bad case of "operator error"..LOL!

I need to get some ceramic cupels.. gotta look on Ebay I guess, also I guess I need to get another MAPP torch with the Oxy hookup to try and recover this stuff.. as of right now, I think this stuff is just going to get bagged up and stuffed in the closet somewhere the dogs can't get to it until I can sink a little more cash into getting the proper equipment.. also need to repair the kiln (apparently not the most difficult task according to the customer service people at Paragon)..

I have a TON of this stuff (probably close to a pound).. if anyone is willing to experiment, I'll mail a couple ounces out to you (you keep what you get in trade for info on a good way to recover it).. just pm me and I'll get your address.. I'll even pay for the shipping.

Here's what the powder has:

1)Black precipitates from a cell built to Lazersteve's specs (as best as I could see from the tutorial).
2)Ash from the coffee filters (not a lot, but there is some carbon)
3)20 Mule Team Borax (thanks for the tip Steve!)
4) "Diamond Dust" glass particles 

all has been fired and ground up as best as I could with a mortar and pestle..

I had originally used Sodium Nitrate and Boric Acid (whoops.. thought it was the same thing  ) but after last nights' posts, I put all the powder in a bunch of coffee filters and continuously poured near-boiling water through them to rinse out the Nitre and Boric Acid while I watched "The Last King of Scotland" (great movie,btw!).. afterwards, I mixed just the Borax with what was left..


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## Gold-Digger (May 17, 2007)

Is anyone using a Kerr Electro-Melt for the smelting process? I wonder if these would work o.k.?


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## lazersteve (May 17, 2007)

The last I heard was that Precious Metals is .


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## EVO-AU (Oct 12, 2007)

Auminimayhem: I know your post is months old, but have you ever tried a Turbo Torch.? Air/acetylene. Goes a long way in cupelling. The highest heat is only about 2700 deg's, but for cupels, why not.? 
evo-au[/b]


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## goldsilverpro (Oct 12, 2007)

EVO-AU,

Just out of curiosity, is your name Mike?


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## EVO-AU (Oct 12, 2007)

Good Lord, no ? The only mike is know is a person on GMW....

Name is kuzak


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## goldsilverpro (Oct 12, 2007)

This is to answer the old post, at the top of this page, about the Kerr Electro-Melt. First off, there are other brands out there besides Kerr. They are all expensive. The last time I looked, they started at about $800. 

http://shorinternational.com/MeltFurnace.htm

I owned one of these gadgets about 25 years ago and didn't care for it. It just sat on the shelf. It seemed to take forever to heat up. Like induction furnaces, you couldn't really flux the metal to clean it up, or you would screw the crucible up. I would much prefer a small home-made gas crucible furnace. Cheaper and better.

It all depends on what you use it for. Not too long ago, we had the idea of using one to buy scrap karat gold, etc., from jewelers or pawn shops. We were going to melt the gold, stir it, pin sample it, and pour it into a bar, in front of the jeweler or pawnbroker, in his own shop. We would keep half of the sample, give him the other half, mark or stamp and weigh the bar, and let him keep it. When we finished our assay, we would go back and do the deal. He could have his sample assayed, in the meantime, if he wished. We figured the customer would like this approach because it kept everybody honest. I still think it's a good idea. 

This is the only good application I have seen for the Electro-Melt. You could also maybe find one handy for doing some jewelry castings. For the refiner, I don't think so.


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## Harold_V (Oct 12, 2007)

goldsilverpro said:


> This is to answer the old post, at the top of this page, about the Kerr Electro-Melt. First off, there are other brands out there besides Kerr. They are all expensive. The last time I looked, they started at about $800.
> 
> I owned one of these gadgets about 25 years ago and didn't care for it. It just sat on the shelf. It seemed to take forever to heat up. Like induction furnaces, you couldn't really flux the metal to clean it up, or you would screw the crucible up. I would much prefer a small home-made gas crucible furnace. Cheaper and better.



There has been some outstanding information posted on this forum through recent months, but this post is likely one of the most informative. 

I heartily endorse it, *every word*. I owned a similar furnace, a Handy-melt, and found the cost of crucibles prohibitive. Being pure graphite, they had a very short life cycle, self destructing by burning away at the top. As has already been mentioned, fluxing created unending problems. 

I do not recommend the use of one of these for refining, and would have considerable trouble coming to terms with the use of one even in jewelry manufacturing. It's just too easy to use a torch, which is faster, cheaper and, in my opinion, far better. The interesting thing is, at the price of one, a person can buy the best of oxy/acetylene torches, including bottles. A torch setup, as described, will far better serve the needs of a refiner. Jewelry supply houses sell a large Hoke torch, which I highly recommend. 

Avoiding a furnace of any kind is in your best interest. With rare exception, it is not a requirement, especially if one refines in small volume. A large melting dish will accommodate more than ten troy ounces of silver with no trouble. Only melting larger volumes would I ever consider the use of a furnace of any type. 

My recommendation for melting is using natural gas and oxygen. It's the most economical way to approach the problem, and will provide enough heat to melt even platinum. 

Regards cupelling, unless you are attempting to eliminate lead, cupelling has no place in the purification of gold. There are other methods to improve gold quality-----none of which include the use of cupels. If you are using one for any other reason, you need to change your method of operation. Cupels do not make good melting dishes. 

Harold


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## goldsilverpro (Oct 12, 2007)

I definitely agree about the natural gas and oxygen. I like it much better than propane/O2 or acetylene/O2. Also, acetylene is very dirty. Have you used hydrogen/oxygen? The cleanest of all. I like it but, you can hardly see the flame. I try to stick with natural gas/oxygen


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## Platdigger (Oct 12, 2007)

What if you have no natural gas supply? Will propane do? Guess it will have to huh.
Randy


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## Harold_V (Oct 12, 2007)

goldsilverpro said:


> I definitely agree about the natural gas and oxygen. I like it much better than propane/O2 or acetylene/O2. Also, acetylene is very dirty. Have you used hydrogen/oxygen? The cleanest of all. I like it but, you can hardly see the flame. I try to stick with natural gas/oxygen



Acetylene, especially for use in melting the platinum group, is not recommended due to the formation of carbides. 

By contrast, there is no better method to blacken a gold ingot mold. An acetylene torch has a place in refining, but should be somewhat limited in use. 

No, I never had the opportunity to use a hydrogen torch, which is the torch of choice for melting platinum. 

I had occasion to have a couple hydrogen fires through the years. My stock pot was always very close to the fume hood, so liberated hydrogen was exhausted, instead of being allowed to accumulate. On a couple occasions, I had ignition due to the use of a torch in near proximity. Nothing serious, but it was interesting to observe the flame, which was not easy to see. It would have been interesting to see a flame from a torch, based on what little I've seen. 

Harold


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## goldsilverpro (Oct 12, 2007)

Propane/oxygen works fine. Like Harold (I think I remember him mentioning it), I always preferred a rosebud tip, especially for large melts. However, a regular cheap tip will work fine.

Even with graphite molds, you get a prettier bar if you smoke the mold first with acetylene alone (using no oxygen with it). I would smoke the molds outdoors. Otherwise, you'll have streamers of carbon lying around everywhere.


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## goldsilverpro (Oct 12, 2007)

Harold,

What's the technical difference in a Hoke torch and a regular torch? I know that C.M. Hoke's father developed it for melting platinum. They are still widely sold in the jeweler's supply catalogs. If I remember right, a lime crucible was also used for platinum.

Speaking of Hoke, I've got to break down and part with the money to buy a new copy of her book. Mine went south about 10 years ago. I sure miss it. I did buy a copy of T.K. Rose's, "The Metallurgy of Gold," the other day. I needed to bone up on the Miller Chlorine process.


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## Irons (Oct 12, 2007)

Harold_V said:


> goldsilverpro said:
> 
> 
> > I definitely agree about the natural gas and oxygen. I like it much better than propane/O2 or acetylene/O2. Also, acetylene is very dirty. Have you used hydrogen/oxygen? The cleanest of all. I like it but, you can hardly see the flame. I try to stick with natural gas/oxygen
> ...



To expand on what Harold said:

Like Nickel, Platinum group metals form volatile and very toxic Carbonyls when heated in a reducing Acetylene flame. Besides losing valuable metals, it can ruin your day.

Some examples are:

Platinum Carbonyl(Chini cluster) [Pt12(CO)24]2−

Palladium Carbonyl Pd3(CO)n- (n=0-6)

Rhodium Carbonyl Rh4(CO)12


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## Harold_V (Oct 12, 2007)

goldsilverpro said:


> Harold,
> 
> What's the technical difference in a Hoke torch and a regular torch?


 
I'm not convinced there is a difference. I don't recall the brand I had, but it had a black plastic grip, and was the size of the standard Victor torch. The tip, for all practical purposes, resembled a rosebud for a Victor torch. There may be some differences in port sizes that I didn't recognize, not sure. 

I had two (identical) tips for my torch, one of which was used exclusively for melting gold prior to pouring shot-----so I had the opportunity to look at the tips quite often. They were easily changed, being held in place by a threaded collar.

I used a smaller Hoke type torch prior to buying the larger model. While the body was small, it had a rather large orifice in the tip for the torch size. Again, aside from tip diameter, it resembled the typical torch. Makes me wonder----could the welder's torch been patterned after the Hoke torch? Dunno!



> If I remember right, a lime crucible was also used for platinum.



By the time I was involved with platinum, such a vessel was not available, at least from my source. They had produced one that will withstand the melting temperature of platinum, although it does melt somewhat as well. I'm not privy to the formulation, but it must certainly be a silicon product. I recall using hydrofluoric acid to pickle the buttons I melted to remove traces of the melting dish, which would stick to the button much like borax does when melting gold. 


Damned shame about not having your copy of Hoke any longer. While I found I could operate without a reference, it was always nice to have it to refresh my memory on operations that weren't performed routinely. 

By now, readers may well understand that I am very bullish on Hoke's book. I consider it a mandatory part of refining----it is not a luxury. If you can get past her endless recommendation of tossing gasoline on the things you incinerate, the information the book contains is priceless. It likely goes without saying------gasoline has no place in the refinery-----unless your objective it to burn the building. 

Harold


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## aflacglobal (Oct 13, 2007)

It likely goes without saying------gasoline has no place in the refinery-----unless your objective it to burn the building. 

If gold is a precious metal then gas should be a precious liquid. 
Both bring about the same price. lol


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## goldsilverpro (Oct 13, 2007)

Actually, if you cut gasoline with 50% diesel, it really tames it down and makes it burn longer. I used it to burn filter papers and cloth, in a steel tray with a screen on top of it. I did it outside, of course


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