Non-Chemical Burning filters

[Lou]

Sure, it can happen. Unlikely, but it can (why, b/c copper oxide is hard to ''stick'' to, try brazing dirty copper). Point is, it is accumulated for years. Worst comes to worst, melt the copper pan into an ingot and part it electrolytically

However, that really doesn't happen because:

you don't need to incinerate to a ridiculously high temperature. It's all on how quick you want to remove the carbon. There's not too much reason to incinerate at brazing temperature (I'll call that 1600F, a good orange heat); it's just faster. I said to use Pyrex. The hottest you can really take Pyrex is about 650C which is more than enough to remove the carbon. You lose carbon quick enough at 400C.

As for stainless being used preferentially, I think it depends on the stainless. Some stainless will heat and age well (316 for instance), other stainless will flake off over time. As Harold said, quartz would be ideal.


Dissolution is something that has a different meaning to a lot of people. I routine use the term dissolve i.e. ''dissolve up the copper to leave the gold''. My idea of dissolving is to take something up into solution and have the option of either making it into something else or making it back into what it was.

Chris caught on instantly:
In the case of the filter paper, I don't really see it as dissolution because it's gone--you can't get it back, it is chemically destroyed beyond all hope of recovery. Whereas you dissolve gold, you can get it back by reducing it, or as Chris mentioned, boiling it down and decomposing it like this:
2 HAUCl4-->2 AuCl3 + 2 HCl -->2 Au + 3 Cl2

Really, this is about as close to disagreement as I come with anything I've ever seen Harold post and it's more me picking pepper than him being wrong. The cellulose does dissolve, but when it does it gets torn apart by the oxidizing and strong acid nature of conc. hot sulfuric.

 

[qst42know]

As far as the dissolving is concerned. I would guess the difference is gold being an element is essentially disassembled when dissolved and can be recovered, where the disassembled elements of the cellulose compound could be found and accounted for (and be recovered in elemental form) but would not be recovered as cellulose as the chemical bonds are broken by the acid, which is the likely source of the energetic reaction.

Does this sound about right for a non-chemist?

 

[qst42know]

GSP

Please don't regret posting this procedure your post was thorough and concise and described the risks involved. It is far better to know of it's existence and the dangers involved than to discover it by accident. Had this knowledge been hidden or veiled in some way I may have attempted this procedure based on my experience with a single droplet oblivious to the consequences of a much larger reaction.

It has been posted that "knowledge is the currency of the Internet". It is also true that shared knowledge is vital to safety in every field.

Had you not enlightened me in this procedure I may have been seriously injured.

As for me I can't thank you enough.

Chris

 

[Harold_V]

you don't need to incinerate to a ridiculously high temperature. It's all on how quick you want to remove the carbon.

It's a matter of volume. When you have a pan full of solids, the bottom may be hot enough to burn, but the top won't be. The bottom also will be devoid of oxygen, and will have great difficulty in absorbing that which is required because of the depth of the material.

In this instance I'm speaking from the position of years of processing exactly such materials. Without elevating the temperature to near redness, it simply doesn't oxidize completely. Once the bottom material was well heated, it was stirred. The reaction was obvious, for the remaining carbon burned brilliantly. You could roast the material for extended periods of time and not achieve equal success. Been there, done that. Whole different scenario from a few pieces placed in a container, where everything is exposed to atmosphere.

There is a place for elevated temperatures, which becomes obvious when you're faced with processing in reasonable time. That comes home to roost real fast when you attempt to process a carpet.

Really, this is about as close to disagreement as I come with anything I've ever seen Harold post and it's more me picking pepper than him being wrong

No problem. I'm not the one with the college education, you are. I expect I will learn from you, and I have.

The cellulose does dissolve, but when it does it gets torn apart by the oxidizing and strong acid nature of conc. hot sulfuric.

In a sense, cold burning. You don't get wood back when you capture and reduce the smoke from a wood fire, either.

I like the description where the elements still remain, they simply don't recombine in the same form from which they came.

Harold

 

[Oz]

First I want to say that yes, it was a good thing for GSP to post the procedure so someone would not try it w/o knowing the hazard. I was only concerned that someone would use it without the expertise needed to do it safely.

Something that Harold could have added that we had discussed late one night, is that you can achieve complete combustion of carbonatious material at a relatively low temperature if you play a bit of pure oxygen from a torch over it.

 

[Harold_V]

Thanks, Oz. I should have made mention. That was very much a part of my incinerating process. I'd heat the pan from below with the Hoke torch, then apply oxygen as the contents were stirred. It's amazing how much carbon was left behind prior to that exercise.

Harold

 

[Lou]

I would certainly bow to Harold's expertise when it comes to incineration!!! I incinerate incoming material to remove oil from the hands and any grease and for me, 2 hours or so at a dull red heat in an oxidizing atmosphere does the trick.

With something as awful as a carpet, or dirty material with a bunch of crap on it, goodness, I could only imagine that as being a real bother.

I do frequently use pure oxygen for burning off filter papers though. That I do in a shallow quartz evaporating dish over a Meker burner.

I once had a bunch of Pt stuck in graphite crucibles (well several times this happened) sent to me. I busted off as much crucible as I could, then gave it a yellow heat and played O2 over it. Worked a treat!

Lou

 

[Harold_V]

2 hours or so at a dull red heat in an oxidizing atmosphere does the trick.

I'm of the opinion that you and I are talking the same talk. My objective was always to get the base of the pan to a dull red heat. That insured combustion. Anything less was troublesome. That was obvious when I played the torch on the base of the pan, which immediately liberated smoke that otherwise would not have been evident. Note that I didn't use an oven---which would have provided a more uniform heat, very unlike heating from the bottom only.

With something as awful as a carpet, or dirty material with a bunch of crap on it, goodness, I could only imagine that as being a real bother.

Carpets are the worst item a refiner will encounter, at least in my opinion. What begins life as a huge volume of carpet ends up being several gallons of dirty ash, after incineration. Typical process for me, not having an oven, was to burn in a barrel. It always resulted in incomplete combustion, so the ash then required roasting. That was accomplished on a small melting furnace, covered with a sheet of stainless. The roasting process reduces the ash considerably in volume. Key to success, however, was the next process. I found only HCl would reduce the ash to virtually nothing, although it foamed up something fierce. In the end, what started life as more than five gallons of clean roasted ash, was now reduced to less than a quart of solids, which contained all the values. Often, the residue was now a light purple color, due in part to the large volume of very fine gold (from polishing, I surmised).

Harold

 

[Oz]

Harold,

Hearing your description of processing carpet makes it sound almost as bad as trying to make a profit from refining electronics. Since you have done a few runs of electronics as experiments, I would enjoy hearing your comparison between the two of them as to work/reward. You are probably one of the few on here that has ever run jewelers carpet.

 

[Harold_V]

I had two experiences that stand out. Each one was the opposite extreme.

The average carpet would yield a few ounces of gold. It's fairly safe to say between two and three. at least according to my experiences.

One of my old customers moved from Utah to Arizona. On his trip south, he dropped off a bunch of carpet squares. This guy didn't do a lot of work, but insisted that the carpet would be worth refining. I had serous doubts, but I catered hand and foot to my customers, always trying to do what was in their best interest.

I spent the better part of a week on his material, only to get a yield of twelve grains. For the record, that's less than a gram (15.432 grains = one gram).

All was not lost. His batch lead to my making test runs on future carpets to insure that they were worth processing.

The good side.

One of my customers dropped by one evening with his peanut can full of bench sweeps to be refined. We talked for a while then he casually mentioned that he brought the small rolled up runner he held under his arm. He said he was going to toss it in the dumpster, but thought better of the idea.

The runner was something like 3' x 5'. In the scheme of things, it was very small---so not a lot of work, but still a week's worth of effort, part time. It yielded over five ounces of gold. My normal fee of 50% for processing carpets was reduced to 35% as a result. Pound for pound, it was akin to processing polishing wastes, but more work.

Turns out the runner was placed in front of the man's polishing lathes, so he'd leave his bench and go to the lathes, regularly dropping particles of gold from his clothing, where they'd get trapped in the carpet runner.

Plated materials tend to be very poor in gold. There are exceptions, which I experienced.

Another of my customers was in the surplus electronics business, plus he was a repair station for electronic gear. He had a keen interest in precious metals, and had accumulated a lot of old military surplus. Included in his store of goods was a generous amount of old micro-wave gear. I had plans to strip the entire lot with a sulfuric cell, but never got the cell in operation. The sample lot I ran with cyanide proved content to be something like 3%---nearly rivaling gold filled materials. Cyanide was not a good choice for stripping because of premature perforation of the precious metal layer, allowing the base metal to be co-dissolved. There was no nickel barrier under the gold in this case, just brass.

I would compare the average carpet to running very high grade electronics-----they're a lot of work, and would border on impossible in today's world, where you would be hard pressed to incinerate such material. Remember, my day was a long time ago, long before there were such severe restrictions on burning. A carpet burns with roughly the same amount of black smoke as does a tire when alight. While it was customary for the out-of-doors types to burn a tire for warmth, it certainly wouldn't be acceptable today----nor would incinerating carpets.

Added comments: After reviewing my previous post, I should explain that I would consider carpets to be the worst material received for those that refine jeweler's wastes. E scrap, in my mind, is a hands-down losing proposition unless handled in huge volume ------or as a hobby, which I heartily endorse. That's especially true in the case where the clever guys have developed these great work-arounds that avoid buying nitric acid. My hat's off to these guys.

Harold

 

[Oz]

That confirms the impression I had from your post as to the economy of processing jewelers carpet. I would do it as I had spare time if I got the material for free. That is what I do with 2 computer repair shops that give me all their dead computers and components (I do not accept monitors). As I am self employed I let it build up and if I have no work for a day or 2 it then becomes productive time, but I would never want to try to earn a living from it.

I live in an area that still allows one to burn their trash in the open. Just recently I had to repossess a house that all the carpets had to be disposed of. Even with a good hot open fire of wood furniture to put it on it is a bitch to burn. This is some of what I had in mind when you talked of running carpets, although with your barrel you probably had holes at the base to give better combustion.

Maybe the carpet I have burned is different from what you have but I have seen tires burn and from a distance and one tire looks like an entire house going down. Then again I burned residential carpet not rubberized commercial runners.

Thanks for the input though, even if it is a break even proposition it may be the value added service I could provide to jewelers to get the rest of their business.

 

[Harold_V]

That confirms the impression I had from your post as to the economy of processing jewelers carpet. I would do it as I had spare time if I got the material for free.

Your closing statement: "even if it is a break even proposition it may be the value added service I could provide to jewelers to get the rest of their business." is key here. If you do not serve your customer to the fullest capacity, you won't have him/her long. Someone like me comes along and steals them from right under your nose. I ran carpets, even when they weren't in my best interest, as a service, showing the customer that I was valuable to them, and provided services that they might not get anywhere else. To be perfectly honest, I regret running only one carpet, the one that yielded only twelve grains of gold. All others were worth the effort.

As I am self employed I let it build up and if I have no work for a day or 2 it then becomes productive time, but I would never want to try to earn a living from it.

Again, a great bit of advice to others. A wise person will do anything that is legal, to make money with idle time. I endorse your concept.

although with your barrel you probably had holes at the base to give better combustion.

No----no holes. You have to use good judgment when incinerating carpet, for your objective is to recover the ashes. Holes would permit loss.

My process was to build a fire under a half barrel, then introduce carpet that was cut in strips. The carpet should be cut up on location, and rolled so the contents do not spill. Cleanup after removal is very important, for fine gold particles have a way of seeking the floor. Gold is visible, so all the dirt that is left behind is included with the carpet. Much is liberated when the carpet is cut up and removed.

Synthetic carpets process very easily, although labor intensive. Wool carpets are a disaster.

That the carpet is burned without holes for oxygen is one of the reasons that it must be roasted afterwards. I did that in my furnace room where I had a large blower on the roof that provided air exchange in the room. All of the smoke and smell was removed from the building, and the ash was reduced to a light, fluffy powder, with no clumps. Processing anything that still showed black was a mistake.

I have seen tires burn and from a distance and one tire looks like an entire house going down. Then again I burned residential carpet not rubberized commercial runners.

While I processed a variety of carpets, they were generally typical of what might be installed in a house. As long as they were synthetic fibers, they burned much like a plastic bag does. It first turns to liquid, then burns like oil, yielding a great deal of smoke.

From your description of your burning process, I gather that you would have a lesser amount of smoke due to the greater availability of oxygen. My process left a great deal to be desired, but I couldn't think of a way to introduce air to the container without going to a great deal of trouble. Considering carpets were a very small part of the refining process, I just suffered through with what worked.

Under ideal conditions, introducing fresh air via a blower and pipe might have been a good move. However, in the end, I had a guy do the incineration for me, for a percentage of the spoils. I didn't have the time to screw with that part, and he was happy to do it. He had a country retreat, where he did the incineration as a part of a weekend away from the normal grind.

Harold