# Burning filters



## qst42know (Oct 7, 2008)

I spilled a small test batch of gold flakes and dust in rinse water. I collected the material with a couple household paper towels. Now I know I could use a torch and burn this material to recover the values and proceed as normal. 

However because there are no PGMs or silver present. After thoroughly dried, could concentrated sulfuric be used to chemically burn the paper away? 

I suspect it will do no harm in the AR processing but thought it best to ask the pros first.

Chris


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## goldsilverpro (Oct 7, 2008)

*Burn the papers! Forget about the sulfuric.* However, *for academic purposes only!*, here's the procedure.

*WET ASHING - CAN BE AN EXTREMELY DANGEROUS PROCESS*

I have done this 100's of times and it still is scary. I would never use it in quantities larger than what I discuss below. *It is not used for the purpose of cleaning up dirty gold.
*
When I wanted some excitement, I used to sometimes dissolve filter paper away from fine gold powder that was stuck to it, using concentrated sulfuric. Analytically, the process is called "wet ashing" and it will completely dissolve the paper. The gold powder ends up alone at the bottom. I wouldn't try it with paper towels. The problem is that a large volume of paper requires quite a bit of extremely hot sulfuric. *As the amount of hot sulfuric increases, the danger of doing this increases geometrically.* Also, the potential for broken flasks is high in this process, due to the great heat required. This process also produces very white, dense, nasty fumes. Very dangerous possibilities. Here's the way I did it. This is for one medium size filter paper. I'm assuming that there is nothing but paper and gold with no contamination. *Use a face shield and gloves - there will definitely be some splattering.*

(1) *UNDER THE FUME HOOD*, put a 1000 ml erlenmeyer flask inside of a flat bottom, white, Corning Ware dish and place on the hotplate. I much prefer using an erlenmeyer flask instead of a beaker. It has a narrow neck and is safer to use than the beaker - there is a much less chance of splatters coming out of the vessel when you add the drops of nitric in step 3.

(2) Add about 200 ml of concentrated sulfuric to the beaker and add the filter paper. Add about 2 ml of nitric acid (2 eyedroppers full) - add the nitric down the inside wall of the flask. Heat. A voluminous, black sludge will soon form. This is carbon. As you continue to heat, the water will be driven off, the sulfuric will become stronger, and the black will settle down into the solution. Use about medium heat at first.

(3) With an eyedropper, add 2 or 3 drops of nitric acid. Be very careful when you do this. When the nitric hits the hot sulfuric, it will pop loudly and will splatter. When the reaction settles down, add more nitric dropwise. Repeat.

(4) At some point, the black will disappear and further additions of nitric will turn the solution red. Stop adding nitric. The red will fade to a light yellow, which will disappear with further heating. Don't overadd the nitric or the gold will actually dissolve. If you do things perfectly, the solution will end up water clear and the gold will be on the bottom. At the end, copious amounts of nasty white fumes will be coming out of the vessel.

(5) Allow to completely cool. Carefully pour off the acid without disturbing the gold. Try to remove as much acid as possible without disturbing the gold. Dilute the small amount of remaining solution so that the sulfuric solution is only about 5% in strength. Start diluting by adding a couple of eyedroppers of water down the inside of the flask. *Go slow* as it will splatter. Stir. Add water slowly (with an eyedropper) and carefully until the sulfuric is about 5% in strength. Filter off the gold. If the sulfuric is too strong, it will eat the paper.

*NOTES:* 

This can be very dangerous and is not for the faint-hearted. *NEVER* do it without a fume hood. It is also a difficult process to do correctly. It takes quite awhile and you must go slow and be patient. The hardest things are to eliminate all of the carbon, to not overdo the additions of nitric, and to get a clear solution. The boiling point of concentrated sulfuric is 550 F. Never heat to boiling. You'll have to watch the temp. setting of the hotplate, as the solution will continue to get hotter and hotter.

Wet ashing is a standard method of analyzing the gold content of cyanide solutions - a 5 ml sample is used with 100 ml of sulfuric - *FUME HOOD!!!!* Also, some people considered using it to recover gold from ion exchange resins, although I never heard of anyone having the guts to actually try it - too much hot sulfuric involved. 

The nitric is only used to speed things up. Some procedures call for sulfuric alone. 

To try this out, I would first do it on a very small scale. I would use about 2 square inches of filter paper, a small pinch of gold powder, and about 30 ml of sulfuric.

Make sure you understand everything I've written before attempting this. Read it a few times.

*On second thought, don't try it at all until you have a few years of experience under your belt working with other chemicals.*


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## Oz (Oct 7, 2008)

GSP is not kidding here at all! Please listen to him stating “this is not for the faint hearted”. Working with hot concentrated sulfuric and adding water to concentrated sulfuric are among the most dangerous things talked about on this forum.

There has been a flurry of discussion lately on safety and I may be out of line saying this, but I shudder to think about someone new to refining trying this not understanding the hazard. Hot concentrated sulfuric is one of the worst things you could get on you. It will spit, pop, and spatter with even small additions (note the use of an eyedropper) and if you’re not careful could do so almost explosively. One could easily become permanently disfigured and blind.

GSP, I am not being critical of your procedure. I just hope that newcomers that have messed up their first refining attempt or two do not see this as a way to clean it up until they have the equipment and experience to do it safely.


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## qst42know (Oct 7, 2008)

Thanks guys. 

I am very glad I asked. Good to know how it's done.

And it sounds like an interesting process but, definitely torch it is then.

Chris


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## watlarry (Oct 7, 2008)

why burn? why not soak in hcl and chlorine making AC then filter and precipitate?


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## qst42know (Oct 7, 2008)

Both AR and AC do not dissolve paper it remains as a fiber pulp. Very quickly slows filtration and holds a lot of your solution. I have pulped small amounts of filters but I think this may be to much to deal with.

Chris


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## Harold_V (Oct 8, 2008)

One of the guys that contributes to this forum regularly keeps harping on incineration. 

Gee------I wonder why? :roll: 

Harold


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## OMG (Oct 8, 2008)

What if you used a somewhat diluted caros acid? Would that not dissolve the carbon? You might not need to deal with the SO3 and it might not have to be so hot.


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## Oz (Oct 8, 2008)

I just fail to understand why one would not just burn carbon with good old fashioned fire. Nothing exotic, no high temps, just a stainless steel pan and a match. If you want every little bit of carbon out heat it from the bottom and stir the ashes to expose all to air.

Am I missing something?


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## Harold_V (Oct 8, 2008)

Oz said:


> I just fail to understand why one would not just burn carbon with good old fashioned fire. Nothing exotic, no high temps, just a stainless steel pan and a match. If you want every little bit of carbon out heat it from the bottom and stir the ashes to expose all to air.
> 
> Am I missing something?


Chuckle!

No sense doing that when you can put life and limb at risk screwing around with dangerous hot acids! :wink: 

Harold


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## qst42know (Oct 8, 2008)

My interest in the "WET" process came from the last time I boiled battery fluid to concentrate. I found a large droplet on the side of the glass while boiling. When I used a coffee filter to blot this drop it melted the filter like cotton candy. It seemed quite easy on such a small scale. I see it's much more trouble and risk when scaled up. Its good to know and may be useful some day but in this case it would only add difficulty.


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## Harold_V (Oct 8, 2008)

qst42know said:


> When I used a coffee filter to blot this drop it melted the filter like cotton candy.


It's more than a good idea to get terminology straight. It helps build one's credibility. 

Melting is a heat process--------while dissolving is not. Fact is, some dissolving processes are endothermic, such as dissolving ammonium chloride in water. 

One does not melt sugar in coffee or tea-----it is dissolved. 

When you blotted that drop, it did not melt the paper---the paper was dissolved. There's a big difference. 

Harold


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## qst42know (Oct 8, 2008)

Fair enough Harold. I stand corrected.

Chris


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## Lou (Oct 8, 2008)

Well let me say this then, when you put hot sulfuric acid and do the wet ashing like Chris suggested (indeed a very, very dangerous procedure), you're not dissolving the cellulose--it is being destroyed. 

Truly dissolving something means you can get it back out if you remove the solvent. So when we dissolve gold in aqua regia, really it isn't dissolving, it's a reaction occurring that makes a soluble product.

Hot sulfuric acid is really aggressive to organics like cellulose in filter paper, or your skin. Add in strong hydrogen peroxide and make Caro's acid and you're just *ASKING *for trouble. The ozone that comes off persulfuric acid is pretty noxious too. 

That said, unless you know what the hell you're doing, are set up to clean a mess of highly corrosive liquids, and are setup to even do it safely, then don't do any wet ashing.


I'm not a big fan of incinerating in stainless because chrome and vanadium oxides can get mixed in, so I'd rather do it in a copper pan or a large Pyrex dish.

Lou


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## Oz (Oct 8, 2008)

Lou said:


> I'm not a big fan of incinerating in stainless because chrome and vanadium oxides can get mixed in, so I'd rather do it in a copper pan or a large Pyrex dish.



That makes a lot of sense Louis. The stainless may be more durable than the copper or Pyrex, but I had not thought of the fact that it may add contaminates that could prove difficult to remove. I’m glad you pointed out the trade-off.

Thanks!
Oz


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## Harold_V (Oct 9, 2008)

Lou said:


> Well let me say this then, when you put hot sulfuric acid and do the wet ashing like Chris suggested (indeed a very, very dangerous procedure), you're not dissolving the cellulose--it is being destroyed.


Yes, but the process is dissolution, not melting. Bottom line is the solid is no longer, and there has been no substantial heat, although the reaction is exothermic. 



> Truly dissolving something means you can get it back out if you remove the solvent. So when we dissolve gold in aqua regia, really it isn't dissolving, it's a reaction occurring that makes a soluble product.


My step-brother-in-law wrote a great essay on the dissolution of gold, a result of his observations of my refining escapades early on, long before I started refining commercially. It's been a long time since I read the document, although I still have it somewhere in storage. He is now a professor of chemistry at one of the Midwest universities. Professor Dennis Bennett.



> I'm not a big fan of incinerating in stainless because chrome and vanadium oxides can get mixed in, so I'd rather do it in a copper pan or a large Pyrex dish.


While I agree in principle, in practice I don't recall ever having any difficulty with the use of stainless. That's a far cry from the use of steel, which erodes rapidly, thus has a very short lifespan. Nice part about the stainless is I never had one break---which I can't say for any glassware I ever used. For all practical purposes, the use of stainless is likely the best of all possibilities. Copper would be prohibitive in price, and would likely melt under some of the conditions that I experienced. 

When you speak of Pyrex, are you talking about ovenware? While it's pretty rugged, I can't imagine it would withstand the heat from a rosebud. That was very much a part of incinerating for me--especially when processing polishing wastes. 

Fused quartz would be ideal. 

Harold


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## goldsilverpro (Oct 9, 2008)

Corning Ware dishes will take a lot of heat, especially the newer amber colored transparent ones. When they first came out, I remember commercials on TV that melted metal in them with a torch. I don't remember which metal. 

A place I worked used a propane torch to dry gold powder and simultaneously burn off the filter papers in a 5 quart, white Corning Ware dish. The dish would get red hot, in some areas, with no damage.


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## goldsilverpro (Oct 9, 2008)

> Well let me say this then, when you put hot sulfuric acid and do the wet ashing like Chris suggested (indeed a very, very dangerous procedure), you're not dissolving the cellulose--it is being destroyed.
> 
> Truly dissolving something means you can get it back out if you remove the solvent. So when we dissolve gold in aqua regia, really it isn't dissolving, it's a reaction occurring that makes a soluble product.



I have learned not to doubt Lou when it comes to technical matters. 

When you dissolve salt in water, you can evaporate the water and end up with the exact amount of solid that you started with. 

With the wet ashing, however, you can't evaporate and end up with a filter paper. You probably wouldn't end up with anything. The paper has definitely been destroyed and the carbon has probably all come off as CO2. It seems like you have actually "burned" the paper. Thus, the term, "wet ashing."

The gold in aqua regia is puzzling, though. If you evaporate the AR to dryness, the gold will precipitate back as metal. That is why you don't evaporate to dryness when refining gold. It seems to me that this would be the same as the salt example.

I just looked up about 10 definitions of "dissolving." Some were from chemistry sites and some from "secular" sites. In one secular dictionary site, they even included melting as a form of dissolving. I can't agree with that. In the chemistry site definitions, none included the requirement that, through the removal of the solvent, the original solid would remain. However, I see Lou's point and it definitely makes sense.

Enlighten me, Lou. Do you have a source for your definition? 

I have begun to regret ever posting the procedure for "wet ashing."


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## Harold_V (Oct 9, 2008)

goldsilverpro said:


> I have begun to regret ever posting the procedure for "wet ashing."


I think it was a good idea, Chris. It has presented the opportunity for various views to be aired, views that may not have been voiced otherwise. 

I've learned a great deal, in spite of the fact that it makes no difference to me now. It's always nice to get enlightened.

Harold


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## qst42know (Oct 9, 2008)

Lou.

When burning in a copper vessel is there any risk in brazing your values to the copper?

Chris


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## Lou (Oct 9, 2008)

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.


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## qst42know (Oct 9, 2008)

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?


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## qst42know (Oct 9, 2008)

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


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## Harold_V (Oct 9, 2008)

Lou said:


> 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


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## Oz (Oct 10, 2008)

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.


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## Harold_V (Oct 10, 2008)

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


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## Lou (Oct 10, 2008)

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


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## Harold_V (Oct 10, 2008)

Lou said:


> 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


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## Oz (Oct 11, 2008)

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.


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## Harold_V (Oct 11, 2008)

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


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## Oz (Oct 11, 2008)

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.


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## Harold_V (Oct 11, 2008)

Oz said:


> 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


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