Pyrolysis reactor

[4metals]

Another option is to use a cupel to separate the precious metals from the base metals and lead. Legend sells 10" cupels that will hold up to 30 pounds of lead leaving the precious metal bead on top of the cupel after firing. I work with a refiner who saves all of his beads from fire assaying, not the clean coronets but the failed beads and dirty silver beads and mixes them with lead and fires them in large cupels to concentrate the metals. It is quick and effective. Not refining but collecting and concentrating.

These large cupels are quite pricey. Years ago in Ecuador, I set up a large furnace in which we set a "brick" we made of bone ash which was about 18" by 24" and a full 6" thick, it had a valley in the center and we fed in the lead and PM's so as to not overflow the top of the brick. There was a pipe feeding into the top of the furnace which allowed additions without interruption. After a full day of feeding and firing continuously, the furnace cooled and the next day we opened it to find a long round tube, shaped like a pepperoni and about as large, which was a gold doré bar. The lead and base metal saturated bone ash was broken out of its frame that held it together and more fresh bone ash was packed in for the next run.

Keep in mind that about 10% of the total lead used is volatilized meaning it is up in smoke so to speak. Not a very kind way to treat mother nature. Today I would be scrubbing the air exhaust to collect that lead.

 

[Platdigger]

So, how would you go about setting up such a scrubber, say in a remote area without many modern resources?

 

[4metals]

A straight pH controlled caustic scrubber would condense and trap the lead but the recirculating water will recirculate the lead hydroxide Pb(OH)2 and it will in short order clog the spray nozzles so I would install an in line filter on the recirculating pump with a gauge to determine when the flow drops off enough to change the filter.

 

[Platdigger]

OK, thanks for that 4metals and Happy New Year!

Would you reuse try and reuse the lead captured?
Or just dispose of the contaminated lead hydroxide?

 

[4metals]

Re-using the lead would most likely be more of a pain than it is worth. Most refiners generate a waste from treating their acid wastes with caustic. It contains metal hydroxides (if refining karat gold mostly copper and zinc) and a few other base metals depending on the alloy. It usually also contains a payable gold content as well as payable copper. Usually the payables cover the charges but save the refiner having to manifest and treat the hydroxides as a recyclable waste. I would be putting the lead hydroxides in with that waste stream.

If your hydroxides do not contain any other RCRA metals then do not add the lead hydroxides to the waste stream because Lead is a RCRA metal and you will now incur an expense because the waste will fail TCLP testing for Lead. If it already has TCLP metals in the waste as hydroxides it is a hazardous waste already so adding the lead is "free" so to speak.

 

[72chevel]

Kurtak wondering about a couple things: Do you have all the chips in from the start? Do you stir them up at all? How long do you figure the whole process takes to get the chips that white?

Kevin

I would be a bit concerned about gases (from the pyrolysis) building up inside that reactor which could lead to a "potential" explosion

I am using my big smelting furnace to do my chips in (details on the whole process will be coming soon)

Pic 1) Chips are in full blown pyrolysis mode - note the orange flame coming out the top hole - little or no smoke - the gasses are being burnt up inside the furnace due to cyclone action of the flame inside the furnace produced by the furnace burner

pic 2) note there is no longer an orange flame coming out top furnace hole - this indicates that pyrolysis is complete as volatiles have been burnt off

pic 3) finished pyrolyzed chips

Kurt

 

[kurtak]

Kurtak wondering about a couple things: Do you have all the chips in from the start?

No - I start with a couple handfuls then ad a couple handfuls at a time

Do you stir them up at all?

This depends somewhat on the chips - if they are thin lite chips they normally don't really need a stir - the heaver thicker ones will need to be stirred to bring the ones at the bottom (of each addition) up to the top so heat & oxygen can get to them

How long do you figure the whole process takes to get the chips that white?

Again this somewhat depends on the chips - thick heavy chips take longer then thin lite chips --- I can "average" about 60 lbs of chips in an 8 - 9 hour day with my set up --- that includes my time of getting everything set up (which includes bring the furnace up to operating temp) for the days run

I should also mention that I run the furnace at full temp which causes "some" actual melting of the metals during the pyrolysis (incinerating) I don't consider that a problem because I smelt my concentrates anyway so melted ball metal that comes out of the incineration process goes into the smelt process as collector metal --- its mostly the exposed metal on the out side edges of the chips that melts

I am sure I could run the furnace at a cooler temp to prevent the melt down but the trade off would be more time to complete the pyrolysis of each load

I mention this because if you plan to leach your ash (after concentrating) you "do not" want metal to melt during the pyrolysis as that will likely lead to "some" loss of gold due to 'some" bonding wires also melting & collecting in the base metals that melt during the pyrolysis

Kurt

 

[g_axelsson]

If you let in air to the chips it's actually incineration, not pyrolysis (no oxygen added).

Göran

 

[kurtak]

If you let in air to the chips it's actually incineration, not pyrolysis (no oxygen added).

Göran

Ok - I guess it depends on just how "technical" we want to get with the words

Yes oxygen is required to achieve true & "complete" incineration the result ( if enough oxygen is provided) being a "complete" reduction of carbon to ash

with out oxygen pyrolysis occurs driving off the volatiles leaving you with carbon & no reduction to ash

What happens in my furnace the way I am using it is in fact pyrolysis (even though yes I am adding "some" oxygen to my flame fuel mix) because the chips are in a crucible little or no oxygen is getting to them during the heating that drives off the volatiles --- the oxygen in the propane flame fuel mix allows for near complete if not complete combustion of the volatiles as they come out the top of the crucible & get carried "around" the inside of the furnace by the cyclone action of the burner flame

Little or no oxygen is actually making it down into the crucible to provide true incineration to the chip (reduction of carbon to ash)

What happens - is that when you open the lid to the furnace ( the burner flame is first turned "way" down & there for reduced cyclone flame action) air is sucked into the furnace & down into the crucible as well --- due to this sudden influx of oxygen the "surface" only of the "red hot" chip will "flash" incinerate to ash (& primarily only the chips at the top) --- that is why the chips in my pics "look" like they have been incinerated

Its actually kind of interesting to watch - when there is no longer the orange flame coming out the center hole of the furnace lid that tells you the volatiles have been burned off - you can then pull the lid "just a bit" to the side (but not open) so you can look down through the hole from an angle into the chips in the crucible - if they are in fact done the chips will have a nice even orange/red glow "all the way to the center" --- then when you "first" open the lid - the chip "surface" cools just enough to see a black carbon surface - this last for only about 1 - 2 seconds & due to the red hot heat of the chip mass the "surface" carbon "flashes" to white ash as the oxygen from the open furnace hits them

They may look like they have been incinerated (reduced to ash) but in fact that is only a surface appearance --- they are in fact 90 - 95 % carbon - they have been pyrolysized - & in short order at that --- The "thin" chips will reduce to about 50 - 60% ash - but not untill after the furnace lid is opened allowing the influx of the large volume of outside air

Edit to add: - if you look at the pics of my chips "after milling" you will see that the "fine" powder is almost entirely "carbon black" - this is then run over my concentrator table to wash "most" of the carbon off - once it is washed down to the concentrates I then have to do a true incineration to reduce the remaining "all" carbon content of the concentrates to ash

Kurt

 

[72chevel]

Thanks for your response, I had trouble adding chips to the crucible as it was running because the vortex of air would make them fly all over, I have a very similar setup like yours maybe I'll have to try to turn the blower down when I need to add chips.

 

[g_axelsson]

If you let in air to the chips it's actually incineration, not pyrolysis (no oxygen added).

Göran

Ok - I guess it depends on just how "technical" we want to get with the words

We want to get very "technical" with our words so people don't start to melt metals with acids and boil off excess nitric to denox. :mrgreen:

I know that you probably doesn't care if you have carbon left as you are melting it all to get the gold, using the base metals as collector, and for those who pans the ash a bit of carbon is no big problem either.
The reason I thought you were incinerating was your answer on...

Do you stir them up at all?

This depends somewhat on the chips - if they are thin lite chips they normally don't really need a stir - the heaver thicker ones will need to be stirred to bring the ones at the bottom (of each addition) up to the top so heat & oxygen can get to them

But if all you do is to cook them to remove the volatile part and get them brittle for milling, and any oxygen entering is more of an accident rather than by design then I would also call it pyrolysis (or maybe incomplete incineration).

Göran

 

[kurtak]

Thanks for your response, I had trouble adding chips to the crucible as it was running because the vortex of air would make them fly all over, I have a very similar setup like yours maybe I'll have to try to turn the blower down when I need to add chips.

Make a simple loading shoot from some scrap sheet metal - as you can see mine is about as simple as you can get - it has a piece of bar iron clamped on the handle end to stiffen it ( that's because the scrap sheet metal was already cut to the odd shape so wasn't long enough to bend a full length angle piece for stiffness)

I also use it for making additions of concentrates & flux to the crucible when smelting - & yes -turn the burner down (&/or blower) when making additions - I turn it down as far as I can without actually shutting it off so there is little or know cyclone vortex

there is about 2 handful of chips in the shoot - my chip additions are 2 - 3 handful depending on if they are heavy thick chips or lite thin chips

Kurt

 

[kjavanb123]

All,

In pursuit of a pyrolysis unit to solve the ewaste processing smoke issues, I have used the ideas offered by members of energyforum, and came up with the following, which was absolutely smoke and smell free.

My scrapper had brought me 40kg of laptop boards, we place it in the large barrel, closed the cap air tight. Fired it up. The shot of whole system as following,

Barrel that has turned black on the outside is where materials are loaded, the big thick reddish pipe is used to increase the flowrate of gasses produced, which is bolted to another smaller in diameter pipe, which is connected to 2 other pieces of pipes and it ends up in a small bucket filled 3/4 in water.


As the temperature inside the barrel increased, so did the bubbling in water and gas production, as can be seen in the following,


The system working until near the end we ran out of fuel, so we are going to optimize it in order to get better results. No smokes or smell at all.


Some locals turned up to see the cool device in action, I collected the thick layer of crudie oil, and gasses which was burned.

More photos and result tommorow, as we will smelt 40kg laptop boards removed from 180 laptops.

Regards
Kj

 

[butcher]

Why not run the small tube of burning gases back into the main fire heating the big tub full of boards, using the gas to supplement your fuel source.

 

[kjavanb123]

Butcher,

I could do that, but the burning gas is not that hot. I am thinking to use a larger barrel to invert over the main reactor, and let the heat to travel to entire reactor body. Plus I am going to switch to gas as fuel instead of diesel.

Best
Kj

 

[Platdigger]

Looks good Kevin!

 

[butcher]

The yellow flame suggests incomplete combustion CARBON MONOXIDE gas as well as other toxins released as un-burnt gases, adding oxygen or air would make it burn to a more complete combustion, and giving you a hotter flame (burning the carbonaceous gases to CO2), this could be done by using a homemade type of torch, which pulls in air with the gases through a venturi effect...

Adding heat to your main flame, conserving fuel, and more completely burning of many of the toxic gases...

I do not believe you could burn all of the toxic gases released from burning electronic scrap, some of which would be dangerous metal oxides, but I do believe you can reduce some more of those pollutants with some adjustments to your design.

Keep up the good work, looking forward to seeing your improvements and results.

 

[kjavanb123]

All,

I have made some changes to the pyro unit above in order to optimize it.

This is done in smaller scale, so here is an over all photo of the new pyrolysis setup,


Here is some info on different components, the main pyrolysis chamber is steel paint can, an inch pipe is inserted to the cap of steel can, which guide the smoke through the long black and red pipes to the plastic jar.

All smokes are condensed in that jar, while excessive smokes exit through the aluminum pipe you see on the left of jar, and enter the furnace where heat and air enter the furnace.

The pyrolysis chamber sits in this basic melting furnace, and it gets hot, melt the plastic components inside and smoke is condensed in the plastic jar.

Excessive smoke from jar is burned off in the furnace.

Some issues that I noticed doing small batches of plastics was following,

1- Aluminum pipe used to re-burn the smoke got melted in furnace so that can be replaced with copper pipe.

2- There is not enough suction in condenser to pull all smokes from pyrolysis chamber, so at the end of each test, upon openning the cap there was still some smoke trapped in the can. I tested by placing the 1 inch pipe a few cm from the hole on the cap and it seemed to suck the smokes out better, so will improve this and observe.

3- Smokes from plastics were not flamable, so I will try to also improve that.

Your input will be great. Here is a shot of system while working.

 

[kurtak]

Kevin

Set yourself up with an actual smelting furnace - you can use it for both your pyrolysis/incineration - & for smelt

I posted about this on the first page of this thread

here :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=22581&hilit=incinerate#p237094

Also 4metals posted about using a smelting furnace & in his design when it is being used for pyrolysis/incineration he is adding a "after burner" chamber to the top of the furnace

The advantage 4metals design (with the after burner chamber) is that you can run the furnace at a cooler temp when doing pyrolysis/incineration --- which means you don't have to worry about metals melting & turning to blobs during the pyrolysis/incineration if you leave the material you are pyrolysis/incineration to long

4metals design is posted by him in this this post about mid way down in the post :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=23680&p=249793&hilit=incineration#p249793

The design description starts with this sentence ---

I made this furnace representation in Paint on my laptop so some of this makes sense.

Kurt

 

[anachronism]

Using copper pipe and light plastic jars around something designed to get extremely hot has always set alarm bells off for me. If you're melting Aluminium then aren't you already too high a temperature for this task?

Edit- The copper should be alright as long as you're working within limits- please scratch that part of my post.