One step pyrometallurgy process for PCB

[Ayham Hafez]

Hello all!

I wonder if we can just use high temperature furnace like rotary furnace with 2000 c temperature to directly smelt pcb's with their full components, adding some fluxes to oxidize base metals then pour mixed metal ingots after that use Hydrometallurgy to seperate PM's and copper.

If that process is not possible, then WHY?

If its OK, then why none use same process?

 

[4metals]

Ayham,

I wonder if we can just use high temperature furnace like rotary furnace with 2000 c temperature to directly smelt pcb's with their full components, adding some fluxes to oxidize base metals then pour mixed metal ingots after that use Hydrometallurgy to seperate PM's and copper.

If that process is not possible, then WHY?

If its OK, then why none use same process?

You ask a lot of questions but never follow up on the discussion. You never detailed exactly what you are trying to accomplish and on what scale. On the thread you started and posted a YouTube video of a refiner processing DIP's, I broke off from that thread and started a thread to discuss the video and discuss options. Surprisingly you apparently did not read that thread which you can find here. If you had it provided the answer to your question on this thread.
Believe it or not you are not the first person to refine this material or the first to ask how it can be done. I suggest you learn to search the forum before bringing up topics that have been discussed. It is fine to come back, after research, and ask questions for clarification.

 

[Ayham Hafez]

Ayham,



You ask a lot of questions but never follow up on the discussion. You never detailed exactly what you are trying to accomplish and on what scale. On the thread you started and posted a YouTube video of a refiner processing DIP's, I broke off from that thread and started a thread to discuss the video and discuss options. Surprisingly you apparently did not read that thread which you can find here. If you had it provided the answer to your question on this thread.
Believe it or not you are not the first person to refine this material or the first to ask how it can be done. I suggest you learn to search the forum before bringing up topics that have been discussed. It is fine to come back, after research, and ask questions for clarification.

I noticed your thread about DIP's, I didn't react because I believed from the original thread that none knows why the video publisher used Urea, and all feedbacks were just thoughts, even from following up your threads I didn't find any new addition from any member, not reacting sometimes means that I don't have valuable info to add.


I always search in the forum before start any thread, I don't post threat until I make sure that there is something new in my question, and regard my questions I think this forum built for questions and discussions so I don't find any issues with posting "a lot of questions"

 

[orvi]

Hello all!

I wonder if we can just use high temperature furnace like rotary furnace with 2000 c temperature to directly smelt pcb's with their full components, adding some fluxes to oxidize base metals then pour mixed metal ingots after that use Hydrometallurgy to seperate PM's and copper.

If that process is not possible, then WHY?

If its OK, then why none use same process?

Not in this setup, I suppose, but it is done on large scale, as it is the only effective way of recycling old PCBs for metals recovery.
Big guys in the industry many times use shaft-like furnances, feed the material in the top, alongside with fluxes. In the upper part of the furnance, material is incinerated in oxidizing atmosphere to burn all organic matter. Then, it progressively gets more warm to the bottom, which cause fiberglass to melt and flux with quicklime. Slag flows from the bottom of the furnance, alongside with liquid metal, which is then processed by another round of pyrometallurgy and then electrorefined.

 

[orvi]

I noticed your thread about DIP's, I didn't react because I believed from the original thread that none knows why the video publisher used Urea, and all feedbacks were just thoughts, even from following up your threads I didn't find any new addition from any member, not reacting sometimes means that I don't have valuable info to add.


I always search in the forum before start any thread, I don't post threat until I make sure that there is something new in my question, and regard my questions I think this forum built for questions and discussions so I don't find any issues with posting "a lot of questions"

Maybe also publisher of the video do not know why he added urea maybe because it fizz nicely. Looking like it is doing something...

We do know why urea kinda works, we know what it can accomplish, but generally, I do not bother as it does not make sense in a way for me to use it in my setup. I pointed it in my reply in the stated article. I do not have resources or time to scientifically prove the assumed benefit of adding urea, but based on several papers regarding reactions of urea with various oxidants, few experiments I performed, and utter fact that urea does not react with nitric acid, I concluded what I concluded.

In original video, thing serving better than urea is high dilution of the liquid, minimizing redissolution of gold powder. Paired with urea, it can maybe serve well, but I would never do it like he does, because ammount of waste produced is just insane.

 

[Ayham Hafez]

Not in this setup, I suppose, but it is done on large scale, as it is the only effective way of recycling old PCBs for metals recovery.
Big guys in the industry many times use shaft-like furnances, feed the material in the top, alongside with fluxes. In the upper part of the furnance, material is incinerated in oxidizing atmosphere to burn all organic matter. Then, it progressively gets more warm to the bottom, which cause fiberglass to melt and flux with quicklime. Slag flows from the bottom of the furnance, alongside with liquid metal, which is then processed by another round of pyrometallurgy and then electrorefined.

So I think that my idea is possible, I mean we can smelt pcb with all its components in furnace together without loosing any PM's value.

 

[orvi]

So I think that my idea is possible, I mean we can smelt pcb with all its components in furnace together without loosing any PM's value.

It is essentially 2in1 setup, which can be tricky to recreate reliably in DIY conditions. You need to assure the pyrolysis and incineration is complete in the upper part of the furnance, otherwise carbon will wreck the whole smelt. Also, to be effective and produce flowing slag from fiberglass, you are generally left only with quicklime as flux of choice. And for this, you will need to go high with temperature. At least around 1400 °C.

I do not precisely know how big guys are doing this (they obviously won´t tell us), but from common fluxes capable of liquifying glass to the point it allow metal to coagulate nicely, I do not know any other cheap flux aside from CaO to accomplish this. Maybe some harsher fluxes like cryolite or fluorospar can help, but these can be very hard on the lining of the furnance.

Summarized, yes, your idea is allright and possible, but for start I would suggest divide it into two stages and perfect them separately. Only then combine it together.

 

[Ayham Hafez]

Man

It is essentially 2in1 setup, which can be tricky to recreate reliably in DIY conditions. You need to assure the pyrolysis and incineration is complete in the upper part of the furnance, otherwise carbon will wreck the whole smelt. Also, to be effective and produce flowing slag from fiberglass, you are generally left only with quicklime as flux of choice. And for this, you will need to go high with temperature. At least around 1400 °C.

I do not precisely know how big guys are doing this (they obviously won´t tell us), but from common fluxes capable of liquifying glass to the point it allow metal to coagulate nicely, I do not know any other cheap flux aside from CaO to accomplish this. Maybe some harsher fluxes like cryolite or fluorospar can help, but these can be very hard on the lining of the furnance.

Summarized, yes, your idea is allright and possible, but for start I would suggest divide it into two stages and perfect them separately. Only then combine it togethe

It is essentially 2in1 setup, which can be tricky to recreate reliably in DIY conditions. You need to assure the pyrolysis and incineration is complete in the upper part of the furnance, otherwise carbon will wreck the whole smelt. Also, to be effective and produce flowing slag from fiberglass, you are generally left only with quicklime as flux of choice. And for this, you will need to go high with temperature. At least around 1400 °C.

I do not precisely know how big guys are doing this (they obviously won´t tell us), but from common fluxes capable of liquifying glass to the point it allow metal to coagulate nicely, I do not know any other cheap flux aside from CaO to accomplish this. Maybe some harsher fluxes like cryolite or fluorospar can help, but these can be very hard on the lining of the furnance.

Summarized, yes, your idea is allright and possible, but for start I would suggest divide it into two stages and perfect them separately. Only then combine it together.

Many thanks, I will keep studying this process and see how I can start with it.

 

[Martijn]

So I think that my idea is possible, I mean we can smelt pcb with all its components in furnace together without loosing any PM's value.

I don't think 'all components' can go in a furnace. Like electolytic capacitors and aluminum heat sinks.

 

[Martijn]

 

[Yggdrasil]

Man



Many thanks, I will keep studying this process and see how I can start with it.

There is a reason to our recommendation of pyrolizing and then incinerate what we run pyrometallurgically.
Most of us do not have access to sufficient equipment to run it directly.
Additionally as Martijn showed, it need to be at least partially depopulated to get rid of unwanted components,
like foil capacitors, heat sinks and so on.

 

[kurtak]

I wonder if we can just use high temperature furnace like rotary furnace with 2000 c temperature to directly smelt pcb's with their full components, adding some fluxes to oxidize base metals then pour mixed metal ingots after that use Hydrometallurgy to seperate PM's and copper.

NO !!! - this will ABSOLUTELY NOT WORK !!!

If that process is not possible, then WHY?

Because the plastics (epoxy & other plastics) on/in the boards MUST first be burned off (incinerated) in order for the flux to "slag off" the ash/carbon created in the FIRST step of the process - which is incineration of the boards (which is actually the second step - because the "very first" step is shedding the boards - then incineration)

So I think that my idea is possible, I mean we can smelt pcb with all its components in furnace together without loosing any PM's value.

NO !!! - you are NOT understanding what orvi is telling you - you are only hearing the "part" you want to hear

In other words - the very first thing orvi said in his first post was -----------

Not in this setup,

In other words - NO - you can NOT just put circuit boards in a furnace with flux & expect a separation of all the plastic from the metal

In fact - what will happen - if you try that - is that the flux will melt together with all the plastic & that molten flux/plastic will simply "incase" the metals in the molten flux/plastic

In other words - the metal will be "tied up" in a matrix along with the flux/plastic - instead of getting an actual separation of plastic from the metal

The plastic MUST first be burned (incinerated) in order to turn the plastic to carbon/ash

The system - that orvi described - is NOT a simple furnace that the BIG BOYS just throw there circuit boards into along with some flux

It is a continuous feed system that automatically feeds the material into the beginning of the process & it continues to feed that material through "different stages" of the process until it comes out the other end as metal separated from the other junk on/in the starting circuit boards (the junk being the plastics, ceramics, fiberglass & "some" of the metals like aluminum, iron etc. etc.)

And this is how that system works -------

The very first thing they do is dump about 20 tons of CBs at a time into a VERY large shredder

As the "shredded" CBs come out of the shredder - a "screw" (kind of like a conveyer belt - but a screw in a tube) feeds the shredded CBs into an "incineration chamber" that burns up all the plastic

In other words - the screw feeds the shredded CBs in one end of this incineration chamber - then once all the plastics are burned up - a screw removes the material from this burn chamber (which is now carbon/ash mixed with the metals in the CBs) as the screw moves the incinerated material from the burn chamber to the actual furnace part of the system flux is added to that incinerated material

In other words - as the screw moves the incinerated fraction of the shredded boards from the burn chamber - to the furnace - flux is added - & the screw acts as a mixer to mix the flux with the ash/carbon/fiberglass/ceramics/metal (this is known as the "smelt load") the screw then feeds this smelt load into the actual furnace - where when the 'smelt load" becomes molten the flux is allowed to "slag off" the carbon/ash/fiberglass/ceramics as well as "some" of the more reactive metals (like aluminum iron etc. etc.)

The molten smelt load is then poured to molds where the molten metal settles to the bottom of the mold with the molten slag on top - once it all cools/solidifies the slag is then knocked off the separated metal

This separation only happens because the plastics FIRST went through an incineration process/stage to burn them to carbon/ash - BEFORE going to the smelt furnace stage/part of the process

Bottom line - if you don't first shred - then incinerate - then smelt --- you will end up with a BIG MESS

The BIG BOYS just have a continuous feed system - that puts the CBs though those "different" stages of the process

They DON'T just put the CBs - mixed with flux into the furnace - & that is because it DOES NOT work - & it WILL NOT work for you ether !!!!

Kurt

 

[Ayham Hafez]

I don't think 'all components' can go in a furnace. Like electolytic capacitors and aluminum heat sinks.

I Know that Aluminum capacitors explodes with high temperature, but I think it will not make an issue in rotary furnace that has enough capacity.
First step after smelting is to dissolve the ingots in HCl to dissolve all tin and Aluminum

 

[kurtak]

I don't think 'all components' can go in a furnace. Like electolytic capacitors and aluminum heat sinks.

The BIG BOYS do it ALL the time

They certainly don't spend time "depopulating" CBs

What they do is shred the boards - them incinerate - then smelt

In the smelt some base metals are able to be slagged off with different fluxes that allow them to be oxidized in the smelt - other base metals are able to be slagged off by sparging air through the molten smelt load to oxidize those base metals (& slag them off) --- they also add A LOT of extra copper to the smelt

Concerning the electrolytic capacitors - they are only an explosion concern when they are "whole" capacitors because pressure builds up in them as the electrolyte starts to boil in them from the heat - shedding of the CBs takes care of that problem as the capacitors are shredded/crushed in the shredding process

Kurt

 

[kurtak]

First step after smelting is to dissolve the ingots in HCl to dissolve all tin and Aluminum

That also will - ABSOLUTELY NOT WORK !!!

That that is because AFTER smelting the tin & aluminum is now "alloyed" with the copper (& other metals)

As an alloy - the acid CAN NOT get to the tin/aluminum to dissolve the tin/aluminum

Kurt

 

[kurtak]

So I think that my idea is possible, I mean we can smelt pcb with all its components in furnace together without loosing any PM's value.

And for what it is worth Ayham Hafez - when I say the things you are proposing - WILL ABSOLUTELY NOT WORK !!!

I am able to say that because ------

1) I ran my own small smelting operation - & -----------

2) I also sent several loads - per year - of 1 - 2 ton of "high grade" boards - to a mid size smelter - that was about 2 hours from where I lived for smelting

So I have "first hand" experience & knowledge of the process that CBs MUST go through to successfully smelt them

And what you propose WILL NOT WORK !!!

So - I am sorry to say - but smelting of CBs just flat out is NOT as simple as you would like it to be - there is MUCH more involved then you "think"

Edit to add; - you will have to invest a whole LOT more then just buying a furnace - starting with doing A LOT of research on the subject of smelting --- then you will need a shedder - a proper incinerator - a proper system for scrubbing TOXIC fumes & gasses - a bag house for collecting fly ash (which will hold values) - & you will need LOTS of extra copper to add to your smelts - etc. etc.

Kurt

 

[Ayham Hafez]

NO !!! - this will ABSOLUTELY NOT WORK !!!


Because the plastics (epoxy & other plastics) on/in the boards MUST first be burned off (incinerated) in order for the flux to "slag off" the ash/carbon created in the FIRST step of the process - which is incineration of the boards (which is actually the second step - because the "very first" step is shedding the boards - then incineration)

NO !!! - you are NOT understanding what orvi is telling you - you are only hearing the "part" you want to hear

In other words - the very first thing orvi said in his first post was -----------

In other words - NO - you can NOT just put circuit boards in a furnace with flux & expect a separation of all the plastic from the metal

In fact - what will happen - if you try that - is that the flux will melt together with all the plastic & that molten flux/plastic will simply "incase" the metals in the molten flux/plastic

In other words - the metal will be "tied up" in a matrix along with the flux/plastic - instead of getting an actual separation of plastic from the metal

The plastic MUST first be burned (incinerated) in order to turn the plastic to carbon/ash

The system - that orvi described - is NOT a simple furnace that the BIG BOYS just throw there circuit boards into along with some flux

It is a continuous feed system that automatically feeds the material into the beginning of the process & it continues to feed that material through "different stages" of the process until it comes out the other end as metal separated from the other junk on/in the starting circuit boards (the junk being the plastics, ceramics, fiberglass & "some" of the metals like aluminum, iron etc. etc.)

And this is how that system works -------

The very first thing they do is dump about 20 tons of CBs at a time into a VERY large shredder

As the "shredded" CBs come out of the shredder - a "screw" (kind of like a conveyer belt - but a screw in a tube) feeds the shredded CBs into an "incineration chamber" that burns up all the plastic

In other words - the screw feeds the shredded CBs in one end of this incineration chamber - then once all the plastics are burned up - a screw removes the material from this burn chamber (which is now carbon/ash mixed with the metals in the CBs) as the screw moves the incinerated material from the burn chamber to the actual furnace part of the system flux is added to that incinerated material

In other words - as the screw moves the incinerated fraction of the shredded boards from the burn chamber - to the furnace - flux is added - & the screw acts as a mixer to mix the flux with the ash/carbon/fiberglass/ceramics/metal (this is known as the "smelt load") the screw then feeds this smelt load into the actual furnace - where when the 'smelt load" becomes molten the flux is allowed to "slag off" the carbon/ash/fiberglass/ceramics as well as "some" of the more reactive metals (like aluminum iron etc. etc.)

The molten smelt load is then poured to molds where the molten metal settles to the bottom of the mold with the molten slag on top - once it all cools/solidifies the slag is then knocked off the separated metal

This separation only happens because the plastics FIRST went through an incineration process/stage to burn them to carbon/ash - BEFORE going to the smelt furnace stage/part of the process

Bottom line - if you don't first shred - then incinerate - then smelt --- you will end up with a BIG MESS

The BIG BOYS just have a continuous feed system - that puts the CBs though those "different" stages of the process

They DON'T just put the CBs - mixed with flux into the furnace - & that is because it DOES NOT work - & it WILL NOT work for you ether !!!!

Kurt

In past, I worked in rotary lead smelting furnace, some times we were feed the rotary furnace with scrap acid batteries without dismantling I mean we feed the scrap batteries with their plastic container into the furnace, plastic container and plastic seperators in the acid batteries is about 10% from the whole battery weight, when start burning the scrap batteries in the rotary furnace we use low heat to incinerate the lead oxide then we start to increase the heat till we melt all lead with fluxes such as iron, when pouring the lead we get slags above the melted lead with no issues, from this my idea came of one step process, I mean using rotary furnace for incinerate then start melt without feed out the pcb batch

 

[Makcc]

Guys, please don't feed the trolls .
Smelting prepared printed circuit boards in rotary tilt furnaces is a standard practice in the industry for large scale processing.
Let's not reinvent the wheel.
Somehow I think the OP is trolling.

 

[Ayham Hafez]

Guys, please don't feed the trolls .
Smelting prepared printed circuit boards in rotary tilt furnaces is a standard practice in the industry for large scale processing.
Let's not reinvent the wheel.
Somehow I think the OP is trolling

Guys, please don't feed the trolls .
Smelting prepared printed circuit boards in rotary tilt furnaces is a standard practice in the industry for large scale processing.
Let's not reinvent the wheel.
Somehow I think the OP is trolling.

What's your issue, could you explain more? Maybe I misunderstood the purpose of this forum.

 

[Makcc]

What's your issue, could you explain more? Maybe I misunderstood the purpose of this forum.

I have no issue.
Carry on.