Ayham Hafez
Well-known member
Can we use CaCO3 instead of soda ash as a flux for incinerated PCB's?
Shifting to pyrometallurgy process
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Ayham Hafez
Well-known member
Finally I start smelt E-waste, I prepared a new furnace design that doesn't use crucible, and use waste oil and gasoline as heat source, will share all its details later.
I poured my first E-waste metal block yesterday, it was 2.5 kg from 12 kg plastic connectors, used con mold, after melting it again to make shots I put shots in a beaker and used dilute nitric acid 67% with 50% water, then putted on the kitchen stove.
The issue is reaction is too slow, nitric acid not consumed quickly, and copper shots after 36 hours on 200 c heat only loss about 50% from its original weight, I tried to add fresh nitric acid with no positive results also tried to add sulphuric acid with nitric to aggressive the reaction but its still very slow.
I'm sure that there is no passivation on the copper shots, cause I washed them in hot water and used fresh dilute nitric acid, shots looks red like pure copper, there is some material in the bottom of the beaker similar to sand, but they are not covering the copper shots, anyone have an idea about what's happening?
I poured my first E-waste metal block yesterday, it was 2.5 kg from 12 kg plastic connectors, used con mold, after melting it again to make shots I put shots in a beaker and used dilute nitric acid 67% with 50% water, then putted on the kitchen stove.
The issue is reaction is too slow, nitric acid not consumed quickly, and copper shots after 36 hours on 200 c heat only loss about 50% from its original weight, I tried to add fresh nitric acid with no positive results also tried to add sulphuric acid with nitric to aggressive the reaction but its still very slow.
I'm sure that there is no passivation on the copper shots, cause I washed them in hot water and used fresh dilute nitric acid, shots looks red like pure copper, there is some material in the bottom of the beaker similar to sand, but they are not covering the copper shots, anyone have an idea about what's happening?
Putting it on your kitchen stove isn't recommended. Everything is going to corrode. Sulfuric acid shouldn't be needed and makes your solution much more dangerous.
Anyway, after your new addition of nitric acid did the solution change color?
Ayham Hafez
Well-known member
Ye
Yes solution change color, is it possible the nickel grade is very high in connectors?
There can be nickel but my sources indicate that there are a couple relevant salts that appear red: Iron nitrate or Cobalt sulfate. But these sulfates are both soluble so passivation is unlikely.
Iron has very poor solubility in nitric acid. Long story short, I think you have an abundance of iron, for which HCL is the best option. (Your other option is lots of sulfuric acid but you are absolutely not set up for that level of danger.)
I'm sure I don't have to tell you that having free nitric in your material when you go to boil in HCL will remove some gold. Someone more experienced here may be able to give you a clear path forward to switch oxidizers without losing values.
Iron has very poor solubility in nitric acid. Long story short, I think you have an abundance of iron, for which HCL is the best option. (Your other option is lots of sulfuric acid but you are absolutely not set up for that level of danger.)
I'm sure I don't have to tell you that having free nitric in your material when you go to boil in HCL will remove some gold. Someone more experienced here may be able to give you a clear path forward to switch oxidizers without losing values.
Ayham Hafez
Well-known member
I think the only option is to use sulphuric with peroxide, I know its dangerous but can't find another option
Ayham Hafez
Well-known member
I have done another smelt for same material, then took some beads and make 4 tests as following:
1- dilute nitric acid, reaction too slow
2- sulphuric acid with peroxide, also reaction too slow
3- HCl, reaction abit better than 1&2
4- Aqua regia, reaction fast
Aqua regia is the fastest, but I will miss the silver, already done a test and silver exist, hope some one can help
1- dilute nitric acid, reaction too slow
2- sulphuric acid with peroxide, also reaction too slow
3- HCl, reaction abit better than 1&2
4- Aqua regia, reaction fast
Aqua regia is the fastest, but I will miss the silver, already done a test and silver exist, hope some one can help
Your silver will be solid (silver chloride). Excess silver would passivate so if you get complete dissolution in AR then you don't have much silver. You probably have iron in your AR which will cost you time and money to deal with.
Here's a saying to live by: slow is smooth, and smooth is fast.
What are your objectives that time seems to be so critical?
Ayham Hafez
Well-known member
I dissolved everything in AR, will try to recover silver by ammonia after filtering the AR.
I just want to know how nitric even piranha solution can't dissolve metal shots, before smelting I removed all iron parts so I don't think its related to iron
I just want to know how nitric even piranha solution can't dissolve metal shots, before smelting I removed all iron parts so I don't think its related to iron
Ayham Hafez
Well-known member
Here is my new smelting furnace, it composed of two main parts, lower part which has a cement refractory formed as a pot, after finished forming it I just splash some water on above of it, and upper size which build with refractory firebricks and castables on the top of it.
I use two drips one for propane and second for waste oil, till now I did two successful smelting, it took about 1 hour for full smelting E-waste.
I use two drips one for propane and second for waste oil, till now I did two successful smelting, it took about 1 hour for full smelting E-waste.
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If you dissolved everything in AR, you would have filtered the silver as it’s insoluble chloride, wouldn’t you?
Maybe run a magnet through any unprocessed material to see about the iron.
In ewaste you have lead in your AR so consider addressing that.
Ayham Hafez
Well-known member
I recovered silver chloride using ammonia.
Am still have no answer about why nitric not dissolve the smelted e-waste quickly as normal l, I removed all big iron parts, left only pins, if I will remove all magnetic parts that mean I will remove all pins since most of them is made by Kovar.
Hope someone can advise
Kovar is very interesting. I've never worked with it but you're right, it'd be very magnetic!
Back to an earlier comment of mine about the red color, cobalt sulfate is a candidate and maybe if you consumed the nitric in the solution the sulfuric would go to work on what I assume is a major amount of cobalt.
Cobalt sulfate is red and soluble in water+ethanol. So the question I have is whether this could cause a passivation layer halting your processing.
I'm out of my element and well into backseat driving
Here's what I'd try to see if cobalt sulfate is the issue:
1. Take a bit of shot and boil in distilled water in a small beaker. This removes any water-soluble salts. You should still observe the red color.
2. If the water is clear, add a bit of ethanol to the warm water, like maybe 10ml to 100ml. If no reaction, go up to about 30ml.
If the solution's color changes red, you may have excess cobalt sulfate.
Since nitric dissolves cobalt readily at room temperature, then to prevent reoccurrence avoid sulfuric acid.
I can't help but think that there's a way better process but since I don't do what you do I'm unable to speak from experience and Hoke's book doesn't address cobalt so the RTFM guys on this forum can't chime in either.
Edit: Just a thought: I mentioned passivation for the cobalt sulfate, but it doesn't really need to be passivation, right? I mean you could have very porous blobs of pretty much nothing but cobalt sulfate and gold left.
In Hokes book she mentions the concept of acquaintance experiments several times. You're on new ground but she gives very principled advice!
Back to an earlier comment of mine about the red color, cobalt sulfate is a candidate and maybe if you consumed the nitric in the solution the sulfuric would go to work on what I assume is a major amount of cobalt.
Cobalt sulfate is red and soluble in water+ethanol. So the question I have is whether this could cause a passivation layer halting your processing.
I'm out of my element and well into backseat driving
Here's what I'd try to see if cobalt sulfate is the issue:
1. Take a bit of shot and boil in distilled water in a small beaker. This removes any water-soluble salts. You should still observe the red color.
2. If the water is clear, add a bit of ethanol to the warm water, like maybe 10ml to 100ml. If no reaction, go up to about 30ml.
If the solution's color changes red, you may have excess cobalt sulfate.
Since nitric dissolves cobalt readily at room temperature, then to prevent reoccurrence avoid sulfuric acid.
I can't help but think that there's a way better process but since I don't do what you do I'm unable to speak from experience and Hoke's book doesn't address cobalt so the RTFM guys on this forum can't chime in either.
Edit: Just a thought: I mentioned passivation for the cobalt sulfate, but it doesn't really need to be passivation, right? I mean you could have very porous blobs of pretty much nothing but cobalt sulfate and gold left.
In Hokes book she mentions the concept of acquaintance experiments several times. You're on new ground but she gives very principled advice!
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I've been watching all of this, since I'll be smelting computer chip and low-grade gold-plated pins. It looks like the best way to process these materials is to use copper as the collector and then electrolyse it in a copper sulfate solution. All the PMs will stay in the slimes. Most of the base metal sulfates will dissolve. Only lead sulfate will remain in the slimes with the PMs, but that's not a problem for the slime refining process.Kovar is very interesting. I've never worked with it but you're right, it'd be very magnetic!
Back to an earlier comment of mine about the red color, cobalt sulfate is a candidate and maybe if you consumed the nitric in the solution the sulfuric would go to work on what I assume is a major amount of cobalt.
Cobalt sulfate is red and soluble in water+ethanol. So the question I have is whether this could cause a passivation layer halting your processing.
I'm out of my element and well into backseat driving
Here's what I'd try to see if cobalt sulfate is the issue:
1. Take a bit of shot and boil in distilled water in a small beaker. This removes any water-soluble salts. You should still observe the red color.
2. If the water is clear, add a bit of ethanol to the warm water, like maybe 10ml to 100ml. If no reaction, go up to about 30ml.
If the solution's color changes red, you may have excess cobalt sulfate.
Since nitric dissolves cobalt readily at room temperature, then to prevent reoccurrence avoid sulfuric acid.
I can't help but think that there's a way better process but since I don't do what you do I'm unable to speak from experience and Hoke's book doesn't address cobalt so the RTFM guys on this forum can't chime in either.
Edit: Just a thought: I mentioned passivation for the cobalt sulfate, but it doesn't really need to be passivation, right? I mean you could have very porous blobs of pretty much nothing but cobalt sulfate and gold left.
In Hokes book she mentions the concept of acquaintance experiments several times. You're on new ground but she gives very principled advice!
Palladium(II) sulfate appears to be one of the few relatively stable and soluble PM sulfates, but it undergoes hydrolysis in aqueous solutions rapidly, so it would still remain in the slimes of a weakly acidic copper sulfate solution.
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Definitely a good plan Alondro after all this is how the big boys do it. The results are based on the processed slimes.
