Smelting/mechanical

Hi

For the last two months i have been in research on e-scrap (PCBs) recycling on a larger scale. It is very interesting and many things gets you thinking.

So far i has been focusing on mechanical methods and i have been in contact with a few company´s that supply equipment. I have gotten a new offers. They range from 25 000 EUR - 300 000 EUR (without electrolyte or 750 000 EUR (incl fire assay & electrolysis).

This has gotten me thinking of smelting. I have read some of the threads here, the excellent thread of 4metals among others.

In your opinion, when would you say it is more effective to use smelting than mechanical methods.

A) In terms of yeld - Can you get more metals out of the PCBs with smeltning?
B) In terms of investment. More expensive with smelting?
C) Difficulty in running operations. Fumes, heat, technical skills needed and so on.

What do you guys think?

/Håkan

The mechanical systems separate your feedstock into more saleable piles. Aluminum, steel, copper, and the PM's. But an entirely mechanical system will not separate all of the precious metals from the other metals. There is a percentage loss.

Smelting will put most of the non precious metals into a slag so they are not in a payable form. You will recover the copper which on PCB's is a decent percentage of the whole package. And of course an electrolytic copper cell will produce the copper and the precious metals will be recovered from the anode slimes.

Then there is granulation and leaching with cyanide.

All methods have some pluses and some minuses. It all depends on what you are feeding into your "system". A lot of refiners have a section with mechanical screwdrivers and nut drivers hanging from above for easy swapping out of tools and they have a staff stripping off the cases and screens, batteries, fans, and getting to the PM containing boards and components which are either sold as is or processed. It's a learning curve to determine what you can sell and what you can refine. The advantage of the mechanical break down section is you can still separate the different metals for sale as scrap. If you are talking about a large operation, cheap labor is a necessity.

Then the PM containing scrap can be either smelted or leached depending on your preference.

I think 4metals is spot on, there is no single way to process all e scrap, there is no right or wrong method as the types of material, make up of said material and varying amounts of values compared to base metals and plastics all of which can have value if sorted correctly.
I think you need to identify what material will make up the bulk of the scrap you will be processing and then design a process to handle it to produce the best return against fixed costs such as labour and plant costs, I don't think anyone can help to determine for you the route that you need to take until you have the above details there are just too many factors only you can identify and address, you are entering an already crowded market place but I'm sure you can make your way in with due diligence and determination and with the correct processes.

Another consideration is change. It always happens. What you set up for today may be entirely different from what you are processing in 2 years. Always select your equipment that will allow the maximum versatility because as quickly as technology changes, scrap changes. Especially e-scrap.

Thank you guys for the answers.

4metals:
My operation will be focusing on PCBs so i dont know what other materials except, Au, Ag, Cu and perhaps Pl, i can sell. Lead, Zink and the other metals found in a PCB is not easy to purify.

And the PCB board material (plastic, resin, fiber glas) i have not found a use for (yet). I have been expecting to handle electrolysis in house to get copper out and resell. But after that i think i will ship it off to someone to take care of the PM extraction. I am not comfortable to handle cyanide or very strong acids. It is simply to advanced for me and i would be stupid to experiment with my life @ stake. I am actually not to fond of electrolysis either but i think it will be manageable. In your thread you talked about 98% copper purity on anodes to get maximum efficiency. Did i understand that correctly? That means putting in extra copper in the beginning until you have a surplus of it.

Its funny you mentioned change. I have been looking for ways to increase flexibility of my operation to have a production line that can accept other raw materials as in feed. For example electrical motors (contains lots of copper). And then use the same/near the same process for both. It will lower the risk a little bit. I hope to have a meeting with a equipment supplier and we will discuss it soon. I don´t know if its possible, time will tell.

As i understand no matter if you use mechanical or smelting, you need electrolysis (or chemicals) to refine the material after? So the question is. Is it a cheaper investment to do smelting or do you guys think its more expensive?

The company that does a lot of smelting here in Sweden does not put plastic into their furnace. In fact they buy, populated boards that are pre sorted from, plastic, iron and aluminum. Plastic, as i understand it, acts as a very efficient fuel in their furnace and it makes it to hot for operation.

nickvc:
I agree, there is no "one good way". So i will make a line for PCBs at the moment (if figures show its profitable) and then i will see how it can be developed.

I have an idea of one tone per day. But im worried that the electrolysis part will be enormous. If i calculated correctly you need 840 amps to extract one kilo of copper per hour. If one tone gives me around 140kg of copper per day then i need to be able to extract 140kg per day. That is 14 units that can produce 10kg per day each... it seems like its getting big. perhaps too big for me to handle. :shock:

/Håkan

If you are getting only circuit boards (and you harbor the deep respect for cyanide and strong acids as you mentioned) then you will do best by pyrolysis followed by crushing and sifting. The powder can go right off to Metech after you sample it for assay. Then the metallic fraction can be melted into a copper rich bar containing all of your PM's. If you apply some smelting techniques to the melt, you can eliminate a good percentage of the lead and tin and zinc. Lead for sure and Tin, if I remember correctly, are metals which incur higher charges at the refinery as they are "undesirable" metals. (Meaning they have to smelt them off so they want to be paid for that service.) A facility to process a ton of this feed a day will require a pyrolysis oven capable of processing about a cubic meter per firing followed by a ball mill of about half that capacity. The sifter is a continuous feed process producing both fine powders and the oversize for smelting. The smelt will likely require a #100 crucible to perform one smelt per day. If you size it right, the equipment should be able to process a ton in a typical 8 hour shift. Then you can grow to 3 tons per day by never sleeping!

Your location may also benefit from the ability to witness the sampling of your powders and the smelted bars at Metech. This will be a wonderful learning experience coupled with a secure feeling that comes from knowing the samples are good and haven't been tampered with.

If you set up as I have described, your operation will use no liquid chemicals except for the assay lab usage. The slags can be crushed up and disposed of after they are analyzed for PM's usually as a non hazardous waste if they meet your country's version of the TCLP protocol. TCLP is a test where the sample is exposed to a mildly acidic leach process to simulate the leaching that would occur in a landfill exposed to acid rain. If it passes that protocol, it is deemed nonhazardous and is inexpensive to dispose of. If it doesn't pass that protocol, there are treatments which can chelate the metals to help them remain insoluble, a little more expense but still much less than the cost of disposing of hazardous waste.

4metals said:

If you are getting only circuit boards (and you harbor the deep respect for cyanide and strong acids as you mentioned) then you will do best by pyrolysis followed by crushing and sifting. The powder can go right off to Metech after you sample it for assay. Then the metallic fraction can be melted into a copper rich bar containing all of your PM's.

Click to expand...

There's a reason 4metals is suggesting this--if you're not aware, electrolysis generally involves highly concentrated acids. Those acids (nitric in some cases, sulfuric in others) is where the electrolysis reactions happen.

knofan said:

I am not comfortable to handle cyanide or very strong acids. It is simply to advanced for me and i would be stupid to experiment with my life @ stake.

Click to expand...

By the way, kudos to you for stating that. After so many people who disregard the dangers of the materials we work with, it does my heart good to see someone with proper respect for hazardous materials and their life.

upcyclist said:

knofan said:

I am not comfortable to handle cyanide or very strong acids. It is simply to advanced for me and i would be stupid to experiment with my life @ stake.

Click to expand...

By the way, kudos to you for stating that. After so many people who disregard the dangers of the materials we work with, it does my heart good to see someone with proper respect for hazardous materials and their life.

Click to expand...

Agreed. However risk management is sensible, rather than not trying something new because of "hype." Research the risks, and how to minimise them and a whole host of options opens up.

4metals.
Pyrolysis is the technique of burning the components of the PCB and make an ash of them, or do you do this on the entire board? I have not done research on this, therefore the newbi question.

That would indeed rule out the chemicals. The problem, as i see it that i will give a way another step to a third party and therefore also some margin. What i like about it is the possibility to sell the ash and get a very smooth process from PCB to ash. The metallic fraction that you mention, is that the copper inside the PCB?

When i said i thought about using electrolysis i meant consulting a professional company to set it up for me and provide me with safety equipment and education on the matter. How ever, i have looked around and it seems very difficult to find such a company here or any were. Do you guys have any ideas on this?

But perhaps this is not an good idea, would you say that it is possible for an novice to operate electrolysis bath with professional equipment and proper training, or i am kidding myself here?

The only company that i managed to get a hold of (for electrolysis) is EMAK (Turkey) and they say that their system can manage 200 kg copper per day. But the system becomes continues after about 20 days. I have searched this forum for something to explain that, but cant find it. Do you guys know what they mean? I asked them and they say it is because of the chemical "rules". Does not make sense to me but maybe to you?

MeTech, is it this company :arrow: http://www.metechrecycling.com? If so they are only in US, it will be a long way to ship the products. But i will look them up.

upcyclist:
Well, i am a pretty safety aware person in general. I don't use power tools i am not familiar with or have very good instructions/safety equipment to use, chainsaws for example. The same is when i drive my car and so on. One mistake can change my life, or end it in an heartbeat. I dont find many things to be worth that risk.

When i started to think about all this stuff i did not think it was so difficult, until i read what 4metals and many others was saying. Whats the point of going in to a forum to learn if you ignore something that can potentially kill you? I have never understood how ppl think about this things

Pyrolisis is a first step in the process. The material, which can be components from the boards, just the boards, or both, is heated in a closed container without oxygen. The various resins used to make the boards and components break down into gasses. Usually, these gasses are either directed back into the flames used to heat the closed container, or otherwise treated to render the gasses less harmful. Material that has been pyrolized still needs to be incinerated (heated in the presence of oxygen) to burn off the remaining carbon.

There are a few members who could provide consulting services to set up an electrolysis system for you. Perhaps they will send you a PM.

It's interesting that we've had a number of new members recently who have wanted to get into the ewaste recycling business, but they have no knowledge of that business. That's a tough way to start a business. It's not impossible, but it's a hard way to go. It's much easier to start a business in a field in which you have some experience. While the potential of a new frontier may seem attractive, knowledge of the challenges involved can dull the shine.

Dave

FrugalRefiner
Thank you for the input i will look it up more closely. Is there company's that make equipment needed for this?

When it comes to business it is always difficult to "break new ground" but i am no newbie at that. I own three company's in a different "branch" and im the "number guy" so i know what to do. And if i come to a situation (which i will) where i need knowhow that i don't have. I will consult a company that can provide me with that.

That being said, i agree that a lot of this research has been very surprising. I would also like to point out that i have no idea if the numbers add up yet, it is to soon to tell. Perhaps i will do research for months or a year and discover that its not a good idea. It has happen several times before

Metech works very closely and for a time was owned by Boliden. I thought they operated in Sweden as well. Check Boliden.

The process I outlined will give you the ability to know the PM value of your material that you ship out. It is very much the process you will have to perfect before you begin to even consider doing the electrolytic copper yourself. I am a strong believer of taking the process step by step, once you can perform efficiently at a given level, you do an analysis and proceed to the next level as the margins allow you. This way your growth as a company is funded by your production and not by going to a bank and buying a truckload of equipment you do not understand and will be overwhelmed by. Experience is your best teacher, experience every different level and perfect the techniques before moving ahead. I had the distinct pleasure of knowing a Romanian chemist years ago who taught me to fire assay sweeps. He always said the way to learn is to take it "easy by easy." Now that was both bad English and bad grammar, but I knew exactly what he meant and it is still true today!

Once you can produce and assay your own copper based bullion that is when you do a benefit cost analysis to determine if you can effectively "do it cheaper". Another source for electrolytic copper is Italimpianti in Italy. http://www.italimpianti.it/en/electrolytic-copper-refining-plant/
I have experience with their electrolytic plants and they produce a nice product.

The metallic fraction is indeed the copper and the PM's left over after pyrolysis of the boards. Easily melted and smelted.

But the system becomes continues after about 20 days.

Click to expand...

Something wrong with this quote, something definitely lost in translation. I believe they mean the system is contaminated in 20 days. Or another way, after producing 4000 kg (or 4 tons) of copper the contamination level from other metals in the copper anodes gets too high in the solution and the solution needs to be changed.

knofan said:

That would indeed rule out the chemicals. The problem, as i see it that i will give a way another step to a third party and therefore also some margin.

Click to expand...

Note that you only lose margin if you can do it for a lower cost than your refiner--this is not a given. The refiner may have an economy of scale advantage over you.

knofan said:

When i said i thought about using electrolysis i meant consulting a professional company to set it up for me and provide me with safety equipment and education on the matter. How ever, i have looked around and it seems very difficult to find such a company here or any were. Do you guys have any ideas on this?

But perhaps this is not an good idea, would you say that it is possible for an novice to operate electrolysis bath with professional equipment and proper training, or i am kidding myself here?

Click to expand...

It is absolutely possible, but your phrase is key: "and proper training." This very forum will give you a good base on the subject, and if you read enough here and do some side research, it'll give you enough to start experimenting on a small scale. Once you develop the skills and understanding, there are forum members here who assist in setting up industrial applications. Start with a search on "copper cell" and you'll be well on your way.

upcyclist
It is very possible that they have an advantage and are able to do it cheaper, due to volume, experience and so on. But they also have a margin, and that is the one i am after. I don't really need to make it cheaper than they do to be able to profit from it, just cheap enough

But i totally understand your point of view here, it is worth thinking about this things. Since there also an investment that needs to be taken into account. Not just the extra margin i have. Will it be enough to get an reasonable ROI.

4metals:
Thank you for this information. I will look into the Italian guys a little bit. And read up on Pyrolysis also. This seems interesting. I have not been able to find out if it will be possible to ship ash to MeTech. You were right about Boliden though. But i think they sold it to an US company after a series scandals that cost them like 10-15 million dollars or so.

I saw that the Italian guys had some interesting equipment including eq for assay. But no PL eq.

Would you say it is difficult to do my own fire assay?

About the quote from EMAK, the conversation is in english. I will post a little bit here:

EMAK
Because of the chemical laws you have to wait approx 20 days for getting the pure copper out. With our design we are feeding everyday 200kg’s and after 20 days the system becomes continuous.
You will collect results everyday.

ME
You wrote that the electrolysis system becomes continuous after 20 days. What does that mean a little bit more exactly?

The electrolysis system is a continuous system. This is the methodology for it the combination of chemicals and electricity need to be adjusted so that the process will bring pure copper sheets as output.
While the process is going on every day anode mud can be collected for further refining.

I do not understood much more from that explanation but perhaps you could?

I am aware that the electrolyte will need changing after some time due to contamination but i dont see anything about that here tho.

FrugalRefiner:
What will be the contents of the ash? If most PMs end up in the "smelt pile"? Do you have any thoughts on who manufacture pyrolysis equipment and incineration?

I believe what they're saying is that for the first 20 days, you'll be feeding copper into the system in your anodes, but it will take 20 days before you'll really have fully harvestable cathodes, so for the first 20 days you're putting copper into the system without taking any out. After 20 days, you'll begin harvesting mature cathodes, so as you put more copper in with fresh anodes, you'll also be harvesting a similar amount from the cathodes. So it becomes a continuous process. Although that seems a little odd, that's my interpretation of their emails.

If you pyrolize, then incinerate components and/or boards, you'll primarily have various metals left. With boards, you may also have fiberglass used to reinforce the boards. How you deal with that depends on your operation.

Dave

I agree with Dave's assessment of EMAK's description, the cathode probably takes 20 days to reach a harvestable weight. So they probably start out by adding a cathode each day so at day 20 the one which has been there for 20 days can be pulled and replaced with a starter sheet and every day from there on a cathode is harvested.

Would you say it is difficult to do my own fire assay?

Click to expand...

Definitely not. You will need to do both powdered "sweeps type" assays as well as scorification assays on the copper based bullion. I believe they have been discussed in detail here but if not we can guide you through it step by step.

4metals:

From what i have read here on this forum, fire assay is a good instrument for determine gold and other PMs in a sample. But how do i effectively determine other metals that i can use? For example copper? All base metals should be burned off in this process, right?

With most methods that i have seen (mechanical) you end up with a pile of metals all mixed. Most of what i have seen so far is that you use different techniques to refine copper, gold, silver and palladium. But not any other metals.

There is a great deal of Pb, Zn and Sn. An value estimation per ton, very roughly, would be:

Zn = $85 (50kg/110lb)
Pb = $38 (27kg/59lb)
Sn = $1060 (51kg/112lb)
Ni = $96 (15kg/33lb)

Figures assuming:
Effectiveness of collecting the metals from the raw material are between 89% and 96%.
Price paid by my customer is 65% av the market value.

By this estimation the value of Sn is actually higher than silver. Could this be right or is my math completely off?

Is it so difficult to refine that one cant turn a profit from it? To be able to refine this would valuable, if it could be done in an reasonable effective manner. It would also reduce the toxic metals if we need to landfill the waste at a later stage, and that could mean lower price for the landfill. An added value.

Many of the more reactive metals become very difficult to refine, or are extremely difficult.
Take aluminum for example, where electrical power becomes about half the cost, aluminum was so difficult to refine that it was not until our modern times that we were able to do it economically, it was not too long ago that aluminum cost more than gold not because of rarity but because it was so difficult, or costly to refine.

Aluminum metal was first produced in 1825 in an impure form by a Danish chemist Hans Christian Ørsted by reacting dried crystals of aluminum chloride with potassium to form an amalgam, yielding a lump of metal looking similar to tin.

Scientist discovered aluminum in bauxite ore in 1859 aluminum trichloride could be reduced by sodium, which was more convenient and less expensive than potassium.

In the mid-1880s, aluminum metal was exceedingly difficult to produce, which made pure aluminum more valuable than gold. So celebrated was the metal that bars of aluminum were exhibited at the Exposition Universal of 1855.
Napoleon III of France is reputed to have held a banquet where the most honored guests were given aluminum utensils, while the others made do with gold.

Aluminum was selected as the material used as a capstone of the Washington Monument in 1884, it was more precious than gold at the time, and the passivization of its outer oxide layer keep it from oxidizing to a pile of salt in the environment, this was a time when one ounce (30 grams) of aluminum cost as much as the daily wage of a common worker, The capstone, which was set in place on 6 December 1884 in an elaborate dedication ceremony, was the largest single piece of aluminum cast at the time. It suffered some damage from lightning strikes, and was redesigned and replaced during the 1934 renovation of the monument.

aluminum oxidizes very easily, this oxidation property not only make aluminum extremely difficult to refine, it is also what makes aluminum so extremely useful for many uses like tanks to hold acids, the oxidation or (rust) is what protects the aluminum from the same acid that oxidizes it so readily, the surface turns to a layer of salt which forms a coating to protect the rest of the metal aluminum from the atmosphere or oxidizing agent like nitric acid.

Bauxite is converted to aluminum oxide( Bayer process).
Al2O3 + 2 NaOH → 2 NaAlO2 + H2O
2 H2O + NaAlO2 → Al(OH)3 + NaOH
In this energy-intensive process, a solution of alumina in a molten around 1,800 °F)) mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyte to produce metallic aluminum:
Al3+ + 3 e− → Al
The liquid aluminum metal sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminum billets for further processing. Carbon dioxide is produced at the carbon anode:
2 O2− + C → CO2 + 4 e−

Aluminum electrolysis uses a lot of energy. The worldwide energy consumption is approximately 15 kilowatt-hours per kilogram of aluminum produced . state-of-the-art smelters operate at about 350 thousand Amps of electrical current, needing a very large power plant close by. Electric power is about 20% to 40% of the cost of producing aluminum.