# Copper recovery from depopulated boards



## kjavanb123 (May 11, 2015)

Hi,

My research and development for grinding the whole circuit boards, then running them on shaker table, has been delayed due to MBMMLLC (Mt Baker Mining and Metals LLC) have been busy with their clients jobs. I sent out 30lbs of metals recovered from circuit boards using blue bowl for electrowinning tests and pilot design.

Meanwhile, to process the existing 1600lbs of boards, I decided to use oscillator multipuporse tool, to clean the boards from components, and use screen to filter all the SMDs and MLCCs as they fall off the board, which I will try to post them in a separate threat.

I used the exiting shredder in the shop, to shred depopulated boards to smaller pieces, as following,



Then fed those to my newly purchased hammer mill with 0.7mm screen, which does a great job to pulverize boards to consistent powder, here is the photo of inside the hammer mill, the motor spins at 21,000 rpm.



I ran 710g of above fine powder in blue bowl, dried the concentrate, and got 135g of copper powder, that is 19% of telecomm boards are laminated copper.



I will process more boards to have a better understnding on copper percentage of the boards. Copper used in components not included here, with that, there will be higher percent copper recovered.

Regards,
Kj


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## 72chevel (May 11, 2015)

Thanks for posting these up. I have been looking at blue bowls myself, with the same idea for catching copper. Could you post more pictures of your hammer mill? I bought something similar that came with out a motor and I have been trying to figure out what size motor to use and at what RPM's. I am surprised to hear how fast your mill operates at!


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## yar (May 12, 2015)

Can you also post where you purchased the hammermill? I have been looking for a small one like that.


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## kjavanb123 (May 12, 2015)

72chevel,

Thanks for your words. They used a motor that is high rpm, around 21,000 rpm. I have asked and they said the similar motor is used in equipments to get the juice out of fruits. I purchased mine at a local shop. Here are some photos of the same machine,

This is an overall photo of the hammer mill,



This is the 0.7mm screen and where fine boards shoots out, there is a pillow case that I attach to this exit port that collect the powder and eliminate the airborne toxins.



Yar,

I bought this locally, for $300. If you can find a motor with 21,000 rpm and harf steel blade, you can do it yourself. There is also another model that has 2 output with screen which presumebly double the output rate.


Best regards
Kj


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## 72chevel (May 12, 2015)

Thanks for the info that helps a lot! Does the mill operate on 220 volts?


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## kjavanb123 (May 12, 2015)

Yes 220v, and it is 1-phase.


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## corsagafa (May 17, 2015)

Thankyou for posting ,Iam also looking at ways to recover copper from the stripped boards.The mill that you are using looks like it is made for grinding food products and I would be interested to know how long it can last grinding the Glass Reinforced Plastic.Also does the screen get blocked,0.7mm screen size sounds too small because I have trouble with my granulator screen blocking and it is 2mm.You need to be very careful about the dust and I dont think one pillow case is good enough to filter the glass fibre particles ,I would divert the mill output straight into your water separation system.If you have some time,I have some videos of my system on youtube.My username is corsagafa, Regards Dave


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## kjavanb123 (May 17, 2015)

Corsagafa,

Welcome to the forum and happy refining. I will be using a stainless steel case I build to be attached to the output port of the mill, and it directly shoots everything to a sealed bucket with 1/2 with water, from there it goes to concentrator.

The 0.7mm showing a bent around the edge that is getting hit, I timed it once, I did 850g of shredded boards in 33 mind before the motor started to smoke a little.

The shop I purchased this from also has one larger mill with two screens, and bigger blade which can double the output rate.

Best regards
Kj


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## johnny309 (Oct 7, 2015)

Simple question...WHY?
You will lose valuable material:
1) tin .... have more value than copper.... contained in the solder
2) silver (in newer bords contained in solder)
3) gold ( dissolved in new solder alloys)
4) fine dust of fiber glass from grinding PCB.
5) huge amount of water used in the process.

Why do you think the "big boys" use to melt them instead of grinding?


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