Chain impact mill

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kjavanb123

Well-known member
Joined
Apr 1, 2009
Messages
1,743
Location
USA
Hi

I finally delivered my latest milling equipment. The design was initially copied by the membets of treasurenet forum which I should thank.

The electromotor used is a 1.5 HP 3000 rpm single phase. The pulley system used increases the mill rpm more than 3000 rpm.
image.jpg

The main shaft used is a 20mm diameter, and 3 sets of modified chains are attached to shaft with screws so chain replacement is easy. As it can be noted, unlike the designs by treasurenet members, I used a length for chains that when it is running, only 1-1.5mm gap is left to the body of mill.

Output holes are 5mm in diameter. This pulverizes rocks into 93% passing mesh 100, and for circuit boards 90% passing mesh 100.
image.jpg

It literally instantly pulverizes rocks or circuit boards into fine powder. Here is an example when I dropped a closed feast size hematite ore into the mill.
image.jpg

I will be using this mill to pulverize left over depopulated circuit boards, then run them on homemade shaker table to recover copper.

Best regards
Kj
 
They work great but the dust is horrible. I taped a plastic bag to the output and then bungee it to the collection can. Even then I have to wear a respirator.



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Goldandsilver123
Thanks for your kind words. I shall thank Treasurenet forum members for main concept.

Kernels,
Thanks for your comment. I will take more photos of inside and outside and post them along the dimensions.

Snoman
Indeed at 3000 plus rpm the dust is crazy, I use 3 bucket system, their caps are sealed using tapes, and output is connected to first bucket, an output connect the first bucket to second bucket and same goes to third bucket and last pipe exit the last bucket to a bag.

I will run a test with the dust control system and post more photos.
 
Dust control using a bucket and woven bag as cap for the bucket, and output from mill is inserted to woven bag and in the bucket.

The door which is screwed to mill, used glue to seal.

Ran few pieces of cut circuit boards and no dusts were visible. So it seems to be working.
image.jpg

More detail photos of inside and out of mill tommorow.
 
please be careful and stay on top of that dust control system and do whatever you can to keep it in tip top shape... I got word of a company around here that was shut down recently because they were grinding PCB boards without use of a fume/dust control... everyone of their employees got lead poisoning.
 
There is a company in Connecticut that makes customized dust control sleeves out of any type material you need. A great option for controlling the path the dust can fly between the mill and the drum. I always said as a refiner what you make for a living is dirt and if you are doing any production milling you know what that means, it goes everywhere! Check out Siftex,https://www.siftex.com/ they can help you put the valuable dust where you want it.
 
4metals
Thank you for the link.

Kernels,
Here are some more photos of inside the mill eth their dimensions.

The chains are 132mm when standing, and screwed to plates which are welded to shaft.
image.jpg

And here is how they are attached,
image.jpg

Here are the output holes, 5mm in diameter. I am going to use water jet and do these holes at 0.1mm that would be really fine powder.
image.jpg

Here is output of 1kg of circuit boards that was ran in the mill. Noticed the mill does much better job pulverizing hard quartz than does circuit boards.
image.jpg

And lastly some of the copper panned from the mix above. More on that subject once they dried and weighed.
image.jpg

Best
KJ
 
Very nice, KJ!
What size pipe is the main chamber?
I have a piece of 16 inch round tube, 3/8 in. wall 11 inches long... I think it will do the trick! :mrgreen:

Thanks!
Phil
 
philddreamer said:
Very nice, KJ!
What size pipe is the main chamber?
I have a piece of 16 inch round tube, 3/8 in. wall 11 inches long... I think it will do the trick! :mrgreen:

Thanks!
Phil

Hi Phil,

My main chamber is 280mm in diameter, 8mm thick wall, 130mm lentgh of the main pipe.

I think 3/8 inch wall may be too thin as the main chamber, takes beating. I noticed that when I dropped a sample of limestone, there were fine pieces of iron cut from the body or chain and showed up in the powder.
 
kernels said:
Hi KJ, how does the front 'lid' work ? Is there another bearing that supports the shaft ? Do you remove the front lid every time you want to clean it out ?

Front lid is rarely open, because when testing the mill I noticed there was zero of materials left in the mill.

There is a bearing on front lid which is screwed to a "L" shape iron piece welded to the lid.

Based on couple experiments I noticed some iron is eroded from either body or chain and end up in output. So maybe using a hard steel would be better choice for main chamber and chains.

Here is the final shot of copper recovered from 1 kg of circuit boards, pulverized by the mill and panned out.
image.jpg

Copper collected from 1 kg of circuit boards
image.jpg

I will pyrolize this copper as it has some pieces of boards, smelt it to find the final weight of copper from a kilogram of circuit boards.

I also check the tailing from panning to see how much copper ended up there.
 
Nice Kevin.
Are you going to run the copper through a cell or sell as is? I’m asking because I suspect the values have been removed but the copper may well have contaminants from the solder.
 
Kernels
Your welcome. Glad my post can help.

Here is a circuit board I cut to run in the mill and observe its output;
image.jpg

Cut into smaller pieces so it fits the feeding shute,
image.jpg

I ran the piece with big IC and the one with two connection ports on it, here is the result not sifted yet,
image.jpg

Panning not-sifted pulverized board,
image.jpg

Here is final clean up pan, as you can see the heavy gray materials possibly solders follow that copper and lighter materials at the bottom, could not see any visible gold but I will dissolve in acids to see if gold was recovered,
image.jpg

Learned from this experiment I need to cut the holes to 0.2mm instead of 5mm they are now to liberate gold.

Best regards
Kj
 
nickvc said:
Nice Kevin.
Are you going to run the copper through a cell or sell as is? I’m asking because I suspect the values have been removed but the copper may well have contaminants from the solder.

I will try to dissolve a sample from it in hcl to see if it can remove solders, then market it as fine powder as price for fine powder is higher locally than melted copper.
 
Very very noisy! At least the one I use.



On addition - ever hit a rock with the lawn mower?

Just imagine it never leaves the deck, and bounces around until it's ground very very fine.

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I know it's noisy, but a steel ball mill with 3" steel balls isn't exactly quiet either. I just would like an idea if it's noisier than a ball mill if he has the two to compare noise levels.
 
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