1.3. Disc mill

Note

It is recommended to complete preliminary cleaning and set up for both the jaw crusher and the disc mill, then run your sample through both, in that order.

1.3.1. Video Tutorial

1.3.2. Set Up

  1. Take apart and thoroughly clean the disc mill and all of it’s associated parts using the metal brush (for the plates), vacuum, compressed air, and damp paper towel as necessary. Be sure to use compressed air to completely dry everything immediately after using a damp paper towel to prevent the build-up of rust.

  2. Cut a line in your sample collection trash bag starting from the open end until about 2/3 of the way down towards the bottom of the bag. Label the bag with your sample name.

Example photo of cut garbage bag.

  1. Attach the spinning plate (the one without the big hole in the middle) to the mill using the wrench to tighten the three (3) bolts.

  2. Place the trash bag into the disc mill with the bottom of the bag pushed into the open area beneath the plates. Wrap the slit you’ve cut in the bag around the back of the spinning plate, and pull it upward to minimize the space around the drive shaft. Use a piece of tape above the drive shaft to hold the two ends of the bag together.

  3. Flatten out the opposite side of the bag over the hinged side of the mill - where the other plate will go. Place the other place (with the hole in it) on top of this side of the bag, and use your finger to feel underneath for where the bolt holes are. Hand-tighten the bolts (with the washers on them) to hold the plate in place.

  4. Lift the hinged side, being careful not to pinch or tear the trash bag, until the plates are facing each other. Adjust the plate on the hinged side (the one with the big hole in the middle) as necessary until the plates are even, and then tighten the bolts with the wrench. You can use the handle on the far right side of the machine if necessary to bring the plates cloer together to check if they are even. Run your finger along the circumference of the plates to check if they are matched up. NOTE: Tightening the bolts will move the plate slightly, so you may have to try a few times until it’s right.

  5. Once the plates are tight and even, re-open the hinge and lay it flat. Using scissors, cut out the part of the trash bag covering the hole in the middle of the left plate. Try to remove as much as you can to prevent sample from getting caught.

  6. Close the hinge again so the plates are facing each other, and again be careful not to pinch or tear the trash bag. Secure in place by screwing in the clamps on the left side of the machine. Adjust the plates using the adjustment wheel on the right side of the machine until the plates are 0.016 mm apart. Use the feeler gauge to measure the gap, and turn the plate on the right side manually to check the gap all the way around. Once the correct width is achieved, secure it in place using the butterfly handle on the right of the machine. **NOTE: Turning the adjustment wheel will push the plates closer together, but it will not pull them farther apart. You will have to unscrew it a bit then push the plate with your hand.

  7. Close the lid above the plates and keep the ends of the trash bag out of the machine. Fold them over the top and tape them down to the machine to keep dust contained.

1.3.3. Running the Sample

  1. Keep your sample under the disc mill hood. You will be using a Dixie cup to deposit sample into the machine.

  2. DON PROTECTIVE GEAR: *Hearing and dust protection.*

  3. Close the hood, turn on the light and fan with the switch on the side of the hood (1), and start the disc mill with the button on the wall (2). Listen for a moment to make sure everything is running smoothly.

  1. Deposit the sample into the slot on the machine in small increments (about 1-2 tablespoons at a time) from the Dixie cup. After depositing, wait and listen for the machine to clear before adding the next bit of sample.

Note

NOTE: For harder rocks, err on the side of caution by depositing smaller amounts of sample to keep the machine from locking up or jamming.

  1. Once the entire sample has been run, turn off the disc mill and the hood. Carefull open the trash bag taped over the top and then open the lid of the disc mill.

  2. Remove the left plate and set aside. Free the trash bag by removing any more tape, and either carefully pull the bag out from the bottom or up through the side, whichever seems easier. Tie off the bag and set aside.

  3. Once the sample is secure, continue disassembling the machine.

1.3.4. Clean Up

Clean the disc mill thoroughly using the methods described in Step 1 of the Set Up section. Be sure to focus on the plates with the metal brush. Re-assemble the machine and hand-tighten the bolts to make it easier to disassemble for cleaning on the next use.