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Cleaning the Vessels
Clean the grinding vessels with a toothbrush and DI water. In some cases the vials are still dirty or have sample stains on them. If so, take a small amount, approximately 5 mL, of silica sand and grind it in the mixer mill for ~3 minutes. Then pour out the sand and clean the vessel with DI water and a toothbrush or Greenie Meanie. Lay out cleaned vessel parts on a Kim Towel and dry with a Kim Wipe. The cork rings take a longer to dry, so collect fresh, dry rings before grinding the next sample.
Then can now pack the samples.
Retsch MM400 mill
Figure 16: Retsch MM400
Grinding Jar
Figure 17 Agate grinding jars and ball.
Each grinding jar has the main jar, the lid and ball. The inside of the jar and lid are lined with agate and the ball of made of agate. Poor freeze dried soft sediment (not hard rock) sediment grains into the jar. Fill the jar half way to three-fourths of the way up with sample. Place one ( can do two) grinding balls in the jar. Clean off any of the sediment sample with a kimwipe that has gotten onto the jars threads and screw the lid on. Be mindful not to cross thread the lid to the jar.
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Place closed grinding jar horizontally in the clamps. Verify the pin is in closed potion position and tighten the clamps by turning the handle until the jar is securely tighten 9 (hand tight is good). Close lid and select desired program to run.
Figure 18 MM400 Grinding jar clamp
Starting the Mill
After grinding jars are secured in clamps, the pin is in the closed position and the clear cover is closed it is time to select grinding settings. Program 1 (A) is currently set for 12 min at 25 1/s. This setting is good for clay rich material. Softer sediments such as CaCO3 typically need less time. It is important to only grind soft sediments in the agate jars and hard material should be ground in the shatter box. After Grinding cycle has completed twist knob counter clockwise and pill pin up and into its open position. Unscrew clamp and open jar to verify grind size. If sediment is still too coarse regrind.
Figure 19 A) Preset programs. B) The shaker frequency C) The time grinder is set for D) The start and stop
Transferring Powder
Cleaning the Jars
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