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Before being crushed in the X-Press, hard rock samples for ICP analysis are polished (Figure 1, Steps 1 and 2) and put in a sonic bath at least three times (for 15-20 minutes each): first bath is with isopropyl alcohol and following baths are with DI water (Figure 1, Step 3; seeICP Preparation for further details). Hard rock samples for XRD analysis do not usually need to be polished before being crushed.
Figure 1. Polishing and cleaning hard rock samples
Crushing Samples in the X-Press
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- First, clean the X-Press with simple green and isopropyl alcohol. Clean the work area and materials with isopropyl alcohol for each sample.
- Place a large KimWipe on your working surfaces for your clean materials. Next collect the following supplies that make up the 'crushing unit' of the X-press (Figure 12). Materials are located in the drawer labeled 'X-PRESS SUPPLIES' in the X-Ray Prep Area in the Thin Section Lab.
- Weigh Paper 6" x 6"
- Core liner
- Two delrin Delrin discs
- Stainless steel base
- Aluminum Die
Figure 12. Materials needed for assembly of ‘crushing unit’. A. Weigh Paper 6”x6”. B. Core Liner C. Two Delrin Discs D. Stainless Steel Base E. Aluminum Die
3. Put on gloves and 'wash' them with isopropyl alcohol. Clean the crushing supplies with isopropyl alcohol and set them down on the clean surface.
4. Collect sample beakers from the drying oven (for ICP preparation) or dessicator located in the X-Ray Lab. Put a piece of Parafilm® over each beaker and bring them over to the X-Press (Figure 1, Step 4).
Assembling the crushing unit
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- Grab the stainless steel dish. This is the base for the crushing unit (Figure 2).
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- .
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- Place a piece of Weigh Paper on the
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- base (Figure
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- 3, Step 1).
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- Put one Delrin disc on top of the weigh paper (Figure
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- 3, Step 2).
Place the sample on top of the Delrin
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disc (Figure
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3, Step 3). These discs can fracture leaving Teflon flakes in the sample so arrange the sample such that the two flattest surfaces are the top and bottom
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.
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- Now place the second
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- Delrin disc on top of the sample (Figure
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- 3, Step 4). Again make sure the disc rests flat against sample.
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- Put the aluminum die on top of the
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- Delrin disc, holding it until you slip the core liner over the unit (Figure
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- 3, Step 5).
- Now slip the piece of core liner over all the pieces and resting inside the stainless steel base (Figure
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- 3, Step 6). This contains the sample pieces inside the unit.
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Figure
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3. Assembling the crushing unit
The crushing unit is now assembled and we can start crushing samples (Figure
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4).
Figure 14: 4. A. Overview of the X-Press. A. Metal platform sample rests on B. Jacksrew C. Pressure Relief Handle. D. ‘On’ toggle E. Pressure Gauge. B. Crushing unit inside the X-Press
Place the crushing unit inside the X-Press in the middle of the metal platform (Figure 14 4A). Put in the sliding polycarbonate door down when crushing samples. Tighten the jackscrew (Figure 14 B) until it rests firmly against the aluminum die. Tighten the 'pressure relief handle' with a clockwise turn (Figure 14 C).
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Vessels must be cleaned in between samples and after all samples have been run for the day. Vessels should never be put away wet. This alters and tarnishes the vessel.
In Between Sample Runs
- Wearing nitrile gloves, wash the individual pieces of the grinding vessels with DI water and a small piece of a scouring pad (no soap).
- After each washed piece piece immediately spray it with isopropyl alcohol and wipe it down with a Kim Wipe. Do not use the ship's compressed air line to dry pieces as the air is too dirty.
- Lay the pieces on, and cover vessels with Kim Wipes.
After the last run for the day
1. Take a scoop of quartz sand and put it in your vessel and run it as you would a sample for several minutes.
2. Remove the vessel and empty out the sand. Scrub the pieces with DI water and a scouring pad. Then spray with isopropyl alcohol and wipe down with Kim Wipe.
If your vessel is particularly dirty run a combination of quartz sand, a little hot water and detergent (Borax). This can be run for several minutes. A thick paste will form and you clean it with DI water and isopropyl as in the other cases.
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