Before being crushed in the X-Press, hard rock samples for ICP analysis are polished (Figure 1, Steps .1 and 1.2) and put cleaned in a sonic bath at least three times (for 10-15 -20 minutes each): the first bath round of cleaning is with isopropyl alcohol and the following baths rounds are with DI water (Figure 1.3, Step 3; see ICP 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
The X-Press is a motorized hydraulic press that crushes hard rock and highly compacted sediment samples into smaller pieces. The X-Press is used to crush hard igneous rocks and highly compacted sediments.
Preparing the X-Press area
- First, clean the X-Press and counter with simple green and isopropyl alcohol. Clean the work area and materials with isopropyl alcohol for each sample.Lay down a Kimwipe or sheet of paper on the counter.
- 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 2). 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 Piece of core liner
- Two Delrin discs
- Stainless steel base
- Aluminum Die
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Figure 2. 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 clean the components with isopropyl alcohol and set before setting them down on the clean surface.
4. Collect Once cool enough to handle, collect sample beakers from the drying oven (for ICP preparation) or dessicator desiccator 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
Now that the X-Press area is clean and the samples are in the Lab, assemble the crushing unit as follows:
- Grab the stainless steel dish. This is the base for the crushing unit. Place a piece of Weigh Paper on the base (Figure 3, Step .1).
- Put one Delrin disc on top of the weigh paper (Figure 3, Step .2).
Place the sample on top of the Delrin disc (Figure 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.
- Now place the second Delrin disc on top of the sample (Figure 3, Step .4). Again make sure the disc rests flat against sample.
- Put the aluminum die on top of the Delrin disc, holding it until you slip the core liner over the unit (Figure 3, Step .5).
- Now slip the piece of core liner over all the pieces and resting inside the stainless steel base (Figure 3, Step .6). This contains the sample pieces inside the unit.
Figure 3. Assembling the crushing unit
The crushing unit is now assembled and we can start crushing samples with the X-Press (Figure 4A4A).
Crushing Samples
Place the crushing unit inside the X-Press (Figure 4B4B) in the middle of the metal platform (Figure 4A4A, arrow A). Put in Slide the sliding polycarbonate door down when crushing samples in the vertical indents (Figure 4C). 4C). Note: The polycarbonate door sits on two interlock switches that enable operation. If the door is not fully closed or pressing down on these switches the machine will not work. Tighten the jackscrew (Figure 4A4A, arrow B) until it rests firmly against the aluminum die. Tighten the ' pressure relief handle ' until just tight with a clockwise turn (Figure 4A4A, arrow C).
Note: The polycarbonate door sits on two interlock switches that enable operation. If the door is not fully closed or pressing down on these switches the machine will not work.
Figure 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. C. Polycarbonate door
Crush the sample by continuously holding down the toggle switch (Figure 4A4A, arrow D). The motor and pump can be heard and the pressure will rise (Figure 4A4A, arrow E). Once When the desired pressure is reached the toggle can be released and toggle is released, the sample will sit under that pressure. Do NOT leave a sample under pressure for any reason. For most samples ~5 tons of pressure is enough force to crack it. If you find the need to go near 10 tons, try rotating the sample onto another side and repeat the process again. Taking the pressure up greater than 10 tons can cause the disks discs and the core liner to shatter, as well as contaminating the samples and creating a safety hazard.
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After the sample has cracked remove the crushing unit, release the toggle switch. To remove the unit, loosen the ' pressure relief handle ' (Figure 4A, arrow C) by rotating it counter clock wise and press down on the toggle switch. The pressure gauge should read zero and the metal platform will lower down. Do not leave the platform up, always make sure to lower it back down after crushing a sample. When the platform is level with the surface let go of the toggle and start unscrewing the jackscrew. Then open the door and remove the unit. The pieces can be poured into a labeled bottle that will eventually hold the finely ground powder. From here the pieces will then be put into the Shatterbox vessels.
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