1) Now that the consistency of the pulp sample is known, the goal now is to get 30 g OD pulp from your bulk pulp sample. To do that, e. g., if your pulp consistency is 4.08%, the weight of wet pulp you need is 735.29 g. Remember to tare and receive your pulp slurry in two 2000 ml glass beaker evenly, i.e. ~367.65 g each.
2) Take the beakers and pulp and fill them up to the 1500 ml mark with distilled water (see figure 5).
Figure 5: On the left, weigh pulp slurry in beakers; one the right, diluted suspensions are heated in microwave oven.
3) Next, if the suspension is a mechanical pulp, take these two beakers of pulp suspension and cook them in the microwave oven for 22 minutes, or until the suspension heats up to ~85-90 °C (see figure 6). This step helps to remove the latency of the mechanical pulp fibres; straightening out the fibres for handsheet making.
Figure 6: The suspension has been heated and is at ~85-90°C.
4) Using heat-proof gloves, take the heated suspension (or room temperature suspension for chemical pulp) and pour one beaker into the stainless steel vessel in each of the two disintegrators. Load the vessel back into the disintegrator and push it back to ensure contact with the sensor button mounted on the disintegrator.
Note: The contact between the vessel and sensor is required for the disintegrator to work (see figure 7).
Figure 7: On the left, the heated pulp being poured into disintegrator apparatus; on the right, the vessel must touch the sensor stub in order for the disintegrator to operate.
5) Depress and hold on the red button. Push the black buttons to change revolution counts. Each count on the console equals 25 revolutions. The pulp needs to undergo minimum 7500 to 25 000 revolutions to be fully disintegrated. Set the button console to 300 to run 7 500 revolutions, 600 (usually recommended) to run 15 000 revolutions or 1000 for 25 000 revolutions (see figure 8). The disintegrator is set to run at 3 000 rpm, and it should take 8-9 minutes for the disintegration process. Depress yellow button to start the disintegrator. Repeat the same procedure to disintegrate the other pulp suspension. During this time, turn on the speed dryer and ensure it is set to 113°C. Make sure you have filter papers with OD weights recorded on them.
Figure 8: On the left, the button pad on the disintegrator; on the right, depress and hold the red button then push the black buttons to reset the revolution counts, which is required before you can disintegrate. Note: Each count equals 25 revolutions.
6) Once disintegration is finished, you may wait for another three minutes to let it cool down further. The pulp is still very hot. Wear woven gloves to hold the handles. At first open the lid slightly just in case the pulp suspension bursts because pressure buildup in the vessel. Note: It is prohibited to disintegrate pulp at extremely high temperature (over 95 °C) in PPC. You should use the pressurized disintegrator in Canfor R&D or Paprican to carry out high temperature disintegration. Quantitatively transfer the contents from the vessel. Always have a squirt bottle handy to wash the pulp stuck at the top of the disintegrator lid, the shaft, and propeller (see figure 9).Transfer all of the disintegrated pulp suspension to a white 12 L bucket or a grey 12 L graduated pail (see figure 10) that has been tared.
Figure 9: Pulp suspension after 7500 revolutions in the disintegrator. Squirt bottle is used to wash fibres off shaft and propeller.
7) Place the bucket on the Mettler balance (max 32.1 kg). The goal is to dilute the suspension to 10 kg at 20 °C. Take cold distilled water from cold room, and, for hot pulp, use it to dilute the suspension to 9 kg. Check the temperature, either use ice, cold or room temperature distilled water to bring it as close to 20 °C as possible (see figure 10). Note: The ice in lab 308 is made by filtered tap water. If you use ice, you must pre-make some ice with distilled water. For room temperature pulp, add some cold distilled water to get it to 20 °C, then prepare and add large beakers of 20 °C water using a mixture of piped and cold distilled water. As soon as the dilution to 10 kg is completed, record the exact temperature. Proceed to the next test, either consistency determination or freeness test. Mix the suspension well before you do anything, as the pulp quickly becomes inhomogeneous.
Figure 10: On the left, the disintegrated pulp has been diluted to 10 kg. Remember to measure sample amounts in weight, as volume is temperature dependent. On the right, the graduations are on the inside wall, 10 kg is at 11 L mark. This inaccuracy would cause serious problems in the following tests.
8) Next, if freeness has already been determined or given, is the consistency determination of the diluted suspension. If freeness is to be measured, skip ahead to the Freeness Determination step now, as consistency will be measured using the freeness sample.
9) Weigh out ~400 g of suspension and use vacuum to filter it through filter papers of known weight. Recycle/re-filter the filtrate 3 times to retain fines. Take the pulp pad and speed dry it. Repeat once. Note: Fines make up a significant portion of TMP.
10) Once the weights of the OD pulp pads are constant, record them and average the two readings. The OD weight subtracts the filter paper weight, divided by the weight of the solution (~400 g) times 100% gives you the consistency in percentage. The target consistency is 0.3% (0.003 g pulp to 1 g suspension).
2.455 g of dry pad – 1.224 g of filter paper = 1.231 g of OD pulp
