Appl. Sci. 2025 , 15 , 9160
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Figure1. Roll with flybars and bedplate of the Valley beater.
( a )
( b )
Figure2. Dimensions of flybars on the roll and bars on the bedplate: ( a ) Flybars on the roll; ( b ) Bars on the bedplate. After disintegrating the pulp fibers using the Valley beater, excess water was removed from the pulp slurry to adjust the concentration to 4–5% for refining according to the ISO/TS 11371 guideline (https://www.iso.org/standard/84109.html, accessed on 1 April 2025). The thick stock was then fed into a single disk refiner (KOSWON Co., Gimhae City, Republic of Korea), designed with a specified disk pattern for ultra-low intensity refining (see Figure 3). The disk plate was fabricated by assembling two distinct metal alloys, resulting in a vertical bar configuration that differed from conventional cast plates with a draft angle [18–20]. The precise dimensions of the bars used for ultra-low intensity refining are illustrated in Figure 4. With a plate diameter of 12 inches and a cutting edge length (CEL) of 97 km/s, the refiner operated at 800 rpm. The primary goal of this refining process was to modify the mixed pulp stocks to achieve a Canadian freeness level of around 190 mL, by ISO 5267-1 [21]. In practice, due to the high efficiency of the ultra-fine bar plate, refining produced some samples with freeness values below 190 mL CSF. Therefore, results are presented for the full range of observed freeness values, including those below the target.
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