Fine paper mill sludge (FPMS) disposal has emerged as a problem since the dumping of FPMS was banned. This study investigated the effects of adding a refined recovered lubricating oil (ion-refined oil) to FPMS pellets to increase its heating value and combustion time and decrease ash content and ignition time. Fuel pellets were prepared in three conditions, C-1, C-2, and C-3. In C-1, ion-refined oil was added to FPMS to examine its burning capability. In C-2, two types of pellets were produced mixing sawdust and FPMS ratios of 25:75 and 50:50. A ratio of 50:50 was selected for C-3, to which the ion-refined oil was added in different ratios. The quality of the energy fuel pellets was determined using proximate and ultimate analyses, except for chlorine content, which was determined through liquid ion chromatography. The properties of fuel pellets were determined and compared with national standards. It was confirmed that the results for pellets at a ratio of 50:50 with 10% and 15% ion-refined oil were acceptable, because these results were comparatively similar to the standards. Finally, it was concluded that ion-refined oil was an effective additive to FPMS to increase the heating value for energy demand and lower the ash content.

No abstract

No abstract

The pitch contained in thermomechanical pulp (TMP) negatively affects paper quality, pulp, and the papermaking process. Serious pitch and stickies problems may occur in paper recycling processes. In this study, the effects of chemicals used to control the pitch in the TMP process were compared. The method used to analyze the pitch control effect was to perform image analysis after using a reagent that selectively stains only the hydrophobic pitch. Three different mechanisms, namely fixation, detackification, and dispersion, were applied to solve the pitch problem from TMP. All the control agents were effective in pitch control, and, in particular, the agents related to fixation and dispersion were found to be more effective in reducing the number and area of tacky particles per unit area in sheets and white water. However, it was difficult to clearly identify the effect of both the detackifiers and the dispersant agents through image analysis after staining except for the fixative agent.

A new lightweight vertical bar plate was developed by inserting individual bars into the plate base rather than the typical sand casting method. The lightweight vertical bar plate has a very sharp bar edge because vertical bars are inserted instead of trapezoidal bars. The refining effects of the mixed stock with softwood bleached kraft pulp (Sw-BKP) and hardwood bleached kraft pulp (Hw-BKP) were compared using two types of lightweight vertical bar plates with cutting edge lengths of 55 km/s (PA55) and 97 km/s (PB97). The fine bar plate (PB97) with large CEL (PB97) was very effective in reducing the refining energy required to reach the final freeness regardless of the mixing ratios of Sw-BKP and Hw-BKP compared to the plate with a small CEL (PA55). PB97 also consumed less refining energy than PA55 until proper sheet strength was achieved. In particular, irrespective of the mixing ratios of Sw-BKP and Hw-BKP, the tensile strength of sheets at the final freeness was greater in PB97 than in PA55. For stock throughput during refining, PA55 with the wide groove was almost similar to PB97 with the narrow groove.