Effect of Valley Beater Refining on Tensile Properties of Molded Pulps from Rice Straws

Rice straw, an abundant agricultural waste, is shown to be a promising resource for pulp and paper packaging manufacturing. In this study, rice straw pulps or cellulose fibers were extracted using a soda-AQ process and then the rice straw pulp slurries were refined by a Valley beater. The effect of refining time (15-60 min) on the pulp fiber characteristics was studied. It was found that both initial fiber length and width were decreased with refining time. The refined fibers became fibrillated, finer, and also more uniform in size confirmed by SEM. The pulp freeness (CSF) was reduced with increasing refining time as expected due to higher water-holding capacity of more fibrillated pulps. Then, the molded sheets were formed from the prepared rice straw pulps and examined. From tensile testing, the results indicated that the tensile properties of the molded sheets from the refined pulps were significantly enhanced (p < 0.05), thanks to an increase in fibrillated fiber surface area and inter-fiber bonding degree. The Valley beater refined rice straw pulp provided the molded sheet with the highest tensile index of 51.96 ± 4.08 Nm/g which are comparable to that of the sheets prepared from PFI mill refining process. The tensile properties of the current refined sheets were also in the acceptable range for typical commercial molded pulp packaging. In addition, the freeness values of the optimal Valley beater refined pulps are relatively high (348-423 ml), implying a benefit in forming process and manufacturing of pulp products.

Research on Microstructure and Refining Performance of Al-Ti-C Grain Refiner Prepared by Ultrasonic Coupling

The application of ultrasonic field in the preparation of Al-Ti-C refiners can lead to the the homogenous distribution of the second phase TiAl3 and the particle phase TiC in the matrix, thus enhancing the refinement effect. In this paper, the Al-Ti-C grain refiner was successfully prepared by the ultrasonic coupling method, and its microstructure was observed. The prepared refiner was added to pure Al to verify the refining performance, and the refining mechanism was analyzed. The results indicate that the Al-Ti-C grain refiner prepared by ultrasonic field has excellent refining performance, which reduces the grain size of Al to 100 μm, and the optimum activation refining time is 3 min. The reason is that the morphology and size of the second phase TiAl3 and TiC in Al-Ti-C are changed by cavitation effect, acoustic streaming effect and thermal effect caused by high intensity ultrasonic, and the α-Al nucleates effectively under the synergistic of TiC and TiAl3 particles.

Enzyme-assisted pulp refining: an energy saving approach

Energy conservation has become an essential step in pulp and paper industry due to diminishing fossil reserves and high cost of energy. Refining is a mechanical treatment of pulp that modifies the structure of the fibres in order to achieve desired paper-making properties. However, it consumes considerable amount of energy. The electrical power consumption has a direct impact on paper manufacturing cost. Therefore, there is a requirement to minimize the energy cost. Enzyme-assisted refining is the environment friendly option that reduces the energy consumption for papermaking. Enzyme-assisted refining is defined as mechanical refining after pretreatment of pulp with enzymes such as cellulases and hemicellulases. It not only reduces the energy consumption but also improves the quality of finished paper. Enzymes improve the beatability of pulp at same refining degree (°SR) and desired paper properties can be achieved at decreased refining time. The selection of suitable enzyme, optimization of enzyme dose and appropriate reaction time are the key factors for energy reduction and pulp quality improvement during enzyme-assisted refining.

Analysis of Cellulose Pulp Characteristics and Processing Parameters for Efficient Paper Production

For economic reasons, increasing the use of various fibrous pulps with high lignin contents—i.e., chemothermomechanical pulp (BCTMP and CTMP), thermomechanical pulp (TMP), and semichemical pulp—is desirable. The relatively good quality and increased efficiency of these pulps make them attractive paper semi-products. In particular, they could alleviate the severe shortage of paper semi-products. Although mechanical pulp and semichemical pulp are achieving increasing quality with substantially increased wood efficiency, their production is often characterised by high consumption of electricity to defibre chips or refine high-lignin-content fibrous pulps. Technological, environmental, and economic evaluations of the manufacture and application of increased efficiency cellulose pulps that take into account potential profits from increased cellulose pulp efficiency and losses due to energy costs and degradation in the properties of the resulting paper are relevant and essential to paper mills. This article reports such an analysis. The authors have analysed the usable properties of ten cellulose pulps with various degrees of digestion and identified the optimum pulp that yields the optimum product properties, considering the yield; pulp refining time, which determines the cost of paper manufacture; and strength properties of the obtained paper.

Refining characteristics of isometric straight bar plates with different bar angles

Bar angle is one of the most important parameters of an isometric straight bar refiner plate and its effects on the change in pulp and paper properties during refining is still unclear. This study investigated the effect of plate bar angle on refining quality and refining efficiency by clarifying the definition of bar angle. Five isometric straight bar plates with different bar angles were used in low consistency refining of bleached sulphate eucalyptus pulp (BSEP). Samples at different refining time intervals were collected, and the fibers, pulp, and paper properties were detected and analyzed. There was a great influence of bar angle on the fibers, pulp, and paper properties. Additionally, a critical static attack angle, or critical bar angle for plates with specific field angle, existed. The modification of fibers and pulp properties was strong when the plate reached a critical bar angle. Meanwhile, there was an optimal static attack angle for a plate with specific field angle, when considering paper properties such as tensile index and tear index. The refining time was shortest when the pulp was refined by the plate with critical bar angle, allowing the paper properties to reach a maximum value. It was shown that the static attack angle of refining should be selected in the range of 45º to 70º, which includes the optimal value and the bar angle was proposed in the range of 11.25º to 23.75º for the plate with common field angle of 22.5º.

Effects of Alloying Process on Inclusions in Fe-9Cr Alloy Reinforced with Y2O3 Nanoparticles

The effects of the alloying sequence and refining time on the inclusions in Fe–9Cr alloy reinforced with Y2O3 nanoparticles were investigated. The size and number of inclusions in the alloys were determined via optical microscopy, and their morphology and composition were determined via scanning electron microscopy. The Y2O3 mainly acted as a nucleating agent in the Si–Mn+Y2O3+Ti alloying process, promoting the precipitation of other oxides, which was beneficial for the formation of Y–Ti–O particles. In contrast, no Y–Ti inclusions were formed when the Si–Mn+Ti+Y2O3 alloying process was employed. In addition, the inclusions in the alloy tended to stabilize after refinement for 5–10 min. This study offers a general pathway for the manufacture of oxide dispersion strengthened steel via a smelting process.

Refining of manganese alloys with high content of phosphorus obtained in electrometallurgical dephosphoration of manganese ores

The expediency of carrying out the process of dephosphorization of the alloy in one stage using a briquetted mixture, which includes iron scale, lime, bauxite and sodium orthosilicate in their following ratio, wt.%: Iron scale - 52.0… 57.4; lime - 6.2… 8.6; bauxite - 4.5… 6.2; sodium orthosilicate - 30.5… 30.4. The achieved degree of dephosphorization of the accompanying manganese alloy is about 70%, the manganese content in the alloy - 64.6%. The implementation of dephosphorization according to the developed method allowed to increase the rate of throughput of manganese from the raw material. Exclusion from the composition of materials for dephosphorization of fluoride compounds increases the environmental friendliness of the refining process. In the real conditions of production in the process of depho-?phorization of the associated alloy may use different processing schemes and conditions of its implementation. In the formation of a concomitant alloy with a temperature of ~ 1300oC in the production of low-phosphorus slag, in order to minimize the cost of dephosphorization of the alloy using existing shop equipment, the refining process can be implemented according to the following scheme and purging the bath with argon, the dephosphorization process scheme may include the following operations: adding 100% pre-briquetted SHUS, to the bottom of the bucket, trans-?orting the bucket to the installation of the oven-bucket, where the optimum temperature will be maintained during refining. This will increase the refining time and, consequently, greater completeness of the refining process .: Key words: highly phosphorous concomitant alloy, slag-forming mixture, ladle furnace, completeness of depho-?phorization.