Chemical-Mechanical Pulps from Eucalyptus and Their Comparison with Eucalyptus Chemical Pulps

2014 ◽  
Vol 68 (8) ◽  
pp. 899-905
Author(s):  
Toshio Okunishi ◽  
Eric C. Xu ◽  
Gary Harris ◽  
Paulo E. Galatti ◽  
Dieter Teubner
Keyword(s):  
Chemical Pulps ◽  
Mechanical Pulps

Strength Loss in Recycled Fibers and Methods of Restoration

1992 ◽  
Vol 266 ◽  
Author(s):  
James L. Minor ◽  
Rajai H. Atalla
Keyword(s):  
Gas Phase ◽  
Lignin Content ◽  
Strength Loss ◽  
Pulp Fibers ◽  
Recycling Process ◽  
Recycled Paper ◽  
Chemical Pulps ◽  
Mechanical Pulps ◽  
Recycled Fibers ◽  
High Lignin Content

AbstractThe reduced interfiber bonding capability and reduced conformability of recycled fibers compared to virgin wood pulp fibers is caused by the drying phase of the first papermaking cycle. Changes in the fiber result in stiffness. This effect is more pronounced in chemical pulps than in high lignin content mechanical pulps. This chapter describes methods for restoring some or all the interfiber bonding. In an attempt to develop a “dry” newspaper recycling process, the water-intensive repulping and paper-forming steps were replaced with dry-fiberizing, air-forming, gas-phase ozone and ammonia treatments, and pressdrying. The tensile strength of the dry-recycled paper approached that of the original newsprint.

Maintaining the Brightness of Mechanical Pulps with Solid-State Perborate Bleaching

Holzforschung ◽  
1998 ◽  
Vol 52 (3) ◽  
pp. 319-324
Author(s):  
Zhaoqing Liu ◽  
Dimitris S. Argyropoulos
Keyword(s):  
Solid State ◽  
Mechanical Pulps

Theoretical analysis of LC-refining – pressure screening systems in TMP

2019 ◽  
Vol 34 (1) ◽  
pp. 46-58 ◽  
Author(s):  
Jorge Enrique Rubiano Berna ◽  
Christer Sandberg ◽  
Mark Martinez ◽  
James Olson
Keyword(s):  
Fibre Length ◽  
Performance Curves ◽  
Average Fibre ◽  
Mechanical Pulps ◽  
Simulation Results ◽  
Save Energy ◽  
Relative Errors ◽  
The Impact ◽  
Screening Systems

Abstract LC refining of mechanical pulps has proven to save energy in the production of TMP pulps. However, the specific role of LC refining as part of a TMP system has not been thoroughly studied since it is difficult to conceive any particular system at industrial-scales and impractical at pilot-scales. In this study, pressure screening and LC refining models that describe fibre length distributions, together with correlations to predict refining power were used to model three basic refining systems. From the simulation results, the impact of important variables such as reject ratio, refiner gap and refining net-power was studied. Performance curves of length-weighed average fibre length were generated from simulation results and were used to assess each system behaviour and also to make comparisons between systems. Data from an industrial scale TMP mill sub-system was gathered and compared to simulation results showing relative errors between 0–18 % on the predicted variables.

Power–gap relationships in low consistency refining

2019 ◽  
Vol 34 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Jorge Enrique Rubiano Berna ◽  
Mark Martinez ◽  
James Olson
Keyword(s):  
Experimental Data ◽  
Force Sensor ◽  
Pilot Scale ◽  
Mill Scale ◽  
Control Power ◽  
Wide Range ◽  
Theoretical Assumptions ◽  
Mechanical Pulps ◽  
The Relationship ◽  
Good Agreement

Abstract Distance between stationary and rotating refining plates, gap, has a direct and significant impact on refining power. Gap is almost universally used to control power in low consistency refining operations. The relationship between power and gap are affected by refiner size, pulp type, plate pattern and refining conditions. In this study, a correlation was developed to describe the power–gap relationships at a wide range of refining conditions and furnish. The correlation was developed using pilot-scale refining data of mechanical pulps. Results showed that a properly defined dimensionless power number is suitable to describe refining power as well as to compare different refiners under the same grounds. The developed correlation was also used to predict mill-scale refining data showing good agreement with between predicted and measured values. Finally, experimental data from force sensor measurements supports the correlation’s theoretical assumptions.

Influence of cellulose supramolecular structure on strength properties of chemical pulp

Holzforschung ◽  
2014 ◽  
Vol 68 (8) ◽  
pp. 861-866 ◽  
Author(s):  
Per Tomas Larsson ◽  
Lennart Salmén
Keyword(s):  
Supramolecular Structure ◽  
Strength Properties ◽  
Cellulose Microfibrils ◽  
Kraft Pulps ◽  
Chemical Pulp ◽  
Chemical Pulps ◽  
Fiber Wall ◽  
Tear Index ◽  
Pulp Strength ◽  
Selective Increase

Abstract The industrially produced chemical pulps have lower strength properties than those obtained under laboratory conditions, and this difference is referred to as the strength delivery (SD) problem. In this study, the hypothesis was put forward that the SD could, at least in part, be accounted for by the supramolecular structure of the cellulose microfibrils of the fiber wall. To test the hypothesis, two bleached softwood kraft pulps (BSKP) were manufactured from the same starting material with different degrees of cellulose aggregation, but the pulps were otherwise as similar as possible in other controllable respects. The chemical and physical properties, including the pulp strength, were tested. A selective increase of the degree of cellulose microfibril aggregation resulted in a pulp with a decreased tear index (TI) at a specified tensile index, and this decrease was similar in magnitude to what is typically encountered in SD. Accordingly, the current experimental study succeeded in mimicking the SD problem. The lateral fibril aggregate dimensions (LFAD) seem to play a pivotal role and it can be safely concluded in general that the supramolecular structure of cellulose in the fibers may be an important factor contributing to the SD problem.

Review: Using magnesium hydroxide as the alkali source for peroxide bleaching of mechanical pulps - process chemistry and industrial implementation

2010 ◽  
Vol 25 (2) ◽  
pp. 170-177 ◽  
Author(s):  
Yonghao Ni ◽  
Zhibin He
Keyword(s):  
Sodium Hydroxide ◽  
Magnesium Hydroxide ◽  
Paper Industry ◽  
Bleaching Process ◽  
Peroxide Bleaching ◽  
Industrial Implementation ◽  
Process Chemistry ◽  
Peroxide Decomposition ◽  
Mechanical Pulps ◽  
Pulp Properties

Abstract Magnesium hydroxide, which is a weak alkali, can be used as the alkali source for peroxide bleaching of mechanical pulps. This magnesium hydroxide-based peroxide bleaching process has been commercialized in the paper industry. In this paper, we review the literature results regarding the process chemistry of the Mg(OH)2-based peroxide bleaching process, including the kinetics, peroxide decomposition, anionic trash/COD/oxalate formation, the effect on pulp properties. The benefits associated with the Mg(OH)2- based peroxide bleaching process are discussed. We also discuss the mill implementation of the Mg(OH)2- based peroxide bleaching process in the pulp and paper industry. A case is presented where magnesium hydroxide completely replaces sodium hydroxide as the alkali source. A partial magnesium substitution for sodium hydroxide can also be an option.

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