This paper presents the results of an assessment of the morphological characteristics of semi-finished wood-fibre products obtained from waste fibreboard using a rotary cutting machine by dry ...grinding. The work has established the influence of machine design parameters, such as the gap between the rotor and stator cutters and the angle of the stator cutter contact with the raw materials, on the mass fraction of small fibres and fines in wood-fibre pulp. These parameters determine the main structural characteristics of boards and ensure fibre bonding. The paper describes the collision of single secondary wood fibres that leads to the development of primary cracks, contributing to external and internal fibrillation in the absence of high temperatures and pressure without using chemical additives or water and steam.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This article presents the rationale for modelling the process of internal recapture of wood fibre from wastewater in fibreboard production using conventional refining methods and a new refiner disc ...design. New experimental studies to obtain mathematical dependencies for confirming the possibility of reusing cellulosic fines in comparing conventional and new refiner discs for fibreboard production are presented. Models reflecting the internal reuse of cellulosic fines from wastewater were developed. In this article, for comparative assessment of the efficiency of the proposed technologies, an environmental and economic assessment of cellulosic fines in modelling the process of its obtainment in fibreboard production was performed.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The refining process is the most important and determines the dimensional and qualitative characteristics of the semifinished fibre product, respectively, and the physical and mechanical properties ...of the composite materials made of it. The present work presents the results of experimental studies carried out in conditions as close as possible to the industrial conditions of the refining process of fibrous semi-finished product in the production of composite materials such as wood-fibre boards, allowing to evaluate the effectiveness of the refining set for the preparation of wood fibre in disc mills at the regulation of the created forces in the refining process. The results of the planned and implemented multifactor experiment allowed to establish the influence of normal forces created by the design of the refiner disc at regulation of the working gap and concentration of wood fibre mass, as well as their paired interaction on the intensity of changes in the main size-quality characteristics of the fibrous semi-finished product (degree of refining, average length and diameter of fibres, the ratio of length to diameter of fibres) in the process of its preparation.
The refining of plant fibre, particularly wood fibre, in a disc refiner involves changes in its geometric parameters and fraction proportions in the general semi-finished material mass. Fibre ...disintegration nature and intensity largely depend on the loads and forces occurring at the intersection of the rotor disc knives and the refiner stator. This research presents data confirming the possibility of regulating both normal and tangential forces by modifying the discs operational part design. It assesses the efficiency of the developed disc design compared to the traditional design used in fibreboard production. The redistribution of knives on the disc surfaces reduced the knife crossing angle (to ≈0–15°) and the number of (contacts) points formed from their intersection (to ≈528 pcs.), thereby increasing the main process parameters of the refining process (length of cut per second, cyclic elementary length, working refining surface) and the share of the normal components of the applied force (to ≈75%). An experimental study of mixed softwood fibre refining was carried out; the dependencies and optimal process conditions for regulating the gap (0.08–0.1 mm) between the refiner discs and the pulp concentration (2.5–3%) were determined taking the fibre properties into account. The new refiner disc design ensures a more intense fibre diameter reduction compared to the length. As a result, the longer and thinner, and therefore more flexible, fibres prevail in the wood pulp (to 50%), ensuring better inter-fibre interaction and improving the strength properties of the finished products (for 20–25%) without the use of binding resins.
This paper presents the results of an assessment of the morphological characteristics of semi-finished wood-fibre products obtained from waste fibreboard using a rotary cutting machine by dry ...grinding. The work has established the influence of machine design parameters, such as the gap between the rotor and stator cutters and the angle of the stator cutter contact with the raw materials, on the mass fraction of small fibres and fines in wood-fibre pulp. These parameters determine the main structural characteristics of boards and ensure fibre bonding. The paper describes the collision of single secondary wood fibres that leads to the development of primary cracks, contributing to external and internal fibrillation in the absence of high temperatures and pressure without using chemical additives or water and steam.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A rationale is presented for the wood fibre process modeling of internally recycled content in fibreboard production. Experimental studies were employed to obtain mathematical dependences in order to ...confirm the possibility of reusing wood fibre at various stages of the technological process. A wood fibre process model of internally recycled content was accrued out in which each processing stage was presented separately. Two methods for the preparation of wood fibre for reuse in fibreboard production were considered. To assess the effectiveness of the technologies proposed, the process modeling of internally recycled content was assessed from an economic and environmental point of view.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A physical coagulator of fines was employed to separate suspensions comprising refined sulphate cellulose and waste paper, where no reagents were required. The physical coagulator was a porous ...cylinder with a rotating disk placed in its cavity. Using the MorFi Neo fibre analyser and the Hitachi SU 3500 digital microscope, a dispersed size distribution of well-developed fines in a suspension derived from softwood and hardwood pulp was obtained. The kinetics of fine sedimentation in the suspension was studied. The sedimentation rate of both individual agglomerates and a mass of them, as well as the magnitude of mass concentration in a cleared liquid, was determined. A relationship between the concentration of fines in the suspension and the structure of the pulp during their sedimentation was established. To intensify the fines sedimentation process, it was proposed to return a part of the sediment to the suspension passing into the physical coagulator. Process parameters for the sedimentation process and the construction of the sedimentation tank were obtained. The unit designed for collecting fines from the suspension is shown schematically. Use of this unit reduced the fibre sedimentation time, decreased the loads in wastewaters, and retained the consumer value of the pulp fibres.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Refining of fibrous semi-finished products is an important stage in fibreboard production because the efficiency of this stage affects the resulting fibres’ dimensional and qualitative ...characteristics. These, in turn, determine the physical and mechanical properties of the finished products, as well as the energy intensity of the process. The efficiency of this process depends on the raw materials used and the geometry of the refiner disc working surface and its operational modes. This article presents the results of the optimisation of wood fibre refining at a low concentration (2 to 4%), using fundamentally new refiner discs in high-density fibreboard production. Based on numerous theoretical and experimental studies, and on the results of processing, the problem of optimising the refining process was solved, taking into account the use of new refiner disc geometry. As a result, the optimal values of refiner process parameters and operation modes making it possible to prepare wood-fibre semi-finished products efficiently while reducing power consumption in refining were established. After optimising the refining process, the new geometry of refiner disc working surfaces provides optimal dimensional and qualitative characteristics of wood fibres, which results in finished products with high physical and mechanical properties in accordance with GOST 4598 (2018) without using bonding resins.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This paper presents the results of research on the treatment of secondary wood fibre semi-finished materials using a dry-grinding-type rotary cutting mill and the possibility of their use in finished ...products for various purposes. The physical phenomena, processes, and regularities of the treatment of secondary wood fibre materials in dry processing conditions were determined and evaluated. The influence of grinding plant design parameters on wood fibre quality indices was evaluated. Mechanical effects on wood fibre waste of face-cross cutting (cutting, crumpling, collapsing, and breaking) and the dry grinding environment (breaking, collision, defibering, and fibrillation) was studied. These phenomena contribute to the formation of external and internal fibrillation of secondary wood fibre and an increase in the specific surface area. This is achieved in the absence of high temperatures and pressure, in the absence of chemical additives, and without the application of water and vapour. The effectiveness of secondary wood fibre semi-finished material treatment was demonstrated under dry processing conditions, thus confirming the environmental and economic feasibility of this method.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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