Modeling the Production Processes of Wood-Fiber Semi-Finished Products Aimed at Expansion of the Raw Material Base of Forest Enterprises

Abstract

Currently, materials made of wood-fiber semi-finished products are widely used in house building as structural, finishing and insulating materials. According to the results analysis of numerous studies, the raw material for their production is technological chips of woodworking waste. While production, the chips are subjected to hydrothermal treatment and further grinding in disk knife grinding machines in two stages. Significant energy consumption of the wood fiber production process is driven not only by grinding wood chips in stages, but also by overcoming the hydrodynamic resistance of the aqueous environment, where grinding is carried out. The process of grinding wood chips, made of from chopping residues, in an aerodynamic medium on an upgraded cross-bar mill was studied in order to solve the problem of expanding the raw material base for the production of a wood fiber semifinished product and reducing the energy intensity of the grinding process. The features of this process were analyzed and its effectiveness was assessed. The influence of the exposure time of wood chips of chopping residues in an acetic acid solution, the size of the working gap and the angle of inclination of the front edge of the knife on the grinding degree and fractional quality of wood pulp grinding was determined. Statistical and mathematical equations, that describe the studied process, were obtained, and the graphical dependencies are constructed. The following basic requirement is fulfilled for the dependencies: the experimental points for a total should lie quite close to the curve. These equations allow predicting the quality of wood pulp depending on the set modes of the grinding process; as well as determining the quality indicators of wood pulp with known values of the technological and structural parameters of the grinding machine. The efficiency of the process of obtaining the wood-fiber semi-finished product in an aerodynamic environment from wood chips produced as a result of chopping residues (branches, twigs, etc.) processing in a mobile wood chipper, is proven.

Assessment of the morphological properties of secondary semi-finished wood-fibre products obtained from production waste

“…In turn, fines contain Group A and B fibrilplasms, as well as Group A and B mehlstoff. Studies show that fines account for 35 to 40% of the total mass of secondary wood fibres (Zyryanov 2012;Morozov 2016).…”

“…Numerous theoretical and experimental studies show that such factors as the gap between the rotor and stator cutters and the angle of the stator cutter contact with the raw material have the greatest effect on the grinding process under consideration. Such factors as the temperature of the wood-fibre pulp, the ratio of coniferous and deciduous species and the rotor rotation frequency have less effect (Chistova 2010;Zyryanov 2012;Morozov 2016;Vititnev 2019).…”

“…The ratio characterizes the intensity of changes in the geometric dimensions of wood fibres in different directions and determines their specific surface area and flexibility. The method for determining the arithmetic mean values of fibre length L and diameter D is presented in earlier studies (Zyryanov 2012;Matygulina et al 2021b). The authors carried out a two-factor experiment according to the second-order Bplan with processing in the STATISTIСA-6 software package (Dell Technologies, version 6.1, Round Rock, TX, USA) using the Quasi-Newton method (Borovikov and Borovikov 1998;Pizhurin and Pizhurin 2005).…”

“…It is soaked, ground in high-speed disk or conical mills, and mixed with press pulp, thereby putting it back into main production. However, studies (Matygulina 2007;Сhistova 2010;Zyryanov 2012;Сhistova et al 2015) have shown that this leads to the quality of finished products deteriorating: the tensile strength and density of boards decrease, while moisture absorption and swelling in thickness increase. Lump waste is also processed into fuel for thermal power plants (ground to a size suitable for loading into boilers).…”