Dry grinding of waste wood fiberboard: Theoretical and practical aspects affecting the resulting fiber quality

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.

Optimization of wood fibre refining process in fibreboard production with new refiner disc working surface geometry

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.

Additional Criteria for Playground Impact Attenuating Sand

Falls within children’s playgrounds result in long bone and serious injuries. To lower the likelihood and severity of injury, impact attenuating surfaces (IAS) are installed within the impact area (fall zone). There are three primary IAS materials used, namely: granulated rubber products, wood fibre products, and sand. There is a deficiency with existing IAS test methods in that they do not take account of sand degradation over time. When children use the playground, sand degradation can occur when sand produces fines and smaller particles with low sphericity and angular which fill the voids between the sand particles. These fines and smaller particles tend to bind the sand and lower its impact attenuating performance. This paper proposes an additional IAS test to eliminate sands that degrade above an established threshold rate after installation due to normal usage. IAS degradation properties of fifteen IAS sands were tested including sand particle shape, sand particle distribution, percentage fines and sand particle degradation. This accelerated ageing test method is applicable only to sands and not rubber or wood fibre IAS products. The best IAS sands were sourced from quarries located on rivers that had eroded volcanic outcrops. These sands were shown to degrade the least and had little to no fines, and their particle shape was rounded to well-rounded. The most reliable source for good quality IAS sands on these rivers was on specific bends. The sand mined at these locations consistently had a tight particle size distribution.

Modeling of internally recycled material in fibreboard production facility as a tool for economic and environmental assessment

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.

Study on the influence of composite soil on the slope stability of farmland during in land consolidation

To improve the stability of sloping farmland, the optimal ratio parameter of composite soil was determined. Single and mixed composite soils were prepared with three improved materials of glutinous rice glue, wood fibres and coarse sand for indoor direct shear tests and pot experiments. Based on the different moisture and soil contents, the shear strength, cohesion, and internal friction angle of the composite soil were analyzed, and the proportioning parameters were adjusted according to the suitability of plant growth. Slope stability analysis was performed in combination with the actual case of slope farmland improvement. The research results show that (1) different soil improvement materials are affected by moisture in different sections. The maximum shear strengths of composite soil with glutinous rice glue, wood fibre, and coarse sand correspond to 11%, 14% and 32% of the optimal moisture content respectively. The change in the content of the modified material will affect the soil structure, and the shear strengths of the single composite soils are the highest when the content of the modified material are 1.5%, 5% and 15%. (2) According to the shear strength and the suitability of plant growth, the contents of the glutinous rice glue, wood fibre, and coarse sand of the mixed composite soil were determined by the optimal ratio parameters of 1.5%:2.5%:15%. (3)In this application, the minimum safety factor of mixed (1.5% glutinous rice glue, 2.5% wood fibre, and 15% coarse sand) composite soil is higher than that of single composite soil at slopes of 10°, 15°, and 20°. Under different water contents, the overall stability of the mixed composite soil slope improves.

Characterization of the Hygrothermal Properties of Wood Fibre Insulaton Board

High thermal resistance building envelopes comprising wood fibre insulation board (WFIB) contribute to a reduction in building energy consumption associated with unwanted heat losses and gains. The longterm performance and durability of the WFIB material may perform differently than expected due to the temperature and moisture dependent material characteristics, including moisture sorption, vapour permeance, and thermal conductivity. This research investigated the characterization of hygrothermal properties of WFIB at temperatures and relative humidities expected for a Canadian climate. The hygrothermal characteristics of WFIB were determined to have a range of values as a result of the variable nature of wood fibre materials with temperature and moisture, and the variability of WFIB materials amongst manufactured products. The variabilities of these hygrothermal properties are expected to impact the materials overall moisture storage at various in-situ temperature and relative humidity conditions, and the materials ability to transport moisture at various in-situ temperature and relative humidity conditions. Additionally, the thermal performance of WFIB is expected to vary with in-situ temperature and relative humidity conditions, with increased thermal losses/gains with increasing temperature and increasing relative humidities.

Characterization of the Hygrothermal Properties of Wood Fibre Insulaton Board

High thermal resistance building envelopes comprising wood fibre insulation board (WFIB) contribute to a reduction in building energy consumption associated with unwanted heat losses and gains. The longterm performance and durability of the WFIB material may perform differently than expected due to the temperature and moisture dependent material characteristics, including moisture sorption, vapour permeance, and thermal conductivity. This research investigated the characterization of hygrothermal properties of WFIB at temperatures and relative humidities expected for a Canadian climate. The hygrothermal characteristics of WFIB were determined to have a range of values as a result of the variable nature of wood fibre materials with temperature and moisture, and the variability of WFIB materials amongst manufactured products. The variabilities of these hygrothermal properties are expected to impact the materials overall moisture storage at various in-situ temperature and relative humidity conditions, and the materials ability to transport moisture at various in-situ temperature and relative humidity conditions. Additionally, the thermal performance of WFIB is expected to vary with in-situ temperature and relative humidity conditions, with increased thermal losses/gains with increasing temperature and increasing relative humidities.