Study On Modification Of High Yield Pulp And Fiber Separation Mechanism

In the traditional pulping possess of high yield pulp, mild chemical pretreatment and defibrination has been used, and most of hemicellulose and lignin are preserved.In high yield pulp, fiber bundles and lignin content is higher, and fiber is quite hard ,and has poor flexibility, low degree of fibrillation, and bonding strength between the fibers is poor. These shortcoming of the high yield pulp has hindered its development,in order to improve the quality of high yield pulp, expand the application range,mechanical modification can significantly improve the quality of the high yield pulp.However, research in mechanical modification of high yield pulp is limited, which to improve the high yield pulp quality is extremely important.In this paper, the pulp, which behind the first defibrination of the high yield pulp mill, were treated by high-shear fiber kneader with different pulp consistency, and some temperature and pressure sensor has installed on the high-shear fiber kneader.Change the cycle index of the fibrous materials in the high-shear fiber kneader, then analysis the changes of physical and chemical properties of the fiber, such as fiber bundle, fiber morphology, fiber fines content, kink index, freeness, water retention value, extraction, ash content, lignin and cellulose. And put the fiber materials into hand sheet to measure the tensile index, tear index and bulk. Then, use the date collected from temperature and pressure sensors to analysis the fibrous materials modification effect, finally, analysis of the stress of fiber and calculate the energy consumption of the high-shear fiber kneader, develop energy consumption model of the high-shear fiber kneader.The results showed that, with the increase of cycle index of fibrous materials in the high-shear fiber kneader, the content of fiber bundle, fiber length, length-width ratio, freeness, lignin, extraction and ash content decreased, the kink index and fiber fines content increased, the width of fiber increased firstly and then decreased. The bulk of hand sheet was decreased, the tensile index and tear index increased firstly and then decreased. pulp consistency would influence the fiber properties after treated by high-shear fiber kneader. In the same cycle index, when increasing the pulp consistency, width of fiber, fiber fines content, kink index and cellulose content increased .when the pulp consistency was 15%, the length of the fiber and extract content, ash content and lignin had the greatest reduction.Fiber bundle of materials reduced to 0.032% after six times cycling in high-shear fiber kneader. when the pulp consistency was 15%, compared with the untreated fiber materials, the weighted length of fiber has decreased 357?m, length-width ratio has decreased 12.8, fines content has increased from 20.85% to 31.9%, extract content has decreased from4.61% to 1.28%, the lignin content has decreased 4.64%,ash content has decreased 3.59%.Analyzing the force of fiber found that, the mainly force of fiber materials in extrusion section of high-shear fiber kneader was the force between the fibers, another force was from tooth and cylinder of high-shear fiber kneader. Fibrous materials in the rheological process of extrusion section of high-shear fiber kneader, mainly including the change of physical state and fluidized state, and the total energy consumption was composed of the change of physical state and fluidized state.