The Effect Of Carbonization Refining Process On The Quality Of The Lime Mud

Lime Mud is a by-product that comes from the alkali recovery process.It can be used as paper filler to replace an amount of Precipitated Calcium Carbonate(PCC).This way not only brings appreciable environment benefits but also reuses the waste resource.However,when using carbon dioxide to refine lime mud,the sizing efficiency of filler paper with carbonized lime mud significantly reduced,which limits its application as a paper filler and utilization rate.In order to improve the application performance of carbonized lime mud,this paper researched the mechanism of carbonization refining technology on the quality of lime mud,and on this basis,the process of controlling the quality of lime mud in the process of carbonization refining was studied.Alkali recovery of lime mud to provide the basis for quality control to promote the use of its resource development technology.The main research results of this paper were as follows.The effect of carbonization on the sizing properties was studied.The results showed that: the deeper the degree of carbonization,the more the content of fine particles of carbonized lime mud,the corresponding sizing efficiency of filler paper with carbonized lime mud was worse;the fine particle content was the key factor which was influenced the sizing efficiency of filler paper with carbonized lime mud.The effects of carbonized lime mud on the sizing properties of AKD sizing and its mechanism were researched.The results showed that: although the low retention characteristics of the fine particles of lime mud would lead to part of its adsorption of AKD loss ineffectively,the use of enhanced the fine particles of carbonized lime mud of the retention did not improve the sizing properties of the filler paper.Therefore,the low residual of the fine particles of carbonized lime mud was not the main reason for the poor sizing efficiency of filler paper with carbonized lime mud.Due to the irregular surface morphology of the fine particles and large specific surface area,pore volume and pore size of carbonizedlime mud,AKD was easily absorbed.When the filler paper in the drying process,these absorbed AKD easier to migrate to the pores of lime mud.The amount of effective AKD that could react with the hydroxyl groups on the surface of the fiber to produce hydrophobic properties was reduced,resulting in a lower AKD sizing efficiency.This was the main reason that poor sizing efficiency of filler paper with carbonized lime mud.Based on the research on the mechanism of the effect of carbonized lime mud on AKD sizing,in this study,polyethylene glycol and sodium polyacrylate were used to carbonize,the morphology and pore structure of lime mud were improved and the sizing efficiency of filler paper was enhanced.The results showed that the use of polyethylene glycol assisted carbonization treatment could improve the pore volume and pore size of lime mud.However,compared with commercial precipitated calcium carbonate,its quality had a certain gap.The use of acrylic sodium salt polymer assisted carbonization treatment could improve the content and surface morphology of fine particles and the specific surface area,pore volume and pore size of carbonized lime mud.When added acrylic sodium salt polymer to thick lime mud before the process of grinding,the mechanical friction would destroy the role of sodium polycrylate and lime mud.During the process of carbonization,the effect of sodium polyacrylate on the fine particles and micro-performance of lime mud was weakened,which was not conducive to the control of the quality of lime mud.Added sodium polyacrylate to thick lime mud after the process of grinding could control the content of fine particles effectively,which was conducive to control the quality of lime mud.In the process of carbonization refining,directly put sodium polyacrylate liquid into lime mud could control the quality of lime mud effectively.When the sodium polycrylate solid was co-carbonized,it was necessary to provide a certain dissolving time to facilitate the sodium polyacrylate,the longer the dissolution time,the better the quality of the carbonated lime mud.