碳化精制工艺对白泥碳酸钙品质的影响研究

发布时间：2018-01-10 07:36

本文关键词：碳化精制工艺对白泥碳酸钙品质的影响研究　出处：《陕西科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：白泥碳酸钙是造纸行业中碱回收工段的固体废弃物,它能够替代轻质碳酸钙(PCC)作为纸张填料,其经济与环境效益明显。然而,白泥碳酸钙精制为纸张填料的过程中发现,利用二氧化碳(CO_2)碳化精制得到的白泥碳酸钙填料加填后,加填纸的AKD施胶效率显著降低,限制了白泥碳酸钙作为造纸填料的大规模应用。因此,为了提高碳化精制后白泥碳酸钙的品质及应用性能,本课题针对碳化精制工艺对白泥碳酸钙品质及其加填纸施胶性能的影响机理进行研究,在此基础上,研究添加剂调控碳化精制工艺实现对白泥碳酸钙品质的改善,以期为提高碱回收白泥碳酸钙的品质控制提供依据,促进其资源化利用技术发展。本论文的主要研究成果如下:研究碳化程度对施胶性能的影响,结果表明:碳化程度越高,制备的白泥碳酸钙细小粒子的含量越多,相应的白泥碳酸钙加填纸的AKD施胶性能越差;细小粒子含量是影响碳化白泥碳酸钙加填纸施胶性能的重要因素之一。研究并阐明碳化白泥碳酸钙对加填纸AKD施胶性能的影响及其作用机理,结果表明:尽管白泥碳酸钙细小粒子在抄纸过程中低留着特性会导致部分被其吸附的AKD无效流失,但采用强化碳化白泥碳酸钙细小粒子组分的留着,并未提高加填纸的施胶性能。因此,细小粒子低留着导致的AKD流失并不是导致碳化白泥碳酸钙加填纸施胶性能差的主要原因。主要原因是由于细小粒子表面形貌不规则,碳化白泥碳酸钙具有大的比表面积、孔体积及孔径,更容易吸附AKD,其加填纸在干燥过程中,这些被吸附的AKD更容易迁移至白泥碳酸钙的孔隙内,使得能与纤维表面的羟基反应产生憎水性能的有效AKD的量减少,最终AKD施胶效率较差。基于碳化白泥碳酸钙对AKD施胶影响机理的研究结果,研究分别采用聚乙二醇和聚丙烯酸钠协同碳化,改善白泥碳酸钙形貌和孔结构,进而强化加填纸的施胶效果。结果表明,采用聚乙二醇协同碳化处理可改善白泥碳酸钙的孔体积及孔径,从而达到控制白泥碳酸钙品质的目的,但其品质与商品轻质碳酸钙相比存在一定差距。采用聚丙烯酸钠协同碳化,通过调控碳化白泥碳酸钙的细小粒子含量,细小粒子表面形貌,碳化白泥碳酸钙的比表面积、孔体积及孔径来达到控制碳化白泥碳酸钙的品质的目的。研磨前投料由于机械摩擦会破坏聚丙烯酸钠与白泥碳酸钙的作用,碳化过程中聚丙烯酸钠对白泥碳酸钙细小粒子及微观性能的调控作用减弱,不利于对白泥碳酸钙品质的控制;研磨后投料聚丙烯酸钠能有效控制细小粒子的含量,有利于控制白泥碳酸钙品质。碳化精制过程中,直接投放聚丙烯酸钠液体可有效控制白泥碳酸钙品质;投放聚丙烯酸钠固体协同碳化时,需要提供一定溶解时间以利于聚丙烯酸钠溶解,溶解时间越长,碳化精制得到的白泥碳酸钙的品质越好。
[Abstract]:White clay calcium carbonate is the solid waste of alkali recovery section in papermaking industry. It can replace light calcium carbonate as paper filler, and its economic and environmental benefits are obvious. During the process of refining the white mud calcium carbonate as paper filler, it was found that the AKD sizing efficiency of the paper was significantly decreased after the filling of the white mud calcium carbonate filler made from carbon dioxide COST2). Therefore, in order to improve the quality and application performance of calcium carbonate after carbonization, the application of calcium carbonate in white mud as paper filler is limited. In this paper, the influence mechanism of carbonation refining process on the quality of calcium carbonate in white mud and the sizing performance of filler paper was studied, and on the basis of that, the effect of carbonation process on the quality of calcium carbonate was studied. To improve the quality of calcium carbonate in white mud, the quality of calcium carbonate in white mud can be improved by adjusting and controlling the process of carbonization refining with additives, so as to provide the basis for improving the quality control of the recovery of calcium carbonate from white mud. The main research results of this paper are as follows: the influence of carbonization degree on sizing performance is studied. The results show that the higher the carbonation degree is. The more the content of fine particles in white clay calcium carbonate is, the worse the AKD sizing performance of the corresponding paper is. The content of fine particles is one of the important factors that affect the sizing performance of calcium carbonate in carbonized white mud. The effect of calcium carbonate in carbonized white mud on the sizing properties of AKD paper and its mechanism are studied and expounded. The results showed that although the low retention characteristics of calcium carbonate particles in the papermaking process would lead to the loss of some AKD adsorbed by the particles, the enhanced retention of the fine particles of calcium carbonate particles in white mud was adopted. Does not improve the sizing performance of the filling paper. The loss of AKD caused by the low retention of fine particles is not the main cause of poor sizing performance of calcium carbonate in carbonized white mud paper, but mainly due to the irregular surface morphology of the fine particles. Calcium carbonate carbonated white mud has large specific surface area, pore volume and pore size, and it is easier to adsorb AKD. During the drying process, the adsorbed AKD is easier to migrate to the pore of calcium carbonate in white mud. The amount of effective AKD which can react with hydroxyl groups on the fiber surface to produce hydrophobicity is reduced, and the final AKD sizing efficiency is poor. Based on the results of the study on the influence mechanism of calcium carbonate from carbonized white mud on AKD sizing. The morphology and pore structure of calcium carbonate in white mud were improved by co-carbonation of polyethylene glycol and sodium polyacrylate respectively, and the sizing effect of filler paper was strengthened. The pore volume and pore size of calcium carbonate in white mud can be improved by using polyethylene glycol in combination with carbonization, thus the quality of calcium carbonate in white mud can be controlled. However, the quality of calcium carbonate is different from that of light calcium carbonate. Sodium polyacrylate combined with carbonation is used to regulate the content of fine particles and the morphology of fine particles in carbonized white mud calcium carbonate. The specific surface area, pore volume and pore size of calcium carbonate in carbonized white mud were used to control the quality of calcium carbonate. The effect of sodium polyacrylate and calcium carbonate in white mud could be destroyed by mechanical friction before grinding. The effect of sodium polyacrylate on the fine particles and microscopic properties of calcium carbonate in white mud was weakened during carbonation, which was not conducive to the quality control of calcium carbonate in white mud. The content of fine particles can be effectively controlled by adding sodium polyacrylate after grinding, and the quality of calcium carbonate in white mud can be controlled by adding sodium polyacrylate liquid directly in the process of carbonation refining, and the quality of calcium carbonate in white mud can be effectively controlled by adding sodium polyacrylate directly. When adding sodium polyacrylate solids together with carbonization, it is necessary to provide a certain time of dissolution to facilitate the dissolution of sodium polyacrylate. The longer the time of dissolution, the better the quality of calcium carbonate obtained by carbonation refining.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS727

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