Preparation Of PAC From Kaolin And Reaction Scraps' Utilization

Using kaolin, hydrochloric acid as the main raw material, adopting one step preparation method which means make the two materials mixed and react with each other then we get the final product. This PAC is grade one product under the GB15892-2003 national standard. After doing DOE factorial design and some other experiments we get optimal process condition as bellow: Kaolin get calcined at 750℃for 3 hours, after that adding 15% hydrochloric acid into the calcined Kaolin under hydrochloric acid and alumina molar ratio of 5, reaction temperature is 90℃and reaction under those condition should last 3.5 hours, then we adjust the pH value to 4.00 by saturated sodium hydroxide, then aging the liquid at 70℃and aging period last 6 hours. Finally, basicity of PAC closes to 40.73%. In addition, self-PAC's application in wet-end also get researched, meanwhile, we compared application effect between self-PAC and commodity-PAC. Results showed that: self-PAC has better effect than commodity-PAC when it used as ATC,retention aid and some other additive in wet-end, when self-PAC used as sizing additive, we can find out the optimal neutral sizing condition like this : anion dispersed rosin dosage is 0.8%, PAC dosage is 0.08%, amphoteric starch dosage is 1.5% , CPAM dosage is 0.02% . On that condition handsheet without filler has Cobb60 value 26.81g/m2 and Cobb60 value is 32.76 g/m2 while add 20% filler into pulp, So it close to AKD sizing effect. Reaction tailing can used as paper filler and it also can use with APAM together as retention system. This paper had done completely research on reaction tailing's application on papermaking industry. Results show that: the Zeta potential of residue is 28.4mv while PCC only half of that ; residue characteristic diameter Dn is 3.28μm, slightly lower than PCC's 3.8μm, but 90% of the residue particle size distribute in the 8.76μm or less; XRD patterns showed that residue match with the SiO2 standard pattern. When residue is filled in pulp can make paper has higher opacity and formation than PCC as filler, meanwhile, strength properties such as bursting strength, tensile strength approach each other no matter use PCC or residue as paper filler while filling dosage less than 20%; Using residue and PCC together with dosage ratio 1:1 ensure pH near neutral, So it can adapt neutral manufacturing environment better.