White Cardboard Used In The Production Are Recorded At The Deinked Pulp Weak Alkaline Deinking Process Optimization

Deinking technology had been matured during years of development and improvementfrom the beginning of the alkaline deinking to the later alkaline deinking, enzymatic deinking,neutral deinking, etc., though it was not yet widespread in the plant application. Take MCCMeili Pulp&Paper Co., Ltd. white cardboard (made from deinking pulp) production line foran example, alkali charge of the deinking process was pretty high. In order to solve the problemsof alkaline deinking, reducing the amount of alkali, without affecting the deinking results in thecase, the thesis focused on improving and optimizing the process of MCC Meili Pulp&PaperCo., Ltd. white cardboard deinking Production line.In this thesis, five deinking agents were selected for the deinking experiments inaccordance with existing MCC Meili Pulp&Paper Co., Ltd.(hereinafter referred to as"Murray") deinking process conditions. The selected five deinking agents had better results inplants at present, and the three deinking agents offered by Murray were named as PM,326and323. The flotation deinking experiments were taken under the weakly alkaline conditions, topoint out the better deinking agent.Then, the five experimental conditions optimization of temperature, time, NaOH dosage,H2O2dosage and Na2SO3dosage for pulping process were taken out with DIA-30as thedeinking agent. The selected pulping conditions were temperature60℃, time20min, theamount of H2O20.5%, Na2SO3dosage of0.3%, NaOH dosage0.5%and pulp density of13%.326, DIA-30, Rhodia were taken as the optimized deinking agents to determine the properdeinking agent dosages.326deinking agent had certain advantages in the whiteness with theoptimal dosage is0.2%; DIA-30deinking agent had advantages in deinking efficiency, stickiesand dust removal in combined flotation and washing process, while its appropriate dosage wasonly0.1%; Rhodia also had its own advantages in flotation deinking efficiency and dustremoval, and the suitable dosage was0.1%.According to the conditions optimization of the above pulping, flotation and deinkingagent selection, three kinds of deinking agent were selected to test on the production line ofMurray white cardboard. Each index before and after optimization was compared. Came to theconclusion:326deinking agent had obvious advantages in the washing ERIC final value, flotation deinking efficiency was slightly better than DIA-30deinking agent while weaker thanRhodia deinking agent, the optimal dosage of326was0.2%; DIA-30deinking agent presentedbest in stickies removal optimal, while its dust removal ability was closer to Rhodia deinkingagent and much better than326deinking agent with the optimal amount of0.1%; Rhodiadeinking agent played the main advantages of ink removal in the flotation process, the dustremove efficiency presented the best, however the washing results was poor, its optimal dosagewas0.1%.Optimized pulping conditions were: pulping temperature60℃, pulping time20min,H2O2dosage of0.5%(relative to the oven dry paper), NaoH was0.5%-0.7%(equivalent to100%compared with the oven dry waste paper), Na2SiO3amount of0.5%(equivalent to100%compared with the oven dry waste paper).Flotation conditions were: temperature50℃, flotation5min, pulp concentration of1%.