The Effects of Some Process Variables on Populus nigra APMP Pulp Yield and Brightness

The Effects of some process variables on P. nigra APMP pulp yield and brightness were investigated.
Wood samples were prepared from poplar plantation fields in the vicinity of Maragheh Paper
Company. Fiber dimentions such as average fiber length, diameter cell cavity and fiber wall thickness were assessed as 853, 22.66, 15.16 and 3.74 microns, respectively.For making APMP pulp, different chemicals namely sodium hydroxide (6 and 7%), hydrogen proxide (5 and 6% ) diethylene triamine pentaacetic acid (0.5%) and sodium silicate (3.5%) (based on O.D chips) were used. Based on the preliminary chemical treatment results, chips treated with preheating of 20 minutes , impregnation times of 20 and 75-105 minutes in first and second stages, pulp conssistency of 34-36% and 23-25 % in the first and second stages of impregnation, respectively, percentages of caustic charge in 3 levels of 40,50 and
60 % in the first impregnation stage, percentages of proxide charge in 3 levels of 20,25 and 44% in the first impregnation stage, percentages of diethylene triamine pentaacetic acid in 2 levels of 60 and 75% as well as percentages of sodium silicate of 50% in each stage of chemical impregnation, were selected as the process coriditions. The APMP pulp brightness and yield obtained in the 24 treatments, were in the ranges of71.7 -78.6 % and 84.17 -93.46 %, respectively. The final results indicated that by using optimum process variables such as total caustic and proxide charges of 7 and 6% respectively , percentages of caustic, proxide and diethylene triamine pentaacetic acid in the first impregnation stage of 60,20 and 75%, consistency of 34 and 23% in the first and second stages respectively, It is possible
to produce APMP pulp of high brightness in an acceptable yield range.