Chemical additives for papermaking include process additives and functional additives, and the amount and method of addition vary with various conditions such as different paper mills, different paper grades, and different paper machine.
The general consideration is: functional additives should be added as close as possible to the place where the problem occurs and the place that may affect the performance; process additives should be considered comprehensively, not only taking into account the reaction time of chemicals and fibers, but also considering the loss of added chemicals and the disruption of the reaction by mechanical action in the process.
Advice on the addition of chemicals
1, Addition of PAM
Adding amount: 100~250g/t
Adding position: Round sieve exit
2, Addition of dyes
Blue dye: 50~100 ml/t (stock solution)
Purple dye: 20 ~40 ml / t (stock solution)
Add position: Round sieve entrance
3, Addition of Cationic Starch
The amount of addition: 8 ~ 12kg/t
Adding position: the discharge port of the adjustment box
4, Addition of brighteners
Addition amount: 0.5~10kg/t (stock solution)
Adding position: Round sieve entrance
5, Addition of AKD
Addition amount: 12~25kg/t (stock solution)
Adding position: the discharge port of the adjustment box
6, Addition of defoamer
Add position: off-line or off-machine white water tank
7, Addition of fungicides
(1) Addition of sizing system:
Adding amount: In summer, add 150~200 ml every 4 hours ; In winter, add 75~100 ml every 4 hours
Adding position: Size forming tank, starch tank, PAM tank, white water tank
(2) Addition of broken paper system:
Added position: Broken pulp tank
Adding amount: In summer, add 150~200 ml every 4 hours ; In winter, add 75~ 100 ml every 4 hours
(3) Adding method: the sizing system and the broken paper system are automatically added with metering pumps
8, Addition of Dispersed Rosin Gum:
Addition amount: 6~28kg/t (stock solution)
Adding position: the discharge port of high-level box
9, Addition of alum:
Addition amount: 25~35kg/t (solid)
Adding position: mixing tank
Precautions on the addition of chemicals
1. When acid sizing is changed to neutral sizing, it must be thoroughly cleaned to prevent chemical deposits or hydrolyzates from affecting production.
2. When all auxiliary raw materials are used, they must be filtered with a 60-100 mesh screen.
3. When adding sizing agent, the dosage should be adjusted according to the sizing degree and Cobb value of the finished paper. Production interruptions should be prevented during the joining process.
4.When cationic polyacrylamide is dissolved, water must be added and the stirrer must be started before feeding. PAM must be dissolved first through the disperser. The temperature should be controlled between 40 and 50°C during stirring. The ideal stirring speed should be less than 30r/min and stirring time. For 90-100min, the weight of dry powder should be accurately weighed to ensure the stability of the preparation concentration, and the filter screen should be cleaned regularly. The ideal stirring speed is less than 30r/min, the stirring time is 90-100min, the weight of the dry powder should be accurate to ensure the stability of the preparation concentration, and the filter screen should be cleaned regularly.
5.When preparing dyestuffs, the nameplate should be clearly seen to avoid confusion and affect the adjustment quality. When the metering pump is started, it must be checked whether the valves are open, otherwise the motor will be burned. When the machine is stopped, the valves must be closed in time to avoid cylinder suction.