From Wood to Paper:A Diagram of the Process & Chemistry
Chemical Additives and Reactions
A
White Liquor added to wood chips.(Na2S + Na OH + Na2CO3)
B
Black Liquor washed out.
C
Pulp treated with Chlorine to oxidize Lignin.
D
Pulp extracted with Caustic Sods to remove Lignin.
E
Pulp treated with Sodium Hypochiorite(Na OCI)
F
Pulp treated with Chlorine Dioxide(CI O2) to increase whiteness.
G
Bleached pulp slurry. Rosin, Alum, Dyes, Clay, Titanium Dioxide (TI O2), added.
H
Paper sheet formed here through dewatering. Rosin and Alum react to size the paper (make it more waterproof).
I
Black Liquor (Spent White Liquor + Lignins from Wood).
J
Converts Black Liquor + added saltcake to Green Liquor thru combustion1. Na2SO4 ---> Na2S2. Na Lignin ---> Na2CO3
K
Contains Green Liquor(Na2CO3 + Na2S)
L
Converts Green Liquor to White Liquor(Na2S + NaCO3 + Ca (OH)2 ---> Na OH + Na2S + Ca CO3)
M
Calcium Carbonate (Ca CO3) is settled out and sent to Lime Kiln. Clarified White Liquor goes back into new cooking cycle at Piont A.
Chemical Additives and Reactions
A
White Liquor added to wood chips.(Na2S + Na OH + Na2CO3)
B
Black Liquor washed out.
C
Pulp treated with Chlorine to oxidize Lignin.
