| 摘要 |
The present invention relates to a technique of producing anhydrous gypsum by recycling phosphogypsum which is an industrial byproduct generated from a process of phosphatic fertilizer production, and using the anhydrous gypsum as paper filler, more specifically to paper filler produced by heat processing the anhydrous gypsum at 500-1,200°C for 1-3 hours for increasing whiteness degrees. The paper filler by the present invention can replace talc, and paper containing the paper filler has similar whiteness degrees, improved opacity, and improved physical properties compare to paper produced by adding talc. [Reference numerals] (AA) Raw material of printing paper; (BB) Select; (CC) Beat; (DD) Mix the raw material and thermally processed gypsum; (EE) Use as the raw material of printing paper; (FF) Pre-process phosphogypsum and manufacture a filler; (GG) Collect the phosphogypsum; (HH) Heat-process at 500-12,000°C during 1-3 hours; (II) Disperse as slurry after grinding and selecting |
