| 摘要 |
<p>The invention describes a method of oxygen delignification of medium consistency cellulose pulp slurry, which includes the steps of providing a pulp slurry (12) of from approximately ten percent to sixteen percent consistency, at a temperature of from approximately 170-240 °F, preferably from 190 to 220 °F, thoroughly impregnating the slurry (12) with oxygen gas (16), and with alkali (14) to bring the slurry (12) to a pH of at least 11, more preferably 12, introducing the slurry (12) to oxygen gas (16) in a high shear mixer (18), for agitating mixing therein, reacting the slurry in a first pressurized reactor (20) for between 5 to 10 minutes, returning the pH of the slurry to at least 11, more preferably 12, with a residual alkali concentration of at least 1.25 gpl (22), thoroughly impregnating the slurry with H2O2 (24) and oxygen gas (26), and reacting the slurry in a second reactor (30) for between 30 to 180 minutes. By only employing the hydrogen peroxide during the slower bleaching reaction, a lower Kappa number with higher % ISO is obtained and these beneficial characteristics being retained in subsequent processing steps.</p> |
