Process for producing a pulp suitable for papermaking from nonwood fibrous materials

A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising the sequential steps of:

• (a) providing a nonwood fiber source material;
• (b) extracting the nonwood fiber source material with an alkaline pulping solution for about 1 to about 90 minutes at a pressure ranging from about atmospheric pressure to about 30 psig and at a temperature ranging from about ambient temperature to about 150° C.;
• (c) treating the nonwood fiber source material with an acid solution at a temperature ranging from ambient temperature to about 90° C. and for a time ranging from about 30 to about 60 minutes to reduce the pH to an acidic pH;
• (d) dewatering the nonwood fiber source material to a consistency of at least about 35% and then diluting the nonwood fiber source material to a lower consistency ranging from about 1% to about 10%;
• (e) treating the nonwood fiber source material having an acidic pH with ozone;
• and
• (f) treating the nonwood fiber source material with a bleaching comprising a bleaching agent different from the ozone of step (e) to form a papermaking pulp having a Kappa value of at least as low as 5, a freeness level of at least 400 mL CSF or greater and a brightness level of at least 70% ISO.

A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising the sequential steps of:

• (a) providing a nonwood fiber source material;
• (b) extracting the nonwood fiber source material with an alkaline hydroxide pulping solution for about 30 to about 60 minutes at a pressure ranging from about atmospheric pressure to about 30 psig and at a temperature ranging from about 80° C. to about 120° C., wherein alkaline hydroxide in the alkaline hydroxide pulping solution is present in a dosage of ranging from about 10% weight to about 30% weight on ODF;
• (c) reducing the pH of the nonwood fiber source material to a pH ranging from about 1 to about 3 with an acid solution at a temperature ranging from about 50° C. to about 70° C. and for a time ranging from about 20 minutes to about 30 minutes;
• (d) dewatering the nonwood fiber source material to a consistency of at least about 35% and then diluting the nonwood fiber source material to a lower consistency ranging from about 1% to about 10%;
• (e) treating the nonwood fiber source material having an acidic pH with ozone at about ambient temperature for about 5 to about 15 minutes, wherein the ozone is present in a dosage ranging from about 0.4% weight to about 1% weight on ODF;
• (f) cleaning the nonwood fiber source material with at least one filtering screen;
• and
• (g) treating the nonwood fiber source material with a bleaching solution comprising a bleaching agent different from the ozone of step (e) at a temperature ranging from about 70° C. to about 110° C. to form a papermaking pulp having a Kappa value of at least as low as 5, a freeness level of at least 400 mL CSF or greater and a brightness level of at least 80% ISO.