Methods of preserving starch in pulp and controlling calcium precipitation and/or scaling

摘要

Methods to preserve starch present in pulp are provided and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.

主权项

1. A method to control or prevent calcium precipitation and/or scaling in a biological oxygen demand reduction (BOD) system that processes process water used in papermaking and that contains calcium from pulp that is being processed, said method comprising in a papermaking process, continuously treating process water containing said pulp with a) chloramine comprising monochloramine such that said process water when said pulp is present has a residual chloramine amount of from 0.3 ppm to 15 ppm, and b) at least one oxidant, wherein a) and b) are added to said process water at different locations or at different times, and then forming paper/paperboard from said pulp, and processing said process water, after pulp removal, by sending said process water to said BOD system to reduce BODS, wherein pre-existing starch and calcium are present in said pulp, before and after said treating, wherein said starch is present in an amount of at least 0.001 wt % based on weight of dried pulp fiber.