Methods To Detect Organic Contaminants In Pulp and Fiber

Abstract

A method to detect organic contaminants in pulp and fiber is described which uses hydrophobic dyes, such as fluorescent dyes.

Description

[0001]This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 60 / 930,414, filed May 16, 2007, which is incorporated in its entirety by reference herein.BACKGROUND OF THE INVENTION[0002]The present invention relates to pulp and fiber and more particularly relates to methods to detect and / or quantify organic contaminants, such as microstickies, present in pulp and fiber.[0003]Conventional recycling of old paper products such as old new print, old corrugated containers, and mixed office waste is an important aspect of papermills today due to environmental demands that many paper containing products have a portion of recycled fibers contained within the paper product. Thus, papermills are in a situation where the recycling of paper products is a necessity. However, the recycling of the paper products generally requires additional processing steps in order to lead to fibers which can be useable in paper products.[0004]Conventional recy...

AI Technical Summary

Benefits of technology

[0022]An additional feature of the present invention is to provide a method to detect and / or quantify organic contaminants in pulp and fiber which provides an accurate reading and can be conducted at the papermill site.

Problems solved by technology

Once caustic agents are used, some yellowing of the fibers occurs which results in a need to bleach the fibers.

Recycled paper fibers contain many components that when repulped in recycle fiber plants become stickies.

Stickies deposit on machine surfaces, fabrics, wires, felts, and rolls and lead to problems such as wet end breaks, pressroom breaks, dryer section breaks, holes, sheet defects, and high dirt counts.

These deposits and associated problems lead to a significant amount of downtime yearly.

Floating removes intermediate size stickies (50-300 microns), which are troublesome, because they're small enough to be accepted by screening and cleaning but too large to be removed by washing.

Measuring and controlling stickies in a recycled paper manufacturing process has always been a challenge.

Variations in recycled paper quality and the trend to increase the amount of waste paper incorporated into each ton of pulp produced are each contributing factors that make this challenge even more difficult to address.

These variations make predicting the amount of stickies that are entering a mill's system troublesome.

However, additional stresses on the screens and cleaner banks such as high furnish consistency, improper in-screen dilution, improper reject rates, and differential pressure control problems will facilitate the acceptance of formed macrostickies (Gallagher, 1997).

These materials remain tacky in the papermaking process, leading to the “stickies” label (Doshi, 1997).

Once the materials are incorporated into the fumish, they are difficult to remove, since they are deformable in nature and are often close to the specific gravity of water.

These physical characteristics present a different screening and cleaning challenge as these contaminants slip through screens and cleaners (Scholz, 1997) that are designed to allow water and fiber to be accepted.

Even if the cleaning and screening systems do perform properly and do remove most of the macrostickies, the remaining microstickies may cause problems.

The cost of stickies deposition is a significant one.

Preventing the agglomeration of microstickies is also an issue in addition to the microstickies problem.

However, most, if not all, of these tests are time-consuming, inaccurate, provide false-positive readings, are difficult to use in the mill, are not based on real time testing, and the like.

Images