Treatment of wood chips using enzymes

Abstract

A method of treating wood chips or saw dust with an enzyme formulation, prior to refining, in order to reduce the total extractives content of the wood chips or sawdust and to modify the wood structure is described herein. The wood chips or sawdust are treated with one or more enzymes such as lipases, esterases, pectinases, cellulases, laccases, hemicellulases and combinations thereof. The enzyme formulation can be applied to the surface of the wood chips or sawdust, e.g. by spraying, or can be impregnated into the wood chips. The enzyme formulation can further comprise one or more surface active agents which can enhance the effectiveness of the enzyme treatment by improving the diffusion or impregnation of the enzymes into the wood chips. The enzyme-based treatment can be applied at any of several different locations prior to the pulping process including chip piles, chip conveyors, chip silos, chips washers, chip washer water stream, impregnation liquor, or during chip storage. The enzyme-based treatment is quick and easy to apply in most commercial mill operations. The enzyme-based treatment is effective at temperatures from about 20° C. to about 100° C., preferably from about 35° C. to about 70° C. The wood chips or saw dust can be treated for a period of time from about 0.10 to about 200 hours, more preferably from about 10 to about 72 hours. The addition of the enzyme formulation into the wood chip or sawdust pile increases the concentration of pitch-degrading enzymes on the chip or dust surfaces which can significantly accelerate the degradation of pitch components inside the chips or sawdust. Decreasing the total extractives content of the wood chips and modifying the structure of the wood chips or sawdust leads to a decrease in the apparent pitch content during pulping and in reduced energy requirements, increased paper strength, improved paper machine runability, and lower costs associated with paper manufacturing.

Description

FIELD ON THE INVENTION [0001] The present invention is generally in the field of managing wood pitch using enzyme treatments of wood chips prior to pulping. BACKGROUND OF THE INVENTION [0002] Wood extractives in wood chips, commonly known as pitch, have a significant impact on pulping and papermaking processes. Minimizing or preventing pitch deposits is critical to minimizing equipment fouling and down time, maximizing production efficiency, and improving paper product quality. Pitch is composed of low molecular weight olephilic materials (primarily triglycerides, resin acids, fatty acids, fatty esters, waxes, resin esters, fatty alcohols, sterols, and terpenes), which are released from wood fibers during chemical and mechanical pulping processes. These resinous substances may precipitate as aluminum, calcium and magnesium salts, causing problems on the paper machines and in the paper products. Generally, the amount of extractives in wood chips depends on the species of tree from wh...

AI Technical Summary

Benefits of technology

[0010] It is further an object of the invention to provide a method for decreasing the total amount of extractives in wood chips or saw dust prior to refining which is effective over relatively short treatment times without any significant decrease in brightness.

[0011] A method of treating wood chips or saw dust with an enzyme formulation, prior to refining, in order to reduce the total extractives content of the wood chips or sawdust and to modify the wood structure is described herein. The wood chips or sawdust are treated with one or more enzymes such as lipases, esterases, pectinases, cellulases, laccases, hemicellulases and combinations thereof. The enzyme formulation can be applied to the surface of the wood chips or sawdust, e.g. by spraying, or can be impregnated into the wood chips. The enzyme formulation can further comprise one or more surface active agents which can enhance the effectiveness of the enzyme treatment by improving the diffusion or impregnation of the enzymes into the wood chips. The enzyme-based treatment can be applied at any of several different locations prior to the p

Problems solved by technology

These resinous substances may precipitate as aluminum, calcium and magnesium salts, causing problems on the paper machines and in the paper products.

This metabolism can lead to an overall decrease in the pitch content of the stored wood.

Seasoning of some hardwoods and softwoods prior to pulping can lead to a decrease in wood extractives and removal of some of the unsaponifiable fractions, which can result in a decrease in digestion and wash times, particular in the summ

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