OVERVIEW

“Wood and Paper Characteristics” focuses on how the processes in a pulp mill and a paper mill influence the characteristics of wood, pulp, and paper.  This unit first examines the basic components of wood and differentiates between the two major groups of trees.  It then explains how mill processes affect the characteristics of pulp produced in a Kraft pulp mill, a semichemical pulp mill, and a mechanical pulp mill.   How these processes affect the making of paper in stock prep, wet-end operations, dry-end operations, and finishing operations is also covered. This unit concludes with a description of common pulp tests and paper tests.

OBJECTIVES

What Is Wood?

·         List and describe the three major components of wood.

·         Explain the major difference between hardwoods and softwoods.

Kraft Pulp Characteristics

·         Describe how the following processes affect the characteristics of pulp in a Kraft pulp mill: cooking, refining, screening, washing, and bleaching.

·         List process variables that affect the production of pulp in a digester and in a bleach plant.

Semichemical and Mechanical Pulp Characteristics

·         Describe how the following processes affect the characteristics of pulp in a typical semichemical pulp mill: cooking, refining, screening, and washing.

·         List process variables associated with the cooking and refining processes in a semichemical pulp mill.

·         Describe how the following mechanical pulping methods affect the characteristics of pulp: stone groundwood pulping, pressurized groundwood pulping, thermomechanical pulping (TMP), and refiner mechanical pulping (RMP).

Paper Characteristics: Stock Prep and Wet-End Operations

·         Describe how the following processes in stock prep affect the characteristics of paper: refining, chemical addition, cleaning, and screening.

·         Explain how the following terms relate to the forming and press sections of a typical paper machine: basis, weight, moisture, sheet formation, and rush/drag ration.

·         List process variables that are associated with processes in stock prep and the wet end operations of a paper machine.

Paper Characteristics: Dry-End and Finishing Operations

·         Describe how the following processes in the dry-end operations affect the characteristics of paper: dryers, coaters, and calenders.

·         List process variables that are associated with processes in the dry-end operations.

·         Describe how a winder affects the characteristics of paper.

·         List process variables that are associated with the finishing operations.

Pulp and Paper Testing

·         List two common pulp tests and describe the basic procedures for each test.

·         Explain the characteristic that each of the following paper test instruments measures: micrometer, tensile tester, tear tester, burst tester, ring crush tester, brightness tester, and oil absorption tester.

SUBJECTS

What Is Wood?

·         Cellulose, hemicellulose, and lignin

·         Hardwoods and softwoods

Kraft Pulp Characteristics

·         Digesters

·         Refiners, screens, and washers

·         Bleaching

Semichemical and Mechanical Pulp Characteristics

·         Semichemical pulp characteristics

·         Digesters and refiners

·         Screens and washers

·         Mechanical pulp characteristics

Paper Characteristics: Stock Prep and Wet-End Operations

·         Stock prep

·         Refining and chemical addition

·         Cleaning and screening

·         Wet-end operations

·         Forming section

·         Press section

Paper Characteristics: Dry-End and Finishing Operations

·         Dry-end operations

·         Dryers

·         Coaters and calenders

·         Finishing operations

Pulp and Paper Testing

·         Pulp testing

·         K number testing

·         Freeness testing

·         Paper testing

·         Structural and mechanical tests

·         Appearance and resistance tests