After the wood chip passes the quality control stage, it will go through a variety of chemical process to manufacturing different products. Following is a list of such products:
• Unbleached Kraft Pulp – When a chip of wood is placed in a pressurized vessel in the presence of hot caustic soda and sodium sulfide, we obtain Kraft Pulp. The pressure and chemicals will eventually dissolve the lignin inside the chip, a phenolic material that glues the fibers to each other in the wood. What come out of this process are brown pulps that become the main structural elements in many paper grades such as corrugated boxes and bags.
• Bleached Chemical Pulp – Chemical Pulp is obtained when wood chips are “cooked” in an alkaline solution for several hours. During this cooking period, lignin is dissolved. Then, the fibers are goes through a complicated bleaching process to make a Bleached Chemical Pulp. For more information on the bleaching process, please visit Aberta Pacific Forest Industries Inc.
• Mechanical and Thermo-mechanical Pulp – This type of pulp is produced through a pulping process that uses grinding applications to turn wood to pulp. Pulps result from this process are usually used for the production of newsprint and magazine paper.
• Panel Board, Medium Density Fiberboard, and Hard board – All of these boards, which are commonly used in areas such as furniture production, use recycled wood as raw material.
• Thermoplastic Composites – Thermoplastics composites uses recycled wood fibers as reinforcements. The process include the combination of wood fiber with molten thermoplastic to form a homogeneous composite material, pushing the material through a die into strands, and then cut the strands into pellets. What come out of this process is the so-called Melt-Blended Wood Fiber-Thermoplastic Composites. For more information on Melted-Blended Wood Fiber-Thermoplastic Composites, please visit Techline.
• Densified Fuel – when the recycled wood chips are pressed together with sawdust, densified fuel in the form of pressed logs or wood pellets are produced. The resins and binders occurring naturally in the sawdust hold the densified fuel together, which is commonly used in pellet stoves.
DIRECT END-USE APPLICATIONS – direct end-use means that the recycled wood will be used directly without going through additional chemical or mechanical processes.
Recycled wood chips can be directly used in direct land applications such as mulch, landscaping, and soil amendments. These recycled wood chips can also be used as bio-fuel or animal beddings.
[Courtesy of: Kentucky Pollution Prevention Center.]
[Courtesy of: Joint Service Pollution Prevention Opportunity Handbook.]
Section I: Introduction
Section II: Present (YOU ARE CURRENTLY IN THIS SECTION)
Section III: Future
Complete Table of Contents
Reference