Wood recycling can be regulated into four major categories: sourcing, processing, product manufacturing, and direct end-use application. Below are the detailed divisions of the four categories of the process.
SOURCING – sourcing refers to the collection stage of the process.
1. Identification
In this step, wood waste materials are identified and collected.
2. Source Separation
In this step, wood waste materials are segregated at demolition and land-clearing sites.
3. Sampling and Testing
In this step, wood waste contaminants are visually identified, and hazardous contaminants such as asbestos and lead paint are handled.
4. Supplier Relationships
After the contaminants are identified, sources of these contaminated wood wastes will be notified and penalized.
PROCESSING – processing refers to the treatment stage of the process.
1. Site Storage
Wood wastes are stored on outdoor concrete surfaces to improve recovery and prevent contamination. Use of concrete surfaces to improve recovery and prevent contamination.
2. Material Handling
Rolling stock is used to sort, pre-process, and conveys raw wood waste. Different conveyors such vibratory, belt, or chain are utilized to transport bulky, and irregular-shaped wood waste. Extraneous materials mixed within the wood waste are removed through mechanical separation techniques using the conveyors.
3. Size Reduction
Bulk of wood wastes are reduced, hogged, and grinded into smaller pieces through the usage of the following equipments (Information of these following machines are obtained from Best Practices of Clean Washington Center:
• Rolling Stock Compaction - This method of bulk reduction is accomplished by driving the rolling stock over large wood waste before loading it into the processing system.
• Hydraulic Compaction - This equipment consists of a crushing surface driven by hydraulic cylinders and the compactor reduces bulk by compressing large wood waste against a reinforced conveyor bottom.
• Mechanical Shearing – This equipment consists of a hydraulically driven shear that periodically slices through the wood waste traveling on a conveyor.
• Pre-Crusher – This equipment features a rotating crushing device and a feeding mechanism to provide coarse size reduction of material prior to further screening and size reduction.
• Punch and Die Designs – These machines have efficient cutting ability, but greater sensitivity to hard contaminants.
• Pan and Disc Design – This hybrid design consists of a disc that is fitted with grinding teeth instead of knives.
After the wood waste is reduced to the appropriate size, it will go through the following screening and contamination removal processes:
• Vibrating and Gyratory Screening – VGS is used to separate fines from acceptable processed wood fiber. Through a vibrating or gyrating movement of the equipment, the relatively small particles fall through the screen while the relatively large particles remain on top of the screen.
• Magnetic and Chip Washing for removal of the dirt and grit.
• Air Density Separator Screening – When the wood waste material enters the air density separator, a high velocity vacuum pulls the light-weight wood materials away from the heavier rock and metals. The heavy materials then fall into a reject conveyor. The remaining material is transferred to a discharge conveyor.
After chips of wood are screened and decontaminated, samples of it will be taken to go through a quality control testing. In this testing process, we are looking for it the chips obtain product uniformity and consistency.
Section I: Introduction
Section II: Present (YOU ARE CURRENTLY IN THIS SECTION)
Section III: Future
Complete Table of Contents
Reference