GENERATION OF WOOD RESIDUES
Table 1. Approximate proportion of residues generated in sawmilling
|
Proportion of solid log volume 4/ |
|
(%) |
||
Log input |
112 |
|
Bark |
12 1/ |
|
|
Net log input |
100% |
Wood residues: |
|
|
Slabs, edging and trimmings |
34 |
|
Sawdust |
12 |
|
|
Sub-total wood residues |
46% 2/ |
Shrinkage (air drying) |
2 |
|
|
Air dried lumber |
52% 3/ |
Shrinkage (kiln drying) |
4 |
|
Wood residues: |
|
|
Sawdust and trim ends |
2 |
|
Planer shavings |
6 |
|
|
Sub-total wood residues 8% 4/ |
|
|
Finished kiln dried lumber |
40% |
1/ Dependent on species
2/ Residues for particleboard furnish and/or fuel
3/ Yields in developing countries tend to be lower
4/ Excluding storage losses
Sources: (41) (47) (100)
Table 2. Approximate proportion of residues generated in the manufacture of plywood
|
Proportion of solid log volume |
(%) |
|
Log input |
105 |
Bark |
5 1/ |
Net log input |
100% |
Wood residues: |
|
Log trim 4/ |
7 |
Peeler core 2/ |
10 3/ |
Green veneer waste 4/ |
12 |
Dry veneer waste 4/ |
8 |
Trimmings 4/ |
4 |
Sanding dust 4/ |
5 |
Rejected plywood 4/ |
1 |
Total wood residues |
47% |
Shrinkage |
5 |
Pressing loss |
1 |
Finished product |
47% |
1/ Approximately 60% recoverable as fuel
2/ To sawmill or chipped for particleboard furnish or for pulp manufacture and/or fuel
3/ Higher on small diameter peeler logs
4/ Potential use as particleboard furnish and/or fuel
Sources: (21) (47) (57)
Table 3. Approximate proportion of residues generated in the manufacture of particleboard
|
Proportion of furnish volume |
(%) |
|
Wood waste and log input |
83 |
Recycled trim waste |
17 |
Total green furnish input |
100% |
Shrinkage |
6 |
Dry furnish |
94 |
Screening fines 1/ |
5 |
Furnish prior to blending |
89 |
7% solid resin added |
6 |
Blended furnish |
95 |
Pressing losses |
1 |
Pressed board |
94 |
Trim waste (recycled) |
17 |
Trimmed board |
77 |
Sanding dust 1/ |
5 |
Finished product |
72% 2/ |
1/ Potential use as fuel
2/ Represents 90% (38) of furnish input excluding recycled trim
Sources: (38) (47)