Detailed process of making charcoal from sawdust

The core of making charcoal from sawdust is to control temperature, oxygen and time, and to adjust the process to suit different raw material characteristics. Families can use the simple iron barrel method, while industrial production requires professional equipment to achieve high efficiency and environmental protection. Reasonable use of waste sawdust can not only reduce pollution but also create economic value!

1. Raw material selection and pretreatment

Recommended tree species:

• Hardwood (such as oak and jujube): high density, suitable for high combustion value charcoal.
• Softwood (such as pine and fir): pretreatment to remove fat to prevent excessive tar.

Prohibited raw materials: plywood, density board chips (containing formaldehyde).

Drying

Natural drying or drying to a moisture content of <15% (too high humidity will reduce carbonization efficiency).

Hardwood: Moisture content recommended 8%-12%; softwood: 6%-10% (needs to be drier due to fat content).

2. Molding (optional but recommended)

Compress loose sawdust into blocks/granules to improve carbonization efficiency and finished product strength:

Mixed binder (optional):

Add 5%-10% starch, wood tar or clay (to enhance adhesion).

Pressing molding:

• Home method: Manual compaction with a mold (such as PVC pipe + jack).
• Industrial method: Use a screw extruder or ring die pelletizer to press into rods or granules.

Secondary drying: After molding, dry/dry until completely dry.

3. Carbonization process

1. Simple carbonization method (home/small scale)

Tools: sealed iron barrel (with exhaust holes on the top), fire pile, heat-insulating gloves.

Filling: Stack the molded sawdust blocks tightly into the iron barrel, leaving 10% space.

Heating: Place the iron barrel in the fire pile to keep the bottom evenly heated.

Temperature control:

• Initial stage (100-300℃): Expel moisture (white smoke).
• Mid-term (300-500℃): decomposition of tar (yellow smoke).
• Late (500-700℃): complete carbonization (green smoke).

Extinguish and cool: seal the iron barrel after the green smoke disappears, isolate the air and cool naturally for more than 24 hours.

Take charcoal: screen the incompletely carbonized debris after opening the barrel.

2. Carbonization furnace method (industrial production)

Equipment: continuous carbonization furnace (recyclable wood tar and wood vinegar).

Feeding: send sawdust into the carbonization furnace through a conveyor belt.

Segmented temperature control:

• Drying zone (200-300℃): evaporate residual water.
• Pyrolysis zone (400-600℃): organic matter decomposes into charcoal and gas.
• Cooling zone: inert gas circulation cooling.

By-product collection:

• Wood tar: condensation recovery, used as adhesive or preservative.
• Wood vinegar: used as deodorant or pesticide after purification.
• Discharge: Automatically output finished charcoal, crush and screen, and then package.

4. Process adjustment of different sawdust

5. Application of finished charcoal

• Fuel charcoal: barbecue, heating, industrial boilers.
• Industrial raw materials: activated carbon, steel smelting reducing agent.
• Agricultural charcoal: biochar to improve soil (need to be crushed before use).