How to use a press briquette machine to convert sawdust into charcoal?

Jan 19, 2026

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Converting wood chips into charcoal using a wood briquette press machine requires strict adherence to three core steps: pretreatment, molding, and carbonization. The control of parameters at each stage directly determines the quality of the charcoal. While the logic of the pretreatment and molding steps is similar to that of wood pellet mills processing pellet fuel, the standards differ.

The first step is wood chip pretreatment, which must simultaneously meet the requirements of both the briquette machine's molding and subsequent carbonization: The wood chips are first crushed to a particle size of 2-8mm, slightly more lenient than the 2-5mm requirement of a wood chip pellet mill, but large particles must be avoided to prevent uneven molding. The moisture content is controlled at 8%-12%, lower than the 12%-15% suitable range for wood pellet mills. Excessive moisture content can lead to cracking after molding and problems such as incomplete burning and charring during carbonization. Moisture can be adjusted through natural air drying or a small dryer. Simultaneously, impurities such as stones and metals should be removed by screening to prevent damage to the briquette machine's rollers and molds.

The second step is briquetting, which is crucial in bridging pretreatment and carbonization. Using a screw extrusion press or hydraulic sawdust briquette press, preheat the forming cavity to 160-200℃ before starting. After the temperature stabilizes, feed the pre-treated sawdust at a uniform speed into the feed inlet. Under high pressure (10-30MPa) from the rollers and die, the lignin in the sawdust softens and melts, forming a natural binder, extruding it into dense lumps of fuel with a diameter of 20-50mm and a length of 5-20cm. During forming, ensure the density of the finished lumps reaches 1.1-1.3g/cm³. Insufficient density will lead to easy breakage during carbonization, reducing the yield. This step is similar to the forming principle of a wood pellet mill, both relying on lignin self-binding; however, the pressure and temperature control of the briquetting machine is more stringent, and the finished product density is higher than that of pellet fuel.

The third step is carbonization, the core of converting sawdust lumps into charcoal. The shaped sawdust blocks are placed in a carbonization furnace and carbonized in three stages: Drying stage (100-200℃) removes residual moisture to prevent cracking during carbonization; pyrolysis stage (200-400℃) decomposes volatiles (such as methane and tar) in the sawdust, requiring controlled heating rate to prevent excessive volatile release and resulting in overly porous charcoal; carbonization stage (400-600℃) maintains a constant temperature for 2-4 hours to ensure complete carbonization, forming charcoal with a high fixed carbon content. After carbonization, the heat source is turned off, and the charcoal is allowed to cool naturally to room temperature to prevent high-temperature contact with air and subsequent combustion loss.

Subsequently, the charcoal can be crushed, screened, graded, packaged, and sold. High-end charcoal can be further polished and shaped to increase its added value. Compared to wood pellet mills, charcoal briquette presses involve more complex processes, but produce charcoal with a higher calorific value (up to 6000-7000 kcal/kg), wider applications, and more significant profit margins.