To produce high-quality charcoal, sawdust selection and preparation is critical. Here are some conditions to consider:

1. Dryness: Sawdust must be dry. Wet wood will cause more smoke and incomplete carbonization during the carbonization process. It is generally recommended that the moisture content of sawdust is below 20%.

2. Wood types: Different types of wood have different carbonization properties and charcoal qualities. Generally speaking, hardwoods (such as oak, birch) produce better quality charcoal, while softwoods (such as pine, fir) produce lower quality charcoal.

3. Sawdust particle size: The particle size of sawdust has an impact on the carbonization effect. Generally speaking, the finer the particle size of the wood chips, the better the carbonization effect, because the fine wood chips are more likely to be completely carbonized. However, wood chips that are too fine may also cause poor ventilation or block the carbonization furnace.

4. Wood treatment: Sawdust should be pure untreated wood without any added chemicals or paint. Treated wood may produce harmful gases that affect the quality and safety of charcoal.

5. Impurity content: Impurities (such as soil, stones, metals) in sawdust will affect the carbonization process and the quality of charcoal. Therefore, before producing charcoal, the sawdust needs to be screened and cleaned to minimize the impurity content.

6. Production capacity: According to the specifications and production capacity of the carbonization furnace, a sufficient amount of sawdust needs to be prepared. Ensure that the supply of sawdust can meet the needs of carbonization production.

In summary, selecting the appropriate dryness, wood type, particle size, and preparing clean and pollution-free wood chips are one of the key conditions for producing high-quality charcoal.