How is biochar produced?

The concept of “biochar” first appeared in scientific literature in the work of the National Assembly of the American Chemical Society. The word was a composite of “bio” (biomass) and “semi-coke” (char). The biochar described in that work was obtained from sorghum grain seeds using the “triple reverse burning ChemChar” process.

Bio-char has a high carbon content and has a fine-grained texture. Currently, it is produced using pyrolysis processes. Pyrolysis is a thermal treatment of biomass in the absence of oxygen, so preventing its combustion. As a result of the process, a mixture of the following substances is obtained: biochar itself, bio-oil, and synthesis gas.

The specific yield ratio of these pyrolysis products depends directly on the conditions of the process itself: temperature conditions, residence time and heating rate. These parameters can be optimized to obtain a specific product. Temperature from 400 to 500 °C (673-773 K) is used for the production of semi-coke. Temperatures above 700 °C (973 K) favour the release of liquid and gaseous components.

The pyrolysis process at higher temperatures is very fast. As a result, as a rule, we get 60% of bio-oil, 20% of bio-coal and 20% of synthesis gas. Slow pyrolysis, that is, the use of lower temperatures, leads to a higher percentage of semi-coke (~ 35%). This can be used to improve soil fertility (terra Preta).

Equipment for producing high-quality biochar – continuous charcoal kiln BIO-KILN