Charcoal: A discussion on carbonization kilns

Charcoal is an important source of renewable biomass and has great industrial importance as a bio-thermoreducer in the production of pig iron and steel. To increase the quality and yield of charcoal, it is necessary to invest in the continuous improvement of kilns and in the control of the carbonization process. However, there is a lack of studies that characterize the technologies currently used in the production of charcoal to achieve the ideal balance, considering advances and limitations. This balance is the starting point for the improvement of current carbonization kilns and development of new proposals for kilns. This study aims to fill this research gap. In this context, the main kilns used worldwide for the production of charcoal were characterized. A total of 21 types of carbonization kilns were found, and the majority presents technological improvements. However, even with carbonization kilns with technological advances available, most of the world charcoal production still uses from traditional kilns with low technology, which results in worse charcoal yield and quality. Therefore, several aspects are discussed that involve the production of charcoal and help to explain the difficulty in the consolidation of kilns with better technology.