Efeitos da segregação de resíduos lenhosos de planos de manejo florestal da Amazônia nas características do carvão vegetal siderúrgico.

Abstract

Although wood wastes from sustainable forest management are a promising alternative for supplying charcoal production in the Brazilian Amazonia, this biomass and derived charcoal present a heterogeneous quality. The segregation of wood proved to be an important alternative to increase the productivity and yield of charcoal in the production unit, as it promotes the homogenization of the raw material inside the kiln. However, this study aims to study the effects of wood waste segregation on the quality, combustibility, and occurrence of spontaneous combustion in charcoal produced in brick kilns in the State of Pará. Thus, 4 groups of woods with similar properties segregated based on the principal components analysis were adopted. In addition, a fifth group was considered, the traditional form of carbonization in the region. This group was composed of twenty-three species. The study of charcoal quality was based on physical (bulk density and moisture), mechanical (friability), chemical (fixed carbon content, volatile materials, and ash), and energy (higher heating value and energy density) properties. The parameters analyzed in combustion were ignition temperature, burnout temperature, maximum temperature, maximum combustion rate, average combustion rate, and ignition time. The combustion characteristic index, ignition index, and flammability index were the studied indices. The study revealed that the segregation of residual wood culminated in an increase in the charcoal quality produced in brick kilns, especially regarding bulk density, friability, ash content, fixed carbon content, higher heating value, and energy density. Group 1, formed by charcoal from wastes of the D. excelsa species, presented the best values for bulk density (0.737 g cm-3), ash content (1.20%), higher heating value (28.9 MJ kg-1), and energy density (21.3 MJ m-3). On the other hand, conventional carbonization proved to be very variable, resulting in more friable and less resistant charcoal. Charcoals from group 1 had the highest ignition temperature (380°C), burnout temperature (547°C), temperature at which the greatest loss of mass occurs (515°C) and ignition time (33.39 min). Group 5 produced charcoals with low ignition temperature (362°C) and low maximum combustion rate (9.54 % min−1). Two groups of charcoal did not show spontaneous combustion (1 and 4), which demonstrates that segregation can reduce the occurrence of this phenomenon. On the other hand, charcoals from groups 2, 3 e 5 (traditional carbonization) showed samples with spontaneous combustion. Therefore, the segregation of wood waste promoted positive results in terms of quality, combustibility, and spontaneous combustion of charcoal produced in brick kilns.