RESUMO Na presente pesquisa, objetivou-se avaliar os rendimentos gravimétricos da carbonização e as características qualitativas do carvão vegetal de clones de híbridos obtidos dos cruzamentos de espécies de Corymbia, e identificar os mais adequados para uso siderúrgico. Seis clones, aos 6 anos e 5 meses de idade, foram utilizados na pesquisa e amostradas cinco árvores de cada material genético. As carbonizações laboratoriais foram realizadas à temperatura final de 450°C, taxa de aquecimento de 100°C.h-1 e tempo de residência de 30 minutos. Os rendimentos gravimétricos da carbonização foram determinados em relação à madeira seca. O carvão produzido foi qualificado, considerando-se a análise química imediata, poder calorífico superior, densidade energética, consumo específico de madeira e a eficiência energética. Na avaliação do experimento, foi utilizado o delineamento inteiramente casualizado com cinco repetições (árvores). A análise multivariada de componentes principais foi empregada para obter a variância dos vetores normalizados, considerando as características avaliadas nos carvões. Os resultados obtidos indicaram o elevado potencial para a utilização dos materiais genéticos de Corymbia, para fins energéticos, sobretudo para a produção de carvão vegetal siderúrgico. O clone 1 foi o destaque para a produção de carvão vegetal e lenha, pois apresenta maiores densidades aparentes e energéticas, maior teor e rendimento em carbono fixo, além de possuir menor consumo específico de madeira por tonelada de carvão vegetal produzido. Os clones 2 e 4 foram os que mais se distinguiram dos demais, respectivamente, em decorrência de seu maior teor de cinzas e por apresentar maior consumo específico de madeira na produção de carvão. O uso de clones híbridos de Corymbia, para a produção de carvão vegetal, pode ser uma boa alternativa, em razão de seu rápido crescimento e qualidades semelhantes de madeira e carvão vegetal a outras espécies que já são usadas para a finalidade energética.

ABSTRACT This research aimed to evaluate the carbonization gravimetric yields and qualitative characteristics of the charcoal of hybrid clones obtained from the crossings of Corymbia species and to identify the most suitable for the steel industry. We used six clones, at six years and five months of age, sampling five trees of each genetic material. The laboratory carbonizations consisted of a final temperature of 450°C, a heating rate of 100°C.h-1, and a residence time of 30 minutes. We determined the carbonization gravimetric yields when compared to dry wood. The charcoal produced was qualified considering the proximate chemical analysis, superior calorific value, energy density, specific wood consumption, and energy efficiency. We organized the experiment in a completely randomized design with five replicates (trees). The multivariate principal component analysis determined the variance of the normalized vectors, considering the charcoal characteristics evaluated. The results indicated a high potential for the use of Corymbia genetic materials for energy purposes, especially for producing charcoal for the steel industry. Clone 1 was prominent for producing charcoal and firewood, given its higher apparent and energetic densities, fixed carbon content and yield, and lower specific wood consumption per ton of charcoal produced. Clones 2 and 4 most distinguished themselves from the others due to higher ash content and higher specific wood consumption, respectively. The use of Corymbia hybrid clones for producing charcoal may be a good alternative due to its rapid growth and wood and charcoal characteristics similar to those of other species that are already used for energy purposes.

Abstract: The use of fast-growing trees is a good economic strategy for charcoal production. Wood with adequate chemical and physical properties generally is positively correlated with charcoal quality. The objective of this research was to evaluate wood quality from fast-growing hybrids for charcoal production. Three Corymbia citriodora x Corymbia torelliana and four Corymba torelliana x Corymba citriodora hybrid clones were evaluated. Parameters used to evaluate wood quality were wood basic density, elemental and structural chemical composition, energy efficiency and thermogravimetric analysis and the parameters evaluated for charcoal quality were apparent relative density, gravimetric yield, high heating value, proximate analysis and energy efficiency. All clones had wood basic density superior than 0,5 g cm-3 and ash inferior than 1%, which are desirable for a good quality of charcoal. Lignin content did not differ among clones with an average less than the 28% recommended for energetic use. Although clones differed in wood parameters, as dry matter, high heating value, energy density, total extractives, holocellulose content, it did not reflect in charcoal quality differences. Wood from all clones had equal and satisfying high heating value of charcoal and energy efficiency quality for charcoal production and differed in apparent relative density and ash content.

ABSTRACT The objective of this study was to evaluate the influence of particle size of charcoal samples on the predictive model statistics of charcoal chemical composition based on the NIR spectroscopy. Spectra of Acacia and of Eucalyptus charcoal were collected in the 100, 60 and 40 mesh granulometry, besides the powder remaining at the bottom of the sieves sets. They were subjected to principal component analysis and partial least square regression in order to estimate of volatile material (VMC), ash (AC) and fixed carbon content (FCC) values. The estimation of the FCC, VMC and AC of Eucalyptus based on NIR was more accurate using spectra of lower-particle-size powder. The models for Acacia charcoal were better using spectra measured at 40 mesh to predict FCC, 100 mesh for AC, and smaller size for VMC. NIR spectroscopy was efficient in estimating the immediate chemical composition of charcoal, except for AC.