Bárbara Luísa Corradi Pereira

Quality of Wood and Charcoal from Eucalyptus Clones for Ironmaster Use

Considering the wide variety of species and clones of Eucalyptus cultivated in Brazil, it is necessary to search for new information on wood properties, so that the selection of genetically superior material may be successful. The present study aimed to determine the properties of wood and charcoal from different clones of Eucalyptus spp. Six clones at the age of 7.5 years were evaluated and the samples were from a clonal, located in the city of Lassance, Minas Gerais, Brazil. Basic density, chemical composition, and higher heating value were determined. Carbonizations in a laboratory kiln were done and the levels of volatile matter, ash, and fixed carbon, higher heating value, and bulk density of the charcoal produced were determined. Evaluated genetic materials showed differences in their properties. According to research results, several properties of wood should be considered together for the selection of clones for charcoal production. However, basic density and chemical composition of wood, especially high contents of lignin and low contents of extractives, are the properties that had more influence on charcoal yield and its quality. Concerning charcoal production for steelmaking, clone 6 stood out and, conversely, clone 4 showed inferior properties to those of others.

ESTUDO DA DEGRADAÇÃO TÉRMICA DA MADEIRA DE Eucalyptus ATRAVÉS DE TERMOGRAVIMETRIA E CALORIMETRIA

RESUMO – O objetivo deste trabalho foi avaliar a degradacao termica da madeira de diferentes clones de Eucalyptus, por meio de analises termogravimetrica (TG/DTG) e de calorimetria exploratoria diferencial (DSC), estabelecendo-se suas relacoes com a producao de carvao vegetal. Foram utilizados seis clones de Eucalyptus spp. aos 7,5 anos de idade, provenientes de um teste clonal pertencente a uma empresa florestal. Foram realizadas as analises TG/DTG e DSC, sob atmosfera de gas nitrogenio. As curvas TG/DTG mostraram tres faixas de degradacao termica, atribuidas a secagem da madeira e a degradacao de hemiceluloses e celulose. Nao foi detectada faixa especifica de degradacao de lignina. As curvas DSC evidenciaram um pico endotermico entre as temperaturas de 50 e 100 oC, o que pode ser atribuido a perda de agua da madeira. A liberacao de calor iniciou-se em temperaturas acima de 275 °C, para todos os clones avaliados, sendo observados dois picos exotermicos. As analises termicas da madeira (TG/DTG e DSC) nao apresentaram variacoes expressivas entre os clones. Conclui-se que, atraves das tecnicas estudadas, e possivel identificar as principais fases das reacoes de liberacao ou absorcao de energia e perda de massa, que estao diretamente ligadas a qualidade do carvao vegetal.

Otimização da produção do carvão vegetal por meio do controle de temperaturas de carbonização

Although in recent years several studies have been done with the aim of improving the wood quality indices (basic density, chemical composition), much of the Brazilian charcoal production still occurs in kilns that have low gravimetric yield and uncontrolled emissions of polluting gases. In an attempt to change this scenario, this work was developed with the objective of evaluating the operation of a kiln-furnace system. The work also aimed to adjust carbonization control ranges according to temperature and time, taking into account the thermal degradation of wood in order to maximize the yield of charcoal. Three kilns were built, attached to a furnace for burning the gases generated during the carbonization. Control of carbonization was conducted using internal temperature, measured by an infrared temperature sensor. According to the results, controlling time and temperature during the carbonization provided average gravimetric yields of 33% charcoal, 8% semi-carbonized wood and 3% fines (particle size less than 12.7 mm). The furnace was efficient in reducing fume to the environment, working for a third time carbonization. It is concluded that the kiln-furnace system presents satisfactory production of charcoal, with low fume during carbonization.

Efeito do Tipo de Chapa de Partículas nas Propriedades Físicas e Mecânicas

This study aimed to evaluate physical and mechanical properties of conventional agglomerate, medium density particleboard and agglomerate with laminate inclusion. Particleboards were made ​​of Acacia mangium particles and laminas of Schizolobium amazonicum were used to produce agglomerate with laminate inclusion. Conventional agglomerate and agglomerate with laminate inclusion showed hygroscopic equilibrium moisture statistically superior to MDP. Agglomerate with laminate inclusion showed the highest rate of thickness swelling after 2 hours of immersion in water, the highest modulus of rupture in bending strength and the best screw withdraw resistance. MDP presented the highest mean value of board internal bond strength. There were no significant differences in other evaluated properties. It was concluded that laminate inclusion improved modulus of rupture and screw withdraw resistance while the use of fine particles on the faces improved physical properties of the particleboards.