Navegando por Data de Publicação, começando com "2010-05-05"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 3 de 3

Análise sistêmica das massas de tamponamento para altos-fornos
(Universidade Federal de São Carlos, 2010-05-05) Ribeiro, Aloísio Simões; Pandolfelli, Victor Carlos; https://lattes.cnpq.br/7369376873984839; https://lattes.cnpq.br/3511102682668805
The increase in the world steel production mainly observed in the last decade demanded a significant growth in the hot metal production through the blast furnace process. A key point in blast furnaces operation is related to the taphole mix used to plug the hole that is where the tapping is carried out. The taphole mix is a key aspect for the production flow of integrated mills because, in the blast furnaces, it is responsible to maintain a stable tapping, ensuring the supply of hot metal to the steelmaking, maintaining all stages of the crude steel plants in synchrony. The taphole mixes for blast furnace are very special products in the broad universe of refractory materials due to its complex chemistry composition, being applied in extreme conditions of temperature and demand. In this context, the literature and the technical aspects related to taphole mixes require a more comprehensive technical contribution, considering the influence of some additives on their properties. The aim of this work is to evaluate the influence of different raw materials and additives on the properties of taphole mixes related to their densification, adhesion and usinability features. The results of the tests were assessed according to the AHP (Analytical Hierarchy Process) method, which allows for the selection of the best formulation considering all the parameters involved.
Potencial alelopático de extratos aquosos de duas espécies de Gleicheniaceae sobre espécies infestantes de culturas e da bioindicadora Lactuca sativa L
(Universidade Federal de São Carlos, 2010-05-05) Voltarelli, Valquíria Marin; Lima, Maria Inês Salgueiro; https://lattes.cnpq.br/2171993314203162; https://lattes.cnpq.br/2475606695695985
This work aims to determine through bioassays the allelopathic potential of aqueous extracts Gleichenella pectinata and Dicranopteris flexuosa adult and mature fronds in two physiological stages (fertile and sterile) over the percentage and average time of germination, besides initial growth of three species of crop weeds (Echinochloa crus-galli, Ipomoea grandifolia, Euphorbia heterophylla). Four aqueous treatments were made (0, 2,5 , 5 and 10%), with five replications. Each plot consisted of 30 seeds for germination tests and 10 seedlings for initial growth of root and hypocotyl / coleoptile. Root growth was the most sensitive parameter to G. pectinata and D. flexuosa allelochemicals, for the three target species. All extracts damaged root growth of target species, excepting the lower concentration of sterile fronds extracts over E. heterophylla. Sterile frond extracts caused a delay on E. crusgalli and E. heterophylla germination under concentrations 5 and 10%. The higher concentration of fertile frond extract decreased germination percentage of the three target species. All D. flexuosa extracts decreased root length of all target species. I. grandifolia was the most sensitive species due to D. flexuosa extracts, having showed decrease in all morphologic parameters. Both other target species also had their shoot part length growth suppressed under 5% and 10% concentrations. A soil experiment was also performed in order to verify the role of different treatments of D. flexuosa fronds on Lactuca sativa germination in presence or absence of microorganisms. Each treatment was tested with 4 lettuce seeds per vase, by 10 days with 6 replications. Treatments were tested in 6 periods of ten days each, related to the 1st, 2nd, 4th, 8th, 16th and 32nd days after treatments application. Light, moisture and temperature conditions were controlled. In general, non-sterilized substrates presented higher allelopathic effects over analyzed parameters. Among treatments, the pre-occupied soil exerted stronger effects, with inhibition of germination in non-sterilized, during the whole period of experiment. That must be an indicative of accumulated allelopathic substances under environmental conditions, and their prolonged effects.
Análise sistêmica dos fornos de cozimento de anodo para a indústria de alumínio
(Universidade Federal de São Carlos, 2010-05-05) Tiba, Paulo Roberto Teruo; Pandolfelli, Victor Carlos; https://lattes.cnpq.br/7369376873984839; https://lattes.cnpq.br/2522985758255838
The recent global economic crisis allied with the trend for sustainable companies and countries have meaningfully changed the aluminum area. Previously, the productivity was the main focus of the metal producer and no concern regarding the impact of this activity in the environment was considered. Nowadays, the search for low metal production cost, the reduction of residues and energy-saving aspects are the driving-force for the companies’ competitiveness increase. In this sense, the materials research can be an additional tool as providing new technologies and improvements to the metal production process. Therefore, a systemic analysis was performed for anode baking furnaces considering the dense refractory materials, the post mortem analysis, the insulating materials and the heat transfer. The results attained for the mechanical and thermomechanical characterization of the dense refractories led to insights for the furnace maintenance cost reduction, such as the choice of high performance compositions and the frequent chemical control of both, fluid coke and green anode. Additionally, this work allowed better commercial inputs for the aluminum producer due to the technical development of new refractory suppliers. Regarding the insulating materials and the heat flow, alternatives for energy-saving were visualized, highlighting the use of an insulating blanket on the upper part of the furnace. As a conclusion of this work, the correlation between refractory, energy, sustainability and productivity was better understood for anode baking furnaces, besides the development of novel actions for the aluminum company in order to improve its competitiveness.