Paoliello F.,Celulose Nipo Brasileira CENIBRA |
Pulliainen M.,Savcor Forest Oy |
Niemelainen P.,Savcor Forest Inc.
NACE - International Corrosion Conference Series | Year: 2012
Digester corrosion has become a major topic for the pulp and paper industry in that it brought about the need for high expenditures with repairs, replacement of components and upgrade of materials, as well as losses in connection with unplanned outages. Risks to life and property are also significant, as catastrophic failure of pressurized equipment may result. From the eighties to present day, corrosion problems in many pulp and paper mills around the world have been intensifying, for reasons ranging from materials and design aspects of the digesters themselves, to process modifications introduced ever since. The present work has the main objective to study the corrosive behavior of continuous digesters with modified processes. Actual corrosion cases in two digesters are presented: (i) carbon steel and (ii) stainless steel clad (316L) digester. Electrochemical testing, metallurgical analyses, corrosion testing and field inspections were used to support the discussions and conclusions. In one field case, a carbon steel digester experienced rapid thinning on its top sections with wall loss of 5 mm over 30 months, after a process change. In the second case, also following a process change, a type 316L stainless-clad continuous digester, the only one in such material known in the Kraft pulping, presented an altered electrochemical profile indicating prospective stress corrosion cracking risk. This prompted the execution of studies and protective measures that are unique for stainless cooking vessels. The risks to carbon or austenitic stainless steel digesters running on modern cooking processes are demonstrated to be significant. The effectiveness of the protective technologies, as well as their compatibility, was proved. The need to consider these technologies upon cooking retrofit projects was established. ©2012 by NACE International.
Paoliello F.,Celulose Nipo Brasileira CENIBRA |
De Freitas Cunha Lins V.,Federal University of Minas Gerais |
Cardoso M.,Federal University of Minas Gerais
Tappi Journal | Year: 2011
Digester corrosion is costly because of repairs, replacement of components and upgrade of materials, and losses in connection with unplanned outages. Risks to life and property also are significant, especially if catastrophic failure of pressurized equipment occurs. From the 1980s to present, corrosion problems in many pulp and paper mills worldwide have been intensifying, some resulting from materials and design aspects of the digesters themselves or later process modifications. The main focus of this study is the corrosive behavior of continuous digesters with modified processes. We discuss actual corrosion cases in two continuous digesters at a pulp mill in Brazil and the protection measures adopted. Results of electrochemical testing, metallurgical analyses, corrosivity testing, and field inspections are discussed. In one case, a carbon steel digester experienced rapid thinning on its top sections, with wall loss of 5 mm over 30 months following a process change. In the second case, also following a process change, a unique, type 316 stainless-clad continuous digester was found to have an altered electrochemical profile, indicating prospective corrosion hazards. This prompted studies and protective measures that are unique for stainless cooking vessels. The risks to carbon or austenitic stainless steel digesters running on modern cooking processes are shown to be significant. The effectiveness of the protective technologies, and their compatibility, was proved, and the need to consider these technologies upon cooking retrofit projects was established.
Evaluation of the use of organic compost produced from pulp mill residues in regards to chlorinated organic compounds and metals [Avaliação da utilização de composto orgânico produzido a partir dos resíduos de fábrica de celulose quanto aos níveis de organoclorados e metais]
Guerra M.A.S.L.,Federal University of Vicosa |
Silva C.M.,Federal University of Vicosa |
Rezende A.A.P.,Federal University of Vicosa |
Rossoni H.A.,University Fedral Of Vicosa Ufv |
And 2 more authors.
Revista Arvore | Year: 2012
Bleached kraft pulp mill sludge may present traces of heavy metals and organochorine compounds even when ECF (elemental chorine free) bleaching sequences are used due to the presence of chlorine dioxide. The objective of this work was to evaluate the absorption potential of heavy metals and organochlorine compounds (PCDD and PCDF) by Brassica juncea when bio-sludge of an activated sludge plant and organic compost prepared from bio-sludge mixed with Eucalyptus bark of a bleached kraft pulp mill. The plants were cultivated in 0.63 dm3 pots in greenhouses during 73 days. The following parameters were monitored in the substrate and in the plants: Fe, Mn, Pb, Ni, Cu, Zn, Cr, Cl-, total organic carbon and AOX (adsorbable organic halogen compounds). Content of heavy metals in the soil after compost application was within the Brazilian legal standards for compost application. Traces of PCDD e PCDF were found in the substrate at concentrations lower than 0.5 ng I-TEQ/kg (ppt). These values were lower than the highest quality criteria of 17 ng I-TEQ/kg from Canada and Germany.
Miguel P.S.B.,Federal University of Vicosa |
de Oliveira M.N.V.,Federal University of Juiz de fora |
Delvaux J.C.,Federal University of Triangulo Mineiro |
de Jesus G.L.,Celulose Nipo Brasileira CENIBRA |
And 4 more authors.
Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology | Year: 2016
The relationships between plants and endophytic bacteria significantly contribute to plant health and yield. However, the microbial diversity in leaves of Eucalyptus spp. is still poorly characterized. Here, we investigated the endophytic diversity in leaves of hybrid Eucalyptus grandis x E. urophylla (Eucalyptus “urograndis”) by using culture-independent and culture-dependent approaches, to better understand their ecology in leaves at different stages of Eucalyptus development, including bacteria with N2 fixation potential. Firmicutes, Proteobacteria (classes alpha-, beta- and gamma-) and Actinobacteria were identified in the Eucalyptus “urograndis” endophytic bacterial community. Within this community, the species Novosphingobium barchaimii, Rhizobium grahamii, Stenotrophomonas panacihumi, Paenibacillus terrigena, P. darwinianus and Terrabacter lapilli represent the first report these bacteria as endophytes. The diversity of the total endophytic bacteria was higher in the leaves from the ‘field’ (the Shannon–Wiener index, 2.99), followed by the indices obtained in the ‘clonal garden’ (2.78), the ‘recently out from under shade (2.68), ‘under shade’ (2.63) and ‘plants for dispatch’ (2.51). In contrast, for diazotrophic bacteria, the highest means of these indices were obtained from the leaves of plants in the ‘under shade’ (2.56), ‘recently out from under shade (2.52)’ and ‘field’ stages (2.54). The distribution of the endophytic bacterial species in Eucalyptus was distinct and specific to the development stages under study, and many of the species had the potential for nitrogen fixation, raising the question of whether these bacteria could contribute to overall nitrogen metabolism of Eucalyptus. © 2016 Springer International Publishing Switzerland
Psychosocial and organizational factors associated with risk of LER/DORT in operators of forest harvesting machines [Fatores organizacionais e psicossociais associados ao risco de LER/DORT em operadores de máquinas de colheita florestal]
Silva E.P.,Federal University of Vicosa |
Minette L.J.,Federal University of Vicosa |
Souza A.P.,Federal University of Vicosa |
Marcal M.A.,Federal University of Health Sciences, Porto Alegre |
Sanches A.L.P.,Celulose Nipo Brasileira CENIBRA
Revista Arvore | Year: 2013
Work organization and psychosocial factors have been suggested as responsible for cases of LER/DORT, and these factors related with the activity of forest machine operators. Therefore, the present study aimed to assess and describe the risk factors linked to these aspects. The research included a variation on the system of short log harvesting (cut-to-length). The system used was harvester and forwarder. The study population consisted of harvesting machine operators from a forest-based company. For the description of work organization aspects, in situ observations were performed, aiming to understand and describe the day-to-day work, i.e., the behavior of the workers on the job. A questionnaire was designed and developed specifically for the study. At the end of the study we concluded that the work could have different impacts on workers exposed to the same working conditions, which can be explained by psychosocial and organizational factors.