LIMITE DE UMIDADE TRANSPORTÁVEL DE MINÉRIOS DE FERRO: ASPECTOS REGULATÓRIOS E TÉCNICOS
TRANSPORTABLE MOISTURE LIMIT OF IRON ORES: REGULATORY AND TECHNICAL ASPECTS
Rodrigo Fina Ferreira, Dany Luiz Vieira Policarpo, Victor Pereira Padula, Marco Tulio Santiago Ferreira
Resumo
Materiais sólidos a granel, contendo umidade, podem estar sujeitos a rupturas, deslizamentos e liquefação. Cargas de minério transportadas em navios não estão isentas destes fenômenos, que colocam em risco as embarcações. Nos últimos 30 anos ocorreram pelo menos 24 acidentes marítimos tendo como causa atribuída a liquefação da carga, somando mais de 177 vítimas fatais. A Organização Marítima Internacional (IMO), braço da ONU que regulamenta o transporte marítimo, estabelece orientações e leis que visam garantir a segurança das operações. Para prevenir a liquefação e fenômenos relacionados, a IMO estabeleceu o Limite de Umidade Transportável (TML), e indicava três métodos para sua determinação: Proctor /Fagerberg, Flow Table e Penetration. Um amplo estudo apresentado à IMO em 2013 concluiu que estes métodos não são adequados para finos de minério de ferro, tendo sido desenvolvido um novo teste, o Proctor/Fagerberg Modificado. O presente trabalho apresenta aspectos regulatórios e técnicos do TML, e um comparativo entre o TML de 35 amostras obtidos pelos três métodos originais, mostrando diferenças significativas entre os resultados, uma evidência de sua inadequação.
Palavras-chave
Abstract
Bulk solid materials containing some amount of moisture may be susceptible to stockpile failure, sliding and liquefaction. Ore cargoes transported by ships are not free from these phenomena, which put the vessels at risk. At least 24 maritime accidents, which attributable cause is liquefaction, happened in the last 30 years, with more than 177 fatal victims. The International Maritime Organization, the United Nations section that regulates maritime transportation, sets guidance and laws that aim to guarantee the operations safety. To prevent liquefaction and related phenomena the IMO stated the Transportable Moisture Limit (TML), and indicated three test methods for its determination: Proctor/Fagerberg, Flow Table and Penetration. A vast study presented to the IMO in 2013 have concluded that these methods are not representative for iron ore fines, and a new test method have been developed, the Modified Proctor /Fagerberg. This paper presents regulatory and technical aspects of the TML, and a comparative evaluation between the TML of the three original test methods for 35 samples, showing significant differences between the results, an evidence of the inadequacy of these methods.
Keywords
Referências
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