Relationship between particle size distribution and the PFD80 transportable moisture limit of iron ore fines.
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Date
2022
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Abstract
Since 2011, mineral cargoes shippers shall comply with a regulatory framework established by the United Nation’s International Maritime Organization (IMO): the International Maritime Solid Bulk Cargoes (IMSBC) Code.
Some wet mineral cargoes, including some types of iron ore fines, may liquefy during ocean transport, i.e., the
cargo can shift and lead the vessel to sink. According to the IMSBC Code, for safe shipping, the moisture content
of these cargoes shall be lower than a regulatory limit: the Transportable Moisture Limit (TML). Iron ore fines
TML can be obtained through the Modified Proctor/Fagerberg Test for Iron Ore Fines (PFD80), a dynamic
compaction test which consists in compacting ore samples at different moisture contents, the TML being the
moisture content at which the material reaches 80% saturation. TML has become a relevant parameter for the
mining industry, firstly due to the crew and ship safety aspect, and because failure to comply with the TML can
legally interrupt an ore shipment or even an entire mining/shipping operation. Therefore, knowledge related to
the TML and the understanding of how it varies with ore characteristics are essential. Despite that, research
works on this topic are still scarce. In this study, the relationship between particle size distribution and the TML
of iron ore fines was experimentally investigated. The results have shown that the TML is highly related to the
particle size distribution of the tested material, and that the TML variations can be explained by structural
packing effects caused by particle interactions during compaction for different types of size distribution. It was
also found that the coefficient of uniformity can be used for numerically representing the particle size distribution in order to establish relationships with the TML. Another relevant conclusion is that the TML of a mixture of different iron ore fines may not be the result of the weighted average of the individual components’ TML. This
knowledge is of utmost importance for the industry, as blends of different ore products are common practice, and
this finding is relevant for other cargoes that are susceptible to liquefaction.
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Keywords
Transportable moisture limit, Iron ore fines
Citation
FERREIRA, R. F.; LIMA, R. M. F. Relationship between particle size distribution and the PFD80 transportable moisture limit of iron ore fines. Powder Technology, v. 414, artigo 118072, nov. 2022. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0032591022009536>. Acesso em: 15 mar. 2023.