Bauxite mining and shipping: transportable moisture limit (TML) tests and further cargo assessments for safe shipping.

• Ano de defesa: 2019
• Autor(a) principal: Correia, Gustavo Ferreira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Bauxita; Bauxite; Carga sólida à granel; Cargo classification; Classificação de carga; Design of experiments; Distribuição granulométrica; Limite de umidade transportável; Particle size distribution; Planejamento experimental; Safe shipping; Solid bulk cargo; Transportable moisture limit; Transporte marítimo (Segurança)
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/3/3134/tde-20032020-100459/

Solid bulk cargoes relatively fine and wet may become unstable during ocean voyages and put a risk to the stability of the ship and life of the crew. To prevent instabilities related to the moisture of the cargo, the international regulation on maritime transportation establishes that certain cargoes can only be shipped if its moisture is below the so-called transportable moisture limit (TML), a regulatory parameter determined in a laboratory test to provide the maximum moisture content of the cargo to assure safe shipping. In 2015, the loss of lives and ship related to instability of wet and fine bauxite cargo under adverse sea conditions led to amendments on relevant bauxite shipping regulations. The Proctor/Fagerberg test method is widely used to determine the TML of solid bulk cargoes. Recent studies have led to improvements in test apparatus and procedures to Proctor/Fagerberg test to make it more suitable and reliable on the TML determination of specific cargoes. This study applied changes on the original Proctor/Fagerberg test and analyzed the effect of variables (compaction energy, type of bauxite and top size) on the TML determination of bauxites. All variables analyzed showed influence on TML results and the level of compaction energy provided by different compaction hammers was the single variable with the highest effect. By the light of joint research carried by bauxite industry players, it was developed a particle size criterion to distinguish between finer bauxites that may exhibit instabilities due to moisture and coarser bauxites that may not present such risk. The borderline defined is 30% in weight passing 1 mm and 40% in weight passing 2.5 mm. The fundamentals behind the particle size criterion developed are presented, while their implementation, adequacy, and relevance for the safety of bauxite shipping are discussed. Finally, a study case of bauxite cargo classification for shipping in accordance with the aforementioned particle size criterion is presented. A particle size distribution database of nearly 500 bauxite shipments since 2015 was analyzed to verify the variation in particle size distributions, the likelihood of variation in cargo classification and relevant practices to assure safe and compliant shipping.