Efeito da adição de cal hidratada na etapa de aglomeração das pelotas de minério de ferro produzidas pela Samarco S.A.

• Ano de defesa: 2014
• Autor(a) principal: Anderson Lucio de Souza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Pelotamento; Minério de ferro; Cal; Engenharia metalúrgica; Tecnologia mineral; Minérios de ferro
• Link de acesso: http://hdl.handle.net/1843/BUOS-9KSFMD

Samarco is a Brazilian mining company, a high quality iron ore pellets producer for the global steel industry. The process is fully integrated and carried out in two industrial plants: the Germano unit, located in Ouro Preto and Mariana, Minas Gerais, and in Ponta Ubu unit, located in Anchieta, Espírito Santo. The mined ore is concentrated in Germano plant and transported as slurry through a pipeline to Ponta Ubu unit. In order to guarantee the necessary rheological conditions of the slurry during transportation by pipeline and avoid a possible obstruction due to sedimentation even after a shutdown, hydrated lime is added to the slurry. For the filtering process of received slurry in Ubu, lime addition in slurry before the pipeline support filtering step, since the lime acts as a coagulant and assists in raising the physical state of the slurry. To assess the lime dosage effect of iron ore slurry in the balling process, tests were done using different masses of prepared lime solutions added to a pellet feed. It was observed that the higher hydrated lime solution added to pellet feed (where the CaO content in the pellet feed increases with the mass of lime used), bigger was the green pellets average diameter obtained in the pelletizing test. Higher dosages of lime solution increased the aggregation state of the ore particles, favoring a faster growth of agglomerated iron ore, during the initial minutes of balling. The Ca2+ cations present in the pellet feed, as a function of lime dosage, interact with organic polymer binder and bentonite; reducing the ability of these agents to control the pellets growth during the pelletizing tests. Satisfactory results of the green pellets average diameter of the raw pellets were obtained only in tests in which CaO content (%) pellet feed as given by hydrated lime was equal or less than 0.08%, regardless the of agglomerating agent used in tests.