Influência da qualidade do pó de zinco na geração de hidrogênio em pilhas alcalinas

• Ano de defesa: 2007
• Autor(a) principal: Tone Takayama Filho
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Materiais e de Minas; Engenharia Metalúrgica; Engenharia metalúrgica; Tecnologia mineral; Zinco
• Link de acesso: http://hdl.handle.net/1843/BUOS-96WJHB

In modern alkaline batteries (Zinc / Manganese Dioxide) high purity zinc dust (Special High Grade) is used as anode. These batteries are substituting the traditional zinc-carbon batteries due to its limitations in applications needing high discharge rates, large working temperature range and longer shelf life. Votorantim Metais is the sole producer of this zincdust in Brazil. The zinc dust characteristics are very important for the alkalinebatteries performance. One of the main factors that affect the alkaline batteries performance and harm their useful life is gassing (hydrogen evolution) that is due to the zinc dust anode corrosion. This phenomenon is highly influenced by the zinc dust quality produced. So, the main objective of this Master of Science Thesis was to evaluate how some main zinc dust characteristics affects gassing. The zinc dust produced by Votorantim Metais was compared with two zinc dust qualities which are reference on the international market through their physical, chemical and morphological characteristics and by their gassing generation. The iron content in the zinc dust has a significant effect in gassing. It may be noticed that even with indium and bismuth contents considerably lower than those of produced Votorantim Metais´ dusts, even so the gassing of zinc dust produced at Votorantim Metais was 50% higher. This was mainly due to the higher iron content of this zinc dust (5 ppm) related to the reference dusts (< 2 ppm). Several zinc dusts were produced at the São Paulos´s State Instituto de Pesquisas Tecnológicas atomization pilot plant and were used to study the effects of iron and indium contents, size distribution and annealing of the zinc dust on gassing. Finer particles and higher fines proportion in the zinc dust show a higher trend for gassing increase. Thermal treatment of zinc dust highly contaminated with iron (> 10 ppm) at 350 oC under vacuum and during 4 hours showed a 40% reduction in gassing as result, independently of the iron content in the zinc dust.