Estudo de mycobacterium phlei (ATCC 11758) como agente agregante para hematita e quartzo

• Ano de defesa: 2007
• Autor(a) principal: Alexandra Alves Rodrigues de Assis
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Hematita; Quartzo; Mycobacterium phlei; Engenharia metalúrgica; Engenharia de minas
• Link de acesso: http://hdl.handle.net/1843/MAPO-7R5JQ7

Several microorganisms have been studied in flotation, sedimentation and filtration processes for several minerals, with positive results. Studies show Mycobacterium phlei as flocculant agent and potential collector for hematite. The objective of this work is to study the influence of the addition of the bacteria Mycobacterium phlei (ATCC 11758) upon sedimentation and filtration of the minerals hematite and quartz. The sample of hematite comes from Quadrilátero Ferrifero in Minas Gerais and has hematite (Fe2O3) as its main mineralogical phase. The quartz sample comes from the town Jaboticatubas (MG) and presents high purity (99.63% of SiO2). Sedimentation tests were done in 250ml graduated vessels and filtration experiments using a Buchner funnel connected to a scale/computer system. All the assays were performed in a laboratory. Results indicated that: a) In the sedimentation assays for hematite: without the bacteria, the lowest turbidity values and the highest values of sedimentation rate were obtained for pH values near the zero charge point. the addition of M. phlei (1000ppm) caused instability in the system, generating particle aggregation, since there was an increase in the Vs value for all pH values (except pH 7), as well as decrease of the supernatant turbidity for all pH values (except pH 8).b) In the filtration assays for hematite: without the bacteria, the lowest times of cake formation, final moisture and specific resistance of the cake were observed near PCZ (pH=6.7). the addition of the bacteria (1000ppm to 2810ppm of M. phlei) increased the filtration rate of the slurry due to the aggregation of the hematite particles. It is evident from this result the decrease in the cake formation time, cake resistance and solids percent in the filtrate, in the pH range tested. in the presence of 2810ppm of M. phlei the cake resistance values decreased significantly for all the pH range, and in pH 10, there was a 90% decrease in the cake resistance comparing to the value without bacterial presencec) There are no results for the sedimentation assays with quartz samples, since it was not possible to visualize the interface in any pH range and solids percent studied. d) The filtration assays for the quartz samples were not positive as to the addition of M. phlei, since no significant variation was observed in any of the variables studied.