Estudo da caulinita como adsorvente de xantato no efluente de flotação da galena

• Ano de defesa: 2016
• Autor(a) principal: Marcelle Prates Sepulveda
• 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; Enenharia Metalúrgica; Engenharia metalúrgica
• Link de acesso: http://hdl.handle.net/1843/BUBD-ACMHSP

This paper aims to show the efficiency of kaolinite as an adsorbent for xanthates. Xantates are a class of reagents widely used during the flotation of sulphide minerals. Xantates become an effluent at the end of the flotation process. The zeta potential for kaolinite was measured and shown negative values in pH less than 2,85. were also obtained X-ray spectra for kaolinite, the results show characteristic peaks in theliterature for the material used. The flotation was conducted using a regular sulphide ore containing galena (PbS), xanthate as the collector reagent and pH between 9.5 and 10. The flotation effluent was used for the adsorption and kinetics tests with kaolinite. It was constructed an analytical curve for measuring the xanthate in the effluent matrixrelating the collector concentration with the absorbance in the UV-visible region and observed its linearity. The initial and final xanthate concentrations in the effluent, before the addition of kaolinite, and also the removal of the xanthate, were measured through interpolation on the analytical curve. The comparison parameters for the contents ofadsorbed xanthate were pH, effluent volume and the adsorbent mass. The initial concentration of xanthate in all tests has varied at an average of 4,7 ppm with a coefficient of variation of 6,3%. The adsorption testes with variable volume was made with 50, 100 and 200mL and constant kaolinite mass: 1g. The best removal percentages were 100mL. For the variable mass tests where the constant volume was 100mL, the mass was used between 0,5 and 2,0g. The results show little adsorptionvariation from 1.0g until 2.0g, which proposes the use of 1g for each 100mL of effluent. The most significant variable for the adsorption efficiency was the pH. The pH tests were made with 100mL of effluent prepared in pH values between 4.0 and 12.0, kaolinite mass 1g, which achieved its optimized condition at pH 4. The results suggest that the large difference in adsorption in the acid pH range can be attributed mainly to the lower negative surface charge of kaolinite and the anionic character of xanthate in the acid pH range. For isotherm analysis was used 100mL effluent, 1g of kaolinite and flotation pH, because xanthate must be degraded at low pH values. The high adsorption capacity was 1.5861 mg g-1, and adsorption of xanthate on kaolinites was better fitted to the Sips isotherm. The kinetics tests were made at the same isotherms condition, the results show a kinetics equilibrium between 15 and 30 minutes and could be explained by a pseudo second-order kinetic model. It is concluded that kaolinites offer significant potential in the treatment of effluents originating from the processing of sulphides ores by froth flotation. In general, the adsorption xanthate on the surface ofkaolinite shown to be promising, since the tests were conducted without any pretreatment of the adsorbent and little change in the industrial process having significant potential removal, approximately 30% in the system treatment of effluents originating from flotation processes of sulphide ores.