Tratamento hidrometalúrgico do resíduo da rota de processamento de zinco primário para a recuperação de sulfato de cálcio visando aplicação industrial

• Ano de defesa: 2009
• Autor(a) principal: Carolina Bittencourt de Abreu
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: recuperação; lixiviação; caracterização; Sulfato de cálcio; Engenharia metalúrgica; Engenharia de Minas
• Link de acesso: http://hdl.handle.net/1843/MAPO-7RLKHH

Many non-ferrous metals ore, such as zinc, are associated with toxic elements, which are implied in the toxicity increase of its residues generated on process. At the primary zinc processing unit of the Votorantim Metals, at Três Marias (MG) (VM-Zn-TM),sodium sulfide (Na2S) and calcium oxide (CaO) are added in the final polishing stage ofthe effluents. This master degree dissertation presents the experimental results for the sulfuric acid leaching of CaSO4 contained in the residue sample and subsequent recovery of this chemical specie. Species like Na2S and CaO are added to precipitate remaining metals, like Cd, Pb and Ni, and the waste water assists the requirements of the Normative Deliberation of COPAM 10/86 which establishes norms and standardsfor water quality and effluents released in water collections. Slurry generated in this process presents, besides precipitated metals, considerable tenor of calcium sulfate (CaSO4), which is generated by the reaction between Na2S and CaO. The use of the statistical approach for the Complete Factorial Method at Two Levels allowed to evaluate the interference of the variables time and temperature of leaching, leach pulpdensity and concentration of sulfuric acid in the extraction of CaSO4. The optimization of experimental results by Method of the Ascending Step allowed to obtain the optimum experimental conditions for the maxim extraction of CaSO4 to the residue sample (leaching during 45 minutes, temperature at 45±2ºC, leach pulp density at 10g/l and sulfuric acid concentration at 0,33M). From the leach liquor of sulfuric acidleaching, obtained in optimized conditions, it was recovered 32% of CaSO4 contained in the solution. The sample of residue by VM-Zn-TM, the sample of CaSO4 recovered from the residues, samples of reference of CaSO4 with application in the building site industry (plaster) and with agricultural application (phosphogypsum) were characterized technologically and the values of them were compared to identify theindustrial potential aplication of CaSO4 recovered. Calcium sulfate recovered from the residue presented the smallest tenor of impurities among the analyzed samples. It was observed a larger similarity between the sample of CaSO4 recovered and the phosphogypsum sample. However, this doesn't exclude the possibility of application ofthe material recovered in the building industry or in others industries sites, because for the application in any area is necessary the study and performe specifics tests.