AvaliaÃÃo dos impactos ambientais gerados pela produÃÃo de resÃduos industriais do ramo metalÃrgico : recuperaÃÃo e reciclagem

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Galvanization is an industrial process used to protect metallic materials surface, in order to extend their durability however, this process generated metallic residues. With the objective to decrease the environment impact from these residues this work considers the development of a methodology to remove metals as Iron, Zinc and Chromium. Initially an factorial planning 24 was carried out observing the influence of the variables: acid concentration (15, 20 or 25% v/v), acid type (sulfuric or hydrochloric), acid volume (15, 20 or 25 mL) and extraction time duration (12, 24 or 36 h) of Zn and Cr. The datas of the statistic analysis showed that a variation of extraction capacity from 173.76 to 1281.05 mg/g of Zn with efficiency of 9.39% to 69.20%. For the Cr this capacity varied from 21.20 to 171.6 mg/g of Cr with 11.25% to 92.24% of efficiency. It was also obtained 44.3% of Iron with this treatment. The extract obtained after the optimization of this process was used for separation and recovery of the Fe, Zn, and Cr metals. For the removal of the Fe, it had been used 15mL NaOH 25% with adjustment of pH for 11, occurring the formation of one brown precipitate that was separated by filtration. The extract was acidified and H2O2 was added to get oxidation of all Cr+3 present in the solution for Cr+6. After that a solution of BaCl2 at 10% was added, in a total of 10 mL, until the formation of BaCrO4 precipitate, that was separated by filtration. For the precipitation of the Zn, the extract resulted from the previous experiment was used after correction the pH to 8 with NaOH and after that it was bubbled H2S in the solution and observing the formation of white precipitate of ZnS. The analysis of the liquid obtained after the precipitation of metals proved the effectiveness of the methodology since the presences of Fe, Zn, and Cr had not been detected, thus such effluent is passable of reuse for not potable purposes. Regarding the sludge resulted from the extraction of metals, only for residual zinc an intervention procedure is required according to CETESB, having to be evaluated its disposal in non-agricultural area

ASSUNTO(S)

chromium zinc extraÃÃo indÃstria galvÃnica cromo recovery zinco politicas publicas extraction galvanic manufacturing recuperaÃÃo

ACESSO AO ARTIGO

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