Recuperação de efluentes industriais em colunas pulsadas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

About 290.000 tons of stainless steel is produced annually in Brazil. This quantity is pickling along the production line to remove the surface of oxides, which form in the finishing stages of the steelmaking process. The pickling bath is a mixture of nitric and hydrofluoric acids and is used until the iron concentration has reached 40 - 80 g/l. At this stage, the bath contain about 50 % unused acids in addition to dissolved metaIs. In Brazil, the neutralization/precipitation method is applied for the treatment of the waste from the pickling process, generating a large amount of sludge and discharge of a large quantity of nitric nitrogen. The aim of this study was develop a process to recover both acids and metaIs values from a stainless steel pickling bath. In a first step, over 99 % of iron were recovered by solvent extraction in a mixer-settler cascade, using di-2-ethil-hexil phosphoric acid 30 % v/v as solvent. The recovery of 99 % of H N O IND. 3 and 80 % of HF was achieved by solvent extraction in a pulsed column, using TBP 75 %v/v in isoparafine as the organic solvent. The other metals, Cr and Ni, can be precipitated and converted to recycle to the metal process or recovered as individual compounds

ASSUNTO(S)

meio ambiente residuos industriais

ACESSO AO ARTIGO

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