Hydrometallurgical recycling of surface-coated metals from automobile-discarded ABS plastic waste.
Waste Manag
; 80: 414-422, 2018 Oct.
Article
em En
| MEDLINE
| ID: mdl-30455024
ABSTRACT
The ammoniacal leaching of surface-coated metals from automobile-discarded ABS plastics followed by their recovery through solvent extraction has been investigated. The leaching of ABS (typically containing 4.1% Cu, 1.3% Ni, and 0.03% Cr) could efficiently dissolve the ammine complexes of Cu and Ni, leaving Cr unleached as fine particles. The optimization studies for achieving the maximum efficiency revealed that the leaching of metal ions in different ammoniacal solutions follows the order CO32-â¯>â¯Cl-â¯>â¯SO42-. The leaching carried out in a carbonate medium by maintaining the total NH3 concentration 5.0â¯M at a NH4OH/(NH4)2CO3 ratio of 41, pulp density of 200â¯g/L, agitation speed of 400â¯rpm, temperature of 20⯰C, and time of 120â¯min yielded the optimum efficiency of >99% Cu and Ni (i.e., 8.14â¯g/L and 2.57â¯g/L, respectively, in the leach liquor). Subsequently, the solvent extraction of metals from ammoniacal leach liquor as a function of extractant (LIX 84-I) concentration and organic-to-aqueous (OA) phase ratio was examined. Based on the extraction data, a three-stage counter-current extraction at OAâ¯=â¯11 was validated using 0.8â¯M LIX 84-I, yielding the quantitative extraction of both metals into the organic phase. Thereafter, the stripping of metals in acid solutions indicated that 0.5â¯M H2SO4 could quantitatively strip Ni from the loaded organic phase; however, â¼27% Cu was also co-stripped. The rest of Cu from the Ni-depleted organic phase was separately stripped with 1.0â¯M H2SO4 that can be directly sent to the electrowinning process. On the other hand, the co-stripped metals from the acidic solution can be easily separated, again using LIX 84-I as the extractant, by adopting the pH-swing method. Finally, a process has been proposed for the hydrometallurgical recovery of surface-coated metals from waste ABS plastics; that does not affect the physicochemical characteristics of the polymer substances for their reuse.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Contexto em Saúde:
2_ODS3
Problema de saúde:
2_enfermedades_transmissibles
Assunto principal:
Plásticos
/
Automóveis
Idioma:
En
Revista:
Waste Manag
Assunto da revista:
SAUDE AMBIENTAL
/
TOXICOLOGIA
Ano de publicação:
2018
Tipo de documento:
Article