ISSN:
0006-3592
Schlagwort(e):
Chemistry
;
Biochemistry and Biotechnology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
Notizen:
A systematic, kinetic study and comparison of the leaching of mixed metal sulfides by galvanic conversion and in the presence of bacteria has been carried out for the first time using both powder (-100 to -400 mesh) and larger (bulk) specimen systems. The rates of dissolution of copper from chalcopyrite and zinc from sphalerite as single, electrically isolated (separate) systems were compared with electrically contacting (galvanically coupled) systems involving CuFeS2/FeS2 and ZnS/FeS2, with and without bacteria and at temperatures of 30 and 55°C. The dissolution of Cu was observed to increase by a factor of 4.6 when the galvanic leaching of CuFeS2/FeS2 was compared to CuFeS2 leaching at 30°C. When bacteria were present, Cu dissolution increased by an additional factor of 2.1 in the CuFeS2/FeS2 system. At 55°C, the corresponding ratios for Cu were 4.3 and 2.7, respectively. The galvanic leaching of Zn in the ZnS/FeS2 system compared to ZnS leaching increased by a factor of 2 at 30°C; in the presence of bacteria the dissolution of Zn from the ZnS/FeS2 system increased by an additional factor of 1.3 at the same temperature. By comparison, the ratio of Cu dissolution from CuFeS2 in acid-bacterial medium and sterile controls (without bacteria) was 5.5. The corresponding ratio for Zn from ZnS was 2.2 at both 30 and 55°C. The order of reaction was found to be essentially first order for the leaching of powder systems at both 30 and 55°C (with T. Ferrooxidans and thermophilic microorganisms, respectively). The corresponding reaction rate constants were observed to be 12.6 and 22.9 for T. ferrooxidans and the thermophilic microorganisms, respectively. Activation energies for the various systems were also determined.
Zusätzliches Material:
12 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/bit.260240413
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