Precipitation of Germanium from Coal Fly Ash Leachates

Authors

Fatima Arroyo, University of Seville, School of Engineering, Chemical and Environmental Engineering Department, Camino de los Descubrimientos, Seville (Spain), phone: 011-03495-448-1379, fax: 011-034-95-448-6082,
Constantino Fernandez-Pereira, University of Seville, School of Engineering, Chemical and Environmental Engineering Department, Camino de los Descubrimientos, Seville (Spain), phone: 011-03495-448-1379, fax: 011-034-95-448-6082,
Pilar Coca, ELCOGAS S.A., 13500 Puertollano, Ciudad Real, Spain

Document Type

Article

Abstract

The valorization of a coal gasification fly ash was studied by leaching the fly ash using different aqueous solutions followed by the subsequent precipitation of the germanium solubilized from the ash. Experimental investigations were focused on the precipitation of a germanium2catechol (CAT) complex with cetyl trimethyl ammonium bromide (CTAB). The influences of pH and amounts of CTAB and CAT on the precipitation yield were investigated. To this aim, a central composite rotatable design and ANOVA Design Expert 7.0.3 Wiley software were employed for experimental design and analysis of the results. Thus, the independent and combined effects of pH, CAT/Ge and CTAB/Ge molar ratios were investigated and optimized using a quadratic mathematical model. The optimum values of these factors were found to be 10, 12, and 4, respectively (in this case, the germanium precipitation yield was 98.8% for water leachates). The precipitation of germanium as a complex compound with CAT and CTAB was found to be selective towards germanium and this element can be effectively separated from As, Mo, Sb, V, or Zn. Total organic carbon in solution was measured to estimate the amounts of CAT and CTAB precipitated with germanium and with the interferences present in aqueous leachates. In addition, thermogravimetric analyses have been performed on the germanium-complex solids as a result of which 600uC was determined as the minimum temperature to completely remove the organic content of the precipitate.

First Page

28

Last Page

34

DOI

https://doi.org/10.4177/CCGP-D-09-00021.1

Volume

2

Publication Date

1-1-2010

Recommended Citation

Arroyo, Ftima, Constantino Fernndez-Pereira, and Pilar Coca. 2010. “Precipitation of Germanium from Coal Fly Ash Leachates.” Coal Combustion and Gasification Products 2 (1): 28–34. https://doi.org/10.4177/CCGP-D-09-00021.1.