Formation of chloropyromorphite from galena (PbS) in the presence of hydroxyapatite

Citation
Pc. Zhang et Ja. Ryan, Formation of chloropyromorphite from galena (PbS) in the presence of hydroxyapatite, ENV SCI TEC, 33(4), 1999, pp. 618-624
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Journal title
ENVIRONMENTAL SCIENCE & TECHNOLOGY
ISSN journal
0013-936X → ACNP
Volume
33
Issue
4
Year of publication
1999
Pages
618 - 624
Database
ISI
SICI code
0013-936X(19990215)33:4<618:FOCFG(>2.0.ZU;2-V
Abstract
Transformation of unstable lead [Pb(ll)] forms into sparingly soluble pyrom orphite [Pb-5(PO4)(3)(OH, Cl, F, ...)] by the addition of phosphate to Pb-c ontaminated soil has been proposed as a remediation technology to reduce th e mobility and bioavailability of Pb. Galena, an insoluble lead sulfide min eral (PbS) frequently found in mining wastes, becomes unstable upon exposur e to oxidizing conditions causing it to become a source of liable Pb forms in soils. Thus, a galena ore was reacted with synthetic hydroxyapatite [Ca- 5(PO4)(3)OH] under various pH conditions to determine the formation rate of pyromorphite and the solubility of galena under the ambient condition. In a 6-day reaction period, the dissolution rate of galena increased with pH d ue to the oxidation of dissolved sulfide. Hence, formation of chloropyromor phite became apparent in the galena-apatite suspensions with increasing pH. The insignificant effect of mineral P/Pb molar ratio on the formation of c hloropyromorphite implied that dissolution/oxidation of galena was the rate -limiting step.