環境

[3301-10-07] Suppression of Pyrite Oxidation using Iron-based Carrier Microencapsualtion

^○Xinlong Li¹, Naoki Hiroyoshi¹, Kosuke Naruwa¹, Carlito Baltazar Tabelin¹, Mayumi Ito¹ (1. Hokkaido University)

司会: 飯塚淳（東北大学）

Keywords:Acid mine drainage, Pyrite, Catechol, Ferric ion

Oxidation of pyrite (FeS₂) is the dominant reason for the formation of acid mine drainage. Carrier Microencapsulation (CME) has been reported as a novel technology to suppress pyrite oxidation by making a protective coating on pyrite surface using Ti⁴⁺- or Si⁴⁺-catechol complex. In this study, CME using Fe³⁺-catechol complexes is proposed as a new option to be used in CME.
Mono-, bis-, tris-catecholate of ferric were synthesized based on the results of thermodynamic calculation and were characterized using UV-vis. Electrochemical properties of ferric-catechol complexes were evaluated using liner sweep polarization. The results showed the complexes were decomposed as follows: Fe(cat)₃^3- to Fe(cat)^- at +0.12 V vs. Ag/AgCl, Fe(cat)^- to Fe(cat)⁺ at +0.3 V vs. Ag/AgCl and Fe(cat)⁺ to Fe³⁺ at +0.42 V vs. Ag/AgCl. The results of leaching experiments showed pyrite oxidation was suppressed by the addition of ferric-catechol complexes. A dark coating was observed in the residues after leaching by microscopy, impling that the passive layer was formed.