粉体精製工学部門委員会　学生賞セッション

[2K62201-08-08] 段階的バイオ処理を施した含炭素銀鉱石のQEMSCANによる分析

○メンドーサ ディエゴ¹、コナドゥ コジョ¹、境 諒太郎¹、笹木 圭子¹ (1. 九州大学)

キーワード：バイオオキシデーション、炭素質物質、難処理銀鉱石、微生物培養上清液、QEMSCAN

In the present study, an anonymous carbonaceous silver ore concentrate was bio-treated sequentially using acidophilic mixed culture of archaea to oxidize sulfides followed by cell-free spent medium (CFSM) from the white-rot fungus of Phanerochaete chrysosporium to decompose carbonaceous matter. Fundamental characterization of the silver species in the as-received sample showed mainly silver oxides associated with silicate gangue and partially locked in sulfides, as well as hessite with 17%. On the other hand, the carbon content was around 5% but carbonaceous matter association in the sample was not clear. Chemical dissolution of the silver oxides occurred in the acidic medium used for the sulfide oxidation, leading to approximately 16% Ag recovery. While this was beneficial side effect, the main silver recovery occurred during the cyanidation step; whereby the silver yield increased from 33% in the as-received to 84% in the solid residue after the sequential bio-treatment. The significant increase in Ag yield was observed after the CFSM decomposition of the carbonaceous matter. However, a deeper understanding of carbonaceous material transformation is still needed for a better application of this sequence in the variety of carbonaceous ores that exist worldwide. For that reason, quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) was utilized to provide detail information about mineral liberation and associations of carbonaceous matter after the proposed sequential bio-treatment.