【一般講演】 鉱物処理／リサイクル

[3K0307-16-01] （学生発表：博士課程） Degradation of carbonaceous matter in double refractory gold ore by extracts from mushroom cultivation industry wastes

○Cindy -¹, Hirofumi Ichinose¹, Keiko Sasaki¹ (1. Kyushu University)

司会：伊藤 真由美（北海道大学）

キーワード：double refractory gold ore, carbonaceous matter, laccase, enzymatic degradation, mushroom cultivation industry waste

The degradation of carbonaceous matter in double refractory gold ore (DRGO) to minimize preg-robbing during gold extraction by cyanidation has changed over time to be more environmentally friendly. Recently, it was reported for the first time that laccase-mediator system was applied to double refractory gold ore for degradation of carbonaceous matter, leading to improvement of gold extraction. Laccase has advantages over lignin peroxidase and manganese peroxidase, the other lignin-degrading enzymes, which are higher stability, wider availability, and easier handling. With the aid of a mediator, such as 1-hydroxybenzotriazole hydrate (HBT), laccase can oxidize not only phenolic compounds, but also nonphenolic compounds in carbonaceous matter. However, laccase-releasing mushroom species are highly diverse. To apply to mining industry, purified laccase is not realistic. Therefore, it is interesting to find new methods in production of laccase with high activities at lower cost due to the huge potential for the development of efficient biotechnology processes. Instead of the expensive purified laccase, crude laccase harvested from mushroom cultivation industry wastes will be applied for carbonaceous matter degradation in DRGO. Some mushroom cultivation industry wastes might be able to be utilized because of their large scale. In the present work, laccase extracted from mushroom cultivation industry wastes of Lentinula edodes was utilized for degradation of carbonaceous matter in sequential treatment of DRGO from the Syama mine, Mali. The laccase extraction process was optimized, then the activity was measured using UV-spectrometry with 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as a substrate. The enzymatic treatment residues were characterized using three dimensional (3D) fluorescence spectrometry and thermogravimetry-differential thermal analysis (TG-DTA) and the gold extraction was determined, then the results were compared with the degradation using purified laccase. To our knowledge, this is the first report utilizing mushroom cultivation industry waste for the degradation of carbonaceous matter in sequential treatment of DRGO.