報告書番号

U02037

タイトル（和文）

高アルカリ性石炭灰の中和処理方策に関する基礎的検討

タイトル（英文）

Experimental study for the developing neutralization methods of coal fly ash with high alkalinity

概要 （図表や脚注は「報告書全文」に掲載しております）

石炭灰には高いアルカリ性を呈するものがあり、処分場保有水のｐＨが上昇すれば処分場の閉鎖手続きに支障をきたすことが懸念される。本研究は石炭灰処分場の早期閉鎖に寄与するため、石炭灰層中のｐＨを低減する方策に関する基礎的検討を行った。中和法として、高圧炭酸ガス処理、灰層中への送気処理、および硫酸カルシウム添加による方法を用いて検討した結果、いずれもｐＨの低減に効果があるという結果を得た。

概要 （英文）

Every year, large quantities of coal fly ash are generated by electric utilities and disposed in landfills. Some coal fly ashes contain alkaline and hydroxide phases, so solution in contact with these ashes initially have extremely high pH values. When the pH of discharge from coal ash landfill exceeds the discharge water criteria, this could interfere in close-down procedure of the site. This study aims at developing the neutralization method of coal fly ash with high alkalinity. Several methods are examined, they are (1) exposure in CO2 gas with high concentration and pressure, (2) addition of gypsum (CaSO4:2H2O) within fly ash, (3) inject the air within fly ash. Infiltration tests using short column are carried out and pH value (and ORP , EC) of discharged water are monitored. The results are as follows:(1) Exposure in CO2 gas with high concentration and pressure The pH of the discharged water was lower than 9.3 throughout 90days (up to 2500mm of discharge).(2) Addition of gypsum The pH of the discharged water was kept lower than 9.4.(3) Injection of air The discharged water showed excess pH 12 value in the early stage of monitoring duration. But pH decrease rate is twice faster than the result of without air injection.

報告者

キーワード