| Project/Area Number |
07455344
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
無機工業化学
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| Research Institution | Tohoku University |
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Principal Investigator |
OKUWAKI Akitsugu Faculty of Engineering, Tohoku University Professor, 工学部, 教授 (70005320)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIOKA Toshiaki Faculty of Engineering, Tohoku University Research Associate, 工学部, 助手 (30241532)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Keywords | Barite / Wet Treatment Process / Ba-EDTA complx / Dissociation / Leaching / Morphology Control / Shrinking-core Model / 湿式書処理 |
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| Research Abstract |
Barite is the major resource for every barium compounds and calcined at 1000-1200ﾟC in the presence of coke or pitch to convert black ash containing barium sulfide. However, this process needs the treatment of sulfide as a by-product. So, a development of new treatment process of Barite is expected, and this process is required energy conservation and low impact for environment. A new process consisting of leaching barite with an EDTA solution at moderate temperature and precipitating barium sufate under hydrothermal conditions is studied in this work. Barium salt can be prepared directly from the leaching Solutions containing Ba (edta)^<2-> complex as controlled morphology and size distribution without producing troublesome hydrogen sulfide in the process. The process operating between 80-250ﾟC can use low temperature waste heat and EDTA liberated in the precipitation can be recycled.
[Leaching of barite with EDTA solutions]
Kinetic study was carried out for processing barite. The leaching rate increased remarkably with temperature and the stirring speed from 450-1100rpm affected little the rate at 60-90ﾟC.The rate increased twice when the particle size became half. The mechanism could not be analyzed by the shrinking core model even within one hour due to the formation of many and deep cracks on the barite particles with processing the leaching. Consequently a modified model was with proceeding the apparent activation energy was 16kcal/mol. Thus, the rate process is controlled by any chemical reaction.
[Precipitation of barite]
Ba (edta)^<2-> solutions containing 0.024M [Ba^<2+>]_T and 0.08M [edta]_T were prepared by leaching barite with [edta]/[barite] molar ratio of 1 at 90ﾟC for 10h. Ten ml of 0.2 or 0.4 M sodium sulfate solution was added to equal volume of the Ba (edta)^<2-> solution and the resulting solution in a glass tube (Duran) was heated in air bath at 180-200ﾟC for 0-10h. Barium ion precipitated as pillar-like barite
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