| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
Neutralization and sedimentation method has been conventionally adopted for long time. Neutralizing chemicals such as slaked lime are added to mine waste water after treated by oxidation process to convert ferrous to ferric ions, to adjust pH value within neutral zone. The sludge return and neutralization method is the alternation of neutralization and sedimentation method, and it is characterized by returning a part of sediment to the neutralization process. Recently, it was developed in our laboratory that a novel and optimum neutralization process that generate stable and compact magnetite precipitation from comparative low concentrated ferrous sulfate solution without oxidation at room temperature.
In this research, the effect of co-existing ion on magnetite formation was examined and sludge recycling method was applied to artificial acid mine water treatment to get high concentrated solid sludge. The influence of aluminum ion and soluble silica, which are expected to prevent the formation of magnetite from mine water, was investigated in laboratory scale. In the case of aluminum, aluminum hydroxide precipitation disturbed the magnetite crystalline.
Soluble and polymerized silica that adsorbed intermediate precipitate had a harmful effect on the magnetite formation.
The ratio of the solid content of sludge vs. recycling time decreased gradually with increasing co-existing concentration. This optimum neutralization method was applied to Komaki and Osarizawa mine water, and was revealed that approximately 4 times high concentrated solid sludge were formed compared to conventional method in Komagi mine water. For Osarizawa mine water, 1.4 times higher densities sludge were formed after 30 times recycling.
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