| 摘要 |
PROBLEM TO BE SOLVED: To obtain a substance which can immobilize arsenic and thallium at the same time. SOLUTION: An aqueous solution containing arsenic ions, thallium ions, and divalent iron ions is heated to a temperature range of more than 150°C, desirably 165-210°C in the presence of an oxidant to precipitate thallium, together with iron and arsenic, thereby synthesizing a crystalline compound to obtain a thallium-containing iron/arsenic compound in which arsenic and thallium are insolubilized. The compound has a crystalline structure different from scorodite, and contains, for example, 20% or more of arsenic and 1,000 ppm or more of thallium at a mass ratio. Suitably, oxygen gas is used as the oxidant. In the case using the oxygen gas, for example, it is preferable that an oxygen partial pressure (a gauge pressure) in a gas phase is kept at 0.1-0.5 MPa in an autoclave to carry out precipitation reaction while stirring the aqueous solution. COPYRIGHT: (C)2008,JPO&INPIT
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