抄録
Some examples of new application of the hydrothermal process to the extraction of rare metals from complex ores are presented. Tungsten can be separated from tin-tailing which contains tungsten and tin oxides under alkaline hydrothermal conditions. Typical rare-earth ores, such as bastnaesite, xenotime, monazite and ionexchange ore, are also extracted with aqueous solution of NaOH to produce a mixture of rare-earth hydroxides under high temperatures and pressures. The possiblity of nickel extraction process by using hydrothermal reaction is discussed.
