| abstract |
A mixed solution production device, which comprises a mixing tank for preparing a mixed aqueous solution containing a dicarboxylic acid and a Nb compound and a filter for the mixed aqueous solution connected via a pipe to the mixing tank, wherein: the mixing tank has anti-corrosive properties; mixed aqueous solution stirring means, heating means and cooling means are provided; and the mixed aqueous solution prepared in the mixing tank is supplied to the filter through the pipe and is filtered under pressure in the filter. |