The invention relates to a method for preparing high-purity
ammonium tetramolybdate, which comprises the steps of: mixing raw
ammonium tetramolybdate with pure water and concentrated
ammonia water to dissolve the raw
ammonium tetramolybdate, then using pure water to adjust density and filtering to obtain filtrate 1; using concentrated
nitric acid to adjust the density of the filtrate 1 at
room temperature, then adding FeCl3, agitating and filtering to obtain filtrate 2; conducting
evaporation and
crystallization and filtering to obtain filtrate 3 and a
filter cake 1; after the filtrate 3 is cooled, filtering to obtain a
filter cake 2; after the
filter cake 1 and the filter cake 2 are mixed with pure water, are agitated and are dissolved, adding concentrated
nitric acid to obtain solution with H+ concentration being 3-8 mol / L, agitating, heating, preserving heat, cooling and filtering to obtain a filter cake 3, and using
nitric acid aqueous solution to wash the filter cake 3 to obtain ammonium dodecamolybdate; adding pure water and concentrated
ammonia water to mix and dissolve, heating, evaporating, regulating pH, cooling and then using pure water to adjust density; and adding concentrate nitric acid to regulate pH, agitating, heating, preserving heat, filtering to obtain a filter cake 4, washing the filter cake 4 and
drying the filter cake 4 to an extent with the
water content being less than or equal to 1.0g / cm<3> to obtain ammonium tetramolybdate with the purity being more than or equal to 99.998 percent. Therefore, the content of impurities in the raw ammonium tetramolybdate is effectively reduced.