反应详情

In one example, the source of molybdenum was acid-washed technical grade MoO3. A series of tests was run in each of which 60 grams of MoO3 was digested in 200 ml NH4OH in a 600 ml pressure reactor to form ammonium molybdate solution. Digestion times varied between one and three hours and digestion temperatures varied between 40° and 80° C. Magnesium was added in the form of 2M MG(NO3)2 6H2O and the amount added varied between 1 ml and 3.8 ml. The molarity of the NH4OH varied between 4.46 (which gave a pH of 9.0) and 6.40 (which gave a pH of 9.8). The ammonium molybdate was then cooled to 30° C. and filtered to remove the precipitate. Magnesium was then removed from the ammonium molybdate solution by ion exchange, as disclosed in U.S. Pat. No. 4,702,895. The solution was then evaporated to dryness to form ammonium dimolybdate (ADM) crystals. The ADM was then fired at 500° C. to form MoO3 for analysis to determine Al content. In all cases Al content was less than 18 ppm. At pH of 9.8 and at 0.04 mole Mg per liter, Al content was only 3 ppm.

1. customDigestion times varied between one and three hours and digestion temperatures
2. customvaried between 40° and 80° C
3. additionthe amount added
4. customgave a pH of 9.0) and 6.40 (which
5. customgave a pH of 9.8)
6. filtrationfiltered
7. customto remove the precipitate
8. customMagnesium was then removed from the ammonium molybdate solution by ion exchange
9. customThe solution was then evaporated to dryness