Calcium molybdate is a compound of molybdenum, one of the most abundant transition metals, and calcium, an important mineral for humans. Calcium molybdate is used in a variety of industrial applications, including fertilizers, ceramics and paint pigments, as well as for lightweight construction materials and acrylic resins.
The chemical structure of calcium molybdate consists of two molybdenum dioxide atoms, each bound to one calcium ion in a tetrahedral shape. This compound is highly insoluble in water and acidic solutions, but readily dissolves in highly alkaline solutions. Calcium molybdate can also be found in nature, but only in very small amounts.
Calcium molybdate is used in a variety of industrial applications. It is employed as a fertilizer additive, both in its concentrated form, as well as its more dilute form, commonly known as molybdenum(VI) oxide. It is also used as an additive in glazes for ceramics, and in enamels and protective coatings. Furthermore, calcium molybdate serves as an important source of molybdenum in paint pigments, as well as in lightweight special construction materials, acrylic resins and integrated circuit boards.
The manufacture of calcium molybdate occurs in two stages, each involving chemical reactions. First, a solution of molybdenum (IV) sulfide is reacted with chlorine to produce molybdenum(VI) chloride. This is then reacted at high temperature with calcium oxide (also known as “lime”). This results in the formation of a finely divided metallic molybdenum and calcium molybdate powder. The molybdenum is then separated from the calcium molybdate powder by alkaline leaching.
The production of calcium molybdate can also be accomplished via co-precipitation. This involves the reaction of molybdenum(VI) chloride with a biguanide molecule—surfactant molecules which form stable complexes with divalent metal ions—in the presence of calcium chloride. Upon the addition of a base such as sodium hydroxide, co-precipitation of calcium molybdate takes place.
Calcium molybdate is highly flammable and should be handled with caution and care. Long-term exposure to high concentrations of molybdenum in the form of calcium molybdate can also have adverse health effects, including breathing difficulty, skin inflammation, and gastrointestinal effects.
In conclusion, calcium molybdate is a versatile compound used in a variety of industrial applications, from fertilizers to lightweight special construction materials. It is easily manufactured, but should be handled and stored with caution due to its flammability and potential adverse health effects.
