C.I. Pigment Blue 28

There are three methods for producing cobalt blue: carbonate method, sulfate method and cobalt oxide method. Cobalt carbonate method. Reaction equation: CoSO4+Na2CO3→Na2SO4+CoCO3↓ 2KAl(SO4)2+3NaCO3+3H2O→K2SO4+2Na2SO4+3co2↑+2Al(OH)3↓Operating method: Potassium alum [Kal(SO4)2·12H2O] : Cobalt sulfate (CoSO4·7H2O): zinc sulfate (ZnSO4·7H2O): sodium carbonate (NaCO3): disodium hydrogen phosphate (Na2HPO4·12H2O) is 100:18.6:1.2:85:4.2. Cobalt sulfate and potassium alum are added together to dissolve into a solution, and then sodium carbonate solution is added to produce a precipitate containing cobalt carbonate and aluminum hydroxide. The precipitate is washed, filtered, dried, and calcined at a high temperature of 1100 to 1200°C for 2 to 2.5 hours. The end point is judged by the color of the pigment. After the calcination is completed and the temperature is lowered, water is added to form a slurry, which is ground in a magnetic ball mill until the fineness meets the requirements, and then vacuum filtered, dried, and crushed to obtain a finished product. Cobalt sulfate method. Reaction equation: CoSO4+Al2(SO4)3→CoO·Al2O3+4SO3↑ Operation method: 61 parts of aluminum sulfate (Al2(SO4)3·18H2O) and 18 parts of cobalt sulfate (CoSO4·7H2O) are fully mixed to make a charge, It is dehydrated at 300-350°C, and then calcined at 1100-1200°C for 2.5 hours. The end point is judged by the color of the pigment. After the calcination is completed and the temperature is lowered, water is added to form a slurry, which is ground in a magnetic ball mill until the fineness meets the requirements, and then vacuum filtered, dried, and crushed to obtain a finished product. Cobalt oxide method. Reaction equation: 2Co3O4+12Al(OH)3→6CoO·Al2O3+O2↑+18H2O↑ Operation method: 72 parts of aluminum hydroxide [Al(OH)3] and 22 parts of tricobalt tetraoxide (Co3O4) and a small amount of zinc oxide (ZnO, Such as 6 parts) mixed into the charge, and then calcined at 1100 ~ 1200 ℃ high temperature for 2.5h, the end point is judged by the color of the pigment. After the calcination is completed and the temperature is lowered, water is added to form a slurry, which is ground in a magnetic ball mill until the fineness meets the requirements, and then vacuum suction filtered, dried and crushed to obtain a cobalt blue finished product.

Cobalt blue [Co(AlO2)2], also known as cobalt ultramarine or azure blue, is a compound of aluminum oxide and cobalt. It is used as a pigment that mixes well with both oil and water. It also has cosmetic uses for eye shadow and in grease paint. Cobalt blue is one of the most durable blue pigments in that it resists weathering in paints and holds up to other wear and tear.