Iron oxide is produced from ferrous sulfate by hot dipping, water removal, decomposition, washing, filtration, drying and grinding.

　　They are produced in the form of water or water. Their hue ranges include yellow, red, brown and black.

　　The food grade iron oxide is different from the technical level, mainly by the low level of other metal pollution, which is achieved by the selection and control of the iron source or the degree of chemical purification during the manufacturing process.