Nickel sulfate has no water, hexahydrate and heptahydrate three kinds of commercial hexahydrate, there are α- type and β- type two variants, the former is blue tetra crystal, the latter is green monoclinic crystal. According to the product classification, it can be divided into electroplating grade nickel sulfate and battery grade nickel sulfate, the former is used in electroplating industry and battery industry, is the main nickel salt of electroplating nickel and chemical nickel, is also the source of metal nickel ion