Generally speaking, the bigger grain diameter of crystalline powder zinc sulfate heptahydrate, the better of the quality. As we all know, the bigger the grain diameter, the smaller the specific area. So less free water and chloridion will be absorbed, and Zn content will be higher.
By compared with the production sample, we found that fiber level zinc sulfate has more advantages than the common one: bigger grain diameter, less surface moisture and better fluidity. And according to the testing report from Inspection Bureau, Zn content of fiber level is higher than the common one.
That is the reason why the price of fiber grade zinc sulfate heptahydrate is expensive than the common one. According to the national standard, Zn content in zinc sulfate heptahydrate is no less than 21%. We produce zinc sulfate heptahydrate in common grade with Zn 21.5%, zinc sulfate heptahydrate in fiber grade with Zn 22%-23%. For agricultural, feed and industry use, the common grade zinc sulfate heptahydrate is Ok.