How to solve the problem of zinc sulfate heptahydrate caking？

In our factory or sample room, every batches of zinc sulfate is store well. The samples of zinc sulfate heptahydrate which has stored over 2 year were caked. Zinc sulfate agglomeration may affect the normal use. How to solve zinc sulfate heptahydrate caking problem？To prevent this, there are two solutions for your reference.
 
First of all, the most common reason for the caking of zinc sulfate heptahydrate is in the process of production that there’s much free moisture on product surface. The zinc sulfate monohydrate which there’re less free water on surface than zinc sulfate heptahydrate, and it shows good liquidity when pouring, would have low caking probability. If there’re much free water on the product surface, is overmuch, hot air drying, or drum drying can help to dry it.
 
Secondly, anticaking agent added in products is widely used in long-distance transportation.
Be worth to attend, sometimes zinc sulfate heptahydrate is in a pseudo agglomerate state, knock it, agglomeration can be knock out. Such agglomeration not affect its normal use.