The manufacturing temperature of zinc sulfate heptahydrate

Pure zinc sulfate wouldn’t turn yellow longtime stored in the air but would lose water and turn to white powder in dry air. Therefore, in the production process, the different temperature will lead to produce zinc sulphate heptahydrate, a variety of hydrate and compound.

Between 0-39 ℃, stability hydrate for zinc sulphate heptahydrate formed;

Between 39-60 ℃, 6 water zinc sulfate formed;

Between 60-100 ℃ for zinc sulphate monohydrate formed;

When heated to 280 ℃, all kinds of hydrate completely lose crystal water,

At 680 ℃, decomposed into oxygen sulfate zinc;

At 750 ℃ above, it further decomposed;

At 930 ℃ or so, decomposed into zinc oxide and sulfur trioxide.

Therefore, sulphate monohydrate is often called as hot crystallization; zinc sulphate heptahydrate is called as cold crystallization.