Seven water zinc sulfate and zinc vitriol, zinc vitriol, relative molecular mass of 287.56, the appearance is white granular or powder, belong to orthorhombic system, relative density 1.97. Gradually the weathering in dry air, production methods mainly include sulfuric acid method and smithsonite method.

Sulfuric acid method to produce seven water zinc sulfate is the use of sulphuric acid to dissolve all kinds of zinc or zinc oxide materials, such as zinc powder byproduct of insurance powder production, defective zinc oxide, metal processing industry and non-ferrous metallurgical industry of scrap, zinc slag, zinc, etc.

Zinc material after ball mill grinding, dissolved in 18% ~ 18% of the sulfuric acid dissolution. When dissolved in the lining have acid materials, such as lead-lined and reaction kettle with a blender.

Reaction is exothermic temperature rises to more than 80 ℃. If the material contains contains a lot of metal zinc, it will produce large amounts of hydrogen, as a result, the reaction kettle must have strong exhaust device.

Seven water zinc sulfate to speed up the late reaction speed, can join excess zinc material. Reaction at the end of the PH control at around 5.1, slurry by the clarification of filter.

Residue contains zinc should be lower than 5%. Out of zinc sulfate in the filtrate, still contain metal impurity generated corresponding sulfate in the material. Remove the impurities can be divided into two steps.

The first is to remove copper, nickel, etc, and then to remove iron. Filtrate the displacer heated to 80 ℃, and join the zinc powder, strong stirring 4 ~ 6 h. As a result of the zinc reduction potential was lower than those of copper, nickel, cadmium, replacement out these metals from the solution.

After the replacement of the solution by filter, remove fine shape metal slag, mud filtrate dishes into oxidation, heated to 80 ℃, adding sodium hypochlorite and potassium permanganate as high iron and manganese dioxide oxidation, oxidation after adding suitable amount of lime milk, make the high price of iron hydroxide precipitation after filtering.

Use bleach, after precipitate out solution to a boil, destroy the rest of the bleaching powder, using potassium permanganate, with free acid precipitation, can be adjusted join zinc oxide solution PH value of 5.1.

The filtrate through evaporation concentration, cooling below 25 ℃, seven water zinc sulfate crystallization ZnSO4 · 7 h2o, precipitation by dehydration, drying, see below.