Copper sulfate generally refers to the sulphate salts of copper: copper (I) sulphate and copper (II) sulfate. It is soluble in water but insoluble in alcohol. Anhydrous copper sulphate is a white crystalline solid, while the hydrated salt is blue. Prepared by the treatment of copper oxides with sulfuric acid, it is commercially available as a pentahydrate compound containing five molecules of water (CuSO4•5H2O) and is known in commerce as blue vitriol. Copper sulphate, blue stone, blue vitriol are all common names for pentahydrated cupric sulphate, which is the best known and the most widely used of the copper salts.
Cupric sulfate is the most important salt of copper, utilized chiefly for agricultural and chemical industries. It also finds wide use in medicine and pigment industries.
In the production of copper sulphate virgin copper is seldom, if ever, used as the starting raw material. Copper ores are used in countries where these are mined. For the bulk of the world's production nonferrous scrap is the general source. The scrap is refined and the molten metal poured into water to produce roughly spherical porous pieces about the size of marbles which are termed "shot". This shot is dissolved in dilute sulphuric acid in the presence of air to produce hot saturated liquor which, if the traditional large crystals of copper sulphate are required, is allowed to cool slowly in large cooling vats into which strips of lead are hung to provide a surface for the crystals to grow on. If the granulated (snow) crystal grades are desired, the cooling process is accelerated by agitating the liquor in water cooled vessels.
Other methods of production are:
1. By heating copper scrap with sulphur to produce copper sulphide which is then oxidized to form copper sulphate.
2. By heating copper sulphide ores to produce copper oxide which is then treated with sulphuric acid to form copper sulphate.
3. By slow leaching in air of piles of low grade ore. Bacterial action is sometimes employed to hasten the process. A solution of copper sulphate drains away from such heaps.
The pentahydrate salt of copper sulfate is used as a fungicide. Together with lime, copper sulphate makes up the Bordeaux mixture, used to control fungus on grapes and other berries. As an herbicide, it helps control invasive exotic aquatic plants and the roots of other invasive plants near various pipes that contain water. A dilute copper sulfate solution is used to treat various parasitic infections in aquarium fish, remove snails from aquariums, or control algae population.
It is used to flotation reagent in the concentration of ores. Copper sulfate exhibits an activating effect on the flotation of sphalerite. It acts directly on the mineral surface, increase the selectivity of collector adherence to the surface of sphalerite, increase the strength of the adherence, reduce the amount of collector used, and impart optimum stability to the mineralized froth.
Copper sulphate is used in copper production during electro-winning and electro-refining. Both processes use electroplating on a large scale and are important techniques for the economical and straightforward purification of copper.
It also functions as a catalyst in some organic syntheses and as a reagent in various analytical tests, It is used as a mordant in dyeing Reagent in tanning processes. It is used to etch zinc plates for intaglio printmaking.