Aluminium sulfate is a chemical compound with the formula Al2(SO4)3. It is soluble in water and is mainly used as a coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking water and wastewater treatment plants, and also in paper manufacturing.
The anhydrous form occurs naturally as a rare mineral millosevichite, found e.g. in volcanic environments and on burning coal-mining waste dumps. Aluminium sulfate is rarely if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al2(SO4)3•16H2O and octadecahydrate Al2(SO4)3•18H2O are the most common. The heptadecahydrate, whose formula can be written as [Al(H2O)6]2(SO4)3•5H2O, occurs naturally as the mineral alunogen.
Aluminium sulfate is sometimes called alum or papermaker's alum in certain industries. However, the name "alum" is more commonly and properly used for any double sulfate salt with the generic formula XAl(SO
4)
2·12H
2O, where X is a monovalent cation such as potassium or ammonium.
Production:
Aluminium sulphate may be made by adding aluminium hydroxide, Al(OH)3, to sulfuric acid, H2SO4:
2 Al(OH)3 + 3 H2SO4 → Al2(SO4)3+6H2O
or by heating aluminium metal in a sulfuric acid solution:
2 Al(s) + 3 H2SO4 → Al2(SO4)3 + 3 H2 (g)
From alum schists:
The alum schist employed in the manufacture of aluminium sulfate are mixtures of iron pyrite, aluminium silicate and various bituminous substances, and are found in upper Bavaria, Bohemia, Belgium, and Scotland. These are either roasted or exposed to the weathering action of the air. In the roasting process, sulfuric acid is formed and acts on the clay to form aluminium sulfate, a similar condition of affairs being produced during weathering. The mass is now systematically extracted with water, and a solution of aluminium sulfate of specific gravity 1.16 is prepared. This solution is allowed to stand for some time (in order that any calcium sulfate and basic ferric sulfate may separate), and is then evaporated until ferrous sulfate crystallizes on cooling; it is then drawn off and evaporated until it attains a specific gravity of 1.40. It is now allowed to stand for some time and decanted from any sediment.
Dubichem chemicals international is a leading supplier, manufacturer and exporter of Aluminum sulfate in Dubai, Ajman, Abu Dubai, Sharjah, Fujairah, Turkey, Saudi Arabia, Qatar, Kuwait, United Arab Emirates, omen, Iraq, Singapore, Malaysia, Indonesia, Lebanon, Greece, India, Sudan, Ghana, Madagascar, Kenya, Nigeria, Zimbabwe, at Dubichem@gmail.com and for more related products visit www.dubichem.com
