Manufacture of Zeolite-A (Detergent Builder) from Bauxite or Bauxite Leachate (Bayer liquor)

Due to the increased demand of detergent powders, and increased awareness about the polluting effects of phosphate builders, demand for Zeolite-A is likely to increase substantially in number of developing countries.

When the first heavy-duty detergents were marketed at the beginning of 19^th century, the first builders it contained was sodium carbonate and sodium silicate. From the 1930s onwards, the more effective sodium phosphates performed the role of builders. The introduction of "phosphate-reduced (1976)" and later "phosphate-free detergents (1983)" marked the beginning of the era of builder systems containing zeolites. Tested under critical conditions, the phosphate-free builder system containing zeolite even proved superior to the earlier sodium triphosphate system.

Detergent grade Zeolite-A is a crystalline aluminosilicate with a three dimensional micro porous structure built up from SiO₄^- and AlO₄^- tetrahedrons in which the negative charges are compensated by extra framework mono or multivalent cations. These cations can easily be exchanged from a solution to Zeolite or vice versa without affecting the lattice structure. This cation exchange property of Zeolites is responsible for its action as a water softener wherein calcium cations present in water are exchanged with sodium ions of the zeolite. This explains its commercially very important application as a water softener in house hold detergents, substituting sodium tripolyphosphate. In recent years, there has been an upsurge of interest in use of Zeolite-A as a builder in the detergent powder. The most important reason is the increased awareness and concern about the polluting effect on the environment caused by the phosphates, the conventionally used builder in the detergent formulation.