Technologies Salt and Marine Chemicals

Pharma and halogen grade synthetic hydrotalcites (SHT) from bitterns

Inventor: P M Oza

IPR Status: US Patent No: 7,022,302

An improved process is described for the preparation of surface modified hydrotalcite. The process comprises reacting a precursor of magnesium and aluminium in the presence of suitable alkali carbonate at high temperature. The product has a BET surface area of 20M2/gm and average particle size of 5 micorns and is useful as halogen scavenger and fire retardant.

Advantages of the invention:

(i) Cheap and easily available sea bittern and non-ferric alum has been used as a source of magnesium and aluminium compound respectively.
(ii) The mother liquor after crystallization can be reused.
(iii) The process does not require costly equipment for drying i.e. spray drier.
(iv) (iv) Product having less surface area (20M2/gm) and fine particle size (average 5 microns) and at least 90% (by volume) particles are under 1 micron) and free from amorphous as well as crystalline impurities, can be obtained with less energy intensive step of 4 -5 hrs of heat crystallization at C.


Technology licensed to:

Yet to be licensed