Based on the thermodynamic analysis of the reaction law between sodium hydrate alumino-silicate and hydrogarnet,it is found that hydrogarnet with more amount of SiO_2(x>1) can not be decomposed by caustic solution easily,while hydrogarnet with x<0.

The alumina recovery from the hydrate garnet after the alkali recovery from sodium hydrate alumino-silicate was studied.

And adding of CaO leads to formation of hydrate garnet.

Studying the adding calcium hydrating garnet into high pressure digestion in Bayer process;