Process for removing reactive silica from a bayer process feedstock

A process for the removal of reactive silica from a feedstock to the digestion step of the Bayer process for the manufacture of alumina, comprising the steps of:

• (a) contacting the Bayer process feedstock with a caustic liquor under process conditions which result in dissolving and stabilizing at least 50% of the silica into solution at a level of at least 3 gpL and without significant precipitation from solution of dissolved silica, said process conditions comprising:
• (i) caustic liquor composition:
• caustic strength (as Na2CO3) greater than 250 gpL alumina concentration (as Al2O3) greater than 125 gpL;
• (ii) contact temperature with caustic liquor:
• 60° C.-125° C.;
• (iii) contact time with caustic liquor:
• greater than 20 minutes;
• to produce a silica bearing liquor and a solid residue;
• (b) separating the silica bearing liquor from solid residue of step (a) under conditions which do not promote significant precipitation of the silica;
• and
• (c) precipitating aluminosilicates from the separated silica bearing liquor from step (b), and forming a solid aluminosilicate product which is free of a majority of all other components of the feedstock.