Magnesium hydroxide recovery, for pharmaceuticals, neutralizing agent, adsorbent or flame retardant in plastics, involves separating colloidal impurities from concentrate by cross-flow membrane filtration before precipitation

摘要

Magnesium hydroxide (I) recovery from concentrated salt solutions (II) of specific density over 1.05, which also contain other precipitable impurities (III) comprises: (a) after pretreatment to convert (II) into a colloidal phase, cross-flow filtration through a membrane with a pore size = 30 Microm, preferably 0.05-0.5 Microm, to separate the finely-divided material and concentrate (III) in the colloidal phase; and (b) precipitating (I) from the permeate.