Process for preparing crystalline calcium hexaborate tetrahydrate

摘要

In the present invention, there is disclosed a process for producing crystalline calcium hexaborate tetrahydrate, which process comprises reacting boric acid and lime in an aqueous slurry, at a temperature in the range of from about 60 to about 85 degC, wherein the molar ratio of boric acid to water is greater than about 0.25 : 1, and the molar ratio of lime to boric acid is in the range of about 0.05 to about 0.15 : 1, wherein said reactants are present in a concentration sufficient to provide at least 25 percent by weight undissolved solids in the aqueous product slurry, and separating said crystalline calcium hexaborate tetrahydrate from said aqueous product slurry. Dehydration of the calcium hexaborate tetrahydrate is carried out at a temperature above 35 degC. The product has many industrial applications. It is used as a source of boron in fiberglass manufacture when the desired glass composition requires that sodium addition be limited, such as for textile fiberglass. It is also useful as fire retardant agent in such materials as plastics and rubber polymers, cellulosics, resins and oils, etc. Further, it is useful in the manufacture of steel and ceramics.