Abstract
A small quantity of boric acid is often absorbed into magnesium hydroxide crystals precipitated by the reaction between bittern and milky lime. Concerning this phenomenon, some studies have already been reported on production of magnesium hydroxide through absorption of boric acid to its crystals (Bulletin of the Society of Salt Science, Japan 14, 234, 275 (1960)).
The present authors studied on some of the effects of the boric acid as mineralizer to the thermal properties of magnesia clinker produced by firing such magnesium hydroxide.
The results were summarized as follows: boric acid easily dissolved into the crystal lattice of periclase at high temperature, as easily as silicon oxide and ferric oxide a solid solution contained boric acid was quickly formed among periclase particles at a temperature lower than the usual firing temperature of clinker, and its constructure was more stable than that of solutions of other components. By X-ray analysis, the mineralogical composition of bond part was found to be mainly Mg3(BO3)2. If the absorbed amount of boric acid was increased by more than 1.0 per cent as B2O3, the themal properties of the clinker would deteriorate remarkably with the increasing volume of bond part.
Sea water magnesia generally contains a little of lime, silica, alumina, ferric oxide etc., as impurities. The absorbed boric acid was found to form several complex double salts with these components which in turn that phase promoted crystallization of periclase.
