Thermal Properties of Hydroboracite

SILVANA K. VALDEZ; HORACIO R. FLORES

Handbook on Borates: Chemistry, Production and Applications

Nova Science Publishers

Lugar: Nueva York; Año: 2009; p. 461 - 468

The elevated content of hydration water of borates allows using a calcination technique to increase the B2O3 content of borate ores and preconcentrated minerals. Pure hydroboracite (CaO.MgO.3B2O3.6H2O) has 26.1% of hydration water, thus using calcination allows increasing its B2O3 content from 50.6% to 68.5%. In this chapter the reaction of thermal decomposition is analyzed by measuring the weight loss during the heating of the sample at constant rate until constant weight is achieved. In addition, the heat content and the specific heat at different temperatures were determined by means of an isoperibol calorimeter. The sample of hydroboracite to be tested had 44.6% of B2O3 (88.0% of purity). The temperature was between 200 and 800ºC, obtaining weight losses of 25.2%. The curves of weight losses and heat content are shown and analyzed. The results obtained are useful when determining the thermal requirement for calcining hydroboracite at different temperatures including anhydration (total dehydration).2O3 content of borate ores and preconcentrated minerals. Pure hydroboracite (CaO.MgO.3B2O3.6H2O) has 26.1% of hydration water, thus using calcination allows increasing its B2O3 content from 50.6% to 68.5%. In this chapter the reaction of thermal decomposition is analyzed by measuring the weight loss during the heating of the sample at constant rate until constant weight is achieved. In addition, the heat content and the specific heat at different temperatures were determined by means of an isoperibol calorimeter. The sample of hydroboracite to be tested had 44.6% of B2O3 (88.0% of purity). The temperature was between 200 and 800ºC, obtaining weight losses of 25.2%. The curves of weight losses and heat content are shown and analyzed. The results obtained are useful when determining the thermal requirement for calcining hydroboracite at different temperatures including anhydration (total dehydration).