Optimization to obtain sodium pentaborate from ulexite with pure carbondi̇oxi̇de and flue gas under pressure and at atmospheric pressure and at atmospheric pressure

Ulexite is one of the most important boron ores of our country. Presently, boric acid is produced by reaacting ulexite with sulphuric acid in some countries. To produce another boron compounds from this ore is important, too. In this study, optimum conditions of dissolution of ulexite have been investigated in water saturated with CO2. For this purpose, optimization of dissolution of original ulexite ore and ulexite ore calcined at 160oC have been examined in water saturated with CO2 at atmospherical pressure. Also, this optimization has been realised for dissolution of original ulexite ore in aqueous media under CO2 pressure. Temperature, particle size, solid to liquid ratio and reaction time have been chosen as parameters in the experiments carried out with pure CO2 and synthetical flue gas at atmospherical pressure. The parameters chosen for studies under pure CO2 pressure are temperature, particle size, solid to liquid ratio, reaction time and pressure, too. In experiments carried out with original ore using pure CO2 under the atmospherical conditions, optimum conditions of dissolution have been found out 70oC for temperature(A3), -250 µm for particle size(B1), 120 min for time(C3) and 125 g/500 g su for solid to liquid ratio(D1). Theoretical estimation value is 94.65%, observed value, 92.36% and confidence limit, 94.65% ±8.94. In experiments carried out with ore calcined at 160oC using pure CO2 under the atmospherical conditions, optimum conditions of dissolution have been found out 90oC for temperature(A4), -75 µm for particle size(B3), 60 min for time(C1) and 100 g/500 g su for solid to liquid ratio(D1). Theoretical estimation value is 95.42%, observed value, 93.45% and confidence limit, 95.42% ±13.86. In experiments carried out with original ore using flue gas prepared synthtically under the atmospherical conditions, optimum conditions of dissolution have been found out 55oC for temperature(A2), -125 µm for particle size(B4), 150 min for time(C4) and 165 g/500 g su for solid to liquid ratio(D2). Theoretical estimation value is 73.55 %, observed value, 71.1% and confidence limit, 73.55% ±23.61. In experiments carried out with original ore using pure CO2 under pressure, optimum conditions of dissolution have been found 75 g/300g water for solid to liquid ratio(A1), 15 bar for pressure(B3), 80oC for temperature(C1), 60 min for time(D3) and -150µm for particle size(E1). Theoretical estimation value is 100,00 %, observed value, 97.45% and confidence limit, 100,00% ±3.18. The solutions from experiments with pure CO2 under pressure were dried in spray drier or after it was concentrated up to 1.25 g/mL of density, was crystallized. A product including 69% B2O3, Na2B10O16.6H2O was obtained in spray drier and a product including 59% B2O3, Na2B10O16.10H2O was obtained.