Preparation background and overview of boric acid-10B
Boron (B) has two stable isotopes: 10B and 11B. Their abundance in nature is approximately 19.8% and 80.2%. Boric acid-10B has a very strong ability to absorb neutrons and is widely used in nuclear power, military equipment, modern industry and medicine.
Among them, enriched boric acid-10B is used as a good neutron absorber in the nuclear industry. It has extremely significant advantages over naturally abundant boric acid: it can greatly increase the concentration of 10B in the reactor cooling system and reduce boric acid. overall dosage. Relevant studies have shown that the benefits of increasing 10B concentration are: enhanced reactor capacity, increased use of MOX fuel (mixed oxide), increased cycle and combustion cycles, reduced fuel consumption per cycle, significant reduction in waste liquid treatment costs, and ultimately Required fuel costs and intermediate and final storage costs.
Preparation of boric acid-10B
Preparation Report of Boric Acid-10B 1.
1. Hydrolysis reaction:
1. Add deionized water and calcium carbonate with a mass ratio of 1.5:1 to the reaction kettle, start stirring, and after mixing evenly, heat to 75°C by electric heating or jacketed steam;
2. Pour boron trifluoride-10 gas into the reaction kettle and stir continuously to make the boron trifluoride-10 gas evenly dispersed in the solid-liquid mixture of calcium carbonate and deionized water. When boron trifluoride Stop ventilation when the volume ratio of -10 gas and solid-liquid mixture of calcium carbonate and deionized water reaches 45:1;
3. The feeding speed of boron trifluoride-10 gas should ensure that the residence time of boron trifluoride-10 gas in the mixture is 15 minutes;
4. After 6 hours of reaction, keep the temperature of the reaction kettle at 75°C, and perform suction filtration or filtration of the solid-liquid mixture in the reaction kettle. The resulting filtrate is a boric acid aqueous solution, and the filter cake is a mixture of calcium carbonate and calcium fluoride; Wash the solid filter cake with deionized water, and mix the resulting washing liquid with the mother liquor. The amount of deionized water used to wash the filter cake is 1/3 of the total amount of deionized water in the reaction kettle;
2. Boric acid crystallization:
1. Add deionized water to the filtered boric acid aqueous solution to dilute, rinse and cool down. Add water in a static mixer. The deionized water and boric acid solution are in counter-current contact in the static mixer and mixed together. In the filter tank, the agitator of the filter tank continues to stir, and the boric acid concentration in the filter tank drops to 1% (wt);
2. After the temperature of the boric acid solution in the filter tank drops to room temperature, perform suction filtration or filtration of the boric acid aqueous solution in the filter tank again. The resulting filtrate is still boric acid aqueous solution, and the filter cake is a mixture of calcium fluoride and calcium carbonate. The boric acid aqueous solution Enter the evaporator;
3. Evaporate and concentrate the boric acid aqueous solution in the evaporation tank. When the temperature of the boric acid aqueous solution reaches 105°C, the solution reaches a saturated state and stops dehydration. At this time, cooling and crystallization begin, and the rotating speed of the stirring paddle is 80 rpm. After the boric acid solution is lowered to room temperature at a cooling rate of 3°C/min, the boric acid crystals obtained by filtration and drying are boron-10 acid solids; the crystallization mother liquor is recycled, and the boron-10 acid solids are dried at a constant temperature of 82°C for 15 hours to obtain boric acid. -10B.
Preparation Report 2 of Boric Acid-10B,
Weigh 55.4g of powdered lithium carbonate (Li2CO3) (0.75mol, the ratio of boron trifluoride to lithium carbonate is 1:1.5), add 277.0g of water dissolves to form a solid-liquid mixture of lithium carbonate and water. After heating the solid-liquid mixture to 40°C, slowly add 33.9g (0.5 mol) of enriched boron trifluoride 10BF3 at a rate of 10ml/min while stirring continuously. 3The access time is about 2 hours. After the introduction of boron trifluoride gas is completed, continue the reaction in the water bath at 40°C for 25 hours to promote the occurrence of reaction (6).
After the reaction is completed, the pH of the solution is around 7, and the generated lithium fluoride is a solid precipitate that is very easy to filter. Filter at room temperature to separate lithium fluoride from the mother liquor, wash the solid filter cake with approximately 100 g of deionized water, and mix the resulting washing liquid with the mother liquor.
All filtrate passes through 732 strongly acidic cation exchange resin for ion exchange at a linear speed of 1cm/min, and the small amount of lithium ions remaining in the solution is exchanged for hydrogen ions. After all the tetraethylammonium tetrafluoroborate filtrate passes through the ion exchange resin, the resin is washed with 200g of deionized water to recover the mother liquor adsorbed by the resin.
Nickel carbonate
Heat the filtrate to evaporate the water until boric acid-10B crystals precipitate. The suspension containing the precipitated solid is then cooled to approximately 0°C, and boric acid-10B crystals continue to precipitate. Filter to obtain the boric acid solid, rinse the boric acid-10B solid with deionized water, and mix the obtained filtrate with the mother liquor to continue evaporation and crystallization. Repeat the operation until no boric acid-10B solid is obtained after evaporation and crystallization. After drying at a constant temperature of 60°C for 30 hours, the boric acid-10B product was obtained. This method yields boric acid-10B with a yield of more than 95% and a purity of more than 98%.
References
[1][China invention, China invention authorization] CN201510101259.X An industrial production method of boron-10 acid and boron-11 acid
[2][China invention, China invention authorization] CN201310583193.3 A preparation method of boron-10 acid
