A device including an LED light source optically coupled to a green-emitting U.sup.6+-doped phosphor having a composition selected from the group consisting of U.sup.6+-doped phosphate-vanadate phosphors, U.sup.6+-doped halide phosphors, U.sup.6+-doped oxyhalide phosphors, U.sup.6+-doped silicate-germanate phosphors, U.sup.6+-doped alkali earth oxide phosphors, and combinations thereof, is presented. The U.sup.6+-doped phosphate-vanadate phosphors are selected from the group consisting of compositions of formulas (A1)-(A12). The U.sup.6+-doped halide phosphors are selected from the group consisting of compositions for formulas (B1)-(B3). The U.sup.6+-doped oxyhalide phosphors are selected from the group consisting of compositions of formulas (C1)-(C5). The U.sup.6+-doped silicate-germanate phosphors are selected from the group consisting of compositions of formulas (D1)-(D11). The U.sup.6+-doped alkali earth oxide phosphors are selected from the group consisting of formulas (E1)-(E11).

A device including an LED light source optically coupled to a green-emitting U.sup.6+-doped phosphor having a composition selected from the group consisting of U.sup.6+-doped phosphate-vanadate phosphors, U.sup.6+-doped halide phosphors, U.sup.6+-doped oxyhalide phosphors, U.sup.6+-doped silicate-germanate phosphors, U.sup.6+-doped alkali earth oxide phosphors, and combinations thereof, is presented. The U.sup.6+-doped phosphate-vanadate phosphors are selected from the group consisting of compositions of formulas (A1)-(A12). The U.sup.6+-doped halide phosphors are selected from the group consisting of compositions for formulas (B1)-(B3). The U.sup.6+-doped oxyhalide phosphors are selected from the group consisting of compositions of formulas (C1)-(C5). The U.sup.6+-doped silicate-germanate phosphors are selected from the group consisting of compositions of formulas (D1)-(D11). The U.sup.6+-doped alkali earth oxide phosphors are selected from the group consisting of formulas (E1)-(E11).

Some embodiments include a molten salt system comprising a reactor with a salt mixture. In some embodiments, the salt mixture includes uranium and a eutectic salt. The eutectic salt may include one or more of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, calcium fluoride, sodium chloride, potassium chloride, aluminum chloride, zirconium chloride, lithium chloride, beryllium chloride, rubidium chloride, magnesium chloride, and calcium chloride. The eutectic salt may have a melting point less than about 800 C.

Some embodiments include a molten salt system comprising a reactor with a salt mixture. In some embodiments, the salt mixture includes uranium and a eutectic salt. The eutectic salt may include one or more of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, calcium fluoride, sodium chloride, potassium chloride, aluminum chloride, zirconium chloride, lithium chloride, beryllium chloride, rubidium chloride, magnesium chloride, and calcium chloride. The eutectic salt may have a melting point less than about 800 C.

Some embodiments include a method comprising: flowing a molten salt out of a molten salt reactor at a first temperature, heating the molten salt reactor to a second temperature above the melding point of the second salt mixture causing the second salt mixture to melt; flowing the second salt mixture out of the molten salt reactor; flowing a third salt mixture into the molten salt reactor; and cooling the molten salt reactor from the second temperature to a third temperature causing the third salt mixture to solidify on the interior surface of the housing. In some embodiments, the molten salt may include a first salt mixture comprising at least uranium. In some embodiments, the first temperature is a temperature above the melting point of the first salt mixture.

A method for recovering lithium from low-content extraction tailwater and recycling extraction tailwater is provided. The disclosure is characterized that recovery of lithium from lithium-containing extraction tailwater is achieved by adding calcium to remove fluorine, carrying out evaporative crystallization and precipitating lithium salts. Recycle of extraction tailwater is achieved by adopting the following steps: in the lithium-containing extraction tailwater, adding calcium to remove fluorine, carrying out evaporative crystallization, recovering condensate water, precipitating a lithium salt and recycling mother liquor. According to the disclosure, lithium is recovered from low-content extraction tailwater via enrichment and sodium sulfate and distilled water therein are incidentally recovered, so that zero release of battery waste treatment wastewater is achieved.

A method for recovering lithium from low-content extraction tailwater and recycling extraction tailwater is provided. The disclosure is characterized that recovery of lithium from lithium-containing extraction tailwater is achieved by adding calcium to remove fluorine, carrying out evaporative crystallization and precipitating lithium salts. Recycle of extraction tailwater is achieved by adopting the following steps: in the lithium-containing extraction tailwater, adding calcium to remove fluorine, carrying out evaporative crystallization, recovering condensate water, precipitating a lithium salt and recycling mother liquor. According to the disclosure, lithium is recovered from low-content extraction tailwater via enrichment and sodium sulfate and distilled water therein are incidentally recovered, so that zero release of battery waste treatment wastewater is achieved.

A process for preparing synthetic calcium fluoride (CaF.sub.2) (min 90% CaF.sub.2 by weight) from fluosilicic acid is provided. The processes comprises the steps of (a) reacting fluosilicic acid (H.sub.2SiF.sub.6) with ammonium hydroxide or ammonia in a first reactor so as to obtain a first slurry and filtering the first slurry so as to obtain a filtrate containing a solution of ammonium fluoride (b) precipitating the solution of ammonium fluoride with calcium in a second reactor so as to produce a second slurry containing calcium fluoride and (c) evolving the major part of ammonia from the second reactor and then scrubbing and returning said ammonia to the first reactor.

A process for preparing synthetic calcium fluoride (CaF.sub.2) (min 90% CaF.sub.2 by weight) from fluosilicic acid is provided. The processes comprises the steps of (a) reacting fluosilicic acid (H.sub.2SiF.sub.6) with ammonium hydroxide or ammonia in a first reactor so as to obtain a first slurry and filtering the first slurry so as to obtain a filtrate containing a solution of ammonium fluoride (b) precipitating the solution of ammonium fluoride with calcium in a second reactor so as to produce a second slurry containing calcium fluoride and (c) evolving the major part of ammonia from the second reactor and then scrubbing and returning said ammonia to the first reactor.

A method of producing a product inorganic compound including: immersing a raw material inorganic compound having a volume of 10.sup.13 m.sup.3 or more in an electrolyte aqueous solution or an electrolyte suspension; exchanging anions in the raw material inorganic compound with anions in the electrolyte aqueous solution or the electrolyte suspension; cations in the raw material inorganic compound are exchanged with cations in the electrolyte aqueous solution or the electrolyte suspension; or including a component (that excludes water, hydrogen, and oxygen) in the electrolyte aqueous solution or the electrolyte suspension not included in the raw material inorganic compound in the raw material inorganic compound; and obtaining a product inorganic compound having a volume of 10.sup.13 m.sup.3 or more from the raw material inorganic compound.