Method for cyclic boron preparation and co-production of sodium cryolite using sodium fluoborate as intermediate

摘要

A method for the preparation of cyclic elemental boron and the co-production of sodium cryolite using sodium fluoborate as an intermediate material, which includes the following steps of: A) adding hydrofluoric acid to boric acid or boron oxide to allow a reaction at a temperature between 100 and 200 ° C to form fluoroboric acid; B) add an aqueous solution of sodium carbonate to fluoroboric acid to allow a reaction to form a solution of sodium fluoborate, concentrate, crystallize and rinse the solution of sodium fluoborate to obtain the intermediate material sodium fluoborate; C) put dried sodium fluoborate in a reactor, inject an inert gas into the reactor after vacuuming, heat the reactor to a temperature between 700 and 1000 ° C, add aluminum in the reactor and stir rapidly to allow a reaction for 4 at 6 hours to form the elemental boron and sodium cryolite, or, put the aluminum in the reactor, inject an inert gas into the reactor after vacuuming, heat the reactor to a temperature between 700 and 1000 ° C, add fluoborate dried sodium and fluid in the reactor and stir rapidly to allow a reaction for 4 to 6 hours to form the elemental boron and sodium cryolite; E) extract the molten liquid sodium cryolite, after it cools, crush it and send it to a rotary reaction boiler quantifiably together with concentrated sulfuric acid to allow a reaction at a temperature between 400 and 500 ºC to form hydrogen fluoride gas and sodium aluminum sulfate; collect the hydrogen fluoride gas and dissolve it in water to obtain an aqueous solution of hydrofluoric acid; react the sodium aluminum sulfate with an aqueous solution of sodium hydroxide after crushing the sodium aluminum sulfate, and obtain an aqueous solution of sodium sulfate after separating the solid aluminum hydroxide; and E) recycle the aqueous solution of hydrofluoric acid obtained at the front end to leach boric acid or boron oxide, in order to achieve the purpose of cyclic preparation of the intermediate material sodium fluoborate.