What methods of producing boric acid? Appropriate chemical industry

there are many ways to the production of boric acid and today to introduce several kinds of method: 1, borax acid neutralization after dissolved the borax. Add sulfuric acid manufacture boric acid system. 2, carbon ammonia method will boron ore powder mixed with ammonium bicarbonate solution, after heating heating decomposed with boric acid material liquid ammonia, then through off of ammonia, a quick boric acid. 3, well salt brine hydrochloric acid method. By boron halide cooking with hydrochloric acid, then through dehydration, crystallization, drying for a quick boric acid. 4, hydrochloric acid. Boron concentrate with hydrochloric acid solution, then through filtration, crystallization and drying, for a quick boric acid.