Boric Acid in the Form of Minerals

Boric acid is a very important chemical product and plays a very important role in various industries. It is a kind of inorganic acid. In addition to being used as a disinfectant, a pest control, a preservative, it can also be used in nuclear power plants to control the rate of uranium fission and make many boron compounds. It is a white powder or transparent crystal that is soluble in water. Boric acid is sometimes present in the form of minerals and is often found to be soluble in certain minerals, volcanic lakes or hot springs. 

Boric acid is usually prepared by reacting borax borate with sulfuric acid:
Na2B4O7 + H2SO4 + 5H2O → 4H3BO3 + Na2SO4

Or mix the boron ore powder with the ammonium hydrogencarbonate solution. And it is decomposed to a liquid obtains an ammonium borate-containing material after heating , and then deaminated to obtain boric acid. It is also possible to acidify the boron concentrate with hydrochloric acid, and to obtain boric acid after filtration, crystallization and drying.

Boric acid was first produced by Holmberg (1652-1715), which was made by a mixture of sulfuric acid and borax. Because it is extremely mild, Holmberg named it "sal sedativum Hombergi" which means " Holmberg's mild salt." Although boric acid is very stable in water, it can be decomposed into metaboric acid (HBO2) by heating it to 170°C. Boric acid is a white crystal that is less soluble in water. The metaboric acid melts at about 236°C. If it is continuously heated to 300°C, It is possible to further decompose into tetraboric acid (H2B4O7) or pyroboric acid, which is a white solid. And if it continues to heat, it will become boron trioxide.