Study On Preparation Of Borax Through Calcining With Boron Concentrate And Sodium

Our nation is abundant of boron resource. Except of national borax of Tibet and Qinghai, most of resource centralized in Liaodong in the form of ascharite and paigeite. Paigeite reserve in Liaodong region reaches280million tons and it belongs to a large boron mineral. For now, ascharite is the main raw material of production of boric acid and borax. Although boron resource in Liaoning Province is rich, the dilution trend of ascharite is clearly after50years of substantial mining. The average grade of ascharite decreases from18%to12%since the early sixties of the20th century. Moreover, the average grade of ascharite used in processing enterprises is only about10%. It is difficult for processing because of its complex structure and more associated mineral. The expedite development and utilization of pageite resource is of important practical significant in the short supply of boron resource in our country.Boron concentrate separated from paigeite by magnetic and gravity separationm and the grade of boron is about10%that can be raw material of borax by replace of ascharite. In this study, with respect to low recovery and pressurized reaction of paigeite for the manufacture of borax by CO2-soda, a new process of sodium calcination for boron concentrate was employed. The experiment of calcinations mixed different conversion agent of single or complex for calculating the leaching rate of boron. Calcining temperature and time, mass of alkali, water leaching temperature and time, liquid-solid ratio were investigated for determining the most technological conditions, respectively.The results show that:the optimum conditions of Na2CO3are that the calcination temperature850℃, addition of Na2CO3is5times of theoretical mass, calcination time3h, leaching temperature99℃, liquid-solid ratio10:1, leaching time2h and it reaches86.27%; the optimum conditions of NaOH are that the calcination temperature600℃, addition of NaOH is10times of theoretical mass, calcination time3h, leaching temperature99℃, liquid-solid ratio10:1, leaching time3h and it reaches95.31%; the optimum conditions of mixed NaOH-Na2CO3are that the calcination temperature700℃, NaOH:Na2CO3is3:1, calcination time3h, leaching temperature99℃, liquid-solid ratio10:1, leaching time2h and it reaches87.19%.Lixivium after leaching of sodium was adjusted to pH9using hydrochloric acid can get amorphous state silica and borax after recrystallization.