Study On Reactive Activity Of Paigeite From Wengquangou

Boron ore is a rare chemical mineral.Boron and boron compounds are widely used in chemical industry,metallurgy,optical glass,national defense,atomic energy,medicine, rubber,light industry and so on.Main boron mineral resources in China are ascharite ore and paigeite.Ascharite ore directly available,nearly exhausted through many years of exploitation, can not fully meet the future needs of boron chemical production.Paigeite,a kind of endogenetic boron mineral,is one of the most important boron resources in China and accounts for 58 percent of the total of boron mineral resources in China.Paigeite reserves in Liaodong region reach 280 million tons,in which B₂O₃ reserves are 21.84 million tons.It belongs to a large boron mineral and its major ore types include ludwigite-magnetite type and ascharite-magnetite type.However,the conventional separation method for it is difficult because of its complex structure and more associated mineral.Therefore,the expedite development and utilization of paigeite resources is of important practical significance in the short supply of boron resources in our country.In this study,with respect to the low reactive activity of paigeite from Wengquangou for the manufacture of borax by the CO₂-soda process,a new process of sodium activated calcination for paigeite was employed.The experiments of calcinations without any additive and sodium activated calcinations were carried out for the ludwigite-magnetite paigeite,boron concentrate and ascharite-magnetite paigeite from Wengquangou.The reactive activity of calcined paigeite can be evaluated by the alkaline hydrolysis ratio at atmospheric pressure and the pressurized water emmersion ratio.The effects of additive type,method of extracting boron,additive addition,calcining temperature and calcining time on the reactive activity of calcined paigeite were investigated,respectively.The results show that the reactive activity of calcined paigeite is obviously increased after the sodium activated calcination by using the additive Na₂CO₃ and with pressurized water leaching method for extracting boron.The suitable processing conditions are obtained.For the ludwigiteomagnetite paigeite from Wengquangou the suitable processing conditions are that the Na₂CO₃ addition is 19%by weight of original mineral,calcining temperature 950℃and calcining time 2 h,and its reactive activity after calcination reaches 93.30%under the suitable condition.For the ludwigite-magnetite boron concentration from Wengquangou the suitable processing conditions are that the Na₂CO₃ addition is 26.7%by weight of original mineral,calcining temperature 950℃and calcining time 2 h,and its reactive activity after calcination reaches 90.49%under the suitable condition.For the ascharite-magnetite paigeite from Wengquangou the suitable processing conditions are that the Na₂CO₃ addition is 18.3%by weight of original mineral,calcining temperature 950℃and calcining time 2 h,and its reactive activity after calcination reaches 92.19%under the suitable condition.The mechanism of improving the reactive activity of calcinated paigeite and boron concentration with the addition of Na₂CO₃ is also discussed in this research by using the thermal analyse,XRD and SEM analyses.The results show that Na₂O decomposed by Na₂CO₃ at the temperature more than its melting point reacts with SiO₂ and mica at first. After the reaction of Na₂O with these minerals it can react with suanite and ludwigite which is decomposed into magnetite and soluble sodium borate,Therefore,the reactive activity of paigeite and boron concentration from Wengquangou after sodium activated calcination can be improved.The sodium activated calcination process is simple and practicable and provides a new way for the comprehensive utilization of paigeite from Wengquangou.