Study On Activity Of Boron Bearing Tailings From Kuandian

Boron bearing tailings were produced by boron iron ore in Dandong Liaoning because of"selecting iron and abandoning boron".In view of the problems that low activity and difficulty in processing and utilization about boron bearing tailings at present,the activity of boron bearing tailings from Kuandian Liaoning was studied in this paper,the main contents are as follows:1.Based on the anslysis results of the composition and structure of boron bearing tailings,the effects of direct calcinations method,sodium calcinations method,calcium calcinations method,ammonium sulfate calcinations method and TiO2 and ZrO2 calcinations method on improving the activity of boron bearing tailing were compared.The results show that direct calcinations method and sodium calcinations method can significantly improve the activity of boron bearing tailings,while other methods have little effect in improving activity.2.We improved the activity of boron bearing tailings with the method of direct calcinations,the effects of calcining temperature and calcining time on the activity were investigated.The results show that before the calcining temperature reaches 700 ?,the activity increases with the rise of calcining temperature,the activity reaches 70.10%at 700 ?;when the calcining temperature exceeds 700 ?,the activity presents a decreasing trend with the rise of calcining temperature as a whole.Before the calcining time reaches 2h,the activity increases with the extend of calcining time;when the calcining time exceeds 2h,the activity has a slight decrease with the extend of calcining time.The main reason for the activity improvement is that szaibelyite which is difficult in alkaline hydrolysis dehydrates and decomposes into suanite which is easy in alkaline hydrolysis by direct calcinations.3.The boron bearing tailings calcined at 700? for 2h were treated as the raw material.On the basis of shrinking core model,the kinetic equation of alkaline hydrolysis reaction in NaOH solution for boron of raw material was deduced,and the alkaline hydrolysis experiment was conducted on the raw material,the kinetic equation theoretically deduced was fit and validated according to the experiment results.The results show that the alkaline hydrolysis reaction process of boron under the experimental conditions coincide well with the shrinking core model.The kinetic equation of boron in the alkaline hydrolysis reaction process is t=42.4954[(1-X)-1/3+1/31n(1-X)-1]+0.0338[(1-X)-2/3-1].The kinetic process is mainly controlled by diffusion mechanism.Elevating the temperature of solution,increasing the concentration of NaOH solution and reducing the particle size of raw material are conducive to shorten the alkaline hydrolysis time and complete the reaction as soon as possible.4.We improved the activity of boron bearing tailings with the method of sodium calcinations,the effects of Na2CO3 addition,calcining temperature and calcining time on the activity were investigated.The results show that the optimal conditions are 5 times theoretical amount of Na2CO3,calcining temperature of 950? and calcining time of 2h.Under these conditions,the activity of boron bearing tailings reaches 86.78%.Through the mechanism analysis of sodium calcinations process,the main reason for improving the activity is that the formation of soluble sodium borate salt by the reaction of Na2O obtained from Na2CO3 with boron in boron bearing tailings.This paper can provide scientific basis for efficient comprehensive utilization of boron bearing tailings.