Experimental Research On Beneficiation Of Low-grade Bauxite With Compound Field

It is well known that the direct or indirect energy consumed in alumina production by Bayer process is far lower than that by sintering method and combination method, and the required A/S for producing alumina by Bayer process should be above 8However, the A/S of 75% of bauxite in our country is less than 7 and it can not meet the demand of Bayer process. Therefore, it is necessary to apply desiliconization technology for diasporic bauxite and improve the A/S of it.In this paper, separation tests were carried out generally in compound field of cyclonic centrifugal and gravitational with low-grade bauxite (A/S=4.39). The main conclusions are as the following:(1) The separation results of cyclonic gravitational tests showed that when the diameter ratio of apex to vortex was 0.71, feed concentration was 7.9%, feed pressure was 0.15MPa, the separation index was the best, namely, the A/S of underflow production was 5.71, the A/S of overflow production was 2.17, the recovery of Al2O3 in underflow was 82.41%, the recovery of SiO2in overflow was 35.95%. The size analysis indicates that feed pressure, feed concentration, the diameter ratio of apex to vortex all have some influence on the classification efficiency.(2) The separation results of cyclonic-reverse flotation showed that when feed pressure was 0.2MPa, air pressure was 0.3MPa, air flow was 0.2m3/h, dosage of modified starch II was 1200g/t, dosage of laurylamine acetate was 150g/t, the separation index was the best, namely, the A/S of underflow production was 6.10, the A/S of overflow production was 2.26, the recovery of Al2O3 in underflow was 79.41%, the recovery of SiO2 in overflow was 41.19%. The quality of underflow by cyclonic-reverse flotation was better than that by cyclonic gravitational separation.(3) The feed grindings had great effect on the technical index of cyclonic-reverse flotation, under the condition of different types of adjusting reagent and different dosage of collector, the separation index attained to optimization when the grinding was 60%-0.074mm.(4) In the process of cyclonic-reverse flotation, air flow had a definite effect on the separation of mineral particles:The increasing of air flow will weaken the classification effect in compound field, but a little of air flow will strengthen the separation effect.