Research On The Activation Condition And Effectiveness Of Phosphate Rock Powder By Mechanical Chemical Process

Our country is rich in phosphate rock resource, but the low and medium grade is the main part.In order to relieve phosphorus resource crisis in our country, it’s significant to study the full use of the preparation technology of low grade phosphate rock and raise the utilization ratio of phosphate fertilizer.In this paper, three types of phosphate rocks (sedimentary type:Yichang phosphate rock and Leibo phosphate rock, metamorphic type:Huangmailing phosphate rock; endogenous type:vanadium phosphate rock mountain) are made into original phosphate fertilizer by the mechanochemical method,the structures of original phosphate fertilizers is analysised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and we use the soil culture experiment to study the influence of mechanical method combined with different phosphorus activators on phosphate rock powder effectiveness. The results were as follows:1. Mechanochemistry can significantly affect the effectiveness of P in phosphate rock powder.The results indicated that activating results were the best when the ball diameter was 15 mm and the revolution was 1500 r·min-1. The best activating time of Yichang, Leibo, Huangmailing, Fanshan is respectively 30 min,36 min,27-30 min and 28 min. According to the results, the activation effect of sedimentary and metamorphic phosphorite was favorable by mechanochemistry method.2. Mechanical activation changed the mineral structure of phosphate rock, which causes the increase of the effective phosphorus. The structural change of phosphate rock powder mainly shows:(1) The particle size was negatively related to the effectiveness of phosphate rock powder. Mechanical activation reduced the particle size of phosphate rock powder and increased its specific surface area; (2) Mechanical activation maked phosphate rock power particle uniformity, passivation, loose structure and increased the surface floe; (3) Mechanical activation maked the distribution of phosphate rock powder compositions uniform and stable, the content of C, Si significantly decreased and P^ Ca increased. (4) Mechanical activation has reduced the gangue minerals of the phosphate rock powder. The reduce of the peak intensity of X-ray diffraction peak and the increase of half peak width indicated that grain size of phosphate rock powder had decreased, it means the crystallinity has decreased and amorphousness has increased.3. The effect of impingement activation equipment is better than that of vibration activation. Used phosphorus activators in vibration activation equipment can reduce the number or times of mechanical activation. When the time of impingement activation is less than 12 min, adding 10% (NH4) 2SO4,10% NH4Cl was better. When the time is more than 12 min, adding phosphorus activators played a negative role to the increase in the rate of rock phosphate citrate acid dissolved.4. Soil culture experiment showed that mechanical activated phosphate rock powder can significantly increase the soil rapidly available p content, which is 72% higher than common phosphate rock powder; rapidly available phosphorus retention rate is higher than the treatments applied triple superphosphate. Adding activator after mechanical activation was the better way of composite activated phosphate rock powder. The effect of adding 10% ammonium sulfate or 5%ammonium chloride composite activation was better. There is no active effect of mechanical activation with adding activator at the same time.