# Improved Technology for Rounding Graphite: Machine Structure and Industrial Test
## 3 Results and Discussion
### Rounding Effect
#### 3.1.3 Effect of the Rotating Speed of Classifier on Graphite Rounding  
Different from shaping time and shaping strength, the rotating speed of the classifier has no direct effect on particle shaping but indirectly influences the characteristics of the final product by capturing and discharging particles. Figure 6 shows the effect of the rotating speed of the classifier on the graphite rounding performance, when the rotating speed of the shaping disk was kept at 1833 rpm and the shaping period was limited to 40 min. Firstly, there is a trend that the yield increases dramatically, with the increase of the rotating speed of the classifier, while diameters containing D\({}_{10}\), D\({}_{50}\) and D\({}_{90}\) all decrease obviously. On the one hand, according to the working principle of the classifier, under the condition of constant air volume, the cutting particle size decreases with the increase of the classifier speed, which means that the number of particles captured by the classifier decreases and the number of particles remaining in the classification chamber as finished products increases [18; 19]. On the other hand, the particle with a larger diameter has greater inertia force, and the spheroidization intensity is higher, which makes D\({}_{90}\) decrease significantly, and the particle size distribution of the finished product is more concentrated. The rotating speed of the classifier has a slight effect on the tap density of the final product, but there is no obvious rule. When the rotating speed of the classifier increases from 2058 to 2646 rpm, the tap density only varies from 0.937 to 0.949 g/cm\({}^{3}\), with a small range of 0.012 g/cm\({}^{3}\). It can be obviously concluded that the rotating speed of the classifier has no direct effect on the tap density but indirectly affects the particle size distribution of the finished product. More directly, the rotating speed of the classifier has an effect on the particle size distribution of the finished product, and the particle size distribution has an effect on the tap density. Therefore, the rotating speed of the classifier should be determined according to the demand for yield and finished particle size distribution.  
Figure 5: Effect of the shaping period on the graphite rounding performance.  
3.1.4. Discussion on Degree of Sphericity of Graphite Particle Impacted by Shaping Period and Shaping Disk Rotating Speed  
Figure 7a shows the degree of sphericity of graphite particles of raw material and shaped treated for 30, 40, 50, 60, and 80 min at a shaping disk rotating speed of 1283 rpm. Figure 7b shows the degree of sphericity of graphite particles of raw material and shaped treated for 30, 40, 50, 60, and 80 min at a shaping disk rotating speed of 1467 rpm. Figure 7c shows the degree of sphericity of graphite particles of raw material and shaped treated for 30, 40, 50, 60, and 80 min at a shaping disk rotating speed of 1650 rpm. Figure 7d shows the degree of sphericity of graphite particles of raw material and shaped treated for 30, 40, 50, 60, and 80 min at a shaping disk rotating speed of 1833 rpm. It is obvious from Figure 7a-d that (1) the degree of sphericity of graphite particle increased slightly with the increase of shaping disk rotating speed from 1283 to 1833 rpm; (2) under different rotating speed conditions, the sphericity increased with the extension of shaping time, and when the shaping time reached 40 min, the increasing rate of sphericity slowed down and gradually became stable. From the aspects of yield, energy consumption and product quality, 1833 rpm and 40 min are also suitable conditions for graphite rounding.