Fly Ash Grinding Mill
Grinding Mill Specially for Fly Ash Powder
Experiments have proved that the mechanical pulverization/grinding method is very effective for the coarse ash activity. With the help of fly ash grinding mill, the coarse and porous glass body is crushed, the glass particles are released from bonding, the bead particles are increased, the particles themselves have less pores, the surface property are improved, the friction during the mixing process is improved, and physical activity is also increased. When grinding, the solid protective film is destroyed, so that the internal soluble SiO2, Al2O3 is dissolved, and specific surface area and the chemical activity are also increased.
Fly ash grinding mill can strength the effect of fly ash, which can be proved by the microscopic comparison between the coarse fly ash and fine fly ash. The size of the ground fly ash particles is uniform.
Fly Ash Grinding Mill to Improve Fly Ash Application
With the help of fly ash grinding mill, the coarse fly ash is ground into fine powder, which not only can increase the activity of the fly ash, but also reduce the water demand ratio. So the fly ash can be made full use. For example, fly ash improves concrete performance mainly due to the presence of 10 ~ 40μm particles. Long time ago, the fly ash had been put into the cement clinker to improve the cement quality. Due to the different abrasiveness of fly ash and clinker, the particles of cement are relatively coarse (80 μm). Fly ash is not fine enough to make full use of its activity. In addition, there are also a small number of users who grind fly ash directly with cement in the grinding mill. Due to the different chemical composition of fly ash and cement, the physical properties are quite different, and the grinding ratio is also very different, which bring low grinding efficiency, high power consumption, low output and high grinding ash cost.
Fly Ash Grinding Mill Structure:
According to the characteristics of fly ash, a special ultra-fine grinding mill for fly ash is used. The tube mill is a very mature equipment with a history of more than a hundred years, it has grinding body, grinding ball, bearing support and driving device. In this article, we put more focus on its internal structure.
1 Grinding ball or Grinding rod
The size, shape and gradation of grinding ball or grinding rod are thekeys to grinding efficiency and the final fineness and particle gradation. Wetested spherical, ellipsoidal, rod-shaped, truncated cone and other forms ofgrinding bodies to determine the appropriate shape of the grinding body. Themaximum ball diameter is related to the particle size, hardness, and productfineness of fly ash. There are many calculation formulas, and the calculationresults are also different. Through experimental comparison, and through a 1.8m grinding mill, the actual maximum ball diameter is 16 mm. The gradation ofthe grinding body is adjusted according to the shape of each fly ash and thetarget fineness of the final product. Ball diameter is between 4 ~ 16 mm.
Becauseinput fly ash size is very small, the factor that influence grinding is not theimpact force, it is grinding times. The special fly ash grinding mill for fly ashuses micro-abrasive bodies as the grinding medium. The number of grindingbodies is about 20 times that of ordinary steel sections. Therefore, the numberof grinding times for fine powder is increased, and the grinding effect isgreatly enhanced; at the same time, the surface area of the grinding body isincreased. It also improves grinding efficiency.
2 Fly Ash Grinding Mill Classifying andActivating Device:
The special grinding mill for fly ash uses micro-abrasive bodies toachieve the purpose of grinding fly ash. The internal structure of aconventional cement mill cannot be adapted to such an abrasive body withoutmodification.
Generally, the fly ash grinding mill is provided with a coarse grindingchamber and a fine grinding chamber. When the fly ash enters the fine grindingbin from the coarse grinding bin, then firstly sorted by a screening device,and the screening device returns the coarse powder to the coarse grinding bin,and the fine powder enters the fine grinding bin. As the screening deviceselects the fine powder in time, the coarse powder content of the coarsegrinding chamber increases, and the fine powder content decreases. The sievingdevice, like the powder separator of the closed circuit system, can separatematerials with qualified particle size.
Afterthe micro-abrasive body is used, due to the more inlaying and entrainmentbetween the layers of the abrasive body, the relative sliding between theabrasive bodies is less, and the exchange and transfer between the layers isdifficult to occur, that is, an abrasive body is retained. Belt, is extremelydetrimental to grinding efficiency and quality. In order to eliminate thisretention zone, an activation device was designed and penetrated into theretention layer. With the rotation of the mill, the activation device broke upand destroyed the retention zone, so that all the micro-abrasive bodies gainedenergy and participated in the grinding. , Greatly improve the grindingefficiency.
3. Fly Ash Grinding Mill Output Device
The small grinding ball or rod is easy to slip out of the mill and mixinto the finished product. For this purpose, a semi-overflow discharge casterand screening device have been specially designed. On the other hand, themicro-segment is prevented from slipping out of the mill, and at the same time,a small number of broken steel segments are forcibly returned to the finegrinding bin with the micro-segment return device.
4 Air speed in the grinding mill chamber:
The air speed in a cement mill is generally around 1.2 m / s, which istoo fast for fly ash. The air speed in the mill should be determined at aboutfive times the suspension speed of the 40μm powder. Experiment has proved thatthis speed is correct.