Grinding equipment and applications (7)

The product fineness of the continuous agitating ball mill depends on the residence time of the material to be ground in the vertical cylinder, and the residence time is controlled by the conveying speed of the pump. This mill uses stainless steel balls or ceramic balls. The steel ball has a diameter of 3.2 to 6.4 mm. For finely ground calcium carbonate and clay mud used in the paper industry, and coal mud and food industries such as sugar.
Circulating agitating ball mill, mainly used for fine grinding of paints, paints, inks, pesticides, fertilizers, pulp and coal powder.
The most important feature of these mills is that the input power is directly used to drive the stirring mechanism on the main (vertical) shaft to generate rotation, and the grinding medium and materials are strongly stirred to achieve pulverization, so the grinding efficiency is higher than that of the conventional ball mill and the vibrating ball mill.
C ring type agitating mill The shape of the ring type mill is very similar to the shape of w (Fig. 34). It is a new ultra-fine grinding device developed in recent years. The main feature of the device is that the mill barrel is composed of a ring-shaped portion similar to the inner and outer layers of the W shape. Before grinding, the material to be pulverized (pulp) and the grinding medium (glass ball, etc.) are simultaneously fed into the annular cylinder. Due to the rotational movement of the inner cylinder, the material in the narrow gap is uniformly sheared. It is ground and broken. The outer cylinder of the mill is made into a double-layered annular portion with a slit, and cooling water is added to the slit, and the cooling effect is good.

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The Eiger Motormill is a horizontal wet grinding agitating grinding machine whose structure is shown in Figure 35. The agitator 1 and the microsphere grinding body 3 are installed in the barrel of the mill; the partition plate 2 is mounted on the cylinder body to prevent the back of the grinding material, and the other end is provided with a sieve to control the discharge of the grinding body; the slurry is fed into the mill by the pump 5 machine. The mill has a simple structure, light weight and no vibration. This grinding mill mostly used zircon, corundum and the like gold, a dye used for fine materials, chemicals, pharmaceuticals, ceramics, graphite, resin, metal powder, and food additives. This type of equipment is made in the UK and assembled in Japan. There are currently three models: (1) Micro (M series) for experimental research; (2) Laboratory type (L series) for research on industrial production transitions; (3) Industrial type (ABM series). The technical characteristics of the Eger electric mixing mill series, Figure 36 shows the product particle size distribution.

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(4) Planetary mills and rotary mills Conventional barrel mills (ball mills, rod mills, self-grinding mills, etc.) are mainly used for grinding under the constraints of the Earth's gravitational field. The working force field of the vibrating mill can be increased to (3~10)g, (g is the gravity of the gravitational force); its basic feature is to grind the material by the high frequency vibration of the grinding medium. The agitating mill has a partial centrifugal force, but this type of grinding machine mainly relies on the rotation of the agitator to drive the grinding medium to produce a grinding effect. Planetary mills and rotary mills are completely different from the movements of the above-mentioned types of mills; such mills rely on the grinding cylinder itself to have a strong rotation and revolution, which causes the grinding medium to produce a huge impact and grinding action to grind the material. . [next]
Figure 37 shows the structure and working principle of the planetary mill. When the drive shaft 6 is rotated by the motor, the connecting rod 2 and the barrel 3 will rotate around the common shaft 6; at the same time, the gear 4 drives the gear 5 to rotate, thereby causing the barrel 3 containing the grinding medium to wrap around itself. The axis rotates. Planetary grinding mainly pulverizes materials by the friction between the materials in the mill and between the materials and the grinding media.

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Figure 38 shows the structure and working principle of the rotary mill. When the rotating shaft 6 rotates, the cylinder 1 rotates in the vertical direction around 2 in addition to the horizontal rotation, which causes the grinding medium to perform a very complicated movement. The appropriate ratio of the cylinder in the vertical direction and the horizontal direction is 1:1~1:1.5.

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(5) Planetary vibration mill The planetary vibration mill is a new type of high-efficiency ultra-fine grinding equipment which combines the principle of planetary grinding and vibration grinding (Fig. 39); it is developed by South China University of Technology. The structure of this new type of mill is shown in Figure 40. It consists of four parts: power system, transmission system, vibration system and planetary system. The motor of the powertrain is connected to the No. 1 shaft via a flexible coupling. The transmission system includes the I-IV tape wheel and the II shaft. The I and II tape wheels constitute a first-stage deceleration system, and the III and IV tape wheels constitute a two-stage deceleration system. The vibration system consists of the No. I shaft, the eccentric weight, the I and II brackets, the vibrating frame and the spring. The vibrating frame fixes the brackets I and II on the spring to form a vibrating frame. The frame vibrates by the inertial centrifugal force generated when the eccentric weight is rotated. The planetary system consists of V, VI tape wheel, main shaft, connecting pipe, grinding cylinder shaft, grinding cylinder and so on. The No. III tape wheel and the main wheel rotate synchronously; the rotation of the No. III wheel forms a revolution of the drum around the No. I axis; the No. II wheel drives the VI No. wheel to form the rotation of the grinding wheel around its own axis.

This kind of mill has the characteristics of both planetary grinding and vibration grinding. It has the dual functions of high frequency impact and grinding and stripping, so it has strong grinding action and is an effective superfine grinding equipment.

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