Traditional Ball Mill’s Three Imperfections Compared with Vertical Roller Mill
Ball mill’s broad prospect in China brings the Chinese ball mill companies unprecedented opportunities. There is no doubt that the main ball mill enterprises will guarantee their industry position and market share in three to five years. The new type environmental ball mills emerge, so the traditional ball mills will be replaced.
Imperfections of traditional ball mills are as follows:
Firstly, abrasion of steel ball and liners is huge, especially wet way grinding operation - chemical corrosion effect increases the abrasion.
Secondly, as the ball material crushing effect lacks selectivity, the so grinding particle size is not uniform, and easy to be crushed. As a result, the traditional ball mills rarely work with open circuit, but in closed circuit operation with classifier, to ensure the product particle size requirements.
Thirdly, steel balls movement in the barrel is perpendicular to the earth's gravitational field, so grinding medium must overcome gravity to do crushing, so the energy consumption is higher.
Vertical roller mill has more advantages no matter from technical point or operation point:
1. The production investment cost is greatly reduced.
Vertical roller mill has simple design, compact layout, small construction area, (about 70% of the ball mill system and outdoor displacement), which directly reduces the investment cost. Vertical roller mill has a separator, no need for any additional classifier or lifting equipment. Vertical mill dust gas can be collected by the bag type dust collector or electric dust collector.
2. High efficiency, energy conservation and environmental protection
Vertical mill grinding principle of grinding material layer, low energy consumption (power consumption is lower than ball mill grinding system by 20% ~ 30%), and along with increase of raw material moisture, the electricity saving effect is more obvious. Vertical mill system energy can save 30% ~ 40% compared with that of ball mill system. There is no steel balls and liners colliding with each other in the vertical mill operation, so the noise is low, (20 ~ 25 db lower than the ball mill operation). In addition, the vertical mill adopts complete sealed system, operation under negative pressure, without dust and clean environment.
3. High drying capability
Materials are conveyed by hot air in the vertical mill, the air temperature will be controlled when the material has high moisture content, to guarantee the products meet the requirements of the final moisture. In the vertical mill can dry materials - grinding materials mositure is as high as 15% ~ 20%.
4. Easy operation, convenient maintenance
Equipped with automatic control system with remote control, easy operation; Maintain oil cylinder by rotating arm, and convenient and quick replacement of roller cover, liner, reduce enterprise stop losses.
5. Product quality stable and easy to detect
The chemical composition of product is stable, particle size distribution are even, is good for the calcination. The time for material to stay in the vertical mill is only 2~3 min, but in the ball mill, it is 15~20 min. So the vertical mill product’s chemical composition and fineness can be measured quickly and correction.
6. Small abrasion, high utilization rate.
Because in the vertical mill roller mill operation, thee is no direct contact between the grinding table and grinding roller, so there is small metal abrasion, the unit metal consumption is 5 ~ 10 g/t.