Grinding Mill

Based on the production demands of millions of customers, ZENITH has developed the industrial milling machines which cover fully the crude powder, fine powder and ultrafine powder. The tens of years of customer service experiences make ZENITH learn better the customer's investment ideas and considerations so as to provide specific solutions.

Ball mill grinding system analysis

The energy issue is the primary problem that plagues the development of the world economy. As the amount of room-temperature gas emitted by human production activities into the atmosphere increases, the surface temperature of the earth becomes higher and higher, and the surface temperature of the earth rises too fast, threatening humanity. Self survival. Therefore, energy saving and emission reduction has become an urgent task. The main power consumption link in cement production is grinding operation, and the electricity consumed by grinding accounts for more than 70% of the total electricity consumption of cement production. There are three main types of grinding operations in cement production: raw material grinding, cement grinding and raw coal grinding, while cement grinding power consumption accounts for about 40% of the total electricity consumption of cement production. Therefore, the selection of a reasonable cement grinding system plays a very important role in energy saving and consumption reduction in cement plants. The following describes the milling system of the ZENITH ball mill.

The choice of the grinding system of the ball mill should take into account factors such as the performance, yield, power consumption, maintenance and ease of operation and maintenance of the material being ground.

The grinding system is available in both open and closed circuits. In the grinding process, when the material becomes a product after passing through the ball mill once, it is called an open circuit system; when the material is ground and the product is selected by the grading equipment, and the coarse material is returned to the grinding machine for re-grinding, it is called a closed circuit system.

The advantages of the open circuit system are: the process is simple, the equipment investment is small, and the operation is simple; but the materials must be fully qualified to achieve the grinding. Therefore, when the fineness of the product is required to be fine, the material that has been prepared for grinding is overgrown, and a buffer layer is formed in the grinding, which prevents the coarse material from being further ground; sometimes even a powder ball is formed, thereby Reduced grinding efficiency and increased power consumption. The closed circuit system can eliminate the phenomenon of over-grinding, increase the output of the ball mill, and at the same time, the product size of the closed-circuit system is uniform; and the method of grading equipment can be adjusted to change the fineness of the product. The finer the fineness of the product, the more coarse material is returned to the mill. The ratio of the amount of coarse material to the amount of product is called the cyclic loading rate of the closed circuit system.

The steel ball mill of the cement plant can be divided into short grinding, medium long grinding and long grinding according to the ratio of its length to diameter. When the aspect ratio is 2 or less, it is short-grinding, which is generally called ball milling; the aspect ratio is about 3 in the medium-length grinding; when the aspect ratio is 4 or more, it is long-grinding. Short grinding is generally a single warehouse, long and medium length grinding is 2 to 4 warehouses. The latter two are also called tube mills or multi-chamber mills.

When the closed circuit system is ground, the short grinding or medium length grinding and grading equipment are generally combined into a closed circuit system because the fineness of the grinding is required to be coarse. When the grading equipment forms a closed circuit with a billiard mill, it is called a first-level closed-circuit system; when it forms a closed circuit with two short-runs, it is called a secondary closed-circuit system.

Due to the thinner discharge of the long mill, it is generally only used for open circuit systems, or for closed circuits with low cycle load efficiency.

The advantage of the secondary closed circuit is that the material is selected after the primary grinding and the product is sorted in time to reduce the fine material in the feeding of the secondary grinding, thereby improving the grinding efficiency of the secondary grinding. However, the secondary closed circuit system requires more equipment and complicated processes. In order to simplify the process, a medium unloader is used. The medium unloading mill is generally a medium and long mill. After the material is discharged from the first bin, it has the meridian equipment first, and then enters the second bin. Medium unloading is a lifting cycle grinding; it is a primary closed circuit system, but has the function of a secondary closed circuit system.

The former has the advantage that the process operation is simple, and the finished product is obtained after the material is ground. The disadvantage is that the flow rate of the material in the mill is slow and the residence time is long. In order to ensure that the particle size of the milled material meets the requirements, the milled material can not be discharged into the ball mill in time, which often causes grinding phenomenon. The open circuit system has relatively low production capacity and high energy consumption, and it is impossible to flexibly adjust the fineness of the ground material at any time.

The latter adds a powder sorting device, which can discharge the finely ground fine powder out of the mill in time, effectively avoiding the phenomenon of over-grinding, and can flexibly adjust the fineness of the finished cement by adjusting the working parameters of the classifier. In addition, the flow rate of the material in the closed-circuit mill is accelerated, and the grinding bodies of the respective warehouses are properly responsible for the crushing or grinding, so the output is increased and the power consumption is reduced. Especially when the fineness of the cement is high, the advantages of high production and low consumption are more. obvious.