1. Closed circuit grinding process

As far as the grinding process is concerned, there are mainly open and closed circuits. The advantage of the former is that the process is simple and the finished product is the finished product. The disadvantage is that the material has a slow flow velocity in the mill and a long residence time. In order to ensure that the particle size of the milled material meets all requirements, the milled material cannot be discharged out of the mill in time. Often caused by grinding phenomenon. Open-circuit grinding system has relatively low production capacity and high energy consumption. It is impossible to flexibly adjust the fineness of the milled material at any time. The latter is equipped with a powder sorting device, which can timely discharge the fine powder that has been ground out of the mill, effectively avoiding the phenomenon of excessive grinding, and can flexibly adjust the fineness of the finished cement by adjusting the working parameters of the separator.

In addition, the flow velocity of the materials in the closed-circuit mill is accelerated, and the grinding bodies of the respective warehouses are properly responsible for the crushing or grinding tasks. Therefore, the output is increased and the power consumption is reduced. Especially when the cement fineness requirement is high, the advantages of high production and low consumption are even greater. obvious. Compared with the open circuit, the closed-circuit grinding process increases the output by more than 30%, and the power consumption decreases by about 20%. Therefore, the closed-circuit grinding process is an inevitable trend in the development of cement grinding mill technology.

2. Pre-crushing multistage series grinding process

The ball mill is ideal as a grinding device, but as a crushing or crushing device, it is inefficient. It is an effective way to improve the production capacity of the ball mill that the grinding process of the material with a size of more than ten mm or even several tens of mm in the mill is moved from the inside of the mill to the outside of the mill in a special comminution equipment. "More crushing and less grinding," that is, efforts to reduce the size of the material into the mill is a valuable experience in the practice of cement grinding operations for many years, so the pre-crushing process came into being is very natural.

According to the crushing theory, brittle materials break from several tens of millimeters to several millimeters. The nature of the fragmentation is the continuous generation and expansion of internal cracks, and the external factors that contribute to this process are the strong forces exerted on it in a certain way. - Crushing force.

(1) Roller press + ball mill grinding process.

The process also includes various process configurations for vertical milling and ball mill cascade grinding. Only the roller grinding machine + ball mill cascade grinding system was used for analysis. The crushing cement clinker enters the roller press first, and the strong roll pressure crushes it from tens of mm to several mm or even finer and enters the ball mill. Since the clinker particles are crushed by a roll press, many micro-cracks are generated inside, so that it is easier to be further crushed in the ball mill and quickly enter the grinding stage. In this kind of grinding system, the main task of the ball mill is to grind, so the coarse grinding chamber can use a smaller size grinding body. The increase in the surface area of ​​the grinding body is obviously conducive to the improvement of the grinding efficiency, thereby greatly increasing the powder Grinding system production capacity. According to the empirical data, after using a roller press + ball mill cascade grinding process, the cement mill system's output can be increased by 40% and the grinding power consumption can be reduced by 10%.

(2) Impact crusher + ball mill grinding process.

The development of fine crushing equipment is one of the hot spots in the current crushing of clinker. From the fine-grained clinker crusher of the 1980s to various impact crushers in recent years, the reform and innovation of the cement grinding process was strongly promoted. These clinker fine crushing equipments are roughly classified into the following types: fine jaw crusher (PEX type), vertical impact crusher (PCF type), vertical hammer crusher (PCL type), vertical axis hammer crusher ( XCL type), energy-efficient crusher (PGXJ type), vertical impact crusher and eddy impact crusher. Their average discharge particle size can reach 3mm to 5mm, of which the vertical impact crusher discharge particle size <2.5mm up to 80% to 90%. It should be pointed out that whether the roller press or the above-mentioned various fine crushers, the technically outstanding problem is the material of the roller surface or the crushing working parts. Only the working parts with high hardness and high wear resistance can ensure their long-term effectiveness. Work; otherwise, shorter life cycles and replacement cycles will inevitably affect the system's operating rate and production capacity. At the same time, it will also increase material consumption, which is not conducive to the improvement of economic efficiency.

CHAENG Machinery Co. main products: Vertical Roller Grinding Mill, Ball Mill, Rotary Kiln , Steel Castings, Cement making machine, GGBS Plant.