The ball mill has a simple and compact structure and high reliability. It is an important grinding equipment in metallurgy, chemical industry, cement, ceramics, construction, electric power and other fields.

However, the shortcomings of the ball mill are also obvious, that is, high energy consumption and high iron loss. In recent years, with the growth of energy and the decline of energy quality, energy saving and consumption reduction have become a hot spot in the research of ball mills. At present, the energy-saving and consumption-reducing measures of ball mills mainly focus on structural improvement, optimization of working parameters, and automatic control.

1. The structure improvement of the ball mill

Compared with small and medium-sized mills, the advantages of large-scale mills are that they can save construction costs, operation and maintenance costs, and simplify equipment configuration and automation requirements. However, the unit energy consumption of large mills is higher than that of small and medium mills, so the development of its specifications is restricted.

The current research focus is to improve the original equipment and develop high-efficiency and energy-saving ball mills. For example, continuous ball mills in the ceramic industry, continuous cone ball mills for ceramic raw materials, static and dynamic bearing ball mills, rolling bearing ball mills, central drive energy-saving ball mills, planetary ball mills, swing ball mills, etc. These new machines and equipment have achieved energy saving Obvious effect.

2. Improvement of ball mill liner

The liner in the ball mill can protect the barrel and prolong the service life of the equipment. At the same time, its shape can directly control the movement trajectory of the steel ball in the barrel. At the same time, the liner is the most easily worn, replaced and consumed spare part of the ball mill, accounting for more than 60% of the consumption of wearing parts.

Changing the material and form of the liner has an important effect on improving the operating rate of the ball mill. In terms of materials, metal liners, rubber liners, magnetic liners, composite liners, etc. are generally used. The modification forms of the liner include tapered grading liner, angular spiral liner, etc.

3. The material and shape of the ball mill media

The role of the grinding medium is to produce punching, squeezing, grinding, and grinding effects in the cylinder to make the material meet the requirements of the fineness and gradation of the finished product. Poor performance of grinding media will lead to poor wear resistance, high unit consumption, and large consumption, which will seriously affect the grinding efficiency, accounting for about 30% of the consumption of wearing parts.

The mill media mainly improves the grinding efficiency by improving its material and shape. In terms of materials, low-chromium white cast iron grinding balls, alloy cast iron balls with natural special alloy pig iron or waste slag alloy pig iron as the main raw materials. Because of its low price and moderate abrasion, the development is relatively fast. In terms of shape, short cylindrical, rod-shaped ball and cylindrical rod-shaped media have higher productivity and lower unit power consumption than traditional steel ball mills.

4. Optimization of ball mill process parameters

The working state of the ball mill is affected by factors such as rotation rate, filling rate, ball-to-material ratio, length-to-diameter ratio, lining board and grinding medium size, and the various factors are coupled with each other and are more complicated. To give full play to the grinding efficiency of the ball mill, we must pay attention to the influence of the design and operating parameters of the mill. Improper selection of grinding parameters will greatly reduce the efficiency of the ball mill, or even fail to work normally.

Among the working parameters of the ball mill, the rotation rate and the filling rate have the most significant influence on the working state of the ball mill. The grinding process is the process of material gradually becoming smaller from large particles. In different grinding stages, the rotation rate and filling rate have different effects on the product size. In-depth study of the mechanism of rotation rate and filling rate on product particle size can provide a reference for the ball mill to propose a more reasonable grinding process, thereby greatly improving the efficiency of the ball mill.

The research on the optimization of ball mill parameters mainly adopts numerical simulation and experiment methods. The grinding mechanism of ball mills is complex and difficult to describe with analytical models. Discrete element method provides a means for the study of grinding mechanism of ball mills. The discrete element method is a numerical method suitable for studying the mechanical behavior of discontinuities.

5. Automatic control of ball mill

The ball mill system is a complex system with multiple inputs, multiple outputs, non-linearity, time-varying, large lag and multi-variable coupling. The influence of many factors makes the mathematical model change with environmental conditions, and it is difficult to establish accurately. The effective and perfect automatic control of the ball mill can make the system adjust and run at the best working point position, reduce the unit consumption of powder making and reduce the energy consumption, because the automatic control of the ball mill is more and more valued by the domestic and foreign mining circles.

For a specific ball mill, assuming that its structural parameters (such as mill specifications, liner shape and material, etc.) and motion parameters are determined (such as mill rotation rate), the operating parameters such as the grinding ball and the material to be ground will also change over time. Changes, thereby affecting its grinding output and energy consumption. Therefore, accurate detection of ball mill load (including medium filling rate, material-to-ball ratio, grinding concentration) is very important in automatic control.

At present, the testing methods of ball mill load include import and export pressure difference method, noise method, power method, vibration method, ultrasonic method and so on. In view of the fact that each method can only measure a certain type of information of the ball mill, and has its own advantages and disadvantages, the information fusion technology under multi-factor detection has also been continuously studied.

In short, as a high-energy-consuming machine, the ball mill is an inevitable trend to improve its operating efficiency. The factors that affect the efficiency of the ball mill are complex, and the factors are interrelated, so more in-depth research is needed. In the next period of time, the research on energy saving and consumption reduction of ball mills in our country will mainly focus on the following aspects:

(1) Development of new structure of ball mill;

(2) Improve the wear resistance of the liner and the grinding medium, and improve the structure of the liner and the grinding medium, so that the grinding medium can move more reasonably;

(3) In-depth study of the theoretical model of the ball mill system to accurately optimize the working parameters of the ball mill;

(4) Develop accurate detection methods of ball mill load, combine multiple control methods and pay attention to real-time problems in actual use, and improve the level of automation;

(5) Improvement and adjustment of the process route in actual production.