5 ways to improve the grinding efficiency of ball mill

Several factors affecting the efficiency of cement grinding of ball mills. In this article, we will examine some of these factors that have been shown to affect grinding efficiency when the grinding ball enters the ball mill.

Grinder geometry and speed

According to Bond (1954), the grinding efficiency of a mill depends on the ball mill diameter, grinding ball size and grinding speed. For a specific power rating, a ball mill with different aspect ratios will produce different material retention times. Longer units are used for high retention rates, while shorter units are used when overgrinding is required.

A discharge device is closely related to the retention of the grinding medium and material. According to Mokken (1978) research, the faster the pulp is, the better. This can be demonstrated by the development trends from furnace to peripherals with pulp lifters to open discharge designs.

Feed preparation

With the increasing popularity of the use of rough ball mills, it is becoming increasingly critical to provide the right feed of the right size to the mill. Inefficiency is ineffective due to the need for larger (and thus fewer) grinding balls. Likewise, since the performance of the ball mill is closely related to the complete particle size distribution of the feed, all previous grading stages and grinding the material to a smaller size will ultimately affect the feed particle size distribution and ultimately affect the grinding efficiency of the ball mill.

Closed circuit grinding

Another factor affecting the efficiency and effectiveness of cement grinding of ball mills is cyclic loads, as it is related to a specific material size distribution. Increased cyclic load and classifier efficiency have been observed; increased grinding efficiency has been improved. When the cycle load increases, it reduces over-grounding and provides a more efficient size distribution for the medium for processing. However, due to material handling and classification requirements, diminishing returns will occur at some point and will be restricted.

Feed composition

In most cases, the feed of the ball mill consists of several components, except for the ore itself. The most common of these ingredients is water, which can have a wide range of effects on the grinding process of the ball mill depending on the properties of the material itself and the amount of solids therein.

In most cases, dry grinding may consume 10-50% more energy compared to wet grinding. However, this is offset by severely reduced liner and media consumption. Adding moisture without introducing heating gas can completely stop grinding of fine materials. When more water is added, it will pass through the viscosity stage, reaching a standard wet grinding stage with solids content of 60-80% by weight.

At this point, the optimal moisture content for effective grinding has been obtained based on the overall effect of some major conditions such as pulp viscosity, physical design parameters of the mill, material conveying characteristics, mill residence time, and internal friction and void filling. the cost.

Media utilization

The usual practice is to match the material size distribution and the most effective size distribution of the grinding media. This will involve the size of the ions on the top of the medium and the charging of the graded grinding balls. The principle applied here is that larger steel balls are suitable for coarse grinding, while smaller steel balls are suitable for fine grinding. The same principle applies to the grinding of the ball mill cement by using a separator, a graded lining or a scalper.

The material selected for grinding balls is usually based on the cost-effectiveness of material consumption. However, it has been reported that the increase in specific gravity and surface hardness has led to a significant improvement in the use of grinding energy.

Control technology

With a few exceptions, the grinding loop will cope with changes in feed characteristics, resulting in general operating conditions always deviating from the expected value. Due to the frequency of these deviations, response time, and operator reliability (automatic control system) have been applied to the report, indicating a 15% increase in energy efficiency.

Broadly speaking, the grinding mechanism of a ball mill can be divided into impact or wear, and each type can explain at least two forms of damage. Impact rupture may be caused by crushing particles between the balls or between the balls and the mill lining. It also includes slow compression fracturing or grinding the particles between the balls of the medium.

On the other hand, wear reduction involves removing the grain surface by friction, and performing wear and debris fragmentation by forces that do not destroy the entire particle. Wearing results in smaller sub-particles as well as larger master particles.