The difference between overflow ball mill and grate ball mill

Ball mill is a type of equipment that crushes raw materials before further crushing, and is commonly used in mineral processing plants at present. According to different mining methods, ball mills can be divided into grid ball mills and overflow ball mills. So what are the differences between these two types?

Similarity

1. Consistent construction

The two types of ball mills have the same structure, with the key components being the head section, feeding section, discharging section, rolling bearing section, transmission system section, and intake system.

2. Similar job responsibilities

When working, after feeding the iron ore into the head of the mining department, the cylinder rotates around the horizontal centerline according to the specified speed ratio. The iron ore is then randomly dropped or thrown for fitness exercise based on the centripetal force and the sliding friction force of the grinding material. As a result, it is politicized and grinded, and the finely ground product is discharged from the mining department.

Difference:

1. Structure of ore discharge department

The basic structure and grinding steps of the two are the same, but the structure of the ore discharge section is different.

The discharge side of the grid ball mill is equipped with grid plates, and there is an additional grid plate at the feeding end, with many small circular holes for discharging on the grid plate. The finely ground slurry is raised to a level higher than the discharge port through a fan-shaped chamber leading to the discharge port according to the grid plate, allowing the slurry to be discharged from the mill.

The overflow type ball mill does not have a grid plate installed on the discharge side, but is equipped with a spiral gear on the inner surface of the hollow motor shaft sleeve at the discharge end, which has a spiral direction and the rotation direction of the mill reversed. The purpose is to prevent water balls or coarse feed ore blocks from being discharged together with the slurry. The discharge of the overflow type ball mill relies on the slurry itself being higher than the lower edge of the hollow motor shaft sleeve and flowing upwards (this is why it is named the overflow type ball mill).

2. Feed particle size distribution (application scope)

The particle size distribution limit of the grinding product of the grid ball mill is usually 0.3-0.4mm, so it is commonly used in the first stage of grinding and often forms a closed-loop system with the spiral classifier.

The particle size distribution of the overflow type ball mill grinding product is usually less than 0.3mm, which is suitable for re grinding concentrate and can obtain finer qualified products.

3. Feeding method

The grid type ball mill feeds according to the sieve plate method, while the overflow type ball mill has fully automatic overflow of raw materials. When the raw material level exceeds the feeding port, it is fully automatically discharged.