The grinding balls automatic loading into a mill

Earlier we have considered the grinding process specifics in the aerated concrete production and we have mentioned about automatic devices for grinding media loading into a mill in automatic mode. In this publication, we will consider this issue in more detail.

Automatic grinding media loading into mill most uses in aerated concrete production, because of these factors:

• The aerated concrete production is a fairly young technology and all modern techniques relating to the grinding process consider in the production design.
• The 40mm and 30mm grinding balls mainly use in the aerated concrete production.
• A small mills amount. In general, one or two ball mills use at the aerated concrete plant.
• The grinding material uniformity, etc.

Let’s note, all foreign aerated concrete manufacturers use automatic grinding media loading. For today, only one enterprise has implemented this technology in Ukraine.

What is this method of loading grinding media into a mill?

This mechanism consists of two main parts: the container for grinding balls and the grinding channel for grinding media entering into mill.

The container equipped with a movable flap. Flap movement can be adjusted (open / close) automatically or in manual mode. In automatic mode: computer monitors the raw material amount fed into the mill and opens the flap after reaching a certain volume and then grinding balls load into the mill. For example, the grinding media specific consumption is 10 kilograms per 1000 tons raw materials grinding. After 1000 tons material loading into the mill, the flap opens for a certain time and 10 kg of grinding balls should enter in grinding channel (approximately 33 pieces of 40 mm grinding balls). Then flap closes and the grinding balls feeding stop. A similar work scheme observed under the condition the person (miller) engaged in flap opening/closing. We draw your attention, it is very important to correctly calculate the grinding balls consumption in order to avoid the mill overloading or underloading by grinding media.

The mill loading can be tied to the mill working time (for example, you can load 3 pieces of grinding balls every two hours of mill operation). Important: if mill productivity has changed, then this method may disrupt the mill loading schedule.

The container with grinding balls should be placed in close proximity to the mill. The container must be securely fastened. It should be freely accessible to ensure filling ease by grinding media and the visually internal inspection possibility by employees of plant. The container should be placed slightly higher the mill “power” and the grinding channel tilt angle is 15 to 25 degrees. The container bottom should be tilted at least 15 degrees. This is necessary for the grinding ball rolling down under gravity influence to the flap location place.

A pipe or a channel can be used as the grinding channel. We advise you to use the channel, because the grinding balls jamming problem easily eliminated in this case. During grinding channel designing need to take into account several features:

• The grinding channel angle should be at least 15 degrees. This is necessary in order to grinding media freely roll from the container to the mill feed;
• The grinding channel diameter should be on 50% greater than diameter of the loading grinding media. This will ensure the grinding media free movement and will disturb the grinding media rolling by pairs (excludes jamming). For example, if you use 40mm grinding balls, then grinding channel diameter should be max. 60mm.
• Use as little as possible the “knees” (bends) during grinding channel installation.

We have briefly considered design features the automatic loading of grinding balls into a ball mill. Please note the introduction of grinding media automatic loading – it is a sufficient technological process and requires an individual approach to each specific situation.