Milling Beads

Content
1. What are milling beads?
    1.1 Hardness of milling beads
2. Notes on purchasing laboratory milling beads
    2.1 Bead mill machine
    2.2 Principle of using milling beads
3. Cleaning milling beads
4. How to buy milling beads?

Milling beads refer to the pellets made from bauxite, roller bar powder, industrial alumina powder, high-temperature calcined alpha alumina powder, and other materials, which are widely used mainly as grinding media through processes such as batching, grinding, powder making (slurry making, clay making), molding, drying, and firing.

Ball mill is widely used in metallurgy, minerals, electric power, building materials, the chemical industry, and other fields, and is the most commonly used crushing equipment. The grinding medium is the ball or cylindrical object rolling in the ball mill. The grinding media of ordinary ball mills are mainly metal balls and cylinders, while in the ceramic production industry, the main grinding media used are ceramic grinding media, followed by natural flint and pebbles. At present, the ceramic grinding media on the market mainly include alumina, zirconium oxide, silicon carbide, silicon nitride, and other series varieties.

Laboratory milling beads are equipped with grinding balls of various materials in order to respond to the ball grinding of various laboratory samples, including stainless steel grinding balls, agate grinding balls, zirconia grinding balls, polyurethane grinding balls, carbide grinding balls, etc. The ball grinding effect of each kind of milling bead is different.

Milling beads are widely used, it is small in size, high in efficiency, simple in operation, and can grind laboratory samples or production materials to 0.1μm quickly while having good mixing, homogenization, and dispersion effect.

Generally, in the ball milling process of laboratory ball mill, as the hardness increases, the wear of grinding balls decreases. At the same time, the small deformation of the grinding ball reduces the energy absorbed by the ball deformation in the impact, and more energy will be used to impact the particles and increase the ball milling efficiency. But the fact is that the harder the grinding ball is, the better it is. Higher hardness grinding balls do have lower wear, but for ball milling efficiency, when the hardness of the grinding balls exceeds the Z best value, it will have adverse effects.

The adverse effects of too high hardness of grinding balls in the laboratory ball mills are roughly two as follows.

a. The rebound of grinding balls after impact is aggravated, resulting in partial energy loss and less energy for ball milling

b. Milling beads with higher hardness slide badly when squeezing particles between balls, so they cannot grind materials effectively.

The first thing to figure out is what is material to be ground, specifically to which substance is better.

The laboratory personnel should find out what is the feed size of the sample before grinding, or the shape of the sample, whether it is powder, granular, lump, strip, etc., and what is the discharge size to be reached after grinding, that is, how fine to grind.

Laboratory personnel also need to know in advance approximately how many samples to grinding each time, in terms of volume. Because the ball mill generally uses a cylindrical grinding jar to load the material, but each sample due to different densities, so each jar can load the sample quality is not the same. You can approximate this based on your daily experiments or the mass-volume formula. Sample loading volume is generally one-third to two-thirds of the volume of the ball mill jar, but also leaves space for loading grinding balls and grinding space.

Some heat-sensitive samples have strict temperature requirements, and the bead mill will generate a lot of heat because of the impact and friction of the grinding balls, resulting in a higher temperature of the ball mill jar, so if the sample has requirements for the temperature environment, you need to choose the ball mill that can control the temperature.

The sample of the laboratory ball mill is in direct contact with the ball mill jar and grinding balls. The sample may be mixed with small particulate matter impurities in the jar and ball during the grinding process, especially the jar and grinding ball made of stainless steel, so if the subsequent testing experiment has requirements in this regard, it is necessary to avoid secondary contamination of the sample by the ball mill. For example, in soil heavy metal detection, you cannot use stainless steel balls and jars, but to use agate material, zirconia material, etc.

For flammable and explosive samples or samples that react easily with air, we need to consider vacuuming the ball mill or filling the ball mill with inert gas for grinding, which has certain requirements for the equipment motor and the ball mill.

Sometimes, although the same sample is ground, it may be used for the synthesis of other substances or for testing and analysis, which affects the choice of grinding accessories and models.

The source of each sample in the laboratory is not consistent, there are homemade, self-collected, and also sent to the test, which involves the frequency of use and equipment accessories and other issues.

Although the bead mill is a universal device, it does not mean that one instrument can grind all types of samples. If there are other samples to be ground in the laboratory, you can make statistics in advance so that you do not buy equipment that is only suitable for a certain type of sample. Another thing to implement clearly is whether the instrument is intended to be operated on the lab bench or on the floor, to see if anti-slip measures are taken.

Milling beads are available in different densities and Vickers hardness. Usually, we use grinding balls with higher density and hardness to increase the grinding efficiency. At the same time, the grinding balls will rub and collide with each other during the grinding process, generating a lot of heat. It can be seen that the heat resistance of the grinding balls is also high. If the sample is acidic or alkaline, there may be a risk of chemical reaction with the grinding ball, so the grinding ball should also have the property of not reacting chemically with the sample so that the sample will not be damaged by the grinding ball.

Large milling beads are suitable for samples with large target particle sizes, on the contrary, small milling beads are suitable for small target particle sizes. Smaller balls are more numerous per unit volume, so the grinding speed will be faster. However, small grinding balls also weigh less and are not suitable for large particle sizes, so laboratory personnel can use 2-3 different particle sizes so that the balls can grind the material progressively finer.

The filling amount of grinding balls should not be too high, otherwise, it will not turn. If the grinding ball is too little, it will lead to lower grinding efficiency, and the ratio of the milling beads and sample should be in the middle of 0.9-1.1.

Different brands have different quality, especially in the case of a small number of grinding balls, the cost of grinding balls is not very high, so we should tend to choose a better reputation for grinding balls. So the laboratory in the choice of milling beads needs to fully consider all aspects to choose the right grinding ball so that different materials have a better grinding effect.

Water is the usual liquid used for cleaning in the laboratory. Soak the ball mill jar and grinding ball before cleaning, and at the same time, you can add detergent, detergent, etc., and then clean it with a brush.

For some sample residues, only water is difficult to remove clean, then you can use the chemical nature of the residue. Add the cleaning solvent that can make it dissolve, such as acetone, butanone, ethanol (alcohol), oxalic acid, hydrochloric acid, etc., and then soak the cleaning. When using solvents for cleaning, you should avoid the chemical reaction between the added solvents and the ball mill tank and grinding ball material. In addition, for the use of wet ball milling samples, you can directly use the same solvent as when grinding for cleaning, which is also good in effect.

When the bead mill is running, the grinding balls in the ball mill tank will be moving at high speed, making impact and friction. Based on this principle, you can combine the two methods mentioned above, put the grinding balls and cleaning solvent into the ball mill jar at the same time, then turn on the machine and let the ball mill run with no load. After about half an hour to an hour, the residual sample on the ball mill tank and the grinding balls will be effectively removed, and you can then rinse with water.

When the ball mill is running at no load, the speed should not be set too high to reduce the loss of grinding balls and the energy consumption of the ball mill. When using this method of cleaning, we can add cleaning materials in addition to water, and detergent, you can also add aluminum trioxide powder, fine sand, quartz sand (for alloying the sample residue), or small size corundum ball, etc., to increase the contact friction, often produces good cleaning results.

This way belongs to mechanical vibration cleaning. It can destroy the residual sample and the adsorption of the surface to be cleaned, so as to achieve the effect of cleaning. For some greasy or sticky samples, this way is more suitable.

If you are interested in our milling beads or have any questions, please write an e-mail to [email protected], we will reply to you as soon as possible.