I suggest the use of alumina balls to prevent eventual contaminations. And never steel balls...

Normally the amount of balls should be 50-55% of the apparent volume of the mill, as in a normal balls-packing we have about 40% of empty space between them, this means that we will have 30% of useful mill volume occupied by balls. It is also defined that the amount of material to be milled must completely fill the spaces between balls at least (never less than 22%) .... Usually about 25% of the useful volume of the mill is advised with quantity of material to be ground.

Water is usually used as the solvent (only with materials susceptible to easy hydration the alcohol is used) and the amount of water to be used depends on the density of the desired final suspension, but is usually between 20-25% of the useful volume of the mill. In practice the mill after charging should have about 25% of its free useful volume.

(Note: a small pdf of a book on milling in ball mills is attached here, see figure 73)

C. Erdamar

Concerning the time that you should I apply ball milling, it depends the (the start grain size, hardness, etc.…). You should make a control during the first milling, taking a small sample to grain size analyze from hour to hour, for example.

Dear Mr. Erdamar,

The wall of the milling container and balls should be harder (or more tough) than the milled powders to restrict the contamination from the wall and balls. I suggest to use zirconia or WC balls. 

You can use water, because al2o3 is so stable material against chemicals. 

Ball to powder ratio can be 10:1 or 30:1, you can increase also the speed milling's shaft. The parameters can be adjusted up to the results.

For this type of experiments, generally trial and error approach is used.

Best regards.

Thank you all for your concern

Regards

I encourage my clients to look at the total scheme when adding a new step into the process, in the hope of process optimization. For example, both wet and dry milling will achieve your particle size goal, so if the powder will be used in a slurry, then wet milling is acceptable. However, if the powder is applied dry, then a drying operation will be needed, so dry ball milling (DBM) is preferred. 

Another consideration is the particle size distribution. If a tail on the high or low side will cause unwanted results, then you will need to change your processing conditions or add a classification step. 

The next consideration is the powder quantity and production rate. Though ball mills are available in a large scale (several meter diameter), there is an advantage to shifting to agitated media mills. Agitated media mills are capable of rapid attrition rates, thus minimizing contamination while offering more processing control.

This general approach can be optimized with a little more project scope.

Enjoy the path.

Clint

My ball milling process ended up with agglomeration so I could not apply sieve analysis to measure particle size. I think that particle size was reduced dramatically after ball milling process. Should I use dispersing agents? What else can I do to avoid agglomeration prior to pressing process? 

How much powder are you making? What is the goal? Pressing and firing?

I will mix alumina with boron carbide and silicon carbide than uniaxially press into cylindrical form than fire. I put 420 g alumina powder into 1200 ml ceramic jar with 420 g ceramic balls and 300 ml pure water. I applied ball mill for 24 hour and dried it for about 16 hour in oven at 105 celsius degree. 

Certainly, being aqueous, you will want some dispersant. See if you can find Darvan or Disperal. 

Though, for the coarse size fraction that you are after, dry milling should work.

What size media do you have?

I'm trying to grind Alumina powder (300nm) and nano aluminum nitride (

what is valu of Ho and k in Hall pitch relationships for alumina ceramics, please guide me

Ardalan Nasiri @Masood Mukhtar

Your comment 'I'm trying to grind Alumina powder (300nm) and nano aluminum nitride (

I agree Fatih Erdem Bastan

The wall of the milling container and balls should be harder (or more tough) than the milled powders to restrict the contamination from the wall and balls. I suggest to use zirconia or WC balls. 

use dispersing agents