[gintoxiccc]

Hello everybody, I am a student in the V semestre of chemical engineering (Germany) and have to manage with other students (3) a problem during the production of metallic powders (flaky) and pastes.
In our Problem we have aluminium powders and pastes and use a dry mill process. This powder should be used later in a process for Aerated autoclaved concrete (ACC). However, here there are difficulties. Though we have exactly the description of the buyers-plant of the product, nevertheless, we are not able to get this. From the physical side we have a problem with the dry milling of the Aluminium.
We know that dry milling is not realy the right way to do but we have to use this technology we do have in here.If somebody can maybe explain to me how dry milling can be used for getting particle dimensions of 80,70 or 60 micron. We allways get 20, 30 or 40 micron. Any known recommended literature for aluminium milling?.

The seconde Question is more chemical... On the other side we have a problem with foaming. With the test (The company later makes ACC ) our powder already after 4 minutes started to form a lot of foam but in the description of the company they want foaming just after 60 minutes. This foam could have come from the organic additions we had to use later with the blendin process. If somebody knows the problem of the foaming of Aluminium Powders (Flaky) and pastes, or somebody knows what kind of Anti foaming chemicals to use... specialy for the production of AL flaky powders..would be great.

Then we have a problem in the reaction.
The aluminium of powders our powder reacts already after one minute (in the production company for ACC , they told it.. we didnt see it, the plant is to far away), nevertheless the reaction should start only after 1 minute and 50 seconds or 2 minutes. This problem should have to do with the Ca. We simply use an organics (which is probably responsible also later for the foam) and have simply used more. This gave us improvements in the beginning reaction-time (instead of 50 seconds then 1 minute), however, we could never reach a value from demanded 1 minute 50 seconds as well as the industry produced.
On the Internet simply we do not find any important "keys". How get these companies an aluminium powder (Flaky powder) that starts just after 2 minutes (so additives, which???) and also only after 60 minutes starts to foam.
How these additives are cpreventing the aluminium powder (flaky powder) so fast to react and if sombody know.. what are the cheapest ones (we have to care about our budget).

Thanks for your attention and hope for information. We everybody feel quite abandonment by our PHD`s from University and assistants, the Guys from this company we make this do not support us at all. This practical work is a important factor for our Bachelor's-Diploma. We want to finish that and make money.. we are all tired of this study.

Greatings from Germany


Fredy