Wednesday, September 8, 2010

Spray drying refinement

I haven’t forgotten about this blog. It’s actually been on my mind for some time. I’ve just been really busy. School has started and I’m overwhelmed at the moment. I’m looking forward to the near future when things settle down a bit and I can get back to focusing on this research.

I’ve been working on several fronts. With regards to testing powder behavior, I’ve built a system for measuring friction within the powder. This should allow me to predict how materials will behave in small batches before committing to larger amounts for the machine. I’ve also started using a new dry mixing system (it’s actually resurrected from the engineering department’s grave). I’ll document both of these as time permits. Finally, I’m still actively searching for a better way to screen material.

In the meantime, I did get some promising results. I re-ran some batches of ceramic powder through our spray drier equipment. In my original attempt, only 22.3% of the material I started off with in slip form ended up being usable after spray drying (where usable = passing through a 200 mesh screen). The vast majority was simply too large.

For this second batch, Hyojin suggested dropping the PEG down to 0.5% He also suggested making a volume suspension of 20%.

This worked out to be 52g dry / 80g water.

In batch terms…

This second batch sprayed much finer and the yield improved dramatically (isn’t it wonderful when theory translates into reality?). Decreasing the PEG and increasing the water increased the amount of material below 200 mesh from 22.3% up to 38.1%. There's probably a trade off somewhere I'm not aware of yet. For now I'm just glad things are working out. I'll be mixing this with binders in the next few days and will post the results soon!

1 comment:

  1. Hello Carlo,
    Having done some experiments with Mark Ganter last year, I am about to start my own experiments at the Digital Manufacturing Centre at the Bartlett School of Architecture in London.
    This is not an official, grant funded project, just something I have been wanting to do for many years!
    I would like to speed up the whole process by 'hitting the ground running' so the advice of Ron Rael and Mark have been extremely useful.
    I propose contact our regular UK clay suppliers to discuss the preparation of clays and wonder if I can make use of your research ?
    Any thoughts. recipes and advice would be very gratefully received and we would be more than happy to help your research.
    Best wishes
    Michael Eden