Alumina can be dense phased with a blow tank but it is considered a tricky material to convey. If you want off the shelf system then there are a number of manufactures who will do dense phase system for alumina conveying. I personally prefer the low velocity pipe in pipe system for alumina. These kind of system should easily do 10 tph in a 3-4” line with approx. 200- 300 m3/hr air.

Alternatively you can go for the air injection type systems, which inject additional air in the conveying line at various points. They come in all different names (boosters, density stabilisers etc.) but the basic principle is same.

If you are thinking of making one yourself keep in mind wear is the function of velocity so design for the lowest possible velocities. But then from other people misfortunes it is common knowledge that alumina doesn’t convey very well in traditional blow tank dense phase system.

Hope my comments are helpful. ■

This sounds more like crushed bath than straight alumina. Dense phase is then quite the norm. Check with Flaght (Norwegian). I also like the Muschelknautz by-pass system but suspect that your distance won't require it.

Don't worry about wear. There is nothing you can do about it in the long run, provided you have reasonably selected the right materials. ■

Dear Optima

6 mm particles with a specific material density of 3800 kg/m3, will have a floating velocity of approx. 20 m/sec.

The air velocity at atmospheric conditions must be approx. 40 – 50 m/sec.

The velocities, combined with a very abrasive material like alumina (Mohs hardness 9) will cause unacceptable wear to the pipelines and bends.

As this is not a fluidisable product (too big particles), a blow tank (whereby the regulation of the loading ratio is done by bypassing air) will not be suitable.

Pneumatic conveying, however, will work.

A system (pressure or vacuum) should be designed by an expert, taking into consideration all aspects.

Success ■

Bend wear is a function of velocity and suspension density. If your conveying velocity is low and suspension density high, wear will be low. Basalt / densit bend should last a reasonable time. ■

Dear optima,

did you already decided how to go on? You mentioned a mohs hardness of 9. That is quite hard. So a hard and strong lining material will be required for the lining of the bends in order to solve the wear problem. We supplied already bends for such applications with good success. Rubber or Basalt will not be hard enough.

Regards,

Homscheid ■

Hello ,

You have been referenced Densit/Basalt or rubber for the bend segments.

We have a very strong reference list of such installations.

If you email to me on trevor@densit.co.uk

I will give you the difinitive solution. ■