Torque Required To Rotate Horizontal Shaft Mixer

Did you multiply by the number of submerged paddles?

Why would you do it that way?????????????????

Do like everybody else in the world and use a rotating drum with the paddles attached to the inside of the drum.

You could do that with 5HP.

Have you ever tried moving cement. I think you may have to reevaluate your process on how your going to mix.

you don't have what you need.

What you need in an understanding of Rheology, viscousity.

not as far as something moving through the cement, Your looking at a mixer.

I see no accounting for the fact that the mixer will tend to lift the concrete in the direction of rotation, therefore it is trying to rotate the entire mass and this is resisted by friction against the body of the mixer. In other words, is your drag coefficient accurate?

For comparison I have a horizontal shaft paddle blender that is used for blending powders, about half the density. It's about 2m long by .8m, has 8 paddles mounted in a spiral configuration and turns at 24.5 rpm. It has a 25hp motor, and runs up to around 110% draw on a typical 1200-1400kg mix.

I was once asked to calculate the horsepower required to deliver paving mix by use of an Archimedes screw. To make a long story short, I gave up calculating and built a dynamometer that read out actual horsepower. It was nice because you could see the effects of different viscosity, temperature, admix, etc. When just the correct size rock gets lodged in the screw, the torque requirement increases dramatically. The calculations will get you so far, then you need data.

This is an ideal candidate for pilot-scale trials and then scale-up from them.

I have some problem with your drum : how do you introduce 1m^3 in a drum with a voulme of only 0.638 m^3? Or may be I am wrong so please compute the drum volume with the values you give D0.8mx1.27m and give the right volume.

How are the paddles arranged ? Do you have also stationary paddles or all 8 rows turn?

Usually for such a mixer the drum volume should be about ≈2x the content.

Concrete is NOT a fluid it is a paste and the formula you use is not the right one. You should look in books about chemical machines where this mixing is a often used process.

The best would be to look at data from different manufacturers and make a correct reverse engineering effort and then estimate your peculiar power need.