Machine Design Help - Calculate Load & Shaft Size

[rhawkbw]

I have a machine I want to build, the principle works on the basis that products enter a cylindrical sieve 900mm long, 2mm thick and 400mm dia, in the center is a shaft of 50mm dia, 1600mm long with 900 rpm. The shaft has paddles at a angle of 45deg to act as a conveyor by agitating the product against the sieve is intend to classify the product into various sizes. Each paddle is 120mm long and 60mm wide. What I would like to know is whether the shaft can handle the load, and how to actually calculate this load so as to determine correct shaft size to use as well as motor requirements. How would density affect this, the product has a density of 800kg/m3

If more info is required I can provide, please help

 

[viscousflow]

A picture/diagram would help