Get a copy of "Industrial Ventilation" published by American Conference of Governmental Industrial Hygienists. Allow for 50% more for 'dry, dusty materials'.

Michael Reid. ■

The MHEA design guide says -

less than 1 m/s - 0.5m3/s/m width of belt

over 1 m/s - 0.7 m3/s/m width of belt

Transfer point enclosure design to provide 0.75 - 1 m/s indraft at all openings ■

The exhaust velocity, exiting a transfer is, in part, dependent on the following conditions:

1. Design of chute which controls flow stream velocity at point of impact with receiving belt

2. Size distribution and bulk density of granular material stream

3. Belt speeds of discharge and receiving conveyors

4. Design and length of skirtboard system once material is on receiving belt

5. Baffles and decanting chamber designs in chute and receiving skirts

6. Work point change in elevation between discharge and receiving conveyors

7. Profile angles to horizontal plane between discharge and receiving conveyors

8. Moisture content of flow stream

The material stream velocity exiting the receiving belt skirtboard can then be predicted based on Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) coupled models, given they can handle reasonable material size distribution. The material size distribution sets the surface roughness that defines the gas turbulence together with receiving belt velocity and ore stream velocity at the skirtboard exit point. All 8 points contribute.

The method is very complex to define in mathematical terms.

I may have forgotten to list some additional values/conditions that can be offered by other knowledgable forum members. ■