It is not good practice to base the design of equipment on the data derived only from the name of a bulk material because this takes no account of the composition or condition of the product. ‘Quick lime’ for example, with a high fines content, can behave as a fluid when aerated or act cohesively when settled.

As a general rule, the term ‘angle of repose’ does not have much meaning for a fine bulk material because it will assume a slope according to how it is handled. Coarse products that settle quickly to a stable bed will tend to form a consistent surface profile when ‘poured’ or ‘drained’, but the former may be influenced by the scale of fall onto the pile when loaded from a belt conveyor. Where practical, information should be secured from testing or practice with a representative sample of the material to be utilised.

Likewise with inclined belts. It is particularly important that fine powers be stabalised before travelling up an incline on a belt conveyor. The design of the feed system is a crucial factor in such cases. Normally, a belt may be expected to cope with a slope of 15 degrees, accepting that it is not loaded to 100% capacity for horizontal transfer. ■