During hand sieving, how is the sieve positioned for effective operation?

The sieve should be positioned at an angle with a cover plate and catch pan during hand sieving to ensure effective operation. When the sieve is angled, gravity aids in the movement of the material down through the mesh openings, promoting better separation of particles based on size. The cover plate helps prevent the material from spilling out and facilitates collection into the catch pan underneath. This setup is crucial for achieving accurate results, as it ensures that all the material falls through the mesh efficiently without causing contamination or loss of product.

The other configurations, such as positioning the sieve horizontally or vertically, do not optimize the sieving process. A horizontal position may lead to clogging of the mesh with larger particles, while a vertical setup might cause difficulty in maintaining control over the material being sorted and risk loss of the finer particles. Using a vibrating table can enhance the sieving process, but it is not suitable for hand sieving, which relies on manual action and gravity for efficient separation. Thus, the angled position with a cover and catch pan is the most effective approach for hand sieving.