ふるいにかける

Meanings

1

expression, ichidan verb

usually written using kana alone

Literally passing something through a sieve to separate particles. Also used for winnowing grain.

砂すなをふるいにかけて小こ石いしを分わける。

Sieve the sand to separate out the pebbles.

2

expression, ichidan verb

usually written using kana alone

Figurative use: examining a group of people or things to select the best or eliminate the unsuitable.

選せん別べつする
選別する is a more formal term for sorting or classifying, while ふるいにかける implies a filtering or screening process, often with a connotation of removing unwanted elements.
篩ふるう
篩う is a single verb meaning 'to sieve', but ふるいにかける is a more common, analytical expression for the same action.

From 篩 (ふるい, 'sieve') + に + かける ('to apply'). The figurative sense extends the idea of passing through a sieve to screening people or things.