How to remove iron filings from the construction site?

Be firm and inform scrap metal collectors that it is illegal to take scrap metal on the site without the consent of the site. If the circumstances are serious, you can call the police.

When telling each other, there must be no physical conflict. Generally, people who pick up scrap iron are old people. Once there is a physical conflict, things will become troublesome. Video can be used as evidence if necessary.