Behaviour as communication
The student who throws chairs is not the problem. He is the messenger. The school's job is to hear the message before responding to the chair. Most schools respond to the chair, repeatedly, for years, and wonder why nothing changes.
What the behaviour is saying
Disruption almost always communicates one of four things: I cannot do this work and I would rather be punished than humiliated. I am unsafe at home. I do not know how to ask for what I need. Or, no adult in this building knows me.
Responding to the message
Sanctions belong in the response. They do not replace the response. The first conversation with a so-called behaviour-challenged student should answer the question the behaviour is asking. Until that question is answered, the chair will be thrown again.