Employee since 2002 at Indiana factory. Has had multiple injuries and has been on work comp and or sick leave for much of the time. Company is now going to terminate. Reason: "Unfit for industrial work". We have a collective bargaining agreement which does not address this. Is there a law specifically adressing this?

No. While an employee cannot be fired BECAUSE they filed a workers comp claim, having filed a workers comp claim is not a guarantee of permanent job protection. An employee who filed for workers comp can still be fired for exceeding the time out mandated by law or permitted by company policy, for violating safety procedures, for poor performance or for any business reason unconnected with the workers comp claims.