Clean Harbors Inc. (NYSE: CLH) will buy Safety-Kleen Inc. for $1.25 billion.Safety-Kleen, headquartered in Richardson, Texas, re-refines and recycles used oil in North America and provides parts-cleaning services. The company generated $1.3 billion in revenue in 2011.Norwell, Mass.-based Clean Harbors provides environmental, energy and industrial services, including hazardous waste management.The deal requires regulatory approval.Gary Cullen, Gregg Noel, Clifford Aronson, Maxwell Miller and Joseph Yaffe of Skadden Arps Slate Meagher & Flom LLP are representing Safety-Kleen on the deal. Credit Suisse served as lead financial adviser, and Houlihan Lokey provided additional financial advice. Davis Malm & D'Agostine served as Clean Harbors' legal counsel.