CHARLESTON, W. Va. – Shareholders overwhelmingly approved coal producer Alpha Natural Resources’ $7.1 billion takeover of struggling rival Massey Energy Co. on Wednesday, the companies said.

Alpha immediately began absorbing Massey, replacing the company’s sign on its West Virginia headquarters and filing at least 18 documents with the Securities and Exchange Commission cancelling Massey shares after the deal closed.

Massey’s safety record has been the focus of renewed scrutiny since 29 miners died in an explosion at its Upper Big Branch mine in southern West Virginia in April 2010.

The combination transforms Alpha, based in Abingdon, Va., from a good-sized company into the world’s third-largest producer of metallurgical coal, a key fuel for manufacturing steel.