NEW YORK — Horsehead Corp. and Shell Chemical LP have amended their option and purchase agreement to extend for six additional months the period of time Shell has to evaluate Horsehead’s Monaca, Pa., site, where it is considering building an ethane plant.

If built, the proposed plant would use a "cracker" to produce ethylene from ethane extracted from the Marcellus Shale at the former zinc production site (amm.com, March 16).

Horsehead is moving its zinc production operations from the Monaca site to a newly constructed facility in North Carolina, which is expected to start up in the second half of 2013 (amm.com, Sept. 19, 2011).

Horsehead Corp. is a subsidiary of Pittsburgh-based Horsehead Holding Corp., while Shell Chemical is a subsidiary of The Hague, Netherlands-based Royal Dutch Shell Plc.