Horsehead Holding (HRRS) 10-K 2014 FY Annual report

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We have issued our reports dated March 2, 2015 with respect to the consolidated financial statements, schedule and internal control over financial reporting included in the Annual Report of Horsehead Holding Corp. on Form 10-K for the year ended December 31, 2014. We hereby consent to the incorporation by reference of said reports in the Registration Statements of Horsehead Holding Corp. on Form S-3 (File No. 333-191441, effective October 3, 2013), Form S-8 (File No. 333-147750, effective November 30, 2007) and Form S-8 (File No. 333-185281, effective December 5, 2012).

/s/ GRANT THORNTON LLP

Cleveland, Ohio

March 2, 2015