CHICAGO -- Zinc products refiner and recycler Horsehead Holding Corp. said it will restart four furnaces refining zinc oxide and metal at its Monaco, Pa., plant by the end of the month and expects to return production to where it was before a fatal explosion in July by early next year.
Company executives said all of the plant's Larvik furnaces are to be restarted in September and that refined zinc metal columns will be restarted in November. Smelting facilities and other operations at the plant have remained active at reduced production rates since the explosion which killed two workers. The smelting facility has been operating five of six furnaces producing zinc metal.
Executives said teams from the US Occupational Safety and Health Administration and the US Chemical Safety and Hazard Investigation Board are continuing separate inquiries into the cause of the blast and circumstances that might have contributed to the accident.
They said it was believed the explosion was caused by liquid zinc escaping into a much hotter combustion chamber surrounding a distillation column. The liquid zinc was believed to have vaporized and expanded rapidly, beaching the column wall and combusting upon reaching the atmosphere.
The company is planning to implement preventive and protective enhancements to the refinery based on results of the investigations so far, executives said. Enhancements are to include changes in the design of the columns and operating procedures. An alarm system will also be installed along with barriers around the column to protect employees, they said.
