Sunoco Inc. said it would build a $230 million plant in Ohio to make coke fuel for steel blast furnaces.

The plant in Haverhill, with the capacity to produce 550,000 tons of blast furnace coke per year, will capture waste heat and use it to produce steam for a 67 megawatt turbine.

This will be Sun Coke Co.'s second coke plant in Haverhill. The company opened $140 million plant with the same capacity in March 2005.

Sun Coke earned $50 million last year, up from $48 million the year before. Most of Sunoco's $979 million in earnings last year came from oil refining.

Shares in Sunoco, which is the largest oil refiner in the Northeastern United States, were down $1.07, or 1.74 percent, at $60.38 on the New York Stock Exchange.

Sunoco's method for making coke, which it acquired in 1979 when it had a large coal-mining business, meets the highest level of standards in the 1990 U.S. Clean Air Act, the company said.

Contact staff writer Harold Brubaker at 215-854-4651 or hbrubaker@phillynews.com.