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

The price tag is 58 percent higher than that of a similar plant that broke ground in February 2004 and began operating in Haverhill in March 2005.

Sunoco attributed the increase to higher prices for steel and other materials, more expensive labor, and additional equipment that will capture waste heat and use it to produce steam for a 67-megawatt turbine.

Like the existing plant, the one announced yesterday will have the capacity to produce 550,000 tons of blast furnace coke per year. The new plant represents a 22 percent increase in production, based on last year's figures.

Customers for the new coke plant include WCI Steel Inc., of Warren, Ohio, which said yesterday it had signed a 15-year contract with Sun Coke. Most of Sun Coke's existing production goes to Mittal Steel USA Inc., part of the largest steel company in the world, under long-term contracts.

The Ohio Department of Development said it had agreed to aid in the expansion project in Haverhill through incentives worth at least $1 million. The state said the expansion would add 49 jobs.

Sunoco's coke-processing method, 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.

"Coking" separates coal into solid carbon and gasses under high heat. The volatile gasses from the coal are burned to heat back into the coal ovens.

Sun Coke earned $50 million last year. That's a small part of Sunoco's $979 million in total earnings, but company executives like the business's stability and its returns on investment.

Shares in Sunoco, which is the largest oil refiner in the Northeastern United States, fell $1.47, or 2.39 percent, to close at $59.98 yesterday on the New York Stock Exchange.

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