| 1. | The metal was then melted down in an open hearth furnace.
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| 2. | This process is very similar to open hearth furnace steelmaking.
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| 3. | Basic oxygen steelmaking eventually replaced the open hearth furnace.
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| 4. | There were also two open hearth furnace steel mills.
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| 5. | Open hearth furnace was first developed by German-born engineer Carl Wilhelm Siemens.
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| 6. | The last open hearth furnace in the former East Germany was stopped in 1993.
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| 7. | The process involved modifying an open hearth furnace to use oxygen instead of air.
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| 8. | By 1962 five of the six open hearth furnaces at the plant had been converted.
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| 9. | This uses open hearth furnaces to convert pig iron to steel by burning off excess carbon.
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| 10. | Open hearth furnaces continued to operate until 1968, when they were replaced by electric arc furnaces.
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