One ton of scrap contains an average of 2 kg of zinc, Suwa says. Researchers believe the NSR process doesn't emit dioxin, although more analysis is needed, Suwa says. During secondary combustion, the process uses the heat, which is as hot as 1,000-1,200 degrees C, to decompose dioxin. Nitrogen oxide emissions are as low as 10-20 particles per million. Beginning in Dec. 1998, Japanese law required EAF steelmakers to reduce dioxin emissions below stipulated levels.
Operators charge scrap, coke, and flux into the melting section.
At the test plant, three burners are around the furnace. Larger furnaces might require more burners. The burners blow combusting oxygen and heavy oil into the furnace. Exhaust gas escapes through the top. Molten metal travels to the pooling, or collecting, section, where a carbon- injection lance at the top shoots pulverized coke into the melt as it's being stirred by gas injected from the bottom.