November 17, 2006 A new manufacturing process developed appears set to make the production of iron much more environmentally friendly. The outstanding feature of the “Corex process” is that it uses conventional coal instead of coking coal, the customary ingredient. The world’s largest Corex-based plant is currently being built in China and is scheduled to begin operation in late 2007. It does not require a coking plant, reducing the discharge of dust and nitrogen oxides by more than 90 percent and sulphur dioxide emissions by 97 percent.
In conventional pig iron production at iron works, coking coal is first mixed with charge consisting of pellets, sinter and lump ore, and then the mixture is put into a blast furnace. At the base of this giant, bell-shaped furnace injected hot air burns the coking coal up into carbon monoxide at 2,000 degrees Celsius. In the upper part of the furnace the soaring carbon monoxide withdraws the oxygen from the iron oxide in the iron ore. Because of the high temperature the reduced ore melts to liquid pig iron. As a result of this traditional process with coking plant, powder metal facility and blast furnace, 1.4 kilograms of sulphur dioxide are created for each ton of pig iron. According to measurements taken by the TUV Rheinland, the Corex process sees this figure reduced to only 40 grams and the discharge of dust and nitrogen oxides is cut by more than 90 percent and sulphur dioxide emissions are reduced by 97 percent.
Corex is a smelting reduction process: Coal gasification, iron ore reduction, and liquefaction of the resulting iron are combined in one process. The gases produced can immediately be used for heating or for generating electricity in a gas and steam turbine power plant.
China’s booming economy and increasing urbanization are also leading to an upsurge of heavy industry. China’s metropolitan areas are now among the most polluted regions on earth, so new steel works are generally built with very environmentally friendly technology, and far from cities. Scheduled to become operational in the autumn of 2007, the new plant of the Baosteel subsidiary Baoshan in Luojing is expected to produce 1.5 million tons of pig iron per year using the Corex process. Baosteel is currently planning another Corex plant, also with a capacity of 1.5 million tons of pig iron.