Green Steelmaking

Worldwide, there is an increasing emphasis on environmental issues and the steel industry is under intense scrutiny. The emissions from integrated steel mills, especially sinter plants and coke ovens, are a particular concern. As a member of the global community, Midrex along with its parent company Kobe Steel, recognizes the importance of the environment and the limits to natural resources. Through the years, we have been proactive in reducing the environmental impact of our iron and steelmaking processes.

Plants are designed to minimize air, water and noise pollution and they meet applicable World Bank standards. If necessary, plants can be designed to meet stricter local standards. Typical emission levels for the MIDREX^® Process are shown in the table below. Carbon dioxide emissions are becoming a concern and in this regard, the MIDREX^® Plant/EAF route to steelmaking has a significant advantage versus the traditional blast furnace/BOF route. Midrex continues to develop technologies and methods to reduce emissions even further.

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Typical Environmental Performance*
 

AIR	AIR EMISSIONS (kg/t of CDRI)
	PM10	SO2	NOx	CO2
				Standard	Low CO2
Charge Hopper	0.0006	trace	0.003	trace	trace
Combustion System    (Reformer Stack)	0.04	0.02	0.04*	500	250
Dust Collection     (typical for one system)	0.004	trace	0.005	trace	trace

*Controlled value. Uncontrolled value is ~0.4 kg/t DRI.
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WATER	WATER EMISSIONS
	Suspended Solids   (kg/t of DRI)	Flow   (m3/t of DRI)
Plant Blowdown	0.01	0.2 - 1.5

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NOISE   (Lower values achievable with modified acoustical design)	NOISE LEVEL (db)
Inside the blower area	95 - 105
Immediately outside the blower area	85 - 90
Miscellaneous stations around the plant	80 - 90
At plant boundaries	70 - 80

*Plants can be designed for even lower values if required.

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Reducing Carbon

The increasing emphasis on the environment creates a need for innovative solutions to reduce carbon emissions from iron and steelmaking facilities. One approach is to use natural gas as a reductant and fuel source, since it results in far less CO₂ emissions than coal.

A proven method is the natural gas-based MIDREX^® Process, paired with an electric arc furnace. Use of 80 percent hot charged DRI in the EAF results in only one-half the carbon emissions per ton of steel produced compared to the blast furnace/BOF route.

Some steelmakers desire greater CO₂ reductions. MIDREX^® has developed a new concept employing a CO₂ removal system that allows for even lower emissions. The advantage of this option is the flexibility it provides the plant operator, with relatively small changes in capital cost, operating consumptions, and operating cost. If the removed CO₂ is used for enhanced oil recovery, sequestered underground, or sold into a pipeline, stack CO₂ emissions per ton of DRI are reduced by 250 kg/t DRI, about 50 percent. This option can also provide significant benefits for an existing MIDREX^® Plant.  The use of CO₂ removal allows for higher DRI production without adding additional reformer bays, and lowers natural gas consumption, in addition to the benefits of lower CO₂ emissions.

It is even possible to build a MIDREX^® Plant with essentially zero carbon emissions to the atmosphere. In addition to removing CO₂ from the top gas, a system could strip it from the flue gas as well. The recovered CO₂ from both streams could be injected underground or sold into a pipeline.

As steel companies become increasingly globalized, they will have many opportunities to incorporate this technology option into their CO₂ management plans by installing direct reduction plants in regions with low cost natural gas. In some cases, it may be possible to apply the carbon credits generated in those facilities to carbon restricted regions such as Europe and North America.