|Environmental Handbook Volume II: Agriculture, Mining/Energy, Trade/Industry (GTZ/BMZ, 1995, 736 pages)|
|Trade and industry|
|49. Iron and steel|
The erecting of iron and steel production plants involves land-use which is measured in terms of the works site with adjoining areas and connecting roads. Before erecting production plants, impacts on the local natural order and the geogenic and anthropogenic burdens on the soil and groundwater and on any bodies of surface water must be investigated in the context of the location planning. An adequate distance from the nearest residential zones must also be guaranteed. Details are contained in the environmental brief Planning of Locations for Trade & Industry.
Iron and steel works involve large-scale production and require large amounts of raw materials. These include primarily ores, coke and limestone. Generally speaking, to produce 1 tonne of crude steel requires 450 to 500 kg coke and fuel oil, 250 kg lime and 5 m3 water.
In an integrated iron works for example, the specific total energy consumption is some 20 GJ/t crude steel. In an integrated iron works, the sintering plant, blast furnace, coking plant, steel works, rolling mill and power station areas are interconnected as a combined energy system. Thus, the top gas is utilised in all areas, its calorific value enriched with converter gas, coking oven gas or natural gas. Power and steam are supplied by the power station. Boilers are usually operated with gas, e.g. top gas. The burners can be fired with top gas, coking oven gas or fuel oil. External power supplies are used in addition to internally generated power. Waste heat boilers from the steel works contribute to steam production.
A mixed iron works is linked to the following other sectors:
- The raw materials (ores, coal, limestone) must be mined in large quantities in open cast or deep mines. (See environmental briefs Surface Mining and Underground Mining).
- Ores must be dressed (see environmental brief Minerals - Handling and Processing).
- Efficient transport routes (canals, railways or roads) are required for transporting raw materials and products. For environmental protection reasons, transport should mainly be via inland waterways and railways. Whether the location of the iron works is chosen because of where the ore, coal or sales market is situated, high-capacity transport facilities must always be provided.
- Coke of specified quality must be supplied for the blast furnace by a coking plant. Reference should be made to the environmental brief Coking Plants, Coal to-gas Plants, Gas Production and Distribution to assess the environmental impacts associated with coke production.
- In view of the quantities of cooling water needed, an adequate water supply must be available. To avoid the adverse consequences of drawing excessive quantities of water from groundwater or surface water resources, extensive recirculation systems must be provided, internal treatment of wastewater and cooling water. Water consumption must be in harmony with the general water framwork planning.
- The large workforce of a mixed iron works may result in the disorganised development of housing at an insufficient distance from the plant. This can lead to water shortages, unsatisfactory wastewater treatment and disorganised dumps, plus immission burdens affecting the areas of habitation.
- Other sectors directly or indirectly linked to the iron and steel industry are: lime kiln plants, cement works, ferroalloy production plants, power generating plants and slag and dust recycling plants. The above plants and establishments are associated with considerable potential atmospheric burdens. Reference is made to the relevant briefs.
- A general or single-purpose dump is to be provided for non-recyclable residual and waste materials including furnace debris from the metallurgical processes with hazardous pollutants. These should be classified according to criteria of environmentally acceptable final storage (see environmental brief Disposal of Hazardous Waste).