Emission factor data for blast furnace gas and coke oven gas are not available and must be estimated. There are 3 facts available for making the estimation. First, the gas exiting the blast furnace passes through primary and secondary cleaners and can be cleaned to less than 0.05 g/m3 (0.02 g/ft3). Second, nearly one-third of the coke oven gas is methane. Third, there are no blast furnace gas constituents that generate particulate when burned. The combustible constituent of blast furnace gas is CO, which burns clean. Based on facts 1 and 3, the emission factor for combustion of blast furnace gas is equal to the particulate loading of that fuel, 0.05 g/m3 (2.9 lb/106 ft3) having an average heat value of 3092 J/L (83 Btu/ft3).

Emissions for combustion of coke oven gas can be estimated in the same fashion. Assume that cleaned coke oven gas has as much particulate as cleaned blast furnace gas. Since one-third of the coke oven gas is methane, the main component of natural gas, it is assumed that the combustion of this methane in coke oven gas generates 0.06 g/m3 (3.3 lb/106 ft3) of particulate. Thus, the emission factor for the combustion of coke oven gas is the sum of the particulate loading and that generated by 12.5-6 EMISSION FACTORS

(Reformatted 1/95) 10/86 the methane combustion, or 0.1 g/m3 (6.2 lb/106 ft3) having an average heat value of 19,222 J/L (516 Btu/ft3). The particulate emission factors for processes in Table 12.5-1 are the result of an extensive investigation by EPA and the American Iron and Steel Institute.3 Particle size distributions for controlled and uncontrolled emissions from specific iron and steel industry processes have been calculated and summarized from the best available data.1 Size distributions have been used with particulate emission factors to calculate size-specific factors for the sources listed in Table 12.5-1 for which data are available. Table 12.5-2 presents these size-specific particulate emission factors. Particle size distributions are presented in Figure 12.5-2, Figure 12.5-3, and Figure 12.5-4.CO emission factors are in Table 12.5-3.6 12.5.2.9 Open Dust Sources Like process emission sources, open dust sources contribute to the atmospheric particulate

Open dust sources include vehicle traffic on paved and unpaved roads, raw material handling outside of buildings, and wind erosion from storage piles and exposed terrain. Vehicle traffic consists of plant personnel and visitor vehicles, plant service vehicles, and trucks handling raw materials, plant deliverables, steel products, and waste materials. Raw materials are handled by clamshell buckets, bucket/ladder conveyors, rotary railroad dumps, bottom railroad dumps, front end loaders, truck dumps, and conveyor transfer stations, all of which disturb the raw material and expose fines to the wind. Even fine materials, resting on flat areas or in storage piles are exposed and are subject to wind erosion. It is not unusual to have several million tons of raw materials stored at a plant and to have in the range of 9.7 to 96.7 hectares (10 to 100 acres) of exposed area there. Open dust source emission factors for iron and steel production are presented in Table 12.5-4.