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equipment. The emission factors can be calculated using the methodology found in Section 11.12 <br /> of AP-42. Table AQ-3 presents the emission factors for the concrete batching operations. The <br /> cement unloading and truck loading points have air emission controls applied to them. <br /> TABLE AQ-3 <br /> EMISSION FACTORS FOR CONCRETE BATCHING <br /> Uncontrolled Controlled <br /> Number of Emission Factor Emission Factor <br /> Emission Point Equipment (lbs/ton of material) (lbs/ton of material) <br /> r <br /> Aggregate Transfer 2 0.0033 0.0033 <br /> Sand Transfer 2 0.00099 0.00099 <br /> Cement Unloading 2 0.46 0.00034 <br /> Weigh Hopper Loading 2 0.0024 0.0024 <br /> Nlixer Loading 2 0.078 0.0038 <br /> Truck Loading 2 0.15 0.051 <br /> SOURCE:Compilation of Air Pollutant Emission Factors,AP-42,Fifth Edition,Volume 1:StationaryPoint and Area <br /> LSources,Section l 1.12 Concrete Batching,October,2001. <br /> Asphalt Batching Operations <br /> Hot mix asphalt paving materials are a mixture of size-graded,high quality aggregate, and liquid <br /> ` asphalt cement,which is heated and mixed in measured quantities. Hot mix asphalt paving <br /> materials can be manufactured by: 1)batch mix plants, continuous mix (mix outside dryer drum) <br /> ` plants,parallel flow drum mix plants, and counter flow drum mix plants. Processing begins as <br /> the aggregate is hauled from the storage piles and is placed in the appropriate hoppers of the cold <br /> feed unit. The material is metered from the hoppers onto a conveyer belt and is transported into a <br /> rotary dryer(typically gas-or oil-fired). <br /> Dryers are equipped with flights designed to shower the aggregate inside the drum to promote <br /> drying efficiency. As the hot aggregate leaves the dryer, it drops into a bucket elevator and is <br /> transferred to a set of vibrating screens,where it is classified into as many as four different grades <br /> ` (sizes) and is dropped into individual"hot'bins according to size. To control aggregate size <br /> distribution in the final batch mix, the operator opens various hot bins over a weigh hopper until <br /> the desired mix and weight are obtained. Concurrent with the aggregate being weighed, liquid <br /> f_ asphalt cement is pumped from a heated storage tank to an asphalt bucket,where it is weighed to <br /> achieve the desired aggregate-to-asphalt cement ratio in the final mix. <br /> r <br /> V <br />