Feed
Feed means the prepared and mixed materials, which include but are not limited to materials such as limestone, clay, shale, sand, iron ore, mill scale, cement kiln dust and flyash, that are fed to the kiln. Feed does not include the fuels used in the kiln to produce heat to form the clinker product.
Source
40 CFR § 98.6
Scoping language
All terms used in this part shall have the same meaning given in the Clean Air Act and in this section.