57.301—General requirements.
Each NSO shall require an interim level of sulfur dioxide constant controls to be operated at the smelter, unless a waiver of this requirement has been granted to the owner under subpart H of this part. Except as otherwise provided in § 57.304, the interim constant controls shall be properly operated and maintained at all times. The NSO shall require the following gas streams to be treated by interim constant controls:
(a)
In copper smelters, off-gases from fluidized bed roasters, flash furnaces, NORANDA reactors, electric furnaces and copper converters;
(b)
In lead smelters, off-gases from the front end of the sintering machine and any other sinter gases which are recirculated;
(c)
In zinc smelters, off-gases from mult-hearth roasters, flash roasters and fluidized bed roasters; and
(e)
In all primary nonferrous smelters, any other process streams which were regularly or intermittently treated by constant controls at the smelter as of August 7, 1977.