CONTROL OF SECONDARY EMISSIONS IN PYROMETALLURGICAL SMELTERS

Existing environmental, health and safety regulations have forced pyro metallurgical facilities worldwide to drastically change some of their traditional methods of operation. In extreme cases, a number of facil ities have been closed due to their inability to conform to these exis ting regulations. Tougher future legislation and government policy wil l lead to more stringent regulations and enforcement policies. The eff icient control of smelter secondary emissions will, therefore, become critical to successful smelter operation. Much attention has been paid to the smelter primary process off-gas systems, including the develop ment of new process designs to reduce the number of uncontrolled trans fer operations. However even the most modern smelter design requires c ontrol of its secondary contaminant sources, which may or may not be d irectly related to the process operation. This paper discusses some of the potential secondary emissions encountered in many of the present process technologies. A few of the emission sources presented are only periodic in nature, such as those caused by maintenance procedures, b ut which have the capability of forcing smelter shut-down because of t heir direct impact on worker health and safety. The paper deals with a variety of topics relating to the efficient control, maintenance and monitoring of secondary emissions in copper, nickel, aluminum, magnesi um and lead smelters, as well as in iron foundries and steel making fa cilities. Examples of the typical problems encountered in each of the above process operations are presented, including fume control at furn ace tapping and slagging locations, metal transfer stations, tapping l aunders, and ladle transfer operations. The parameters for the most ef ficient design of fume capture systems, problems encountered with the handling and clean-up of certain collected emissions, and examples of successful solutions in particular operations are discussed.