Finishing operations in steel foundries

Concerning steel foundries, specific cutting, scarfing and welding processes are used. Average dust emission values are given in Table 3.56. These ply for the use of the following techniques  

Cutting (of runner system) Tetrene-acetylene-iron oxide for stainless cutting Scarfing Carbon electrode covered with copper Welding Using electrodes or wire. 

The emissions from heat treatment furnaces mainly comprise combustion gases, particularly from gas- and oil-fired furnaces. The composition of the combustion gases depends on the fiiel-t) e used. Oil-fired furnaces will generate S02-emission, which are not present for natural gas burners. Where quenching processes are carried out, emissions of fume, water vapour, or oil mist will also occur, depending on the quenching media. 

Heat treatment furnaces are known to be continuous sources of well known non-air components. Emission levels are closely related to energy consumption, burner design and maintenance. Emission collection is trivial in annealing furnaces. The capture of the emissions in the different furnaces does not differ considerably, and emissions are expelled via the waste gas pipe. In general, no further waste gas treatment is applied. 

Generally, quenching is a batch process. For this reason emission levels alternate substantially. Emissions from the quenching baths are regarded mostly to be irrelevant for the environment, although they may become more relevant with large scale production. Data about source strength (emission rates) and chemical compounds have not been found. 

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