There are four(4) major method of producing Ferro alloys additives for steel making processes. By (1) blast furnace, 2) electric melting or submerged arc, 3) alumino  siliconthermic and electric disposition.

The most commonly used process is the submerged Electric arc closed or no roof type furnace. Temp. with in the furnace is from 3000- 3500 deg C , temp that are collected to be ventilated usually ranges between 160-320 deg C at the interface of the hooding depend upon the type of furnace.

The main system in capturing the escaping fumes from the furnace is an open roof ventilation (side and back holds and supports the electrodes) This distance is generally @ 3 mt. High.
Listed below is a qualitative spectra chemical analysis of the collected Ferro silicon fumes:

When Ferro alloy has been refined to its final constituents, that is removing all the necessary impurities , the submerged arc furnace will then be tapped. This involves boring or lancing a hole in shell of the furnace above the tap spout, which is plugged during its melting operation. This will allow the Ferro alloy to be transferred from the furnace into the ladle, which is then taken, to continuous casting machine or to its final cooling area. After the Ferro alloy is cooled , its usually crushed and screened to its required sizes and shipped to its final destination. The furnace generally is basic lined, usually with magnesium oxide refractory.

The melting practice of Ferro silicon and silicon metal, and most Ferro alloys includes and addition of wood chips to produce a fluid melt and carbon to form the CO and CO2. This also allows semi porous channels for evolution of CO from bath.(it is because of this practice silicon cannot be successfully produced in a fully enclosed furnace). As a result of addition of this carbon and wood chips, many sparks are being emitted continuously. To protect the Fabric filters from this spark, some type of pre-chamber /cleaner should be added to FES system