The document discusses furnaces used in primary metal production. Primary metals are metals extracted from ores without scrap. Various furnaces are used to produce primary metals through high-temperature chemical reactions. These furnaces include shaft furnaces, which continuously supply ore and fuel from the top while blowing air into the bottom, muffle furnaces which isolate materials from furnace gases, and hearth furnaces like reverberatory furnaces which need high temperatures. Hearth roasters arrange multiple hearths vertically to roast coarse ores, while flash smelting uses rapid reactions for fine particulate matter. All involve gas and air to produce chemical reactions forming ingots for further processing.

1. Furnaces in Primary Metal Production
Primary metals are metals extracted from minerals that are free from scrap. NAICS (North American
Industry Classification System) defines the primary metal sector as: a sector of the manufacturing
industry which deals with the smelting and/or refining of ferrous/non-ferrous metals from ores;
employing various metallurgical processes and techniques. The metallurgical processes used to produce
primary metals involve various chemical reactions at high temperatures, which are carried out using a
variety of furnaces.
Below are a few of the furnaces used for primary metal production:
1. Shaft Furnace: “Fuel and ore are continuously supplied through the top of the furnace, while
air (sometimes with oxygen enrichment) is blown into the bottom of the chamber, so that
the chemical reactions take place throughout the furnace as the material moves
downward.” (wikipedia.org)
2. Muffle Furnace: Used in processes whose feed is sensitive to direct interaction with the fuel,
so the subject material is isolated from the gases, air, and fly ash.

2. 3. Hearth Furnaces: A furnace used where high temperatures are need and where direct
heating is admissible. Reverberatory furnaces and rotary kilns are the best example of
hearth furnaces.
4. Hearth Roasters: typically, 6-12 hearths are arranged vertically to roast coarse ores. Most of
the roasting occurs as the particles drop from one hearth to the next.

3. 5. Flash smelting is another process often used in the primary metal production, due to the
rapid reaction rate, and thus, the excellent efficiency. Flash smelting is used with only fine
particulate matter.
These are only a few of the furnaces and processes used for primary metal production. However, you
can see that they all use gas and air to produce the chemical reaction needed for the desired end
product. In addition, the final output from the majority of primary metal manufacturing processes is
typically a formed ingot which is later processed into wire, sheet, rod, strip, ect.

4. All images are credited to unique source: http://www.chem.mtu.edu/chem_eng/faculty/kawatra/CM2200_Primary_Metals.pdf
For more information, please visit www.stelterbrinck.com or call Stelter & Brinck at 513-367-9300
Keywords: Primary Metal Manufacturing, Stelter & Brinck, air and gas, shaft furnace, muffle furnace,
hearth furnace, electric furnace, hearth roaster, flash smelting.