write on pyro-extraction of metals

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Request for Question Clarification by techtor-ga on 10 Jul 2004 06:33 PDT

How specific is the information you are looking for? Are you looking
for the descriptions of the processes of pyro-extraction?

Pyro means fire. Extraction could be removing the ore from the ground,
improving the metal contant of the ore and/or separtating the metal
from the ore. Some extraction is done with little or no heat, so this
would not be pyro extraction.   Neil

Basically, you can either use hydro or pyro methods to purify metals
from ores. Each requires the use of various chemical reactions to some
extent. Aluminum is mainly extracted by hydrometallurgy?current is
conducted through a molten bath, and the aluminum is reduced out.
Copper and nickel mainly use pyrometallurgy. For nickel,
pyroextraction uses large furnaces to remove moisture from lateritic
and sulfidic ore and to catalyze the oxidation (burning) of iron and
sulfur that causes the nickel to melt out (this use of oxidation
diminishes the amount of electricity used by utilizing exothermic
reactions). Blast and reverbatory furnaces are no longer allowed
because of pollution, so electric furnaces are used. Check out the
following websites:

http://ifcln1.ifc.org/ifcext/enviro.nsf/AttachmentsByTitle/gui_nickel_WB/$FILE/nickel_PPAH.pdf

http://wbln0018.worldbank.org/essd/essd.nsf/GlobalView/PPAH/$File/54_coppr.pdf

If you actually want to smelt the metals, this website helps:

http://home.europa.com/~heritage/ironsmelt.html

mechanical process is fairly straight forward. The brick lined 
    furnace, in essence an elongated cauldron of crucible, bosh and stack, 
    is loaded with a balanced mixture of crushed ore, charcoal and 
    limestone. Air is pumped into the fire of the bosh and the temperature 
    of the operation is held at 600 to 1000 degrees Centigrade.
         Blowing in the furnace takes several days an must allow for the 
    moisture contained in the fire-brick lining to evaporate in order to 
    prevent damage to the furnace. Once the furnace is heated, the 
    smelting process becomes a continual cycle of top-loading the stack 
    and drawing off iron from the tap hole and slag from the cinder notch 
    located near the bottom of the bosh. The mechanical constraints 
    limiting the size of the bosh are that the furnace be tall enough to 
    allow the chemical reduction process and small enough that the fuel 
    (charcoal at Oswego) is able to support the load of ore and flux.
         A approximately eighteen month intervals, the furnace is "blown 
    out" as the lining becomes consumed by the smelting process. Blowing 
    out is a standard procedure allowing for replacement of the furnace 
    lining and general examination of the bosh interior. The sporadic 
    production history of the Oswego smelters can, in part, be attributed
    to blowing out and maintaining the stack.