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US 3,995,987 AGranted
Heat treatment of particulate materials
OwnerDonald MacAskillinventor
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Abstract
A multiple-stage calcining system employing different conditions in each calcining stage so that quality, capacity and temperature control can be maximized. Advantage is taken of the difference in ignition temperatures of fuels.
Claims7
A method for heat treating a material selected from ores, precipitates, concentrates and residues so that hydrates, carbonates and the like are decomposed while volatiles are expelled, comprising:
- introducing said material into a first high capacity fluidized stage;
- controlling the introduction of oxygen-containing gases to said first stage to create an environment wherein incomplete oxidation will occur while said fluidized material is being heated to about 1100.degree. F;
- transferring said partially oxidized material from said first stage to a second fluidized stage;
- adding sufficient oxygen to substantially complete combustion of said partially oxidized material by heating to a temperature in excess of 1100.degree. F;
- and
- recovering said material from said second stage.
3 more elements
Dependencies are inferred from the claim text.