Abstract Apparatus and process for reducing iron ore and making sponge iron therefrom wherein a reduction column is formed by charging a vertical shaft furnace with iron-oxide ore and about 5 percent coke in lump form. The iron ore of the column is reduced at a temperature of 800* - 850* C. by a reducing gas mixture consisting essentially of 40 to 50 percent by volume hydrogen, 35 to 45 percent by volume carbon monoxide, 2 to 10 percent by volume nitrogen, 3 to 5 percent by volume methane, 2 to 5 percent by volume carbon dioxide and 2 to 4 percent by volume H2O. Thereafter the hot outlet gas is recovered, combined with a quantity of methane such that the methane in the resulting gas mixture is stoichiometrically equal to the quantity necessary to convert all of the carbon dioxide and H2O of said outlet gas into carbon monoxide and hydrogen, and reformed by passing it successively through a previously heated regenerator zone thereof to 700 to 900* C, through a nickel-catalyst zone adapted to convert substantially all but a maximum of 4 percent by volume methane of said gas mixture into carbon monoxide and hydrogen by reaction with the carbon dioxide and H2O of the gas mixture, and through a preheated regenerator zone to raise the temperature of the reformed gas mixture to 800 to 850* C. The sponge iron is recovered along with the major part of the coke added to said column with said charge.
A process as defined in claim 1 wherein the successive zones of step (c) are provided one beneath the other in each of two regenerator columns, said process further comprising the steps of f. heating one of said regenerator columns by burning at the base thereof a gaseous fuel with oxygen to produce a hot combustion gas induced to flow upwardly through the zones of said one of said generator columns during one phase of regenerator-column operation; g. simultaneously with said one phase of said regenerator-column operation of said one of said regenerator columns, passing said resulting gas mixture of step (c) downwardly through the successive zones of the other regenerator column and interchanging the functions of said regenerator columns to heat said other regenerator column while said one regenerator column carries out step (c); h. continuously supplying the reformed gas mixture to the reduction column in step (d); and i. treating the reformed gas mixture emerging from the last of said zones in step (d) with a burner supplied with methane and oxygen in the precise stoichiometric relationship necEssary to produce hydrogen and carbon monoxide, thereby further raising the temperature of said reformed gas mixture prior to its admission to said reduction column in step (d).
Claim 2
Independent Claim
280 words
An apparatus for the direct reduction of iron ore comprising: a vertical reduction shaft furnace; means for delivering to said furnace a charge consisting of iron ore and about 5 percent coke; a pair of functionally interchangeable regenerator columns each having in vertical succession a first refractory-packed regenerative heating zone, a nickel-catalyst zone and a second refractory-packed regenerative heating zone; respective first burner means at one end of each of said regenerator columns for burning a fuel-oxygen mixture and passing the resulting combustion products through said regenerator column in a first direction, thereby heating said zones; second burner means at said end of said column for combustion of methane therein for admixture with a gas traversing the generator column in a direction opposite said first direction; means for recovering from the upper end of said vertical shaft furnace nd an outlet gas containing water vapor, carbon dioxide, carbon monoxide, hydrogen, nitrogen and methane and including: dust-removal means for abstracting particulate matter from the outlet gas, scrubbing means for washing said outlet gas with water, means for removing excess water from said outlet gas, and means for feeding the treated outlet gas through one of said regenerator columns in said opposite direction while the other of said regenerator columns is heated by said combustion products; means for introducing the gas emerging at said one end of said one of said regenerator columns to said furnace at the bottom thereof; and an additional burner connected with the last-mentioned means for combustion of methane with oxygen in the precise stoichiometric ratio required for conversion of all of the combusted methane to hydrogen and carbon monoxide, thereby heating the gas admitted to said furnace.