Hylsa, S.a.

Jorge O Becerra Novoa

Enrique R Martinez Vera

Federico A Rodriguez

Julian Sanchez Ramirez

A method and apparatus are disclosed for achieving improved reduction efficiency and thermal economy in the reduction of particulate metal ores, e.g., iron ore, in a vertical shaft, moving bed reactor. The reactor consists of a primary reduction zone, a cooling zone and a secondary reduction zone located between the primary reduction zone and the cooling zone wherein ferric carbide formed in the primary reduction zone further reduces the residual iron oxide in the presence of an inert gas at a temperature below the melting point of the sponge iron. In one embodiment of the invention the gas produced by the reaction in the secondary reduction zone is withdrawn into a combustion chamber where it is mixed with air and burned, carbon dioxide is removed from the effluent gas of the combustion chamber and the remaining inert gas is recirculated to the secondary reduction zone. In another embodiment of the invention inert gas is supplied from an external source and carbon dioxide is eliminated from the system by means of a controlled purge. Use of the disclosed secondary reduction system allows for a lower residence time of the metal ore through the reactor and increased thermal economy.

Method and apparatus for the secondary gaseous reduction of metal ores

Method for rapid and accurate weight determination of molten metal in a slag-containing bath preferably without any necessity for direct gross weighings in a hostile steel works environment or otherwise, by the addition to the molten bath of a known weight amount of a 'trace' element (preferably of a type which is completely diluted in the molten metal, to the practical exclusion of the slag); awaiting the even dispersal of the trace element in the molten metal (aiding the speed of dispersal by promoting a boiling action, if necessary); taking a sample of the molten metal; analyzing the sample to determine the weight percent of trace element in the molten metal (for example by spectrometric analysis); and determining the weight of the metal from the known values of weight of the trace element added and its weight percent in the molten metal after addition. In the event that a measurable amount of the trace element exists in the molten metal prior to the addition of the weighed amount, then it is also necessary to take a sample of the metal prior to addition and determine the weight percent of the trace element in that first sample. Alternatively, the trace element may selectively dissolve in the slag, thus similarly permitting the determination of the weight of the slag; but requiring a knowledge of the net weight of the molten bath if the weight of the molten metal is ultimately required. Similarly, if the trace element used dissolves in both the molten metal and the slag; then it will be necessary in this case also to know the net weight of the molten bath (e.g. by crane weighing load cell systems) as well as the weight percentages in the slag (e.g. determined by x-ray fluorescence).

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San Pedro Garza Garcia, Mexico

Jorge O Becerra Novoa