RECOVERY OF FERRONICKEL FROM OXIDIZED ORES

摘要

1,232,184. Producing ferro-nickel. FALCONBRIDGE NICKEL MINES Ltd. June 27, 1969 [July 24, 1968], No.32510/69. Heading C7D. A process for recovering FeNi from oxidized Ni ores containing fine-sized high-Fe constituents and coarse-sized low-Fe constituents comprises separating e.g. by screen 1 the finesized constituents from the coarse-sized constituents, comminuting the coarse-sized constituents e.g. by tumbling mill 3 to form low-Fe fragments, adjusting (at 2) the moisture content of the finesized constituents and forming micropellets therefrom, forming a blend (at 4) of the low-Fe fragments and micropellets thereby producing an intermediate-Fe mixture, forming (at 5) uniformly sized briquettes from the intermediate- Fe mixture, feeding the briquettes to the top of a column 7 of downwardly moving briquettes in shaft furnace 6, the column comprising three superposed heat treatment zones, an upper drying zone, a middle preheating zone, and a lower reduction zone, passing a hot reducing gas containing CO and H 2 in excess of that required for reduction of the Ni and an equivalent quantity of Fe into the column at the bottom of the reduction zone and upwardly therethrough countercurrent to the descending briquettes thus reducing Ni and Fe in an amount equivalent to at least twice the amount of Ni but leaving unreduced to metal any oxides of Cr and Si and forming spent reduction gas, passing a free-O 2 -bearing gas into the column at the top of the reduction zone, reacting exothermically the spent reduction gas and the O 2 in contact with the briquettes in the preheat zone thereby preheating the briquettes and forming reacted gas, passing reacted gas upwardly through the drying zone to dry the briquettes and form top gas containing the moisture of the briquettes, removing top gas from the drying zone, discharging reduced briquettes from the bottom of the column at a rate corresponding to that at which briquettes are fed thereto, melting the reduced briquettes e.g. in electric furnace 8. to form a Ni barren slag and FeNi underlying the slag, and separating FeNi from the slag.