GB729146A - Apparatus and process for the reduction of metal oxides by gases - Google Patents

Abstract

729,146. Shaft furnaces. MATTHEWS, S. E. (Electrolyser Corporation, Ltd.). June 18, 1952, No. 15327/52. Class 51 (2). [Also in Group II] A shaft furnace for the reduction of metal oxides without fusion comprises pre-heating, reducing and cooling zones one below the other, means for circulating a hot gas through the pre-heating and reducing zones and means for subsequently repeatedly passing a hot reducing gas through the reducing zone only until the ore is reduced. In the form shown, a pipe 3 from a gasometer leads to a heat storage unit 4 of intersticed brick which is connected via a superheater 6 to ports 10 in a shaft furnace 11, and a pipe 18 from another gasometer leads through a similar heat storage unit 17 and a similar superheater 15 to ports 12 in the furnace. In. the furnace, the preheating zone between the lower feed bell 22 and the ports 10 contains cold ore, the reducing zone between the ports 10 and the ports 12 contains pre-heated ore, and the cooling zone between the ports 12 and the discharge mechanism 19 contains hot sponge iron. Cool hydrogen is fed through a pipe 26 and passes up through the furnace and out through the pipe 27, thus cooling the sponge iron and heating the ore in the reduction and pre-heating zones. Hot hydrogen is then injected through the ports 12 and removed through the pipe 27 to heat further the ore in the reducing and pre-heating zones. The ore in the reducing zone is reduced by passing hydrogen from one gasometer through the heat storage unit 4, where it is pre-heated by contact with the hot brickwork, and through the superheater 6, where it is heated to 1900‹ F. to the ports 10 and down through the ore to the ports 12 from whence it is passed through the cold superheater 15 and the heat storage unit 17, which is heated by its passage, to the other gasometer. The superheater 6 is now switched on and the superheater 15 switched off and the direction of the gas flow reversed so that the hydrogen takes up heat from the hot brickwork of the heat storage unit 17 and from the superheater 15, passes upwards through the reducing zone and then passes out to the gasometer giving up its heat to the heat storage unit 4 in passage. This reversing cycle is repeated until all the ore in the reducing zone is reduced, after which the cold sponge in the cooling zone is discharged by the mechanism 19 thus causing the reduced metal from the reducing zone to fall into the cooling zone and the ore from the pre-heating zone to drop into the reducing zone. Fresh ore is fed into the furnace from the space between the two feed bells 22, 23, the space being purged by hydrogen from a pipe 24. Reducing gases other than hydrogen may be used, e.g. carbon-monoxide or a mixture of two-thirds carbon-monoxide and one-third hydrogen, and an inert gas, e.g. nitrogen may be added. The superheaters may comprise (a) electrical resistance elements over which the reducing gas is passed, (b) pipe coils, externally heated by electrical resistance elements or fuel burners, through which the reducing gases pass, or (c) brick chambers similar to the heat storage units which are heated by burning gas or oil to a high temperature before the reducing gas is passed through.