Improvements in processes for producing metal sponge

摘要

343,954. Metal sponge. GUSTAFSSON, E. G. T., 95, Birger Jarlsgatan, Stockholm. Nov. 19, 1929, No. 35366. Convention date, Nov. 28, 1928. [Classes 72 and 82 (i).] In a process for producing metal sponge, e.g. iron, cobalt, chromium nickel or chrome iron sponge without fusing the ore or metal, finely divided ore and carbonaceous reducing agent and/or thermic reducing agent in excess of the amount required for the complete reduction of the ore are intimately mixed and transformed into briquettes or other form of pieces, and the briquettes &c. are reduced in a shaft or rotary furnace by heat given off by combustion gases of such a character that they burn at least part of the excess of reducing agent in the briquettes. The excess of the reducing agent is applied to the surfaces of the briquettes by powdering or blowing the briquettes with powdered coal or rolling them in the coals before the briquettes are dried. The shaft furnace 12, Fig. 1, is provided with an annular combustion chamber 16 for the fuel burnt in burners 17, Fig. 2, and the gases produced pass through openings 18 into the reducing part 12b of the furnace. The gases produced pass upward through the furnace charge and with the addition of air supplied through the openings 19, 20 from pipes 21, 22 are converted into oxidizing gases which preheat the charge in the part 12a of the furnace. The sponge passes into the cooling zone 12c, the cooling being effected by a double.walled hopper 30 in the interspaces of which air or water is circulated. The cooled sponge is discharged by screws 32, 33. In the rotary furnace, Fig. 3, the briquettes are fed into the preheating part 12a where the combustion gases are burnt with air from the ports 19, 20 and pass into the reduction part 12b where they are acted upon by gases produced by the combustion of gases from an electric furnace 53 in a burner 17 with air supplied by a pipe 58. The partly-reduced charge passes by an opening 51 into a shaft 52 and thence into the furnace 53 where the reduction is completed, an ore carbon charge being introduced through the hopper 14a to increase the production of reducing gases. Thermic reducing agents such as ferro-silicon, ferro-aluminium, .ferro-aluminiumsilicon or aluminium may replace, wholly or partly, the carbonaceous material.