Improvements relating to electric smelting furnaces and to smelting plant and processes employing such furnaces

摘要

713,506. Smetting - furnaces. ELEKTROKEMISK AKTIESELSKAP. June 27, 1952 [June 27, 1951], No. 16295/52. Class 51 (2). [Also in Groups XI and XXXVI] An electric smelting furnace (see Group XI) has a single vertical electrode 3 centrally arranged in a furnace to extend down into the charge in a furnace 2 rotated or oscillated about a vertical axis, current being passed through the charge, which has been pre-heated by gas evolved in the furnace. The furnace may have a stationary. roof with one or two diametrically spaced charging openings, so that on rotation of the furnace the charge is evenly distributed. Heavy pokers as described in Specification 608,474 may break up the crust at points immediately before the charging apertures on rotation of the furnace, which may be oscillated through 120 degrees or 180 degrees or rotated at a speed of from 20 minutes to 2 hours for one rotation. Iron ore, ilmenite, purple copper ore, ferro alloys, e.g. ferro-manganese, iron rich in silicon and calcium carbide are referred to. The gases leaving the furnace 2 by pipe 16 pass at 10 into the base of a vertical' pre-heating shaft furnace 1, and air for combustion is delivered by a fan 11 into combustion chambers 12 built into the upper part of the shaft lining. Combustible air is drawn as shown from the shaft and delivered while burning to the shaft at a lower level. The gas, mainly carbon monoxide, passes in counter-current to the charge, is only partially burnt and is drawn off at 15 at 100‹ - 2000 C. The shaft may be under reduced or increased pressure. The charge may be pre-heated in an inclined rotary drum 34 in counter flow to the gases. Combustion air is supplied at the lower end and at points along the drum. The gas from the furnace 2 may travel to the pre-heater through the pipe by which the furnace is charged. Coal or coke dust is used as reducing agent for the ore in the preheater, where reduction is partial or with extra gas or fuel oil may be complete. Ilmenite or ferro alloys, e.g. ferro-manganese or iron rich in silica may be treated, or limestone turned to lime for the formation of calcium carbide. The reducing agent may be fed to the furnace separately from the ore and may be unheated. Reducing agent may be added to the ore from a supply 39 and flows therewith through a bin 37 to the electric smelter ; or the preheated ore and coke may enter through adjacent roofopenings or alternately through the same charging opening. Tapping of the electric furnace may take place during its rotation, a stepped platform 80 being detachably connected thereto. The platform 80 runs on wheels and carries a ladle 82, into which the metal runs from a launder 81 on the platform 80 beneath the tapping spout 79. When slag and metal are simultaneously tapped, the launder 81 is Y-shaped and has a skimmer 84, whereby metal runs down channel 81 to the ladle, while slag runs down channel 83 to an annular granulation pit 87 in the floor. The tapping may be complete before a complete revolution of the furnace. With ferro-silicon or calcium carbide, where there is no slag, the product may be run directly into moulds arranged arcuately below the tapping spout 79.