Method for the manufacture of iron

摘要

749,823. Agglomerating ores; reducing iron ores. STEWARTS & LLOYDS, Ltd. Dec. 23, 1953 [Nov. 10, 1952], No. 28221/52. Classes 72 and 82(1). A method of producing iron from its ores in a blast furnace, whereby the final composition of the iron is controlled and in which at least a proportion of the burden consists of pelletised ore comprises pre-heating a proportion of the pellets, then adding the pre-treated pellets to the rest of the burden and subjecting the whole to blast furnace treatment. The pellets are made by reducing ore fines to preferred size grading, wetting the graded fines as necessary, subjecting the wetted fines to mixing and to vacuum or other treatment to remove occluded air, extruding the mixture and sub-dividing the extrusion into pellets. The pre-heating may be effected to modify the percentage of sulphur in the pellets in which case it takes place in an oxidising atmosphere at a temperature between 1175‹C. and 1250‹C. or to vary the percentages of ferrous and ferric iron in the ore in which case it takes place in the appropriate oxidising or reducing atmosphere at a temperature between 900‹C. and 1100‹C. In manufacturing the pellets ore fines 1, to which may be added lime, limestone or other flux or enriching material such as scale, high grade ores, ore concentrates or scrap metal, with or without carbon in the form of, for example, flue dust or coke breeze 2, are ground and plasticized in a pan-mill 3, if necessary with the addition 4 of water or dilute acid or alkali and are screened 6, if need be, with the oversized material 6A, returning to the pan-mill via 3A. The screened material 6 proceeds either directly to a mixer 8 where provision is made for the addition 9 of water and also materials as at 2, or via a chamber 7 in which the moisture content is reduced. The mixed and pugged material proceeds into the first scroll 10 of the conveyer 11, which may be surrounded by a heating element 12 and then, through a plate or cone shredder 13, into a reduced pressure chamber 14 from which it is removed by a scroll 15, extruded through the die 17 and cut off at 18. A rotating drum 19 may be provided to remove from the pellets any sharp edges caused in the cutting operation. The pellets then proceed to the curing chamber 20 wherein a humid atmosphere may be caused 21, together with an elevated temperature by heaters 22 and wherein the pressure may be varied by the pressure fan 23 or vacuum fan 24. After curing, the pellets may be stored in suitably humid containers 25 or proceed to the point of usage.