GB1091101A - Production of powder,strip and other metal products from refined molted metal - Google Patents

Abstract

In a process of granulating molten iron or steel to form particles of irregular and angular shape, the molten metal is refined and discharged into an atomizer where the stream of molten metal is atomized with high pressure solid flat streams of a liquid such as water and the particles are then dried. As shown in Figs. 1A and 1B refining is effected in an open hearth furnace, L.D. converter or electric furnace 11, the molten metal is discharged into ladle 12 and then into atomizer 13. The streams of molten metal from openings 18 in the atomizer are atomized by flat sheets of water issuing from nozzles 19 at a pressure greater than 400 p.s.i., the nozzles being positioned at an angle of 26 DEG to the vertical to prevent frothing. Vacuum degassing of the molten metal may be effected by evacuating the atomizer or alternatively a hydrogen or argon atmosphere may be used. The formed particles are pumped to a dewatering unit 26, dried and screened at 30 in a controlled <PICT:1091101/C6-C7/1> atmosphere of argon or nitrogen and particles of graded sizes are stored at 33 under nitrogen. Alternatively the particles may be diverted from screening section 30 into storage bags at 56 and stored with silica gel. The powder from store 33 is blended at 36 with e.g. detergents, activators, lubricants, binders and metal and alloy powders such as copper and steel to adjust the carbon content. The blended powder is preheated at 38 to 950 DEG - 1200 DEG F., and rolled at 39 to a green strip of 70 - 95% density. The powder is fed from the preheater via a series of evacuated tubes and the feed is controlled magnetically and by vibrators Figs. 4 and 5 (not shown). The green strip is heated at 42 to 1600 DEG - 2200 DEG F., and rolled to 100% density at 43. Treatments such as carburizing, decarburizing, reduction, nitriding, chromizing, nickelizing and infiltration with copper may be carried out in furnace 42. Further hot rolling is then carried out at 45 and 46 to a minimum thickness of 0.010" and the strip is then cooled by sprays 50. All these operations are performed in an argon or nitrogen atmosphere in enclosure 48 and the strip is then cold rolled at 51 and sheared at 52. The process is particularly exemplified in the production of low carbon steel for electrical applications and also for stainless steel.