GB1472118A - Molybdenum and ferromolybdenum production - Google Patents

Abstract

1472118 Obtaining molybdenum KENNECOTT COPPER CORP 29 April 1974 [23 May 1973] 18608/74 Heading C7D Briquettes of molybdenum or ferromolybdenum with sufficient density to penetrate the slags used in alloy steel manufacture are produced by briquetting molybdenum oxide (MoO 3 ) or a mixture of MoO 3 with iron oxides with about 3% water and feeding to the first zone of a two stage reducing furnace running at 500-650‹C in the presence of a gaseous reductant, i.e. H2, CO, cracked ammonia. After the MoO 3 has been reduced to molybdenum dioxide, the mixed solids 11 are fed to the second furnace zone, running at 800-900‹C where the molybdenum dioxide or oxide mixture present are reduced to a metallic product 13, which may be crushed, and rebriquetted to produce a surface bonded compact of Mo or ferromolybdenum with discrete particles of the elements. The preferred composition contains 30 wt per cent iron, with less than 7, preferably 0-2, by wt per cent oxygen, and has a specific gravity of 4À5-7. The preferred reductant 3, hydrogen from cracked ammonia is fed countercurrent into zone 2 of the furnace together with recycled gas 5 as feed gas 9. A portion of the gas leaving zone 2, 15, is dried and recycled to give input gas 9 a 50:50 H 2 : N 2 composition, the remainder of the gas from zone 2 being fed 17 into zone 1 to reduce the MoO 3 to MoO 2 . The preferred starting materials are particulates within the size range minus 20 to minus 325 mesh, and the mixed oxides may result from the preroasting of MoS 2 and FeS 2 , or by the mixing of MoO 3 with mill scale.