Control of pollution by recycling solid particulate steel mill wastes

摘要

1487786 Briquetting steel mill waste FERROCARB AGGLOMERATION Ltd 19 Dec 1974 [19 Dec 1973] 54786/74 Heading C1A A process for disposing of iron and carbon containing waste which contains at least 5% of iron and also contains zinc oxide to give a product containing the iron without the zinc oxide comprises: (1) mixing the particulate waste with a bituminous binder having a ball and ring softening point below 212‹ F. and being free of combustibles volatile at 500‹ F., and with sufficient added carbonaceous solid to reduce the zinc oxide present to zinc metal, to produce a mix containing from 2-15% preferably 3-8%, of binder; (2) briquetting the mix; (3) treating the briquettes to ensure sufficient mechanical strength to feed them to; (4) a heating step where the briquettes are heated to 1800-2500‹ F. for a time sufficient to reach the volatilization temperature of the zinc contained therein, whereby the zinc oxide present is converted to zinc metal and the zinc metal is converted to zinc vapour; (5) removing the zinc vapour from the vicinity of the briquettes with a gas stream containing a reactant which converts the zinc vapour to zinc oxide; and (6) recovering the zinc oxide. Step 3 is preferably carried out by heating the briquettes in a gas containing at least 10% of oxygen for 30-90 minutes at a gas temperature of 350-600‹ F. or by incorporating 5- 15% of water in the mix before briquetting. In a modification of the process, lead oxide may be recovered by the method of the invention instead of or as well as zinc oxide.