US 6,379,421 B1 · Method and apparatus removing undesirable metals from iron-containing materials

Abstract

The present invention relates to a method and apparatus for separating undesired toxic metals, such as Zn, Pb and Cd, from iron-containing materials by: sintering a mixture of such materials (typically including EAF dust and mill scale) with carbonaceous particles to form sturdy sinter lumps; preheating such lumps in a non-reducing atmosphere, if needed, to achieve an elevated temperature generally above the vaporization temperature of the undesired metals, but below the sticking temperature of iron-containing lumps (which is typically below the vaporization temperatures of such undesired metals in their oxide form), feeding the lumps at such elevated temperature into a reduction reactor; flowing hot reducing gas through lumps to volatilize undesired reduced metals and carry the volatilized metals out of reduction reactor leaving the iron-containing lumps largely stripped of the undesired metals and ready for discharge and safe and/or useful disposal or re-use, and finally cooling the off gas from the reactor to separate out the resulting solidified unwanted metals (typically in their oxide form resulting from a water quench cooling).

Claims17

Dependent claims

A method for removing one or more undesirable generally toxic metals including at least one of zinc, lead, and cadmium from an iron-containing material, said method comprising:

sintering said iron-containing material producing at least one sinter mass and sinter flue gas;
crushing such sinter mass into oxidized sinter lumps for handling;
preheating said sinter lumps in a non-reducing atmosphere, if needed, to achieve a non-sticking temperature above 650° C.;
introducing said hot oxidized sinter lumps at such temperature above 650° C. into a moving bed reduction reactor;
introducing a hot reducing gas at a temperature above about 850° C. into said reduction reactor;
contacting said hot sinter lumps in said reduction reactor with a stream of said hot reducing gas thereby reducing said sinter lumps and entraining in said stream of reducing gas said undesirable metals in vaporized form and/or in the form of molten aerosols;
withdrawing from said reduction reactor the hot reducing gas used to reduce said sinter lumps as an off reducing gas containing and maintaining the vapors and/or aerosols of said undesirable metals;
cooling said off reducing gas to a temperature low enough to solidify the vapors and/or aerosols of the undesirable metals contained therein;
separating said solidified undesirable metals from said off gas;
and
withdrawing the resulting reduced iron-containing sinter lumps from said reduction reactor.

8 more elements

Dependencies are inferred from the claim text.

Method and apparatus removing undesirable metals from iron-containing materials

Life of this patent

Method and apparatus removing undesirable metals from iron-containing materials

Life of this patent

Abstract

Claims17