US 5,667,556 AGranted

Method of reprocessing zinc- and iron oxide-containing residual material

AssigneeMetallgesellschaft Aktiengesellschaft

InventorsAndreas Orth, Peter Weber, Uwe Harter, Ernst Wallis

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Abstract

This invention describes a method of reprocessing zinc- and iron oxide-containing residual material. Zinc- and iron oxide-containing dust and/or sludge is granulated with water, granules and carbonaceous material are fed to a circulating fluidized bed system, the gas-solids suspension circulated in the circulating fluidized bed system is fed to a second fluidized bed reactor, the solids discharged from the second fluidized bed reactor are recycled to the reactor of the circulating fluidized bed system, 50 to 75% by volume of the oxygen required to gasify the carbonaceous material are fed as fluidizing gas to the reactor of the circulating fluidized bed system and 25 to 50% by volume of said required oxygen are fed as a fluidizing gas and secondary gas to the second fluidized bed reactor, iron oxide-containing material is discharged from the reactor of the circulating fluidized bed system and zinc-containing material is discharged with the exhaust gas from the circulating fluidized bed system.

Claims13

Dependent claims

A method of reprocessing zinc- and iron oxide-containing residual material, which comprises the steps of:

(a) granulating a zinc- and iron oxide-containing dust or sludge with water to form granules of the residual material;
(b) feeding the granules of the residual material formed according to step (a) and carbonaceous material to a first fluidized bed reactor of a circulating fluidized bed system comprising said first fluidized bed reactor, a cyclone and a second fluidized bed reactor connected to said cyclone and said first reactor, temperature in said first reactor being in the range of 950.degree. to 1100.degree. C., feeding a gas-solids suspension from said first fluidized bed reactor to said cyclone;
(c) feeding solids from said cyclone to said second fluidized bed reactor containing a fluidized bed of solids;
(d) discharging solids from the second fluidized bed reactor and recycling the solids to the first fluidized bed reactor of the circulating fluidized bed system;
(e) feeding as a fluidizing gas to the first fluidized bed reactor 50 to 75% by volume of the oxygen required to gasify the carbonaceous material in said first fluidized bed reactor;
(f) feeding as a fluidizing gas to the second fluidized bed reactor 25 to 50% by volume of the oxygen required to gasify the carbonaceous material in said second fluidized bed reactor;
and
(g) discharging iron oxide-containing material from the bottom of the first fluidized bed reactor and withdrawing an exhaust gas containing a zinc-containing material from the first cyclone and feeding said exhaust gas to a gas-solids separator.

5 more elements

Dependencies are inferred from the claim text.