Sustainable method for recycling smelting works dusts and sludges to produce iron-containing, heavy-metal-depleted reclaimed materials with recovery of lead and zinc

Patent metadata

Field	Value
Publication number	US-2023295765-A1
Application number	US-202117798709-A
Country	US
Kind code	A1
Filing date	Feb 25, 2021
Priority date	Feb 28, 2020
Publication date	Sep 21, 2023
Grant date	—

Abstract

The present invention relates to a sustainable regeneration process for metallurgical plant dusts and sludges for producing iron-containing, heavy metal-depleted secondary raw materials and recovering lead and zinc, by providing a first starting material which comprises at least one iron, zinc, lead and further heavy metal components containing metallurgical plant dust and/or sludge, and a second starting material containing at least one chlorine component, mixing the starting materials and drying the mixture, pyrolyzing the mixture for expelling zinc, lead and further heavy metal components, capturing the gas phase of the pyrolysis in sulfuric acid, and providing the residue which remains as an iron-containing secondary raw material depleted in zinc, lead and further heavy metal components.

First claim

1 . A regeneration process for producing iron-containing heavy metal-depleted secondary raw materials and recovering lead components and zinc components from metallurgical plant dust and/or sludge, comprising the steps of:
VII) providing a first starting material which comprises at least one iron, zinc, lead and optionally further heavy metal components containing metallurgical plant dust and/or sludge, and a second starting material containing at least one chlorine component, VIII) mixing the first starting material with the second starting material, optionally transferring the mixture to an oven unit, and optionally subsequently pelletizing it, IX) drying the mixture with expulsion of steam, and optionally subsequently pelletizing it, X) reacting zinc, lead and further heavy metal components and chlorine components by pyrolysis, XI) capturing the gas phase from the pyrolysis from step IV) in sulfuric acid, optionally with cooling,
V-a 1 ) subsequent to step V) the sulfuric acid solution containing Zn in the form of ions is optionally transferred to a further vessel and heated for removing residual chloride until the sulfuric acid fumes off,
V-a 2 ) the sulfuric acid solution containing Zn in the form of ions from step V-a 1 ) is optionally cooled and transferred to a container with water, sulfuric acid and metallic zinc,
V-c 1 ) PbSO4 from step V) is taken off as a solid,
XII) providing the pyrolysis residue which remains as an iron-containing secondary raw material depleted in zinc, lead and optionally further heavy metal components.

2 . The process of claim 1 , characterized in that the SO3 formed and expelled in step V-a 1 ) is captured and optionally returned to step V) or into the corresponding vessel.

3 . The process of either of the preceding claims, characterized in that in step V-a 2 ) heavy metals selected from the group containing As, Cd, Pb and Sn are deposited on the Zn surface by electrolytic cementation.

4 . The process of any of the preceding claims, characterized in that pure zinc is produced by electrolytic reduction in a step V-a 3 ) from the sulfuric acid solution containing Zn in the form of ions from step V-a 2 ).

5 . The process of claim 3 , characterized in that the sulfuric acid solution containing Zn in the form of ions in step V-a 2 ), after deposition of the heavy metals, is used as an electrolyte in a zinc coating plant.

6 . The process of any of the preceding claims, characterized in that subsequent to step V) the hydrogen chloride expelled is introduced into water in a step V-b 1 ) to form hydrochloric acid.

7 . The process of any of the preceding claims, characterized in that the PbSO4 taken off as a solid in step V-c 1 ) is filtered.

8 . The process of any of the preceding claims, characterized in that the metallurgical plant dust and/or sludge used comprises at least one substance selected from the group containing (or consisting of) converter dust, coke dust, blast furnace dust, blast furnace sludge, dust from secondary metallurgy, sintering dust, mill scale, mill scale sludge, zinc slags, copper industry slags, oil-containing sludges, electric arc furnace dust (EAF dust), hall dusts from electric steelworks, filter dusts, oxygen furnace dust and blast furnace throat sludge, preferably metallurgical plant dust and/or sludge from secondary iron/steel production, more preferably blast furnace throat sludge and/or oxygen furnace dust.

9 . The process of any of the preceding claims, characterized in that as chlorine component at least one substance selected from the group containing (or consisting of) hydrogen chloride, hydrochloric acid, Cl2, PVC, PCB, PCT, oils containing PCB or PCT, preferably hydrochloric acid, more preferably hydrochloric acid pickle is used.

10 . The process of any of the preceding claims, characterized in that the steam expelled in step III) is condensed and the water is captured.

11 . The process of claims 6 and 10 , characterized in that the hydrogen chloride expelled is introduced into the water condensed from the steam, and is optionally used as regenerated hydrochloric acid.

12 . The process of any of the preceding claims, characterized in that the process is carried out continuously or discontinuously.

13 . The process of any of the preceding claims, characterized in that the basicity of the iron-enriched, heavy metal-depleted secondary raw material is adjusted by admixing CaO to at least one of the starting materials or mixture thereof.

14 . The process of any of the preceding claims, characterized in that the secondary raw material from step VI) is iron-enriched.

15 . The process of any of the preceding claims, characterized in that at least one starting material comprises alkali metal components and the secondary raw material is alkali metal component-depleted in comparison to the starting material, with the alkali metal components passing through the process together with the zinc and further heavy metal components.

Assignees

• Thyssenkrupp Steel Europe Ag

Inventors

• Tebeck Andreas
• Pappert Eckhard

Classifications

• C22B7/02 Primary

  Working-up flue dust · CPC title

• C22B1/08 Primary

  Chloridising roasting · CPC title

• C22B1/2406

  pelletizing · CPC title

• C22B19/30

  from metallic residues or scraps · CPC title

• C22B19/26

  Refining solutions containing zinc values, e.g. obtained by leaching zinc ores (treatment or purification of solutions by liquid-liquid extraction, by ion exchange or by adsorption C22B3/00) · CPC title