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US-12624417-B2 - Method of removing volatile constituents from an industrial dust, and valuable material-containing product

US12624417B2US 12624417 B2US12624417 B2US 12624417B2US-12624417-B2

Abstract

A product and method for producing a valuable material product from industrial dust having the steps of providing the industrial dust, which has at least one valuable material and a first concentration of volatile constituents, to a heating device with an operating temperature of 600° C. or more, preparing the industrial dust by means of the heating device, wherein the preparation comprises heating the industrial dust at a rate of 20° C./min or more, thermally treating the industrial dust by means of the heating device at a treatment temperature in the range from 900° C. to 1200° C., in particular in the range from 1000° C. to 1100° C., for 30 minutes or more, and controlling and/or regulating the oxidizing conditions during the preparation, wherein the preparation comprises at least partially removing the volatile constituents from the industrial dust, and providing the valuable material product.

Inventors

  • Jürgen Antrekowitsch
  • Stefan STEINLECHNER
  • Michael Auer

Assignees

  • Montanuniversität Leoben

Dates

Publication Date
20260512
Application Date
20210909
Priority Date
20200911

Claims (18)

  1. 1 . A method of manufacturing metals or metal oxides from an industrial dust, wherein the method comprises: preheating a heating device to an operation temperature of 600° C. or more; providing the industrial dust which comprises at least one metal or metal oxide and a first concentration of volatile constituents to the preheated heating device with an operation temperature of 600° C. or more; processing the industrial dust by the heating device, wherein processing comprises: heating the industrial dust with a rate of 20° C. per minute or more, thermally treating the industrial dust by the heating device with a treating temperature in a range of 900° C. to 1200° C. for 30 minutes or more, and controlling or regulating oxidizing conditions during processing, wherein the processing comprises: at least partially removing the volatile constituents from the industrial dust; and providing the metals or metal oxides.
  2. 2 . The method according to claim 1 , wherein the metal or metal oxide comprises the at least one valuable material and a second concentration of volatile constituents which is lower than the first concentration of volatile constituents.
  3. 3 . The method according to claim 1 , wherein the volatile constituents comprise a halogen; or wherein the volatile constituents comprise a metal.
  4. 4 . The method according to claim 1 , wherein the metals or metal oxides comprises a metal oxide.
  5. 5 . The method according to claim 1 , wherein the industrial dust is substantially in the form of dust particles.
  6. 6 . The method according to claim 5 , wherein the dust particles comprise steel mill dust or dust from the copper industry.
  7. 7 . The method according to claim 1 , wherein providing the industrial dust further comprises: agglomerating the dust particles of the industrial dust.
  8. 8 . The method according to claim 1 , wherein processing is performed in a batchwise manner.
  9. 9 . The method according to claim 1 , wherein providing the industrial dust further comprises: drying the industrial dust.
  10. 10 . The method according to claim 1 , wherein thermally treating further comprises: controlling or regulating water vapor in a heated atmosphere, such that a water vapor partial pressure of 0.1 bar or more is present.
  11. 11 . The method according to claim 1 , wherein thermally treating further comprises: mixing the industrial dust.
  12. 12 . The method according to claim 1 , wherein controlling or regulating the oxidizing conditions comprises: supplying an oxidizing agent, such that a combustion air ratio is hyperstoichiometric.
  13. 13 . The method according to claim 1 , wherein the industrial dust comprises a first concentration of the at least one metal or metal oxide, and wherein processing further comprises: concentrating the metal or metal oxide, such that the processed metal or metal oxide product comprises a second concentration of the at least one metal or metal oxide, which is larger than the first concentration.
  14. 14 . The method according to claim 1 , wherein processing further comprises: at least partially inhibiting a chemical reaction of a halogen or a metal to a non-volatile constituent; or promoting a chemical reaction of a halogen or a metal to a volatile constituent.
  15. 15 . The method according to claim 1 , wherein heating the industrial dust is performed with a rate of 30° C. per minute or more; and wherein the method comprises at least one of the following features: removing 90% of at least one of the group which consists of chlorine, lead, and cadmium, from the industrial dust; removing 80% fluorine or potassium from the industrial dust; removing 45% sodium from the industrial dust.
  16. 16 . The method according to claim 1 , wherein thermally treating the industrial dust by the heating device is performed for 60 minutes or more.
  17. 17 . A method of providing a metal oxide, comprising: manufacturing a metal or metal oxide product according to claim 1 ; and further processing the metal or metal oxide product, to provide a metal oxide or a secondary metal oxide.
  18. 18 . The method according to claim 17 , wherein further processing the metal or metal oxide product is performed in an electrolysis-free manner.

Description

This application is a national US phase of PCT/EP2021/074842 which claims the benefit of the filing date of European Patent Application No. 20 195 687.7 filed 11 Sep. 2020, the disclosure of which is hereby incorporated herein by reference. TECHNICAL FIELD Embodiments of the invention relate to a method of manufacturing a valuable material product from an industrial dust. Furthermore, embodiments of the invention relate to the valuable material product which is obtained by processing the industrial dust. Thus, embodiments of the invention may relate to the technical field of processing industrial dusts. In particular, embodiments of the invention may relate to the technical field of removing volatile constituents from industrial dusts, to thereby obtain a valuable material product. TECHNOLOGICAL BACKGROUND Industrial dusts, for example from the metal production or metal processing (for example in a steel mill) frequently contain undesired and recoverable valuable materials, but also undesired residues which encompass undesired metals (in compounds and/or elementary) and volatile constituents (for example halogen compounds). Nevertheless, economically processing industrial dusts for obtaining processed valuable material products, which in turn may serve as a raw material source, still constitutes a technical challenge. In the following, this is illustrated by means of an example of prior art, wherein the valuable material zinc oxide shall be recovered from a halogen-contaminated steel mill dust. The main product by the processing of steel mill dusts with a suitable process is the so-called secondary zinc oxide which may serve almost up to 100% as a replacement or supplement for zinc concentrates which are recovered from ores. Due to lead portions and halogen contamination, respectively the concentration of other volatile constituents, in this recycling product with a high zinc oxide portion, in conventional methods (the so-called rolling method is mainly applied), the substitution rate in the primary zinc industry is limited to 10-15%. Although the rolling oxide (this is the zinc oxide which is contaminated with disturbing substances) is generally washed, a charging in the roasting stage of the zinc industry is unavoidable, to remove residual amounts of halogens (fluor, chlorine, bromine or iodine), respectively halogen compounds and other volatile compounds. The reason for this is that, in the zinc-recovering electrolysis, chlorine leads to an increased corrosion of the electrodes and the formation of potentially hazardous chlorine gas. The disadvantage of fluor in electrolytes is the attack and the resolving of the aluminum-oxide layer at the surface of the cathodes. This leads to an increased gluing tendency of the refined zinc at the cathodes and associated downtimes and accompanying zinc losses and increased cathode wear. Nevertheless, the substitution of primary ore concentrates by secondary zinc oxide is desired. The large iron loads, which are introduced via the ore concentrate in the primary zinc manufacture, serve for a high portion of precipitation residues, for which until today no economic processing method exists and which therefore have to be stored with high costs and environmental requirements. Per ton of produced zinc, one ton iron residue—mainly jarosite—is generated. An increase of the secondary zinc oxide portion with typically low iron amounts in the zinc recovery is therefore advantageously. A zero-waste-process is targeted, in which ideally, instead of a disposal, for example iron alloys are supplied to a use in a steel mill, and halogen containing substances are supplied to a use in the chemical industry, and slacks are supplied to a use in the construction material industry. With respect to a portion of more than 65% residual substances which are to be stored in case of a rolling process, this constitutes a vast improvement. In case of the electric arc furnace dust (EAFD), the impurities origin from melted steel scrap and partially from slag formers. Surface coatings, lacquers, and plastic fractions are typical sources for the introduction of halogens in the steel mill dust. Under the process temperatures which are prevailing there, chlorine and fluor volatilize as compounds with lead, potassium, or sodium, and collect with other volatile elements, such as cadmium oxide and mainly zinc oxide in the dust. The main product in recycling of EAFD is ZnO which is contained in the dust. Usually, this is converted to Zn by a reduction with carbon and is evaporated at process temperatures of 1000° C.-1100° C. (the boiling point of Zn is 907° C.). Due to the high oxygen affinity of gaseous zinc, an immediate exothermic re-oxidation of the Zn to ZnO occurs in the exhaust gas system, which at the same time constitutes the product of the recycling method. Since a main portion of the present halogen compounds in the steel mill dusts comprise a high vapor pressure, partially even boiling points wh