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1. EP3553191 - PROCÉDÉS DE PRODUCTION DE CHROME MÉTALLIQUE À FAIBLE TENEUR EN AZOTE ET D'ALLIAGES CONTENANT DU CHROME

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]
Claims

1. Processes for producing metallic chromium or chromium-containing alloys comprising:

vacuum-degassing a thermite mixture comprising chromium compounds and metallic reducing agents, contained within a vacuum vessel capable of withstanding a thermite reaction;
igniting the thermite mixture to effect reduction of the chromium compounds within said vessel;

solidifying the reaction products; and

cooling the reaction products,

wherein igniting, solidifying and cooling are conducted under a pressure below 1 bar.


  2. Processes according to claim 1, wherein the vacuum vessel is a ceramic or metallic container lined with refractory material.
  3. Processes according to claim 2, wherein the vacuum vessel is placed inside a vacuum-tight, water-cooled chamber for the entire reduction reaction.
  4. Processes according to any one of claims 1 to 3, wherein the reducing agent is aluminum.
  5. Processes according to claim 4, wherein the aluminum reducing agent is in powder form.
  6. Processes according to any one of claims 1 to 5, wherein the thermite mixture additionally comprises at least one energy booster.
  7. Processes according to any one of claims 1 to 6, wherein the thermite mixture additionally contains an element selected from the group consisting of nickel, iron, cobalt, boron, carbon, silicon, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, rhenium, copper, and mixtures thereof in their metallic form or as compounds thereof capable of metallothermic reduction.
  8. Processes according to any one of claims 1 to 8, wherein after vacuum-degassing and before ignition, the pressure within the vacuum vessel is increased up to 200 mbar by introduction of a non-nitrogenous gas.
  9. Processes according to any one of claims 1 to 8, wherein cooling the reaction products includes cooling the reaction products to ambient temperature under a pressure below 1 bar.
  10. Processes according to any one of claims 1 to 9, wherein the produced metallic chromium or chromium-containing alloys have a nitrogen content less than 5 ppm by weight.
  11. Processes according to claim 1, wherein the produced metallic chromium or chromium-containing alloys have a nitrogen content less than 10 ppm by weight.
  12. Processes according to any one of claims 1 to 11, wherein igniting the thermite mixture and solidifying the reaction products are conducted under a pressure up to 200 mbar.
  13. Processes according to any one of claims 1 to 12, wherein igniting the thermite mixture and solidifying the reaction products are conducted under a pressure of 200 mbar.
  14. Processes according to any one of claims 1 to 13, wherein vacuum-degassing the thermite mixture includes vacuum-degassing the thermite mixture to an initial pressure less than 1 mbar.
  15. Processes according to any one of claims 1 1o 14, wherein vacuum-degassing the thermite mixture includes vacuum-degassing the thermite mixture to an initial pressure less than 1 mbar, wherein the produced metallic chromium or chromium-containing alloys have a nitrogen content less than 5 ppm by weight, wherein after vacuum-degassing and before ignition, the pressure within the vacuum vessel is increased up to 200 mbar by introduction of a non-nitrogenous gas, wherein cooling the reaction products includes cooling the reaction products to ambient temperature under a pressure below 1 bar, wherein igniting the thermite mixture and solidifying the reaction products are conducted under a pressure up to 200 mbar.