EP0144868B1 - Procédé de fabrication de fine poudre métallique de chrome à faible teneur en oxygène - Google Patents

Procédé de fabrication de fine poudre métallique de chrome à faible teneur en oxygène Download PDF

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Publication number
EP0144868B1
EP0144868B1 EP84114148A EP84114148A EP0144868B1 EP 0144868 B1 EP0144868 B1 EP 0144868B1 EP 84114148 A EP84114148 A EP 84114148A EP 84114148 A EP84114148 A EP 84114148A EP 0144868 B1 EP0144868 B1 EP 0144868B1
Authority
EP
European Patent Office
Prior art keywords
mixture
calcium
oxygen
particle size
cao
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84114148A
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German (de)
English (en)
Other versions
EP0144868A3 (en
EP0144868A2 (fr
Inventor
Horst Eggert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evonik Operations GmbH
Original Assignee
TH Goldschmidt AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TH Goldschmidt AG filed Critical TH Goldschmidt AG
Publication of EP0144868A2 publication Critical patent/EP0144868A2/fr
Publication of EP0144868A3 publication Critical patent/EP0144868A3/de
Application granted granted Critical
Publication of EP0144868B1 publication Critical patent/EP0144868B1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/30—Obtaining chromium, molybdenum or tungsten
    • C22B34/32—Obtaining chromium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon

Definitions

  • the invention relates to a process for the production of low-oxygen chromium metal powder with an average particle size of 9 20 about by metallothermic reduction of a mixture of chromium oxide and calcium oxide with calcium metal in a closed against ingress of oxygen reaction vessel at temperatures of 1000 to 1250 ° C and an initial pressure of S 10- 3 bar at room temperature.
  • DE-PS-441 640 describes a process in which the oxide is combined with an alkaline earth metal (e.g. calcium) and a halogen compound of the same or another alkaline earth metal (e.g. calcium chloride or barium chloride) or an alkali metal (e.g. potassium chloride) is heated.
  • an alkaline earth metal e.g. calcium
  • a halogen compound of the same or another alkaline earth metal e.g. calcium chloride or barium chloride
  • an alkali metal e.g. potassium chloride
  • DE-AS-1 030 033 relates to a method of the aforementioned type, which is characterized in that the reducing metal and the oxide to be reduced are introduced into a melt of alkali metal or alkaline earth metal halides dried by prolonged heating. This does indeed mean that the content of non-reduced metal oxide is reduced. However, this method does not obtain a finely divided, but at most a coarse-grained metal powder or a metal regulation.
  • DE-PS-935 456 discloses a method for producing alloy powders by reducing metal compounds or mixtures of metal oxides with calcium.
  • the addition of indifferent oxides to the reduction mixture is recommended. This addition is intended to prevent the resulting alloy from melting as a result of the strong development of heat during the reduction or from the resulting powder being very coarse. It has been shown, however, that when calciothermally reducing a mixture of chromium oxide and calcium oxide, a relatively low-oxygen chrome metal powder can be obtained, but this is still relatively coarse-grained and has a particle size of> 100 ⁇ m.
  • An essential feature of the process of the aforementioned DE-PS-3 017 782 is therefore that one does not reduce mixtures of the metal oxides to be reduced calciothermally, but instead only burns these mixtures to an oxidic multi-substance system, the number of phases of which is smaller than the sum of the starting components.
  • This annealing process makes it possible to produce alloy powder, with all particles of the alloy powder having the same composition and the same structure.
  • the present invention is based on the object of producing a low-oxygen chrome metal powder with an average particle size of S 20 ⁇ m.
  • the oxygen content should be ⁇ 0.1% by weight if possible. It is of particular interest here to produce a chrome metal powder which has a particle size Z 10 ⁇ m, in particular ⁇ 5 ⁇ m.
  • this object can be achieved according to the invention by first mixing a mixture of Cr 2 O 3 and CaO in a molar ratio of 1: 0.5 to 1: 2 at temperatures of 650 to 1200 ° C. with the addition of oxygen until the weight increases from 1 to 6 g per mole of Cr 2 0 3 is annealed, the annealing product is crushed to a particle size of 5 100 ⁇ m and the product thus obtained is metallothermally reduced.
  • the necessary annealing time depends on the respective annealing temperatures and the equipment conditions.
  • Figure 2 shows the dependence of the annealing time on the temperature.
  • the time periods required for a 25% conversion at annealing temperatures of 1200 ° C, 1000 ° C, 800 ° C and 650 ° C are designated T 1 , T 2 , T 3 and T 4 .
  • the actual glow time depends on various factors, such as B. from the amount of oxygen offered, the size of the surface presented and the molar ratio of chromium oxide to calcium oxide.
  • the annealing time is shortened by continuously circulating the annealing product and annealing the product in flowing air. It has been shown that, depending on the conditions used, an annealing time of 2 to 48 hours must generally be used.
  • the calcium oxide can be replaced in whole or in part by calcium carbonate.
  • the annealing process must be carried out at temperatures of 1000 to 1200 ° C in order to split off CO 2 from the calcium carbonate. With this procedure, a fresh and therefore particularly reactive calcium oxide surface is formed during the annealing process. The fresh calcium oxide thus formed reacts faster with chromium oxide and atmospheric oxygen to calcium chromate.
  • the molar ratio of chromium oxide to calcium oxide (or calcium carbonate) should be 1: 0.5 to 1: 2.
  • a ratio of 1: ⁇ 0.5 is inappropriate in view of the above reaction equation.
  • a molar ratio of 1:> 2 leads to unfavorable space-time yields per batch.
  • the calcium chromate obtained in the mixture of Cr 2 0 3 and CaO annealed according to the invention can be detected by X-ray diffraction. It is therefore understandable to the person skilled in the art that, instead of the weight gain, which is only a measure of the oxidation, other analytical data can also be used, which allow the degree of oxidation to be recorded.
  • the glow product obtained according to the invention is comminuted after cooling to a particle size of 9 100 ⁇ m. If the particle size is significantly exceeded and reduced z.
  • the annealing product ground to a particle size 100 100 ⁇ m is then homogeneously mixed in a manner known per se with amounts of calcium metal in the form of calcium shavings which are at least equivalent with respect to the chromium and its average oxidation state. It is advisable to tablet this mixture or to compress it into green compacts and to reduce the tablets or green compacts in a chrome crucible at a temperature of 1000 to 1250 ° C.
  • the crucible is expediently evacuated to a pressure of 5 10 -3 bar beforehand. During the reaction, the calcium vapor pressure corresponding to the temperature is then set.
  • reaction product After the reaction, the reaction product is roughly crushed. The calcium oxide contained in the reaction product is then leached out by dilute acids or complexing agents and the metal powder obtained is washed and dried.
  • the chrome metal powder obtained by the process according to the invention has a low oxygen content of 0.1% by weight or less and is very finely divided, the mean grain size being 9-20 ⁇ m. It is understood by the person skilled in the art that the surface area of the chrome powder increases with decreasing grain size and therefore the content of oxygen bound to the surface of the chrome powder can increase again.
  • Example 1 below is not according to the invention and describes the production of a chrome metal powder from a mixture of chromium oxide and calcium oxide.
  • Example 2 is according to the invention and shows the production of a chrome metal powder of the desired fineness.
  • the Fisher average grain size is 29 ⁇ m.
  • the grain distribution has the following values:
  • the metallographic examination shows a globular chrome metal powder.
  • the bulk density of the annealed mixed oxide is approximately 1.1 g / cm 3 and the tap density is approximately 2.3 g / cm 3 .
  • the yield of the metal powder is 479.8 g - 96% based on the theoretical yield.
  • the dried chrome powder has a bulk density of 3.2 g / cm 3 - 44.5% and a tap density of 4.3 g / cm 3 - 59.8% of the theoretical density.
  • the grain distribution has the following values:
  • Average particle size 6.5 ⁇ m according to Fisher.
  • the metallographic examination shows a fine spherical metal powder grain.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Claims (2)

1. Procédé pour la fabrication d'une poudre de chrome métallique à faible teneur en oxygène, ayant une granulométrie moyenne < 20 µm, par réduction métallothermique d'un mélange d'oxyde de chrome et d'oxyde de calcium à l'aide de calcium métallique, dans un réacteur étanche à l'entrée de l'oxygène, à des températures de 1000° à 1250°C et sous une pression initiale < 10-3 bar à la température ambiante, caractérisé en ce qu'on calcine d'abord un mélange de Cr203 et de CaO, selon un rapport en moles de 1 : 0,5 à 1 : 2, à des températures de 650° à 1200°C avec apport d'oxygène jusqu'à une augmentation de poids de 1 à 6 g par mole de Cr203, qu'on broie le produit de calcination jusqu'à une granulométrie ≤ 100 µm, puis qu'on fait subir au produit ainsi obtenu une réduction métallothermique
2. Variante du procédé selon la revendication 1, caractérisée en ce qu'on remplace le CaO, en totalité ou en partie, par du CaC03, et qu'on calcine le mélange de Cr203 et de CaC03 ou de Cr203 et de CaO/CaC03 à des températures de 1000° à 1200°C, l'augmentation de poids de 1 à 6 g par mole de Cr203 étant calculée sur un mélange initial de Cr2O3/CaO.
EP84114148A 1983-12-06 1984-11-23 Procédé de fabrication de fine poudre métallique de chrome à faible teneur en oxygène Expired EP0144868B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3343989 1983-12-06
DE3343989A DE3343989C1 (de) 1983-12-06 1983-12-06 Verfahren zur Herstellung von feinteiligem,sauerstoffarmem Chrommetallpulver

Publications (3)

Publication Number Publication Date
EP0144868A2 EP0144868A2 (fr) 1985-06-19
EP0144868A3 EP0144868A3 (en) 1987-09-16
EP0144868B1 true EP0144868B1 (fr) 1989-01-25

Family

ID=6216121

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84114148A Expired EP0144868B1 (fr) 1983-12-06 1984-11-23 Procédé de fabrication de fine poudre métallique de chrome à faible teneur en oxygène

Country Status (3)

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US (1) US4767454A (fr)
EP (1) EP0144868B1 (fr)
DE (2) DE3343989C1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5354354A (en) * 1991-10-22 1994-10-11 Th. Goldschmidt Ag Method for producing single-phase, incongruently melting intermetallic phases
US20090162273A1 (en) * 2007-12-21 2009-06-25 Howmedica Osteonics Corp. Chromium oxide powder having a reduced level of hexavalent chromium and a method of making the powder
CN111922350B (zh) * 2020-09-22 2021-01-01 西安斯瑞先进铜合金科技有限公司 一种低盐酸不溶物金属铬粉的制备方法
CN111922351B (zh) * 2020-09-23 2021-01-01 西安斯瑞先进铜合金科技有限公司 一种高纯低氧金属铬粉的制备方法

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB336970A (en) * 1929-07-22 1930-10-22 Ig Farbenindustrie Ag Improvements in or relating to the working up of chromium ores
GB507362A (en) * 1938-03-29 1939-06-14 Walter Hene Improvements in and relating to the treatment of chromium ores
DE935456C (de) * 1938-08-26 1955-11-17 Hartmetallwerkzeugfabrik Meuts Verfahren zur Herstellung von Legierungspulvern
GB545965A (en) * 1939-11-16 1942-06-22 Marvin J Udy Chromium recovery
US2332415A (en) * 1940-08-15 1943-10-19 Marvin J Udy Chromium recovery
US2854327A (en) * 1954-02-12 1958-09-30 Diamond Alkali Co Exothermic chromium compound containing composition and method of making same
US2889218A (en) * 1956-04-30 1959-06-02 Transition Metals & Chemicals Continuous process for metallothermic reactions
US3053649A (en) * 1957-04-02 1962-09-11 Onera (Off Nat Aerospatiale) Methods for the obtainment of articles of chromium or containing chromium and in articles obtained by these methods
US3623861A (en) * 1969-08-28 1971-11-30 Nasa Production of metal powders
DE3017782C2 (de) * 1980-05-09 1982-09-30 Th. Goldschmidt Ag, 4300 Essen Verfahren zur Herstellung von sinterfähigen Legierungspulvern auf der Basis von Titan
JPS5877548A (ja) * 1981-10-31 1983-05-10 Kawasaki Steel Corp クロム鉱石の溶融還元法

Also Published As

Publication number Publication date
US4767454A (en) 1988-08-30
DE3343989C1 (de) 1984-12-13
EP0144868A3 (en) 1987-09-16
EP0144868A2 (fr) 1985-06-19
DE3476347D1 (en) 1989-03-02

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