JPS60155608A - Reduction of producing powdery alloy from mixed metal iron oxide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION (Field of the Invention) The present invention relates to mixed metal iron oxides.
The present invention relates to a method for producing a powdered metal-based iron alloy from 1ronoxide) by treatment with calcium as a reducing agent. This alloy produces hydrocarbons from CO and H2 using Fischer-Tropsch technology.
-Tropsch) is useful as a catalyst.

BRIEF DESCRIPTION OF THE PRIOR ART Calcium metal is known particularly in steelmaking technology as it is a strong reducing agent and has the ability to reduce many metal oxides to their respective metals. However, in the production of powdered metal alloys, hydrogen gas is usually the preferred reducing agent because of its ease of handling and because of the disadvantages associated with handling calcium metal.

A common route used to produce many powdered metal alloys is to heat a mixture of at least two metal components to 1500°C.
This is accomplished by heating at a temperature above, that is, a temperature above the melting point of either of the two elements. In some cases, typically the oxide, carbonate, or hydroxide of the component 81
Produced by heating at a temperature around 000℃,
and two or more different metal ions in close atomic proximity (approximately 10
Since each oxide component itself is easily reduced, the mixed metal oxide contained in the alloy is easily reduced to an alloy with hydrogen at low temperature (about 500° C.). This is, for example, Fe-
This has been found to be true in the case of Co oxide or Fe-Ni oxide. However, other mixed metal oxides such as Fe-Cr, Pe-Mn, Fe-Ti, F
In the e-Zn type, high temperature (1000'C) hydrogen reduction reduces some or all of the iron to ferrous metal leaving the oxide component as a residue and generally does not produce a substantially pure alloy as a product. .

U.S. Pat. No. 4,373,947 discloses a method for producing powdered titanium-based alloys from calcium reduction of an interface between titanium oxide and a second metal oxide. However, this disclosure does not suggest or teach the suitability of this type of process for producing iron-based alloys from single-phase mixed metal iron oxides.

What is desired in the present technology is that the relevant mixed metal iron oxides, especially one of the mixed metal oxides, is refractory and that reduction occurs at a temperature lower than the melting point of the respective metal or mixed metal oxide. Another method that effectively produces powder metal-based iron alloys is directly by reduction of what can be done.

SUMMARY OF THE INVENTION Calcium metal is a refractory mixed metal iron oxide in an iron-based alloy, and is below the melting point of either the metal alone or the mixed metal oxide. It has been discovered that it is an effective reducing agent for reducing at reduction temperatures significantly below 1000°C. A mild acid treatment leaves the powdered alloy to remove the calcium oxide and cardiomium by-products that form and the impurities formed during the reduction of the mixed metal iron oxides. These alloys are CO/1
It has adaptability to catalysts for synthesis of 12 hydrocarbons.

According to the present invention, there is provided a method for producing a powdered metal-based iron alloy comprising the following steps: lal consisting of a powdered mixed metal iron oxide that is refractory in hydrogen gas and at least a stoichiometric amount of metallic calcium. The mixture is reduced in a non-oxidizing atmosphere at a temperature below the melting point of the mixed metal iron oxide to substantially reduce all of the metal oxides present, and
heating for a time sufficient to form a metal-based iron alloy of the product as determined by line diffraction; and (bl) treating the reducible mixed metal iron oxide with an aqueous acid solution to remove calcium impurities and by-products. and (01) recovering the metal-based iron alloy of the product.

Further provided by the present invention is a method for producing a powdered iron-manganese alloy comprising the steps of: (a) melting a powdered iron-manganese spinel together with a small amount (also a stoichiometric amount of metallic calcium) of said spinel; (b) heating the spinel at a temperature below the point for a period sufficient to substantially reduce the spinel and form the product alloy;
Step (contacting the reduced spinel from al with an aqueous acid solution to remove calcium impurities and by-products; and +01 recovering the powdered iron-manganese alloy of the product.

DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS As applied to the present invention, the aforementioned mixed metal iron oxides contain metal s ite in one or more positions in the oxide lattice, as determined by X-ray diffraction. It contains a single phase substance and is generally a single phase substance.
terial). Single-phase can be easily measured compared to simple mixtures of individual metal oxides. The metal has a coordination number of 2 to 12, usually 4 or 6, as in the case of tetrahedral or octahedral coordination positions. Metals are generally first row transition metals, first [B, I[IB, IVB, VB, VIB] of the weekly rate table.
and (2) selected from group B, ie, 5c4i+V+Cr+Mn+Zn. The other metal in the mixed metal iron oxide is preferably Mn, ν.

Selected from Cr. Preferred metal oxides applicable to the method are mixed metal oxides consisting of iron and manganese, preferably iron-manganese spinel.

The metal of the oxide is bonded directly to the oxygen atom and thus to other metal atoms through the oxygen. Generally, the oxide has a crystalline structure of corundum or spinel as determined by X-ray diffraction, with spinel being preferred.

Spinel has the following empirical formula: Fex My 04 where M is selected from the group of first row transition metals, X and y are integers or decimals excluding O, and the sum of x + y is 3. The crystal structure of this spinel consists of 10 ~
Place metal within the vicinity of 15 people or less. single-
Phase oxide structures, such as spinel, allow for the use of multiphase mixtures of oxides due to the close proximity of the metal atoms in single-phase oxides (c
(lose proximity) and atomic mixing (ab
omic mixiug) in that a separate alloying step is not required after calcium reduction. However, after reduction, multiphase materials undergo separate annealing to help the respective metals diffuse together to form an alloy.
Requires an alloying process.

The mixed metal iron oxides applied in the present invention are typically oxides of the component metals such as hydroxides, carbonates, bicarbonates, oxy-hydroxides, sulfates, oxy-sulfates, chlorides, or oxy-
The high temperature solid state of the chloride is carried out at a temperature of less than 1000° C. with several intermittent grindings or mixings during continuous calcination. The reaction can also be carried out in an air, inert or vacuum atmosphere.

When both metals as their respective oxides in the mixed oxide are readily reduced by hydrogen, the alloy in question is generally produced by directly reducing the mixed metal oxide in a hydrogen atmosphere at moderately low temperatures. For example, C0
Jn and Fe50. and the more easily produced phase CoFez
O4 is crystallized with a spinel crystal structure. At a temperature of 500 °C, hydrogen directly and substantially transforms this phase into a CoFe,
reduced to an alloy of

However, in many cases one or both of the metal oxides present in the alloy will be eg an iron-manganese mixed metal oxide,
That is, F''2.25 MnO, 7504 is not easily reduced in the presence of hydrogen at temperatures below 850°C.

According to the present invention, tH in a high temperature state in hydrogen gas
Mixed metal iron oxides that are ferrous or substantially non-reducible can be formed at reaction temperatures that are much lower than those required to melt the mixed metal oxide or two-component metal, generally below 1000°C. I can do it. The present invention involves the reduction of mixed metal oxides, particularly spinels, at moderate temperatures below the melting point of the mixed metal oxide and of the two components to produce at least a stoichiometric amount of said mixed metal oxide to produce an alloy. It is materialized by contacting with calcium metal.

Calcium metal may be in any form conveniently and usefully utilized in the reduction process, including alloys or eutectic alloys, such as calcium-silicon alloys or eutectic alloys that lower the melting point of calcium metal. can do.

These mixed metal iron oxides can be reduced by reaction with metallic calcium at moderate temperatures. The amount of calcium is used in at least a stoichiometric amount and/or preferably about 5-10% or more on a molar basis for ease and convenience in the reduction as determined by the following formula: FexMyOn+4Ca −+ FexMy+
4CaO where M is SC+TI+V+Cr+ML
A metal selected from Zn, x and y are integers or decimals,
The total of x and y is 3.

Spinel is produced in a high temperature solid state sintering reaction between the respective component metal oxides and/or metals under normal pressure or vacuum at temperatures in the range of about 600-1000<0>C.

The calcium is contained in contact with the mixed metal oxide in a container, usually of iron or nickel construction, capable of resisting attack at high temperatures of calcium metal or calcium oxide.

The reactants are contained under reduced pressure, such as in a non-oxidizing atmosphere, such as an atmosphere or stream of an inert gas such as helium, argon, nitrogen, and the like, or in a vacuum. 600 to 100°C, preferably 800 to 100°C, lower than the melting point of the mixed metal oxide
The temperature is raised next to 900°C. The process temperature is the melting point of the calcium metal, i.e. 8
Particularly preferred is a temperature of 45°C or higher. The mixture is 1-10
The reaction is allowed to proceed for 0 hours, preferably from 50 to 75 hours, with special reaction conditions used to ensure substantially complete reduction to the metal alloy. Following the reduction reaction, calcium by-products, including calcium oxide and unreacted calcium, must be removed from the solid alloy by leaching. Dilute aqueous solutions of water-soluble organic or mineral acids such as acetic acid, hydrochloric acid, nitric acid and the like are brought into contact with the impure product alloy from the reduction step for a short time, e.g. 10-20 minutes, at a concentration of about 1-2 normal. . 1 to 2 normal is a convenient acid concentration to utilize, although more concentrated or dilute aqueous acid solutions can be used.

Following contact with the aqueous acid solution, the alloy is separated or removed from the aqueous solution and the product alloy is substantially reducibly pure.
ndant) with a particle size of about 0.1-5 m”/g, which can be used directly for co/llz hydrocarbon synthesis in this particle size range. The contacting step with acid provides good mixing and This can usually be carried out at room temperature or slightly elevated temperature to ensure extraction of the calcium by-product.Following the aqueous acid extraction, the resulting alloy is recovered as described above.

It is further provided by the present invention that the powdered iron-manganese spinel is heated with at least a stoichiometric amount of calcium metal at a temperature of 600 to 1000° C. under reaction conditions as outlined above. It is a method of producing alloys. The preferred single-phase spinel applied in this embodiment has the empirical formula 'Fe2.25 MnO,75
o4, and the resulting alloy has the formula: Fe2,25 Mno,7
It has s. The apparatus for carrying out the method of the invention as described herein is conventional and will be obvious to those skilled in the art after reading the examples and description.

The following examples should not be construed as limitations on the scope or spirit of the invention; they are the best modes of carrying out the invention attempted by the inventors.

Comparative Example Stoichiometric amount of iron-manganese oxide, Fe2.25'' 0,
7504, is 1.5969 g of pe2o3; 0
．． 1396 g Fed and 0.5720 g Mn3
The intimately ground mixture of O4 was evacuated in a sealed quartz tube.
It was synthesized by heating at 000°C for 24 hours.

The resulting solids were reground, refilled and sealed in new quartz tubes, and then reheated at 1000° C. for 24 hours. X-ray diffraction patterns demonstrated that the product crystallized as a single-phase organic acid into a spinel crystal structure. A subsequent high temperature 2 reduction at 1000 degrees produced a mixture of Fe metal plus MnO.

Example 1 Fe2.25 MI'lO,75 produced as described above
040-5g was placed in a 13m m00D iron tube along with 0.7g of metallic Ca (6 mesohydrium), then evacuated and placed in a sealed quartz tube.The iron tube was plugged to prevent calcium or spinel from coming into contact with the walls of the quartz tube. install),
The reaction was carried out at 850°C for 72 hours. After cooling, the contents are approximately 30
0 ml of 1N acetic acid solution at room temperature, approximately 3
CaO, calcium by-products, and unreacted calcium were completely leached out by stirring for hours. The suspended solid alloy is filtered and
The solids are washed with running water until free of acid and the resulting solids are air dried. The powder X-ray diffraction pattern of the formed solid phase is a = 3,
A face-centered cubic lattice with 596 lattice constants is shown. The solids produced are structurally identical to gamma-iron and Fe-Mn alloys commonly produced from processes involving molten iron and manganese metal at temperatures above 1500°C.
It was structural. The surface 11'i of the Fe--Mn alloy obtained in this example was about 0.3 m2/g.

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Claims (1)

[Claims] 1. (Al) A mixture of a powdered mixed metal iron oxide, which is difficult to reduce in hydrogen gas, and at least a stoichiometric amount of calcium metal is heated in a non-oxidizing atmosphere. heating at a temperature below the melting point for a time sufficient to substantially reduce all metal oxides present and form the product metal-based iron alloy as determined by X-ray diffraction; (b) contacting said reducible mixed metal iron oxide with an aqueous acid solution to remove calcium impurities and by-products; and then (C) recovering said product metal-based iron alloy. 2. The method of claim 1, wherein the temperature is in the range of about 600-1000°C. 3. The method of claim 1, wherein the temperature is in the range of about 800-900°C. The method according to claim 2. 4. The method according to claim 1, wherein the temperature is approximately the melting point of calcium metal or higher. 5. The non-oxidizing atmosphere comprises an inert gas. 6. The method according to claim 1, wherein the acid in step (bl) is selected from acetic acid, nitric acid, hydrochloric acid. 7. 8. The method of claim 1, wherein the mixed metal oxide is a single oxide as measured by X-ray diffraction.8. 9. The method according to claim 1, comprising IVB, VB, VIB, ■B and I [and at least one other metal selected from the first row transition metals of group B.9. The method according to claim 7, wherein said mixed metal oxide comprises iron and at least one other metal selected from scandium, titanium, vanadium, chromium, manganese, and zinc.10.
2. A method according to claim 1, which is not completely reduced at temperatures below .degree.