SE1650211A1

SE1650211A1 - Process for producing molybdenum-containing units

Info

Publication number: SE1650211A1
Application number: SE1650211A
Authority: SE
Inventors: Sjöberg Dag; ANTONOV Filip
Priority date: 2016-02-18
Filing date: 2016-02-18
Publication date: 2017-08-19
Also published as: WO2017140832A1

Abstract

A process (100) for producing at least one molybdenum-containing unit is disclosed. The process (100) comprises providing (110) at least a molybdenum-containing powder and a carbon-containing powder. An intermediate process product in the form of a mixture is provided (120), wherein the providing (120) of the intermediate process product comprises mixing (130) at least the molybdenum-containing powder and the carbon-containing powder. The intermediate process product is vacuumized (150), pressurized (160) and extruded (170) into at least one unit.(Figure 1 elected for publication with the abstract.)

Description

PROCESS FOR PRODUCING MOLYBDENUM-CONTAINING UNITS TECHNICAL FIELDThe present invention relates to a process for producing at least one mo lybdenum-containing unit and a unit obtained (or produced) by the process.

BACKGROUNDMolybdenum (Mo) does not occur as a free metal but rather in various oxidation states in minerals. Mo lybdenum can for example be used to forrn hard, stablecarbides in alloys, and a majority of the amount of mo lybdenum that is produced Worldwide isused in making of various types of steel or iron alloys, such as high strength alloys and socalled superalloys. In making of such steel alloys, a molybdenum-containing material isusually added to a melt in order to introduce a mo lybdenum content into the melt by Way ofthe mo lybdenum-containing material dissolving into the melt, so as to achieve a desiredamount or fraction of mo lybdenum in the alloy. One example of such a mo lybdenum-containing material is ferromolybdenum, Which is an iron-molybdenum alloy Which usuallyhas a mo lybdenum content of 60% to 80% by Weight. Ferromolybdenum may for example beproduced from mo lybdenum trioxide (MoOg) by means of carbotherrnic reduction, hydrogenreduction, aluminotherrnic reduction, and/or silicotherrnic reduction. Another example of sucha molybdenum-containing material is disclo sed in the intemational application havingpublication number WO 2014/ 193298 Al. WO 2014/ 193298 Al discloses a process forproducing iron and mo lybdenum containing compacts, Which compacts may have a density inthe range of l.0 to 4.0 g/cm3, and Which may be used as a substitute to molybdenum trioxidepowder or ferromolybdenum for addition to a melt in making of steel alloys. HoWever, thereis still a need in the art for mo lybdenum-containing materials having relatively high amountsof mo lybdenum per unit volume, and With relatively high densities, and Which materials can be used for addition of mo lybdenum in melts for making for example steel or iron alloys.

SUMMARY In view of the above discussion, a concem of the present invention is toprovide a process for producing a mo lybdenum-containing material or unit (e.g., a piece ofmaterial containing molybdenum and possibly having a predef1ned or selected shape), Whichmay be used for addition of mo lybdenum to melts, for example in melts in the steel, foundry, alloy and superalloy industries, for making of for example steel or iron alloys.

To address at least one of this concern and other concerns, a process inaccordance with the independent claim is provided. Preferred embodiments are defined by thedependent claims.

According to a first aspect of the present invention there is provided a processfor producing at least one mo lybdenum-containing unit. The process comprises providing atleast a mo lybdenum-containing powder and a carbon-containing powder, and providing aninterrnediate process product in the forrn of a mixture. The providing of the interrnediateprocess product comprises mixing at least the mo lybdenum-containing powder and thecarbon-containing powder. The process comprises vacuumizing the interrnediate processproduct, pressurizing the interrnediate process product, and extruding the interrnediate processproduct into at least one unit.

Embodiments of the present invention are based on an idea of producing one ormore units comprising mo lybdenum by means of vacuum extrusion. The interrnediate processproduct, which according to one or more embodiments of the present invention includes or isconstituted by a mixture of at least the mo lybdenum-containing powder and the carbon-containing powder, may be vacuum-treated and subjected to pressure before and/or during theextrusion into one or more units of desired forrn. It has been found by the inventors that unitsproduced by means of a process according to the first aspect may attain a density exceeding4.0 g/cm3, for example in the range of 5.0 g/cm3 to 5.5 g/cm3 . The resulting unit or units are inthe forrn of compacted powder(s) comprising mo lybdenum and carbon, which can readily beused for addition of mo lybdenum to melts, for example in melts in the steel, foundry, alloyand superalloy industries, for making of for example steel or iron alloys, and may dissolverelatively quickly into the melts. The resulting unit or units may readily be used as a substitutefor traditionally manufactured ferromolybdenum alloys, or as a substitute for mo lybdenumoxide as addition to a melt for making of for example steel or iron alloys. The unit(s)produced by the process may be placed in desired positions in a melt and/or mould, and byway of the unit(s) being in the forrn of compacted powder(s), there may be only little or evenno dispersion of powder into the surroundings when adding the unit(s) to a melt, in contrast toaddition of a (non-compacted) powder into a melt. There may be substantially no losses fromthe (vacuum extrusion) process according to the invention. Consequently, there may berelatively low losses of material as compared to other methods. By way of the (vacuumextrusion) process according to the invention, the unit or units may possibly be produced atlower cost as compared to standard grades of ferromolybdenum.

The mo lybdenum-containing powder may for example comprise (possibly amixture of) one or more mo lybdenum oxides, such as, for example, mo lybdenum trioxide(MoOg), or molybdenum dioxide (MoOg). The mo lybdenum-containing powder may forexample comprise a mo lybdenum oxide powder. The mo lybdenum oxide powder may according to one or more embodiments of the present invention contain 50 to 80 weight-% of M0, and the remaining elements may be oxygen and impurities. According to one or moreembodiments of the present invention, the mo lybdenum-containing powder may comprise socalled technical grade MoOg. According to one or more embodiments of the presentinvention, at least 90 weight-% of the particles of the molybdenum oxide powder may besized so as to pass through a so called “test° sieve having nominal aperture sizes of about 300 um, and at least 50 weight-% of the particles of the molybdenum oxide powder may besized so as to pass through a test sieve having nominal aperture sizes of about 125 um.According to one or more other embodiments of the present invention, at least 90 weight-% ofthe particles of the molybdenum oxide powder may be sized so as to pass through a test sievehaving nominal aperture sizes of 125 um, and at least 50 weight-% of the particles of the mo lybdenum oxide powder may be sized so as to pass through a test sieve having nominalaperture sizes of about 45 um. According to one or more other embodiments of the presentinvention, at least 90 weight-%, or even at least 99 weight-%, of the particles of the mo lybdenum oxide powder may be sized so as to pass through a test sieve having nominalaperture sizes of 250 um, or 125 um, or even 45 um.

The carbon-containing powder may for example comprise (possibly a mixtureof) sub-bituminous coal, bituminous coal, lignite, anthracite, graphite, coke, petroleum coke,bio-carbon such as charcoal, soot, carbon black, and/or activated carbon.

The mixture of at least the mo lybdenum-containing powder and the carbon-containing powder may according to one or more embodiments of the present inventioncomprise 50-95 weight-%, or 65-95 weight-%, of the molybdenum-containing powder and 5-30 weight-% of the carbon-containing powder.

The providing of the interrnediate process product may comprise providing aniron-containing powder. The providing of the interrnediate process product may comprisemixing at least the mo lybdenum-containing powder, the carbon-containing powder and theiron-containing powder.

The iron-containing powder may for example be constituted by or comprise(possibly a mixture of) one or more powders selected from a group comprising iron powderM40 from Höganäs AB, Sweden, or similar, iron sponge powder, water-atomized ironpowder, gas-atomized iron powder, iron filter dust (such as, for example, X-RFS40 fromHö ganas AB, Sweden) and/or iron sludge powder. The iron-containing powder maypreferably contain at least 80 weight-% of Fe, preferably at least 90 weight-% of Fe, morepreferably at least 95 weight-% of Fe, and more preferably at least 99 weight-% of Fe. Theiron-containing powder may be constituted by or include an iron oxide powder, such as, forexample, FeO, FezOg, Fe3O4, and/or FeO(OH).

According to one or more embodiments of the present invention, the grain size of the iron-containing powder may be within the range of 1 um-500 um, or preferably 10 um-500 um, or more preferably 100 um-300 um. A relatively wide range of grain sizes mayfacilitate or allow for achieving a relatively high degree of process customization.

According to one or more other embodiments of the present invention, at least90 weight-% of the particles of the iron-containing powder may be sized so as to pass througha test sieve having nominal aperture sizes of 125 um, and at least 50 weight-% of the particlesof the iron-containing powder may be sized so as to pass through a test sieve having nominalaperture sizes of about 45 um. According to one or more other embodiments of the presentinvention, at least 90 weight-%, or even at least 99 weight-%, of the particles of the iron-containing powder may be sized so as to pass through a test sieve having nominal aperturesizes of 250 um, or 125 um, or 45 um, or even 20 um.

The mixture of at least the mo lybdenum-containing powder, the carbon-containing powder and the iron-containing powder may according to one or moreembodiments of the present invention comprise 50-94 weight-%, or 65-94 weight-%, of themo lybdenum-containing powder, 5-30 weight-% of the carbon-containing powder, and 1- 30 weight-% of the iron-containing powder.

In altemative or in addition, the providing of the interrnediate process productmay comprise providing at least one binder. The providing of the interrnediate processproduct may comprise mixing at least the mo lybdenum-containing powder, the carbon-containing powder and the at least one binder. The at least one binder may for examplecomprise at least one material selected from a group comprising bentonite, starch, Portlandcement and dextrin. However, another type or other types of binders are contemplated (suchas, for example, sodium silicate, lime and/or gelatin) and may be employed according to oneor more embodiments of the present invention. The at least one binder may for exampleprovide suff1cient green strength to the powder grains, i.e. the mechanical strength which acompacted powder must have in order to withstand mechanical operations to which it issubj ected after pressing.

The starch may for example comprise or be constituted by starch in powderform as provided by Acros Organics BVBA, J anssen Pharrnaceuticalaan Sa, 2440 Geel,Belgium. The bentonite may for example comprise or be constituted by Volclay DC-2Westem Bentonite as provided by American Colloid Company, 2870 Forbs Avenue HoffmanEstates, IL 60192, USA.

The mixture of at least the mo lybdenum-containing powder, the carbon-containing powder and the at least one binder may according to one or more embodiments ofthe present invention comprise 50-94.9 weight-%, or 65-94.9 weight-%, of the molybdenum-containing powder, 5-30 weight-% of the carbon-containing powder, and 0.1-10 weight-% ofthe at least one binder. According to one or more embodiments of the present invention, the mixture may comprise 0.25-5 weight-% of the at least one binder.

According to one or more embodiments of the present invention, the mixture ofat least the mo lybdenum-containing powder, the carbon-containing powder, the iron-containing powder and the at least one binder may according to one or more embodiments ofthe present invention comprise 50-95 weight-%, or 65-95 weight-%, of the molybdenum-containing powder, 5-30 weight-% of the carbon-containing powder, 0-40 or 0-35 weight-%of the iron-containing powder, and 0.1-10 weight-% of the at least one binder. According toone or more embodiments of the present invention, the mixture may comprise 0.25-5 weight-% of the at least one binder.

The mixture of at least the mo lybdenum-containing powder, the carbon-containing powder and possibly the iron-containing powder and/or the at least one binder mayconstitute or be comprised in the interrnediate process product. For example, after havingmixed at least the molybdenum-containing powder, the carbon-containing powder andpossibly the iron-containing powder and/or the binder, the mixture may be vacuumized,pressurized, and extruded.

As mentioned in the foregoing, the mo lybdenum-containing powder may forexample comprise (possibly a mixture of) one or more molybdenum oxides. The providing ofthe interrnediate process product may according to one or more embodiments of the presentinvention comprise reducing the mixture of at least the mo lybdenum-containing powder andthe carbon-containing powder (and possibly iron-containing powder and/or one or morebinders) so as to obtain at least one reduced compact.

The reducing of the mixture of at least the molybdenum-containing powder andthe carbon-containing powder may for example be carried out using a reduction fumace, forexample including or being constituted by a continuous fumace, a walking beam fumace, or abatch fumace. The reducing of the mixture of at least the mo lybdenum-containing powder andthe carbon-containing powder may be carried out by means of at least one reductant, orreducing agent, which possibly may be in powder form.

Preferably relatively large amounts of at least the mo lybdenum-containingpowder and the carbon-containing powder are mixed, such that during the reducing of themixture of at least the mo lybdenum-containing powder and the carbon-containing powder, arelatively high degree or extent of so called self-compaction of the mixture of at least themo lybdenum-containing powder and the carbon-containing powder can be achieved.

The reducing of the mixture of at least the molybdenum-containing powder andthe carbon-containing powder may for example be carried out at a temperature in a range of800 °C to 1500 °C, preferably in a range of 800 °C to 1350 °C, more preferably in a range of1000 °C to 1200 °C. The reducing of the mixture of at least the molybdenum-containingpowder and the carbon-containing powder may for example be carried out during a period oftime of at least (about) 10 minutes, even though longer periods of times are possible, such as at least (about) 20 or 30 minutes, or even one or a few hours.

The reducing of the mixture of at least the molybdenum-containing powder andthe carbon-containing powder may be carried out using a reduction fumace which iscontinuously or continually supplied with an inert or reducing gas, preferably a relativelyweakly reducing gas. The gas supplied to the reduction fumace may for example beconstituted by or include Ar, Ng, H2, or any mixture thereof During the reducing of the mixture of at least the mo lybdenum-containingpowder and the carbon-containing powder, the reduction furnace may for example beoperated at a pressure in a range of 0.1 atm (1 atm being equal to 101325 Pa) to 5 atm,preferably in a range of 0.8 atm to 2 atm, more preferably in a range of 1.05 atm to 1.2 atm.

The at least one reduced compact may according to one or more embodimentsof the present invention be in the form of relatively porous, generally disc-like lumps ofmaterial. The providing of the interrnediate process product may comprise breaking thereduced at least one compact into particles, or grains, so as to obtain a powder mixture. Thebreaking of the reduced at least one compact into particles so as to obtain a powder mixturemay for example comprise at least one of tearing, grinding or milling the reduced at least onecompact. However, another or other ways of breaking the reduced at least one compact intoparticles so as to obtain a powder mixture are contemplated. For example, any way known inthe art of breaking the reduced at least one compact into particles so as to obtain a powdermixture could be employed.

The interrnediate process product may be constituted by or include the powdermixture. For example, after having obtained the powder mixture, the powder mixture may bevacuumized, pressurized, and extruded. According to another example, an iron-containingpowder may be mixed with the powder mixture, and the resulting mixture may then bevacuumized, pressurized, and extruded. Thus, the providing of the interrnediate processproduct may comprise providing an iron-containing powder, and mixing the iron-containingpowder and the powder mixture, wherein the interrnediate process product may be constitutedby or include the mixture of the iron-containing powder and the powder mixture.

The pressurizing of the interrnediate process product may comprisepressurizing the interrnediate process product at an elevated pressure up to about 450 kPa. Theterm “elevated pressure” should in the context of the present application be understood as apressure which exceeds the ambient (norrnally atmospheric) pressure.

The extruding of the interrnediate process product into at least one unit maycomprise extruding the interrnediate process product using an extrusion nozzle having a formsuch that the at least one unit is extruded into a form selected from a group comprising bars,rods and wires. Thus, there may be considerable ﬂexibility in the shape of the at least one unitwhich is produced by the process according to embodiments of the present invention.

The vacuumizing of the interrnediate process product implies subj ecting the interrnediate process product to (at least partial) vacuum. The pressurization of the interrnediate process product may be carried out for example by means of an augerarrangement Which may be part of an extrusion system for carrying out the extruding of theinterrnediate process product.

In the context of the present application, by the term “extruding” it is meantsubstantially any extrusion method Which may be used to create units, pieces or elementshaving a certain (selected) cross-sectional proﬁle, Wherein the mixture is pushed through anextrusion nozzle having a desired or required shape, for example a die of the desired cross-section. The vacuumizing, pressurizing and extruding of the interrnediate process product intoat least one unit may preferably be performed by means of a so called stiff extrusion processcombining a relatively high (auger) pressure and at least partial vacuum de-airing.

The vacuumizing, the pressurizing, and the extruding of the interrnediateprocess product into at least one unit may all be carried out in one (that is, a single) processingdevice. The processing device may for example be constituted by or include a stiff extrusionsystem.

According to a second aspect of the present invention there is provided a unitobtained (or produced) by, or obtainable by, a process according to the first aspect.

The unit may according to one or more embodiments of the present inventionfor example comprise 60-80 Weight-% of molybdenum and 20-45 Weight-% of carbon, or 60-80 Weight-% of molybdenum, 20-45 Weight-% of carbon, and 0-35 Weight-% of iron.

The unit may according to one or more other embodiments of the presentinvention for example comprise 60-99.99 Weight-% of molybdenum and 0.0l-l5 Weight-% ofcarbon. This may for example be the case if the providing of the interrnediate process productcomprises reducing the mixture of at least the mo lybdenum-containing poWder and thecarbon-containing poWder (and possibly iron-containing poWder and/or one or more binders)so as to obtain at least one reduced compact. The unit may according to one or moreembodiments of the present invention for example comprise 60-99.99 Weight-% ofmolybdenum, 0.0l-l5 Weight-% of carbon, and 0-35 Weight-% of iron.

Further objects and advantages of the present invention are described in thefollowing by means of exemplifying embodiments. It is noted that the present inventionrelates to all possible combinations of features recited in the claims. Further features of, andadvantages With, the present invention Will become apparent When studying the appendedclaims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.

BRIEF DESCRIPTION OF THE DRAWINGSExemplifying embodiments of the invention Will be described below With reference to the accompanying draWings.

Figure 1 is a schematic illustration of a process for producing at least onemo lybdenum-containing unit according to an embodiment of the present invention.Figure 2 is a schematic illustration of an extrusion nozzle for extruding at leastone molybdenum-containing unit in accordance with an embodiment of the present invention.Figure 3 is a schematic illustration of a process for producing at least onemo lybdenum-containing unit according to another embodiment of the present invention.All the figures are schematic, not necessarily to scale, and generally only showparts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION The present invention will now be described hereinafter with reference to theaccompanying drawings, in which exemplifying embodiments of the present invention areshown. The present invention may, however, be embodied in many different forrns and shouldnot be construed as limited to the embodiments of the present invention set forth herein;rather, these embodiments of the present invention are provided by way of example so thatthis disclo sure will convey the scope of the invention to those skilled in the art. In thedrawings, identical reference numerals denote the same or similar components having a sameor similar function, unless specifically stated otherwise.

Figure 1 is a schematic illustration of a process 100 for producing at least onemo lybdenum-containing unit according to an embodiment of the present invention. Theprocess 100 comprises providing 110 (at least) a molybdenum-containing powder and acarbon-containing powder. The process 100 comprises providing 120 an interrnediate processproduct in the form of a mixture. According to the embodiment of the present inventionillustrated in Figure 1, the step of providing the interrnediate process product 120 comprisesmixing 130 (at least) the mo lybdenum-containing powder and the carbon-containing powder.The mixture of the mo lybdenum-containing powder and the carbon-containing powder mayfor example comprise 50-95 weight-%, or 65-95 weight-%, of the molybdenum-containingpowder and 5-30 weight-% of the carbon-containing powder. The interrnediate processproduct, which hence in accordance with the embodiment of the present invention illustratedin Figure 1 comprises a mixture of the mo lybdenum-containing powder and the carbon-containing powder (and possibly one or more other elements and/or powders, as will bedescribed further in the following), is then vacuumized 150, pressurized 160, and extruded170 into at least one unit. The extruded unit may in general be constituted by a piece ofmaterial containing molybdenum and possibly having a predefmed or selected shape.

Water or some other appropriate liquid may be used in the extrusion process.Thus, the step of providing 120 the interrnediate process product may further comprise adding water to the mixture of the mo lybdenum-containing powder and the carbon-containing powder. The mixture of the mo lybdenum-containing powder, the carbon-containing powderand water may subsequently be vacuumized, pressurized, and extruded into at least one unit,in steps 150, 160 and 170, respectively. Water (or some other appropriate liquid) may forexample be added in such amount that it comprises up to 10 or 15 weight-% of the mixtureconstituting the interrnediate process product, which subsequently is vacuumized, pressurized,and extruded into at least one unit, in steps 150, 160 and 170, respectively.

The process 100 may comprise drying of the extruded unit(s). For drying theextruded unit(s) different types of industrial dryers may be used. The extruded unit(s) may bedried without use of active heating. The extruded unit(s) may be dried until a desired orrequired water content, or moisture content, in the extruded unit(s) has been obtained.Preferably, the moisture content in the extruded unit(s) should be at most a few weight-%, orpossibly less than 2 weight-%. The moisture content in the extruded unit(s) may bedeterrnined for example by means of a loss on drying analysis in accordance with ASTMD2216-10 (Standard Test Methods for Laboratory Deterrnination of Water (Moisture) Contentof Soil and Rock by Mass, ASTM Intemational, West Conshohocken, PA, 2010).

One or more of the steps of vacuumizing 150, pressurizing 160, and extruding170 of the interrnediate process product may be performed in an (stiff extrusion) arrangementas disclosed. Thus, the vacuumizing 150, pressurizing 160, and extruding 170 of theinterrnediate process product may in accordance with one or more embodiments of the presentinvention be carried out in one (a single) processing device. The vacuumizing 150 impliessubj ecting the interrnediate process product (mixture) to (at least partial) vacuum. Theinterrnediate process product is also pressurized 160 by the process 100, e.g. at a pressure inthe range of 0-450 kPa, or at an elevated pressure up to about 450 kPa. The pressurization160 of the interrnediate process product may for example be performed by an augerarrangement in the extrusion process.

The at least one unit which is produced by means of extruding 170 theinterrnediate process product may have a density exceeding 4.0 g/ cm3 , for example in therange of 5.0 g/ cm3 to 5.5 g/ cm3 . By way of the vacuum extrusion process, the extruded unit(s)may exhibit a higher density and/or a higher degree of compaction compared to for examplebriquettes formed by briquetting mo lybdenum-containing powder mixture. Further, there maybe only little or even no dispersion of powder into the surroundings when adding the extrudedunit(s) to a melt, in contrast to the case of adding of a (non-compacted) powder into a melt.

It will be appreciated that the at least one unit which is produced by means ofextruding 170 the interrnediate process product may have different shapes depending on theconfiguration of the extrusion arrangement used. The extruding 170 of the interrnediateprocess product may for example be carried out using an extrusion nozzle having a form suchthat the at least one unit is extruded into a form selected from a group comprising bars, rods and wires. Thus, there may be considerable ﬂexibility in the shape of the at least one unit which is produced by the process 100. Figure 2 is a schematic illustration of an extrusionnozzle 300 for extruding at least one molybdenum-containing unit in accordance with anexemplifying embodiment of the present invention. By the shape or configuration of theextrusion nozzle 300 illustrated in Figure 2, units which are produced by means of extruding170 the interrnediate process product may be in the forrn of bars, rods, wires or threads. Thewidth of the three quadratic openings of the extrusion nozzle 300 illustrated in Figure 2 maybe approximately 0.5 cm.

The mo lybdenum-containing powder, which is provided in step 110 and whichis mixed with (at least) the carbon-containing powder, preferably comprises a mo lybdenumoxide powder (comprising one or more mo lybdenum oxides). The mo lybdenum oxide powderwhich is provided in step 110 may according to one or more embodiments of the presentinvention be pre-reduced to a selected or predefined extent or degree. The molybdenum oxidepowder preferably comprises mo lybdenum trioxide, MoOg. According to one or moreembodiments of the present invention, the mo lybdenum-containing powder may for examplebe produced or obtained by means of carbotherrnic reduction and/or hydrogen reduction of anoxide of molybdenum, e.g., MoOg.

The process 100 may optionally comprise providing 140 an iron-containingpowder. The step 120 of providing the interrnediate process product may comprise mixing themo lybdenum-containing powder, the carbon-containing powder and the iron-containingpowder. The resulting mixture of the mo lybdenum-containing powder, the carbon-containingpowder and the iron-containing powder may thereby constitute the interrnediate processproduct which subsequently is vacuumized, pressurized, and extruded into at least one unit, insteps 150, 160 and 170, respectively. It is however to be understood that the iron-containingpowder is optional and not required. Hence, the interrnediate process product whichsubsequently is vacuumized, pressurized, and extruded into at least one unit, in steps 150, 160and 170, respectively, may be constituted by only a mixture of the mo lybdenum-containingpowder and the carbon-containing powder, as described in the foregoing.

The at least one unit which is produced by way of the process 100 illustrated inFigure 1 may for example be used as a substitute for traditionally manufacturedferromolybdenum alloys possibly according to standard specifications, or as a substitute formo lybdenum oxide (powder) as addition to a melt for making of for example steel or ironalloys. The extruded unit(s) produced by way of the process 100 illustrated in Figure 1 maynot have been reduced. However, it is possible to obtain extruded units which have beenreduced. A possible way of obtaining extruded units which have been reduced is describedfurther in the following with reference to Figure 3. In altemative or in addition, themo lybdenum-containing powder (e.g. a mo lybdenum oxide powder) which is provided in step110 may according to one or more embodiments of the present invention be pre-reduced to a selected or predef1ned extent or degree. 11 The extruded unit(s) produced by way of the process 100 illustrated in Figure 1may for example comprise 60-80 weight-% of molybdenum and 20-45 weight-% of carbon.Possibly the extruded unit(s) may comprise 60-80 weight-% of molybdenum, 20-45 weight-%of carbon, and 0-35 weight-% of iron.

The process 100 may optionally comprise providing 180 at least one binder.The at least one binder may for example comprise at least one material selected from a groupcomprising bentonite, starch, Portland cement and dextrin. The step 120 of providing theinterrnediate process product may comprise mixing the mo lybdenum-containing powder, thecarbon-containing powder and the at least one binder (and possibly an iron-containing powderas described in the foregoing). The resulting mixture of the mo lybdenum-containing powder,the carbon-containing powder and the at least one binder (and possibly the iron-containingpowder) may thereby constitute the interrnediate process product which subsequently isvacuumized, pressurized, and extruded into at least one unit, in steps 150, 160 and 170,respectively. It is however to be understood that the at least one binder is optional, and notrequired.

Figure 3 is a schematic illustration of a process 100 for producing at least onemo lybdenum-containing unit according to another embodiment of the present invention. Theprocess 100 illustrated in Figure 3 is similar to the process 100 illustrated in Figure 1 butdiffers therefrom in that the step 120 of providing the interrnediate process product comprisesfurther steps, as will be described further in the following, in addition to mixing 130 of amo lybdenum-containing powder and a carbon-containing powder as described in theforegoing with reference to Figure 1. The steps 140 and 180 of the process 100 illustrated inFigure 3 are similar to or the same as the steps 140 and 180, respectively, of the process 100illustrated in Figure 1.

Similarly to the process 100 illustrated in Figure 1, the process 100 illustratedin Figure 3 comprises providing 110 (at least) a molybdenum-containing powder and acarbon-containing powder, and the step of providing 120 the interrnediate process productcomprises mixing 130 (at least) the mo lybdenum-containing powder and the carbon-containing powder. As in the process 100 illustrated in Figure 1, the mo lybdenum-containingpowder provided in step 110 and which is mixed with (at least) the carbon-containing powderpreferably comprises a mo lybdenum oxide powder (comprising one or more molybdenumoxides). The mo lybdenum oxide powder preferably comprises mo lybdenum trioxide. Themixture of the molybdenum-containing powder and the carbon-containing powder may forexample comprise 50-95 weight-%, or 65-95 weight-%, of the molybdenum-containingpowder and 5-30 weight-% of the carbon-containing powder.

As mentioned in the foregoing, the mo lybdenum-containing powder may forexample comprise (possibly a mixture of) one or more molybdenum oxides. In accordance with the embodiment of the present invention illustrated in Figure 3, the step of providing 120 12 the interrnediate process product may further comprise reducing 190 the mixture of at leastthe mo lybdenum-containing powder and the carbon-containing powder so as to obtain at leastone reduced compact, and breaking 200 the reduced at least one compact into particles so asto obtain a powder mixture. The reduced compact may for example be in the forrn ofrelatively porous, generally disc-like lumps of material. The reduced compact may be brokeninto particles so as to obtain the powder mixture for example by way of tearing, grindingand/or milling the reduced compact. The resulting powder mixture, obtained by way of step200, may thereby constitute the interrnediate process product obtained at step 120, whichinterrnediate process product in the form of the powder mixture subsequently is vacuumized,pressurized, and extruded into at least one unit, in steps 150, 160 and 170, respectively. Theinterrnediate process product may hence, in accordance with the embodiment of the presentinvention illustrated in Figure 3, be constituted by the powder mixture obtained by way ofstep 200. The at least one unit which is produced by means of extruding 170 the interrnediateprocess product may, similarly to the at least one unit produced by means of the process 100illustrated in Figure 1, have a density exceeding 4.0 g/cm3, for example in the range of 5.0 g/ cm3 to 5.5 g/ cm3 . By way of the vacuum extrusion process, the extruded unit(s) mayexhibit a higher density and/or a higher degree of compaction compared to for examplebriquettes formed by briquetting mo lybdenum-containing powder mixture Water or some other appropriate liquid may be used in the extrusion process.Thus, the step of providing 120 the interrnediate process product may further comprise addingwater to the powder mixture obtained by way of step 200, and the mixture of the powdermixture and water may subsequently be vacuumized, pressurized, and extruded into at leastone unit, in steps 150, 160 and 170, respectively. Water (or some other appropriate liquid)may for example be added in such amount that it comprises up to 10 or 15 weight-% of themixture constituting the interrnediate process product, which subsequently is vacuumized,pressurized, and extruded into at least one unit, in steps 150, 160 and 170, respectively.

Similarly to the process 100 illustrated in Figure 1, the process 100 illustratedin Figure 3 may comprise drying of the extruded unit(s).

The reducing 190 of the mixture of at least the mo lybdenum-containingpowder and the carbon-containing powder may for example be carried out using a reductionfumace (not shown in Figure 3). The reductant(s), or reducing agent(s), used may possibly bein powder form. The reducing step 190 may for example be carried out by means of carbonand/or hydrogen reduction. The reducing step 190 may for example be carried out at atemperature in a range of 800 °C to 1500 °C, preferably in a range of 800 °C to 1350 °C,more preferably in a range of 1000 °C to 1200 °C, and during a period of time of at least(about) 10 minutes, even though longer periods of times are possible, such as at least (about)20 or 30 minutes, or even one or a few hours. The reduction fumace may be continuously or continually supplied with an inert or reducing gas, such as a gas comprising Ar, Ng, H2 or any 13 mixture thereof. The reducing gas is preferably a relatively weakly reducing gas. Thereduction ﬁamace may for example be operated at a pressure in a range of 0.1 atm (1 atmbeing equal to 101325 Pa) to 5 atm, preferably in a range of 0.8 atm to 2 atm, more preferablyin a range of 1.05 atm to 1.2 atm.

During the reducing process CO and/or C02 may be formed from reactions e. g.between the carbon-containing powder and reducible oxides in the mo lybdenum-containingpowder. For example by monitoring the formation of CO and/or C02 in the reduction fumaceduring the reducing process, it may be deterrnined when the reducing process is completed.Reaction gases such as CO and/or C02 formed during the reducing process may continuouslyor continually be evacuated from the reduction ﬁamace.

A relatively high degree or extent of so called self-compaction of the mixtureof at least the mo lybdenum-containing powder and the carbon-containing powder may beachieved during the reducing 190 of the mixture of at least the mo lybdenum-containingpowder and the carbon-containing powder. This may particularly be the case for example ifsuff1ciently large amounts of at least the mo lybdenum-containing powder and the carbon-containing powder are used in the reducing process.

The process 100 illustrated in Figure 3 may optionally comprise providing 210an iron-containing powder. The step 210 may be in altemative or in addition to the optionalstep 140. The process 100 may further optionally comprise mixing 220 the iron-containingpowder and the powder mixture obtained by way of step 200. The resulting mixture of theiron-containing powder and the powder mixture may thereby constitute the interrnediateprocess product obtained at step 120, which intermediate process product subsequently isvacuumized, pressurized, and extruded into at least one unit, in steps 150, 160 and 170,respectively. It is however to be understood that the steps 210 and 220 are optional, and notrequired. In case of using water or some other appropriate liquid in the extrusion process suchas described in the foregoing, the step of providing 120 the interrnediate process product mayfurther comprise adding water to the mixture of the iron-containing powder and the powdermixture obtained by way of step 220. The mixture of the iron-containing powder, the above-mentioned powder mixture, and water may subsequently be vacuumized, pressurized, andextruded into at least one unit, in steps 150, 160 and 170, respectively. Water (or some otherappropriate liquid) may for example be added in such amount that it comprises up to 10 or 15weight-% of the mixture constituting the interrnediate process product, which subsequently isvacuumized, pressurized, and extruded into at least one unit, in steps 150, 160 and 170,respectively.

The at least one unit which is produced by way of the process 100 illustrated inFigure 3 may for example be used as a substitute for traditionally manufacturedferromolybdenum alloys possibly according to standard specifications, or as a substitute formo lybdenum oxide (powder) as addition to a melt for making of for example steel or iron 14 alloys. Since the extruded unit(s) produced by way of the process 100 illustrated in Figure 3have been reduced, the carbon content of the unit(s) may be much lower compared to theextruded unit(s) produced by way of the process 100 illustrated in Figure 1.

The extruded unit(s) produced by way of the process 100 illustrated in Figure 3may for example comprise 60-99.99 weight-% of molybdenum; and 0.01-15 weight-% ofcarbon. Possibly the extruded unit(s) may comprise 60-99.99 weight-% of molybdenum, 0.01-l5 weight-% of carbon, and 0-35 weight-% of iron.

In conclusion, a process for producing at least one mo lybdenum-containingunit is disclosed. The process comprises providing at least a molybdenum-containing powderand a carbon-containing powder. An interrnediate process product in the form of a mixture isprovided, wherein the providing of the interrnediate process product comprises mixing at leastthe mo lybdenum-containing powder and the carbon-containing powder. The interrnediateprocess product is vacuumized, pressurized and extruded into at least one unit.

While the present invention has been illustrated in the appended drawings andthe foregoing description, such illustration is to be considered illustrative or exemplifying andnot restrictive; the present invention is not limited to the disclo sed embodiments. Othervariations to the disclosed embodiments can be understood and effected by those skilled in theart in practicing the claimed invention, from a study of the drawings, the disclosure, and theappended claims. In the appended claims, the word “comprising” does not exclude otherelements or steps, and the indef1nite article ”a” or “an” does not exclude a plurality. The merefact that certain measures are recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

:

1. A process (100) for producing at 1east one nio 1ybdenun1-containing unit, theprocess coniprising: providing (110) at 1east a nio lybdenuni-containing powder and a carbon-containing powder; providing (120) an interrnediate process product in the forrn of a niixture,wherein the providing of the interrnediate process product con1prises niixing (130) at 1east thenio lybdenuni-containing powder and the carbon-containing powder; vacuuniizing (150) the interrnediate process product; pressurizing (160) the interrnediate process product; and extruding (170) the interrnediate process product into at 1east one unit.

2. A process according to c1ain1 1, wherein the nio lybdenuni-containing powder con1prises a nio lybdenuni oxide powder, preferably coniprising n1o1ybdenun1 trioxide.

3. A process according to c1ain1 1 or 2, wherein the niixture of at 1east thenio 1ybdenun1-containing powder and the carbon-containing powder con1prises 50-95 weight-% of the nio 1ybdenun1-containing powder and 5-30 weight-% of the carbon-containing powder.

4. A process according to any one of c1ain1s 1-3, wherein the providing of theinterrnediate process product further con1prises providing (140) an iron-containing powder,and niixing (130) at 1east the nio lybdenuni-containing powder, the carbon-containing powder and the iron-containing powder.

5. A process according to c1ain1 4, wherein the niixture of at 1east thenio lybdenuni-containing powder, the carbon-containing powder and the iron-containing powder constitutes or is con1prised in the interrnediate process product.

6. A process according to c1ain1 4 or 5, wherein the niixture of at 1east thenio lybdenuni-containing powder, the carbon-containing powder and the iron-containingpowder con1prises 65-95 weight-% of the niolybdenuni-containing powder, 5-30 weight-% of the carbon-containing powder, and 0-40 weight-% of the iron-containing powder. 16

7. A process according to any one of claims 1-6, wherein the providing of theinterrnediate process product further comprises providing (180) at least one binder, andmixing (130) at least the mo lybdenum-containing powder, the carbon-containing powder andthe at least one binder, wherein the at least one binder comprises at least one material selected from a group comprising bentonite, starch, Portland cement and dextrin.

8. A process according to claim 7, wherein the mixture of at least themo lybdenum-containing powder, the carbon-containing powder and the at least one binder constitutes or is comprised in the interrnediate process product.

9. A process according to claim 7 or 8, wherein the mixture of at least themo lybdenum-containing powder, the carbon-containing powder and the at least one bindercomprises 50-94.9 weight-% of the mo lybdenum-containing powder, 5-30 weight-% of the carbon-containing powder, and 0.1-10 weight-% of the at least one binder.

10. A process according to any one of the preceding claims, wherein thepressurizing of the interrnediate process product comprises pressurizing the interrnediate process product at an elevated pressure up to about 450 kPa.

11. The process according to any one of the preceding claims, wherein theextruding of the interrnediate process product into at least one unit comprises extruding theinterrnediate process product using an extrusion nozzle (300) having a form such that the at least one unit is extruded into a form selected from a group comprising bars, rods and wires.

12. The process according to any one of the preceding claims, wherein thevacuumizing of the interrnediate process product, the pressurizing of the interrnediate processproduct and the extruding of the interrnediate process product into at least one unit are carried out in one processing device.

13. A process according to any one of claims 1-12, wherein the providing of theinterrnediate process product further comprises reducing (190) the mixture of at least themo lybdenum-containing powder and the carbon-containing powder so as to obtain at least one reduced compact.

14. A process according to claim 13, wherein the providing of the interrnediateprocess product further comprises breaking (200) the reduced at least one compact intoparticles so as to obtain a powder mixture, wherein the interrnediate process product is constituted by or includes the powder mixture. 17

15. A process according to c1ain1 14, wherein the breaking of the reduced compactinto particles so as to obtain a powder niixture con1prises at 1east one of tearing, grinding or n1i11ing the reduced at 1east one compact.

16. A process according to c1ain1 14 or 15, wherein the providing of theinterrnediate process product further coniprises providing (210) an iron-containing powder,and niixing (220) the iron-containing powder and the powder niixture, wherein theinterrnediate process product is constituted by or inc1udes the niixture of the iron-containing powder and the powder niixture.

17. A unit obtained by a process according to any one of the preceding c1ain1s.

18. A unit according to c1ain1 17 obtained by a process according to any one ofc1ain1s 1-12, the unit coniprising:60-80 weight-% of n1o1ybdenun1; and20-45 weight-% of carbon.

19. A unit according to c1ain1 18, ﬁarther con1prising:60-80 weight-% of n1o1ybdenun1;20-45 weight-% of carbon; and0-35 weight-% of iron.

20. A unit according to c1ain1 17 obtained by a process according to any one ofc1ain1s 13-16, the unit coniprising:60-99.99 weight-% of n1o1ybdenun1; and0.01-15 weight-% of carbon.

21. A unit according to c1ain1 20, further con1prising:60-99.99 weight-% of n1o1ybdenun1;0.01-15 weight-% of carbon; and0-35 weight-% of iron.