WO2017140832A1

WO2017140832A1 - Process for producing molybdenum-containing units

Info

Publication number: WO2017140832A1
Application number: PCT/EP2017/053594
Authority: WO
Inventors: Dag SJÖBERG; Filip ANTONOV
Original assignee: FERROLEGERINGAR AB; Nordic Elements AB
Current assignee: FERROLEGERINGAR AB; Nordic Elements AB
Priority date: 2016-02-18
Filing date: 2017-02-17
Publication date: 2017-08-24
Anticipated expiration: 2018-08-18
Also published as: SE1650211A1

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.

Description

PROCESS FOR PRODUCING MOLYBDENUM-CONTAINING UNITS

TECHNICAL FIELD

The present invention relates to a process for producing at least one

molybdenum-containing unit and a unit obtained (or produced) by the process. BACKGROUND

Molybdenum (Mo) does not occur as a free metal but rather in various oxidation states in minerals. Molybdenum can for example be used to form hard, stable carbides in alloys, and a majority of the amount of molybdenum that is produced worldwide is used in making of various types of steel or iron alloys, such as high strength alloys and so called superalloys. In making of such steel alloys, a molybdenum-containing material is usually added to a melt in order to introduce a molybdenum content into the melt by way of the molybdenum-containing material dissolving into the melt, so as to achieve a desired amount or fraction of molybdenum in the alloy. One example of such a molybdenum- containing material is ferromolybdenum, which is an iron-molybdenum alloy which usually has a molybdenum content of 60% to 80% by weight. Ferromolybdenum may for example be produced from molybdenum trioxide (M0O3) by means of carbothermic reduction, hydrogen reduction, aluminothermic reduction, and/or silicothermic reduction. Another example of such a molybdenum-containing material is disclosed in the international application having publication number WO 2014/193298 Al . WO 2014/193298 Al discloses a process for producing iron and molybdenum containing compacts, which compacts may have a density in the range of 1.0 to 4.0 g/cm³, and which may be used as a substitute to molybdenum trioxide powder or ferromolybdenum for addition to a melt in making of steel alloys. However, there is still a need in the art for molybdenum- containing materials having relatively high amounts of molybdenum per unit volume, and with relatively high densities, and which materials can be used for addition of molybdenum in melts for making for example steel or iron alloys.

SUMMARY

In view of the above discussion, a concern of the present invention is to provide a process for producing a molybdenum- containing material or unit (e.g., a piece of material containing molybdenum and possibly having a predefined or selected shape), which may be used for addition of molybdenum 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 in accordance with the independent claim is provided. Preferred embodiments are defined by the dependent claims.

According to a first aspect of the present invention there is provided a process for producing at least one molybdenum-containing unit. The process comprises providing at least a molybdenum-containing powder and a carbon-containing powder, and providing an intermediate process product in the form of a mixture. The providing of the intermediate process product comprises mixing at least the molybdenum-containing powder and the carbon-containing powder. The process comprises vacuumizing the intermediate process product, pressurizing the intermediate process product, and extruding the intermediate process product into at least one unit.

Embodiments of the present invention are based on an idea of producing one or more units comprising molybdenum by means of vacuum extrusion. The intermediate process product, which according to one or more embodiments of the present invention includes or is constituted by a mixture of at least the molybdenum-containing powder and the carbon- containing powder, may be vacuum-treated and subjected to pressure before and/or during the extrusion into one or more units of desired form. It has been found by the inventors that units produced by means of a process according to the first aspect may attain a density exceeding 4.0 g/cm³, for example in the range of 5.0 g/cm³ to 5.5 g/cm³. The resulting unit or units are in the form of compacted powder(s) comprising molybdenum and carbon, which can readily be used for addition of molybdenum to melts, for example in melts in the steel, foundry, alloy and superalloy industries, for making of for example steel or iron alloys, and may dissolve relatively quickly into the melts. The resulting unit or units may readily be used as a substitute for traditionally manufactured ferromolybdenum alloys, or as a substitute for molybdenum oxide 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 by way of the unit(s) being in the form of compacted powder(s), there may be only little or even no dispersion of powder into the surroundings when adding the unit(s) to a melt, in contrast to addition of a (non-compacted) powder into a melt. There may be substantially no losses from the (vacuum extrusion) process according to the invention. Consequently, there may be relatively low losses of material as compared to other methods. By way of the (vacuum extrusion) process according to the invention, the unit or units may possibly be produced at lower cost as compared to standard grades of ferromolybdenum.

The molybdenum-containing powder may for example comprise (possibly a mixture of) one or more molybdenum oxides, such as, for example, molybdenum trioxide (M0O3), or molybdenum dioxide (M0O2). The molybdenum-containing powder may for example comprise a molybdenum oxide powder. The molybdenum oxide powder may according to one or more embodiments of the present invention contain 50 to 80 weight-% of Mo, and the remaining elements may be oxygen and impurities. According to one or more embodiments of the present invention, the molybdenum-containing powder may comprise so called technical grade M0O3. According to one or more embodiments of the present invention, at least 90 weight-% of the particles of the molybdenum oxide powder may be sized so as to pass through a so called 'test' sieve having nominal aperture sizes of about 300 μιη, and at least 50 weight-% of the particles of the molybdenum oxide powder may be sized so as to pass through a test sieve having nominal aperture sizes of about 125 μιη.

According to one or more other embodiments of the present invention, at least 90 weight-% of the particles of the molybdenum oxide powder may be sized so as to pass through a test sieve having nominal aperture sizes of 125 μιη, and at least 50 weight-% of the particles of the molybdenum oxide powder may be sized so as to pass through a test sieve having nominal aperture sizes of about 45 μιη. According to one or more other embodiments of the present invention, at least 90 weight-%), or even at least 99 weight-%), of the particles of the molybdenum oxide powder may be sized so as to pass through a test sieve having nominal aperture sizes of 250 μιη, or 125 μιη, or even 45 μιη.

The carbon-containing powder may for example comprise (possibly a mixture of) 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 molybdenum-containing powder and the carbon- containing powder may according to one or more embodiments of the present invention comprise 50-95 weight-%o, or 65-95 weight-%o, of the molybdenum-containing powder and 5- 30 weight-% of the carbon-containing powder.

The providing of the intermediate process product may comprise providing an iron-containing powder. The providing of the intermediate process product may comprise mixing at least the molybdenum-containing powder, the carbon-containing powder and the iron-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 powder M40 from Hoganas AB, Sweden, or similar, iron sponge powder, water-atomized iron powder, gas-atomized iron powder, iron filter dust (such as, for example, X-RFS40 from Hoganas AB, Sweden) and/or iron sludge powder. The iron-containing powder may preferably contain at least 80 weight-% of Fe, preferably at least 90 weight-% of Fe, more preferably at least 95 weight-% of Fe, and more preferably at least 99 weight-% of Fe. The iron-containing powder may be constituted by or include an iron oxide powder, such as, for example, FeO, Fe₂0₃, Fe₃C"4, 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 μιη-500 μιη, or preferably 10 μηι-500 μηι, or more preferably 100 μιη-300 μιη. A relatively wide range of grain sizes may facilitate or allow for achieving a relatively high degree of process customization.

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

The mixture of at least the molybdenum-containing powder, the carbon- containing powder and the iron-containing powder may according to one or more

embodiments of the present invention comprise 50-94 weight-%), or 65-94 weight-%), of the molybdenum-containing powder, 5-30 weight-%o of the carbon-containing powder, and 1- 30 weight-% of the iron-containing powder.

In alternative or in addition, the providing of the intermediate process product may comprise providing at least one binder. The providing of the intermediate process product may comprise mixing at least the molybdenum-containing powder, the carbon- containing powder and the at least one binder. The at least one binder may for example comprise at least one material selected from a group comprising bentonite, starch, Portland cement and dextrin. However, another type or other types of binders are contemplated (such as, for example, sodium silicate, lime and/or gelatin) and may be employed according to one or more embodiments of the present invention. The at least one binder may for example provide sufficient green strength to the powder grains, i.e. the mechanical strength which a compacted powder must have in order to withstand mechanical operations to which it is subjected after pressing.

The starch may for example comprise or be constituted by starch in powder form as provided by Acros Organics BVBA, Janssen Pharmaceuticalaan 3a, 2440 Geel, Belgium. The bentonite may for example comprise or be constituted by Volclay DC-2 Western Bentonite as provided by American Colloid Company, 2870 Forbs Avenue Hoffman Estates, IL 60192, USA.

The mixture of at least the molybdenum-containing powder, the carbon- containing powder and the at least one binder may according to one or more embodiments of the present invention comprise 50-94.9 weight-%o, or 65-94.9 weight-%o, of the molybdenum- containing powder, 5-30 weight-%o of the carbon-containing powder, and 0.1-10 weight-%o of the 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 of at least the molybdenum-containing powder, the carbon-containing powder, the iron- containing powder and the at least one binder may according to one or more embodiments of the 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 to one 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 molybdenum-containing powder, the carbon- containing powder and possibly the iron-containing powder and/or the at least one binder may constitute or be comprised in the intermediate process product. For example, after having mixed at least the molybdenum-containing powder, the carbon-containing powder and possibly the iron-containing powder and/or the binder, the mixture may be vacuumized, pressurized, and extruded.

As mentioned in the foregoing, the molybdenum-containing powder may for example comprise (possibly a mixture of) one or more molybdenum oxides. The providing of the intermediate process product may according to one or more embodiments of the present invention comprise reducing the mixture of at least the molybdenum-containing powder and the carbon-containing powder (and possibly iron-containing powder and/or one or more binders) so as to obtain at least one reduced compact.

The reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may for example be carried out using a reduction furnace, for example including or being constituted by a continuous furnace, a walking beam furnace, or a batch furnace. The reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may be carried out by means of at least one reductant, or reducing agent, which possibly may be in powder form.

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

The reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may for example be carried out at a temperature 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. The reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may for example be carried out 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 reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may be carried out using a reduction furnace which is continuously or continually supplied with an inert or reducing gas, preferably a relatively weakly reducing gas. The gas supplied to the reduction furnace may for example be constituted by or include Ar, N₂, H₂, or any mixture thereof.

During the reducing of the mixture of at least the molybdenum-containing powder and the carbon-containing powder, the reduction furnace may for example be operated 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 embodiments of the present invention be in the form of relatively porous, generally disc-like lumps of material. The providing of the intermediate process product may comprise breaking the reduced at least one compact into particles, or grains, so as to obtain a powder mixture. The breaking of the reduced at least one compact into particles so as to obtain a powder mixture may for example comprise at least one of tearing, grinding or milling the reduced at least one compact. However, another or other ways of breaking the reduced at least one compact into particles so as to obtain a powder mixture are contemplated. For example, any way known in the art of breaking the reduced at least one compact into particles so as to obtain a powder mixture could be employed.

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

The pressurizing of the intermediate process product may comprise pressurizing the intermediate process product at an elevated pressure up to about 450 kPa. The term "elevated pressure" should in the context of the present application be understood as a pressure which exceeds the ambient (normally atmospheric) pressure.

The extruding of the intermediate process product into at least one unit may comprise extruding the intermediate process product using an extrusion nozzle having a form such 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 unit which is produced by the process according to embodiments of the present invention.

The vacuumizing of the intermediate process product implies subjecting the intermediate process product to (at least partial) vacuum. The pressurization of the intermediate process product may be carried out for example by means of an auger arrangement which may be part of an extrusion system for carrying out the extruding of the intermediate process product.

In the context of the present application, by the term "extruding" it is meant substantially any extrusion method which may be used to create units, pieces or elements having a certain (selected) cross-sectional profile, wherein the mixture is pushed through an extrusion nozzle having a desired or required shape, for example a die of the desired cross- section. The vacuumizing, pressurizing and extruding of the intermediate process product into at least one unit may preferably be performed by means of a so called stiff extrusion process combining a relatively high (auger) pressure and at least partial vacuum de-airing.

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

According to a second aspect of the present invention there is provided a unit obtained (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 invention for example comprise 60-80 weight-% of molybdenum and 20-45 weight-% of carbon, or 60- 80 weight-%) of molybdenum, 20-45 weight-%o of carbon, and 0-35 weight-%o of iron.

The unit may according to one or more other embodiments of the present invention for example comprise 60-99.99 weight-% of molybdenum and 0.01-15 weight-% of carbon. This may for example be the case if the providing of the intermediate process product comprises reducing the mixture of at least the molybdenum-containing powder and the carbon-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 more embodiments of the present invention for example comprise 60-99.99 weight-% of molybdenum, 0.01-15 weight-%) of carbon, and 0-35 weight-%o of iron.

Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims 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 DRAWINGS

Exemplifying 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 one molybdenum-containing unit according to an embodiment of the present invention.

Figure 2 is a schematic illustration of an extrusion nozzle for extruding at least one 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 one molybdenum-containing unit according to another embodiment of the present invention.

All the figures are schematic, not necessarily to scale, and generally only show parts 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 the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not 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 that this disclosure will convey the scope of the invention to those skilled in the art. In the drawings, identical reference numerals denote the same or similar components having a same or similar function, unless specifically stated otherwise.

Figure 1 is a schematic illustration of a process 100 for producing at least one molybdenum-containing unit according to an embodiment of the present invention. The process 100 comprises providing 110 (at least) a molybdenum-containing powder and a carbon-containing powder. The process 100 comprises providing 120 an intermediate process product in the form of a mixture. According to the embodiment of the present invention illustrated in Figure 1, the step of providing the intermediate process product 120 comprises mixing 130 (at least) the molybdenum-containing powder and the carbon-containing powder. The mixture of the molybdenum- containing powder and the carbon-containing powder may for example comprise 50-95 weight-%, or 65-95 weight-%, of the molybdenum- containing powder and 5-30 weight-% of the carbon-containing powder. The intermediate process product, which hence in accordance with the embodiment of the present invention illustrated in Figure 1 comprises a mixture of the molybdenum-containing powder and the carbon- containing powder (and possibly one or more other elements and/or powders, as will be described further in the following), is then vacuumized 150, pressurized 160, and extruded 170 into at least one unit. The extruded unit may in general be constituted by a piece of material containing molybdenum and possibly having a predefined or selected shape.

Water or some other appropriate liquid may be used in the extrusion process. Thus, the step of providing 120 the intermediate process product may further comprise adding water to the mixture of the molybdenum-containing powder and the carbon-containing powder. The mixture of the molybdenum-containing powder, the carbon-containing powder and 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 for example be added in such amount that it comprises up to 10 or 15 weight-% of the mixture constituting the intermediate 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 the extruded unit(s) different types of industrial dryers may be used. The extruded unit(s) may be dried without use of active heating. The extruded unit(s) may be dried until a desired or required 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-%, or possibly less than 2 weight-%. The moisture content in the extruded unit(s) may be determined for example by means of a loss on drying analysis in accordance with ASTM D2216-10 (Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass, ASTM International, West Conshohocken, PA, 2010).

One or more of the steps of vacuumizing 150, pressurizing 160, and extruding 170 of the intermediate process product may be performed in an (stiff extrusion) arrangement as disclosed. Thus, the vacuumizing 150, pressurizing 160, and extruding 170 of the intermediate process product may in accordance with one or more embodiments of the present invention be carried out in one (a single) processing device. The vacuumizing 150 implies subjecting the intermediate process product (mixture) to (at least partial) vacuum. The intermediate process product is also pressurized 160 by the process 100, e.g. at a pressure in the range of 0-450 kPa, or at an elevated pressure up to about 450 kPa. The pressurization 160 of the intermediate process product may for example be performed by an auger arrangement in the extrusion process.

The at least one unit which is produced by means of extruding 170 the intermediate process product may 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) may exhibit a higher density and/or a higher degree of compaction compared to for example briquettes formed by briquetting molybdenum-containing powder mixture. Further, there may be only little or even no dispersion of powder into the surroundings when adding the extruded unit(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 of extruding 170 the intermediate process product may have different shapes depending on the configuration of the extrusion arrangement used. The extruding 170 of the intermediate process product may for example be carried out using an extrusion nozzle having a form such 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 unit which is produced by the process 100. Figure 2 is a schematic illustration of an extrusion nozzle 300 for extruding at least one molybdenum-containing unit in accordance with an exemplifying embodiment of the present invention. By the shape or configuration of the extrusion nozzle 300 illustrated in Figure 2, units which are produced by means of extruding 170 the intermediate process product may be in the form of bars, rods, wires or threads. The width of the three quadratic openings of the extrusion nozzle 300 illustrated in Figure 2 may be approximately 0.5 cm.

The molybdenum-containing powder, which is provided in step 110 and which is mixed with (at least) the carbon-containing powder, preferably comprises a molybdenum oxide powder (comprising one or more molybdenum oxides). The molybdenum oxide powder which is provided in step 110 may according to one or more embodiments of the present invention be pre-reduced to a selected or predefined extent or degree. The molybdenum oxide powder preferably comprises molybdenum trioxide, M0O3. According to one or more embodiments of the present invention, the molybdenum-containing powder may for example be produced or obtained by means of carbothermic reduction and/or hydrogen reduction of an oxide of molybdenum, e.g., M0O3.

The process 100 may optionally comprise providing 140 an iron-containing powder. The step 120 of providing the intermediate process product may comprise mixing the molybdenum-containing powder, the carbon-containing powder and the iron-containing powder. The resulting mixture of the molybdenum-containing powder, the carbon-containing powder and the iron-containing powder may thereby constitute the intermediate process product which subsequently is vacuumized, pressurized, and extruded into at least one unit, in steps 150, 160 and 170, respectively. It is however to be understood that the iron-containing powder is optional and not required. Hence, the intermediate process product which subsequently is vacuumized, pressurized, and extruded into at least one unit, in steps 150, 160 and 170, respectively, may be constituted by only a mixture of the molybdenum-containing powder 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 in Figure 1 may for example be used as a substitute for traditionally manufactured

ferromolybdenum alloys possibly according to standard specifications, or as a substitute for molybdenum oxide (powder) as addition to a melt for making of for example steel or iron alloys. The extruded unit(s) produced by way of the process 100 illustrated in Figure 1 may not have been reduced. However, it is possible to obtain extruded units which have been reduced. A possible way of obtaining extruded units which have been reduced is described further in the following with reference to Figure 3. In alternative or in addition, the molybdenum-containing powder (e.g. a molybdenum oxide powder) which is provided in step 110 may according to one or more embodiments of the present invention be pre-reduced to a selected or predefined extent or degree. The extruded unit(s) produced by way of the process 100 illustrated in Figure 1 may 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-%o of carbon, and 0-35 weight-%o 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 group comprising bentonite, starch, Portland cement and dextrin. The step 120 of providing the intermediate process product may comprise mixing the molybdenum-containing powder, the carbon-containing powder and the at least one binder (and possibly an iron-containing powder as described in the foregoing). The resulting mixture of the molybdenum-containing powder, the carbon-containing powder and the at least one binder (and possibly the iron-containing powder) may thereby constitute the intermediate process product which subsequently is vacuumized, 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 not required.

Figure 3 is a schematic illustration of a process 100 for producing at least one molybdenum-containing unit according to another embodiment of the present invention. The process 100 illustrated in Figure 3 is similar to the process 100 illustrated in Figure 1 but differs therefrom in that the step 120 of providing the intermediate process product comprises further steps, as will be described further in the following, in addition to mixing 130 of a molybdenum-containing powder and a carbon-containing powder as described in the foregoing with reference to Figure 1. The steps 140 and 180 of the process 100 illustrated in Figure 3 are similar to or the same as the steps 140 and 180, respectively, of the process 100 illustrated in Figure 1.

Similarly to the process 100 illustrated in Figure 1, the process 100 illustrated in Figure 3 comprises providing 110 (at least) a molybdenum-containing powder and a carbon-containing powder, and the step of providing 120 the intermediate process product comprises mixing 130 (at least) the molybdenum-containing powder and the carbon- containing powder. As in the process 100 illustrated in Figure 1, the molybdenum-containing powder provided in step 110 and which is mixed with (at least) the carbon-containing powder preferably comprises a molybdenum oxide powder (comprising one or more molybdenum oxides). The molybdenum oxide powder preferably comprises molybdenum trioxide. The mixture of the molybdenum-containing powder and the carbon-containing powder may for example comprise 50-95 weight-%o, or 65-95 weight-%o, of the molybdenum- containing powder and 5-30 weight-%o of the carbon-containing powder.

As mentioned in the foregoing, the molybdenum-containing powder may for example 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 the intermediate process product may further comprise reducing 190 the mixture of at least the molybdenum-containing powder and the carbon-containing powder so as to obtain at least one reduced compact, and breaking 200 the reduced at least one compact into particles so as to obtain a powder mixture. The reduced compact may for example be in the form of relatively porous, generally disc-like lumps of material. The reduced compact may be broken into particles so as to obtain the powder mixture for example by way of tearing, grinding and/or milling the reduced compact. The resulting powder mixture, obtained by way of step 200, may thereby constitute the intermediate process product obtained at step 120, which intermediate 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. The intermediate process product may hence, in accordance with the embodiment of the present invention illustrated in Figure 3, be constituted by the powder mixture obtained by way of step 200. The at least one unit which is produced by means of extruding 170 the intermediate process product may, similarly to the at least one unit produced by means of the process 100 illustrated 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) may exhibit a higher density and/or a higher degree of compaction compared to for example briquettes formed by briquetting molybdenum-containing powder mixture

Water or some other appropriate liquid may be used in the extrusion process. Thus, the step of providing 120 the intermediate process product may further comprise adding water to the powder mixture obtained by way of step 200, and the mixture of the powder mixture and 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 for example be added in such amount that it comprises up to 10 or 15 weight-% of the mixture constituting the intermediate 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 illustrated in Figure 3 may comprise drying of the extruded unit(s).

The reducing 190 of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may for example be carried out using a reduction furnace (not shown in Figure 3). The reductant(s), or reducing agent(s), used may possibly be in powder form. The reducing step 190 may for example be carried out by means of carbon and/or hydrogen reduction. The reducing step 190 may for example be carried out at a temperature 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 furnace may be continuously or continually supplied with an inert or reducing gas, such as a gas comprising Ar, N₂, H₂ or any mixture thereof. The reducing gas is preferably a relatively weakly reducing gas. The reduction furnace may for example be operated 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.

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 molybdenum-containing powder. For example by monitoring the formation of CO and/or CO2 in the reduction furnace during the reducing process, it may be determined when the reducing process is completed. Reaction gases such as CO and/or CO2 formed during the reducing process may continuously or continually be evacuated from the reduction furnace.

A relatively high degree or extent of so called self-compaction of the mixture of at least the molybdenum-containing powder and the carbon-containing powder may be achieved during the reducing 190 of the mixture of at least the molybdenum-containing powder and the carbon-containing powder. This may particularly be the case for example if sufficiently large amounts of at least the molybdenum-containing powder and the carbon- containing powder are used in the reducing process.

The process 100 illustrated in Figure 3 may optionally comprise providing 210 an iron-containing powder. The step 210 may be in alternative or in addition to the optional step 140. The process 100 may further optionally comprise mixing 220 the iron-containing powder and the powder mixture obtained by way of step 200. The resulting mixture of the iron-containing powder and the powder mixture may thereby constitute the intermediate process product obtained at step 120, which intermediate process product subsequently is vacuumized, 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 not required. In case of using water or some other appropriate liquid in the extrusion process such as described in the foregoing, the step of providing 120 the intermediate process product may further comprise adding water to the mixture of the iron-containing powder and the powder mixture 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, and extruded into at least one 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 the mixture constituting the intermediate process product, which subsequently is vacuumized, 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 in

Figure 3 may for example be used as a substitute for traditionally manufactured

ferromolybdenum alloys possibly according to standard specifications, or as a substitute for molybdenum oxide (powder) as addition to a melt for making of for example steel or iron alloys. Since the extruded unit(s) produced by way of the process 100 illustrated in Figure 3 have been reduced, the carbon content of the unit(s) may be much lower compared to the extruded 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 3 may for example comprise 60-99.99 weight-% of molybdenum; and 0.01-15 weight-% of carbon. Possibly the extruded unit(s) may comprise 60-99.99 weight-% of molybdenum, 0.01- 15 weight-% of carbon, and 0-35 weight-%) of iron.

In conclusion, a process for producing at least one molybdenum-containing unit is disclosed. The process comprises providing at least a molybdenum-containing powder and a carbon-containing powder. An intermediate process product in the form of a mixture is provided, wherein the providing of the intermediate process product comprises mixing at least the molybdenum-containing powder and the carbon-containing powder. The intermediate process product is vacuumized, pressurized and extruded into at least one unit.

While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that 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 least one molybdenum-containing unit, the process comprising:

providing (110) at least a molybdenum-containing powder and a carbon- containing powder;

providing (120) an intermediate process product in the form of a mixture, wherein the providing of the intermediate process product comprises mixing (130) at least the molybdenum-containing powder and the carbon-containing powder;

vacuumizing (150) the intermediate process product;

pressurizing (160) the intermediate process product; and

extruding (170) the intermediate process product into at least one unit.

2. A process according to claim 1, wherein the molybdenum-containing powder comprises a molybdenum oxide powder, preferably comprising molybdenum trioxide.

3. A process according to claim 1 or 2, wherein the mixture of at least the molybdenum-containing powder and the carbon-containing powder comprises 50-95 weight- % of the molybdenum-containing powder and 5-30 weight-% of the carbon-containing powder.

4. A process according to any one of claims 1-3, wherein the providing of the intermediate process product further comprises providing (140) an iron-containing powder, and mixing (130) at least the molybdenum-containing powder, the carbon-containing powder and the iron-containing powder.

5. A process according to claim 4, wherein the mixture of at least the

molybdenum-containing powder, the carbon-containing powder and the iron-containing powder constitutes or is comprised in the intermediate process product.

6. A process according to claim 4 or 5, wherein the mixture of at least the molybdenum-containing powder, the carbon-containing powder and the iron-containing powder comprises 65-95 weight-% of the molybdenum-containing powder, 5-30 weight-%) of the carbon-containing powder, and 0-40 weight-% of the iron-containing powder.

7. A process according to any one of claims 1-6, wherein the providing of the intermediate process product further comprises providing (180) at least one binder, and mixing (130) at least the molybdenum-containing powder, the carbon-containing powder and the 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 the

molybdenum-containing powder, the carbon-containing powder and the at least one binder constitutes or is comprised in the intermediate process product.

9 A process according to claim 7 or 8, wherein the mixture of at least the molybdenum-containing powder, the carbon-containing powder and the at least one binder comprises 50-94.9 weight-% of the molybdenum-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 the pressurizing of the intermediate process product comprises pressurizing the intermediate process product at an elevated pressure up to about 450 kPa.

11. The process according to any one of the preceding claims, wherein the extruding of the intermediate process product into at least one unit comprises extruding the intermediate 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 the vacuumizing of the intermediate process product, the pressurizing of the intermediate process product and the extruding of the intermediate 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 the intermediate process product further comprises reducing (190) the mixture of at least the molybdenum-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 intermediate process product further comprises breaking (200) the reduced at least one compact into particles so as to obtain a powder mixture, wherein the intermediate process product is constituted by or includes the powder mixture.

15. A process according to claim 14, wherein the breaking of the reduced compact into particles so as to obtain a powder mixture comprises at least one of tearing, grinding or milling the reduced at least one compact.

16. A process according to claim 14 or 15, wherein the providing of the intermediate process product further comprises providing (210) an iron-containing powder, and mixing (220) the iron-containing powder and the powder mixture, wherein the intermediate process product is constituted by or includes the mixture of the iron-containing powder and the powder mixture.

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

18. A unit according to claim 17 obtained by a process according to any one of claims 1-12, the unit comprising:

60-80 weight-% of molybdenum; and

20-45 weight-% of carbon.

19. A unit according to claim 18, further comprising:

60-80 weight-% of molybdenum;

20-45 weight-%) of carbon; and

0-35 weight-%) of iron.

20. A unit according to claim 17 obtained by a process according to any one of claims 13- 16, the unit comprising:

60-99.99 weight-%) of molybdenum; and

0.01-15 weight-%) of carbon.

21. A unit according to claim 20, further comprising:

60-99.99 weight-%) of molybdenum;

0.01-15 weight-%) of carbon; and

0-35 weight-%) of iron.