SE537536C2 - Iron and molybdenum-containing briquettes and a process for producing these briquettes - Google Patents

Abstract

The present invention relates to a process for producing briquettes containing iron and molybdenum. It also refers to briquettes produced by the process.

Description

TECHNICAL FIELD The present invention relates to a process for producing jamm- and molybdenum-containing briquettes. It also refers to briquettes produced with the process.

BACKGROUND Ferromolybdenum is a yam-molybdenum alloy which usually has a molybdenum content of 60-80% by weight.

In most commercial applications, the ferro molybdenum is produced from molybdenum trioxide (MoO 3) by a carbothermal reduction, an aluminothermal reduction or a silicon thermal reduction. The carbothermal process produces a high carbon content ferromolybdenum, while the latter two produce a low carbon ferromolybdenum. Low carbon ferromolybdenum is more common than high carbon alloy. Lumps of ferro-molybdenum produced by these methods usually have densities around 9 g / cm 3. Dissolving the lumps in the steel malt may be black due to the high melting point of the lumps; for example, the commercial grade FeMo70 has a melting point of 1,950 ° C, and since the temperature of the steel malt is considerably lower, the dissolution of the ferromolybdenum is mainly affected by diffusion processes, which prolong the dissolution time of the ferromolybdenum. Another factor is the high rayaru cost in the aluminothermal reduction and the silicon thermal reductions. In addition, around 2% of the Mo content can be lost in the slag in these processes.

OBJECTS OF THE INVENTION It is an object of the invention to provide a new jam- and molybdenum-containing material which is suitable for molybdenum addition in the smelting industry, for example the foundry and superalloy industry, and a process for producing side material in a comparatively cost-effective manner.

A further object is to provide all a new jam- and molybdenum-containing material which has a comparatively fast dissolution time in a steel malt, as well as a process for producing such material in a comparatively cost-effective manner. 1 537 536 A further object is to provide a new jam- and molybdenum-containing material with low carbon and high Mo content, as well as a process for producing such material in a comparatively cost-effective manner.

A further object is to provide a material which can be easily handled when added to the melt, as well as a process for producing such material in a comparatively cost-effective manner.

SUMMARY OF THE INVENTION At least one of the above objects is achieved, at least to some extent, by a process for producing jam- and molybdenum-containing briquettes comprising the steps of: mixing: an iron-containing powder, a molybdenum oxide powder, a carbonaceous powder, an aqueous, ethereal, ether binder, and / or a lubricant and / or a slag former, briquettes to produce a plurality of briquettes.

Preferably the bricks have a geometric density in the range 1.0-4.0 g / cm 3, preferably 1.2-3.5 g / cm 3, more preferably 1.2-3.0 g / cm 3. The density can be regulated by varying the briquetting pressure. It is possible to produce briquettes with a geometric density below 2.0 g / cm3, as well as briquettes with a geometric density between 2.0 and 4.0 g / cm3. The non-reduced briquettes can be used as substitutes for conventionally manufactured ferromolybdenum alloys or even as a substitute for molybdenum oxide, in the alloying of smaltan in industrial production. The jam- and / or molybdenum-containing bricks can be manufactured at lower cost than standard grade ferro-molybdenum. Their porous structure facilitates rapid dissolution in a steel malt.

Preferably the dry matter composition in step a) contains, in weight percent: 1-15, preferably 1-10 ferrous powder, 5-25, preferably 10-20 carbonaceous powder, Optional 0.1 lubricant and / or binder and / or slag former, and balanced with at least 50-90 molybdenum oxide powder. 2,537,536 Water, preferably water, is preferably added in quantities of 1-10% by weight of the dry matter weight, preferably 2-5% by weight.

Preferably, neither binder nor slag former is used. When the ferrous powder is mixed in an aqueous state, it strengthens the briquettes, which makes the use of binders unnecessary. Damned, the quantity of Pollutants can be reduced.

Optionally, the method comprises the step of: c) drying the briquettes.

By drying the apricots, the risk of cracking is minimized due to rapid evaporation of the liquid when they are heated at high temperatures.

Preferably, the optional drying step comprises at least one of the following: drying the briquettes to a moisture content below 5% by weight, preferably below 3% by weight, drying the briquettes at a temperature in the range of 50-250 ° C, preferably 80-200 ° C, more preferably 100- 150 ° C. Preferably, the method comprises the step of: d) reducing the briquettes to produce a plurality of reduced briquettes.

Preferably, the reduction moment comprises at least one of the following: reduction at a temperature in the range 800-1 500 ° C, preferably 8001 350 ° C, more preferably 1000-1 200 ° C, reduction for at least 20 minutes, more preferably at least 30 minutes, reduction in a furnace fed with an inert or reducing gas, preferably fed with a weakly reducing gas, reduction at a working pressure in the range 0.1-5 atm, preferably 0.8-2 atm, more preferably 1.05-1.2 atm.

Preferably, the method further comprises the step of: e) cooling the reduced briquettes in a non-oxidizing atmosphere to a temperature below 200 ° C, more preferably below 150 ° C, preferably in an inert atmosphere.

In one embodiment, briquetting is performed at a briquetting pressure in the range of 801,000 kg / cm 2, preferably 100-500 kg / cm 2. 3 537 536 In one embodiment, briquetting is performed at a briquetting pressure in the range 1,00010,000 kg / cm 2, preferably 2,000-5,000 kg / cm 2.

The jam- and molybdenum-containing red briquettes have a dry matter composition of, in weight percent: 1-15, preferably 1-10 ferrous powder, 5-25, preferably 10-20 carbonaceous powder, Optional 0.1 lubricant and / or binder and / or slag former , and balanced with at least 50-90 molybdenum oxide powder.

The dry matter composition refers to the composition of a dried specimen, i.e. excluding any moisture present in the briquettes. The moisture content is defined as the water present in the briquettes in addition to crystal water. The moisture content can be determined by an analysis of the type LOD (Loss On Drying, loss on drying) in accordance with ASTM D2216-10.

The reduced jam and molybdenum-containing briquettes have a composition of, in weight percent: 1-20 Fe, less than 10 0, less than 10 C, less than 15 of other elements, and balanced with at least 40 Mo, preferably at least 50 Mo.

Preferably the reduced briquettes have a geometric density in the range 14 g / cm 3, preferably 1.2-3.5 g / cm 3, more preferably 1.2-3.0 g / cm 3. The density can be regulated by varying the briquetting pressure for the briquettes. It is possible to produce reduced briquettes with a geometric density below 2.0 g / cm3, and reduced briquettes with a geometric density between 2.0 and 4.0 g / cm3.

The briquettes can replace conventionally manufactured ferromolybdenum alloys when alloyed with molybdenum in smelting processes. The jam- and / or molybdenum-containing briquettes can be produced at lower costs than standard grade ferro-molybdenum. The jam and molybdenum-containing briquettes dissolve faster than the standard grade ferromolybide of 4,537,536. Depending on the reduction time, the relative quantity of carbon in relation to the quantity of reducible oxides and the reduction temperature, the oxygen content of the briquettes can be reduced partially or completely. The briquettes can be easily transported on a conveyor belt without the risk of rolling.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic overview of the process of producing jam- and molybdenum-containing briquettes according to the invention.

DESCRIPTION OF THE INVENTION The invention will now be described in more detail and with reference to the figures.

Fig. 1 is a schematic overview of the process of producing jam- and molybdenum-containing briquettes according to the invention. In the mixing station 3, a powder mixture is prepared by mixing an iron-containing powder, a carbonaceous powder, a molybdenum oxide powder and water. The mixing in the mixing station 3 can be carried out batchwise or continuously. Before the molybdenum oxide powder is added to the mixing station 3, it can be ground in the rod mill 1. Of course, other mills or crushers can be used to probe the molybdenum oxide into smaller particles. In addition, the ferrous powder and / or the carbonaceous powder can also be probed into smaller particles by grinding and / or crumbling and / or crushing.

The ground and / or crumbled and / or crushed molybdenum oxide particles can be sieved in a sieve 2 to achieve a desired particle distribution. Of course, screening Liven can be applied to the ferrous powder and / or the carbonaceous powder.

In one embodiment, the molybdenum oxide powder and the carbonaceous powder are mixed and ground together, and then the iron-containing powder is added and mixed with the molybdenum oxide powder and the carbonaceous powder. However, any combination of mixing order can be executed.

Yeast powder is added in quantities of 1-15% by weight, preferably at most 10% by weight of the dry matter (i.e. excluding added liquid). In a preferred embodiment 2% by weight. Jam powder is mainly used to strengthen the briquettes (acts as a binder, for example) but can also balance the desired quantity of Fe and Mo in the final product. Molybdenum oxide powder is added in quantities of 50-90% by weight of the dry matter, preferably 70-90% by weight.

Preferably, the quantity of carbonaceous powder is selected so that a reduction of the oxygen content to less than 10% by weight is possible, while the carbon content after full reduction is kept at less than 10% by weight, preferably less than 5% by weight. Preferably, the carbonaceous powder is balanced so that most, preferably alit, of the molybdenum oxide can be reduced to Mo, for example MoOx, where x <0.5. As a result, the majority of the recovered oxides after reduction become oxides which are responsible for reducing with carbon. Examples of oxides which are responsible for reducing with carbon are Al 2 O 3, SiO 2, MgO, CaO. Preferably 5-25% by weight of carbonaceous powder is added to the mixture, more preferably 10% by weight. The percentage by weight refers to the dry matter content of the mixture (i.e. excluding added liquid).

Optionally, lubricants and / or binders and / or slag formers may be added during mixing. The possible binders can be organic or inorganic binders. The binders may, for example, be a carbonaceous binder which partially replaces the carbonaceous powder. Other binders may be, for example, bentonite and / or dextrin and / or sodium silicate and / or lime. The possible slag former may be limestone, dolomite and / or olivine. The total quantity of any lubricants and / or binders and / or any slag formers may be 0.1-10% by weight of the dry matter content of the mixture, more preferably less than 5% by weight. It can be in the range 1-10% by weight. The binders are optional because the briquettes, by adding the water and the iron, become sufficiently strong to be reduced in the reduction furnace without severe cracking. If lubricant is added, it is preferably added in the quantities of 0.1-2 percent of the dry matter content of the mixture, for example about 0.5-1% by weight. The lubricant may, for example, be zinc stearate. However, other lubricants used in powder metallurgy may be added.

Liquid, preferably water, is preferably added in quantities of 1-10% by weight of the dry matter content of the mixture, preferably 2-5% by weight.

From the mixing station 3, the prepared powder mixture is transferred to a briquetting machine 4. In the briquetting machine 4, the powder mixture is briquetted to produce a plurality of briquettes.

In one embodiment, the powder mixture is briquetted at a comparatively applied briquetting pressure, preferably using a briquetting pressure in the range of 80-1,000 kg / cm 2, more preferably 100-500 kg / cm 2. The low briquetting pressure has been shown to improve the quality of the manufactured briquettes.

In another embodiment, the briquetting machine operates at higher pressures, for example 1,000-10,000 kg / cm 2. Flatter pressures can be used to increase the geometric density of the bricks. 6 537 536 Preferably, the briquetting machine 4 is a roller press. However, other types of briquetting machines can be used.

The briquettes produced from the powder mixture are preferably reduced in a reduction furnace 6. Alternatively, the non-reduced briquettes can be used as an alloy additive in jam and steel production.

Optionally, the briquettes are dried before being transferred to the reduction oven 6. Many different types of industrial dryers can be used. The briquettes can also be dried without active heating, for example at ambient temperature. In a dryer, steam can be removed with a gas steam or with a vacuum. The briquettes can be dried until the desired moisture content has been reached. The briquettes can be dried to a moisture content of less than 10% by weight, more preferably less than 5% by weight, most preferably less than 3% by weight. The briquettes can be dried at a temperature in the range 50-250 ° C, more preferably 80-200 ° C, most preferably 100-150 ° C. For improved process economy, the drying time is preferably in the range of 10-120 minutes, more preferably 20-60 minutes. But longer drying times are of course conceivable. The moisture content is defined as the water present in the briquettes in addition to crystal water. The moisture content can be determined by an analysis of the type LOD (Loss On Drying, loss on drying) in accordance with ASTM D2216-10.

The briquettes are preferably reduced in a reduction furnace 6. The reduction furnace is preferably a feed furnace but can also be a batch furnace. The feed-through furnace 6 has an inlet 7 and an outlet 8, and the briquettes are transported during the reduction from the inlet 7 to the outlet 8. In a preferred embodiment, an oven with a conveyor belt is used.

The briquettes are reduced at a temperature in the range 800-1 500 ° C, preferably 8001 350 ° C, more preferably 1000-1 200 ° C, preferably for at least 20 minutes, more preferably at least 30 minutes. By monitoring the formation of CO / CO2, it can be determined when the reduction process is completed. Preferably the reduction time is at most hours, preferably at most 2 hours, more preferably at most 1 hour. Depending on the reduction time, the reduction temperature and the ratio between carbon and reducible oxides in the briquettes, the reducible oxides of the briquettes can be partially or completely reduced.

Optionally, the briquettes are heat-treated at a lower temperature before reduction. Preferably, the briquettes are heat treated at a temperature in the range of 200-800 ° C, 7,537,536 more preferably 400-700 ° C. Preferably, the possible heat treatment takes place at a lower temperature from 10 minutes to less than 2 hours, preferably less than 1 hour. By heat treatment at lower temperatures, any lubricant can be burned off in a controlled manner. In addition, molybdenum trioxide can be reduced to molybdenum dioxide. This can be used as a pre-reduction step before the reduction described in the preceding paragraph or in the production of partially reduced briquettes. The possible heat treatment at 200-800 ° C can be carried out in the same oven as the reduction. The possible heat treatment and the possible drying can also be combined.

Unexpectedly, it has been shown that briquettes can be reduced at high temperatures without noticeable sublimation losses of Mo03. Consequently, the patent-pending process results in a simplified process that results in improved yield and higher Mo content in the final product. Thus, there is no need to perform a pre-reduction with respect to sublimation losses of Mo03.

During the reduction, CO and CO2 can be formed by reactions with the carbon dioxide and the reducible oxides in the briquettes. In addition, residual moisture can evaporate. The reduction time can be optimized by feeding the formation of CO and CO2, in particular CO because CO2 is formed mainly during the first minutes of the reduction after which the CO formation dominates until the carbon dioxide is consumed or all reducible oxides have been reduced.

The reduction reactions are endothermic and require heat. Preferably, heat is generated by heaters which do not affect the atmosphere inside the oven, more preferably the tax is generated by electric heating.

The atmosphere inside the furnace 6 is preferably controlled by feeding an inert or a reducing gas, preferably a weakly reducing gas, into one spirit of the furnace, and evacuating gases (for example reaction gases (for example CO, CO2, and H 2 O) and the feed gas) in the opposite spirit, more preferably in that the inert or reducing gas is fed countercurrently at an outlet side 8 of the furnace 6, and that gases are evacuated at an inlet side 7 of the furnace 6. This means that the inert or reducing gas is preferably fed countercurrently. The inert gas or a reducing gas may be, for example, argon, N2, H2 or any mixture of H2 / N2 (for example in the ratio 5:95 with respect to volume).

Preferably the furnace operates at a pressure in the range 0.1-5 atm, preferably 0.8-2 atm, more preferably at a pressure in the range 1.0-1.5 atm, most preferably 1.05-1.2 atm. 8 537 536 At the outlet 8 of the reduction furnace, the briquettes are transferred to a cooling section 9, so that the briquettes are cooled in a non-oxidizing atmosphere (for example reducing or inert) to a temperature below 200 ° C to avoid re-oxidation of the briquettes, more preferably below 150 ° C in an inert atmosphere. The atmosphere can be, for example, argon, N2, H2 or any mixture of H2 / N2 (for example in the ratio 5:95 with respect to volume). Other atmospheres can also be used. If it is Onskvart to have very 18ga levels of nitrogen in the briquettes, the briquettes can be cooled in a nitrogen-free atmosphere such as an argon gas atmosphere.

Molybdenum oxide powder The molybdenum oxide powder is preferably a molybdenum trioxide powder. The powder may be a molybdenum dioxide powder or a mixture of molybdenum trioxide powder and molybdenum dioxide powder.

The molybdenum powder should contain 50-80 Mo, with the other basic constituents being oxygen and impurities. The purer the quality of molybdenum oxide, the cleaner the jam- and molybdenum-containing briquettes can be made. However, cleaner grades of Mo03 on the other hand are more expensive.

In a preferred embodiment, Mo03 of technical quality is used. Such powders are less expensive than purer grades of MoO 3 and may contain oxides which are likely to reduce on solid state reduction with carbon. Examples of such oxides are Al 2 O 3, SiO 2 and MgO. Fortunately, these oxides can be easily degraded to the slag phase by alloying in steel malts and they can be added to the product.

Preferably, at least 90% by weight of the particles in the molybdenum oxide powder pass through a test sieve with a nominal neck size of 300 μm, and at least 50% by weight of the particles in the molybdenum oxide powder pass through a test sieve with a nominal neck size of 125 μm. More preferably, at least 90% by weight of the particles in the molybdenum oxide powder pass through a test sieve with a nominal neck size of 125 μm, and at least 50% by weight of the particles in the molybdenum oxide powder pass through a test sieve with a nominal neck size of 45 μm. The nominal neck sizes in the present patent application are in accordance with ISO 565: 1990, which standard is hereby incorporated by reference.

In one embodiment, at least 90% by weight, more preferably at least 99% by weight, of the particles in the molybdenum oxide powder pass through a test sieve with a nominal neck size of 250 μm, more preferably 125 μm, most preferably 45 μm. 9 537 536 Containing powder The iron-containing powder is preferably a yeast powder containing at least 80% by weight of Fe, preferably at least 90% by weight of Fe, more preferably at least 95% by weight of Fe, most preferably at least 99% by weight of Fe. The yarn powder may be an iron mushroom powder and / or a water atomized iron powder and / or a gas atomized iron powder and / or an iron filter dust and / or an iron lamp powder. For example, the filter dust X-RFS40 from Hogands AB, Sweden is a suitable powder.

The jam powder may be partially or completely replaced by a jam oxide powder, for example but not limited to: powders consisting of one or more from the group FeO, Fe 2 O 3, Fe 3 O 4, FeO (OH), (Fe 2 O 3 * H 2 O). The iron oxide powder can be, for example, the frying pan. Preferably the ferrous powder contains at least 50% by weight of metallic jam, more preferably at least 80% by weight of metallic Fe, most preferably at least 90% by weight of metallic Fe.

Preferably, at least 90% by weight of the particles in the uniform powder pass through a test sieve with a nominal neck size of 125 gm, and at least 50% by weight of the particles in the uniform powder pass through a test sieve with a nominal neck size of 45 μm.

In one embodiment, at least 90% by weight, more preferably at least 99% by weight, of the particles in the ferrous powder pass through a test sieve with a nominal neck size of more preferably 45 lam. In one example, at least 90% by weight, more preferably at least 99% by weight, of the particles in the iron-containing powder pass through a test sieve with a nominal neck size of 20 gm.

Carbonaceous powder The carbonaceous powder is preferably selected from the group of: subbituminosa carbons, bituminosa carbons, lignite, anthracite, coke, petroleum coke and biochar such as tracol, or carbonaceous powders processed from these resources. The carbonaceous powder may be, for example, soot, carbon black, activated carbon. The carbonaceous powder may also be a mixture of different carbonaceous powders.

For the choice of carbon powder, consideration is first given to the reactivity of the carbon, since both the productivity and the yield of Mo depend on this factor. High reactivity is undesirable. In particular, it is desirable to have a carbonaceous powder which is reactive at lower temperatures (preferably <700 ° C). For example, German lignite (lignite) is usually reactive at lower temperatures than petroleum coke, and is therefore suitable because it has 537 536 comparatively high reactivity at low temperatures. Trachol as well as bituminosa and subbituminosa carbon species can show comparatively high reactivity. Particularly suitable examples are soot, carbon black and activated carbon.

The quantity of carbonaceous powder is preferably determined by analyzing the quantity of oxides in the molybdenum oxide powder, and optionally the ferrous powder. Preferably, the quantity of reducible oxides is determined. The oxygen content can, for example, be analyzed with a LECOO TC400. In addition, alien male is preferably taken into account for the maximum permissible carbon content of the briquettes. Preferably, the quantity is selected so that it stoichiometrically corresponds to or in flakes one exceeds the quantity of reducible metal oxides in the molybdenum oxide powder and the ferrous powder. However, the quantity of carbon can also be understochiometric.

The quantity of carbonaceous powder can be optimized by feeding the carbon and oxygen levels in the reduced briquettes (for example by reducing briquettes in a laboratory oven and by feeding the carbon and oxygen levels). Based on the feeds, the quantity of carbonaceous powder can be optimized to achieve desired levels of carbon and oxygen in the briquettes produced. Some oxides that may be present in the molybdenum oxide powder are responsible for reducing with carbon. All oxides with higher affinity for oxygen at the maximum temperature of the reduction will remain as oxides in the finished product and therefore do not consume carbon in the reduction process. Such oxides may, for example, be oxides of Si, Ca, Al and Mg and may be included, for example, if more impure grades of molybdenum trioxide are used, for example technical molybdenum trioxide. However, these oxides can be handled in many applications of steel metallurgy, for example by being deposited in the steel malt slag, and they can be allowed in the briquettes. If smaller quantities of these oxides and the elements are desired, purer grades of molybdenum trioxide may be used, for example grades containing less or no quantities of these oxides.

By regulating the quantity of carbonaceous powder and adapting it to the quantity of reducible oxides in the briquettes, jam and molybdenum-containing briquettes can be produced which have a carbon content (after reduction) of less than 10% by weight, preferably less than 5% by weight, more preferably less than 1% by weight, most preferably less and 0.5% by weight. 11 537 536 However, it is awn possible to provide briquettes with intentionally high carbon content after reduction, for example 1-5% by weight C. Such briquettes can be used in alloying high carbon steels.

Preferably at least 90% by weight, more preferably at least 99% by weight, of the particles in the carbonaceous powder pass through a test sieve with a nominal diameter of 125 lam, and at least 50% by weight of the particles in the carbonaceous powder pass through a test sieve with a nominal diameter of 45 μm.

In one embodiment, at least 90% by weight, more preferably at least 99% by weight, of the particles in the carbonaceous powder pass through a test sieve with a nominal size of pm, and at least 50% by weight of the particles in the carbonaceous powder pass through a test sieve with a nominal size of 20 lam. In one example, at least 90% by weight, more preferably at least 99% by weight, of the particles in the carbonaceous powder pass through a test screen with a nominal size of 20 μm.

Jam and molybdenum-containing rosettes Jam- and molybdenum-containing rosettes with a dry matter composition of, in weight percent: 1-15, preferably 1-10 iron-containing powder, 5-25, preferably 10-20 carbonaceous powder, Optional 0.1 lubricant and / or binder and / or slag former, and balanced with at least 50-90 molybdenum oxide powder.

In one embodiment, the dry matter composition of the briquettes consists, in weight percent: 1-15, preferably 1-10 ferrous powder, 5-25, preferably 10-20 carbon powder, balanced with 50-90 molybdenum oxide powder.

As for the elements, the jam- and molybdenum-containing bricks preferably have a dry matter composition of, in weight percent: 1-15 Fe, 15-40 0.5-25 C, less than 15 of the other elements beyond 0, C, Mo and Fe, and the balance. is at least 30 Mo.

Jam is preferably in the range of 1.5-10% by weight.

Carbon preferably constitutes 7-20% by weight.

Oxygen preferably constitutes 15-30% by weight.

Molybdenum is preferably 40-65% by weight.

Other basic elements preferably constitute at least 1% by weight and less than 12,537,536% by weight, more preferably at least 2% by weight and less than 7% by weight.

In subsequent reduction steps, the relative quantity of iron and molybdenum will increase in the briquettes as the reduction progresses. The same applies, of course, to the 5 other basic subjects that remain.

The briquettes can be cost-effective substitutes for few MoO3 powders or standard FeMo for alloying in smelting processes, with regard to price and / or exchange of the Mo additive in the smelter. Normally, such an additive could be made, for example, in an electric candle baking oven and, for example, constitute a Mo additive in stainless steel, tool steel or high-speed steel.

The briquettes have a geometric density in the range 1.0-4.0 g / cm 3, preferably 1.23.5 g / cm 3, more preferably 1.2-3.0 g / cm 3. The density can be increased by increasing the briquetting pressure. A lower geometric density results in higher porosity, which is considered to give a shorter dissolution time for the briquettes. The geometric (envelope) density can be fed in accordance with ASTM 962-08.

Reduced jam- and molybdenum-containing briquettes The reduced jam- and molybdenum-containing briquettes have a composition of, in weight percent: 1-20 Fe, less than 10 0, less than 10 C, less than 15 of other elements in addition to 0, C, Mo and Fe , and balanced with at least 40 Mo, preferably at least 50 Mo.

Preferably the content is less than 10% by weight, more preferably less than 8% by weight, even more preferably less than 6% by weight, most preferably less than 4% by weight, and preferably only a minority of the oxygen content comes from molybdenum oxide which has not been reduced, i.e. a briquette containing Mo0x, where x <0.5. Preferably, substantially all of the molybdenum oxide is reduced to Mo, i.e. where x is around 0. Hdr, the remaining oxygen content will mainly frail oxides in the molybdenum oxide powder and the iron-containing powder which there respond to reduce, for example oxides of Si, Ca, Al and Mg. By using purer grades of the molybdenum oxide powder, the jam-containing powder and the carbon-containing powder, the oxygen content of the briquettes can, if desired, be lowered by 2% by weight. However, since many of these oxides which are responsible for reducing can be handled in steel malt metallurgy (for example by being deposited in the slag phase), they can be allowed in the jam- and molybdenum-containing briquette. The lower limit for oxygen can be about 0% by weight, but normally the oxygen is at least 1% by weight, more often at least 2% by weight. The molybdenum content of the briquettes can be controlled by varying the relative proportions of the molybdenum oxide powder in relation to the iron-containing powder. For substantially completely reduced briquettes (i.e. briquettes containing MoOx dar x <0.5), the molybdenum content is preferably controlled to the range of 60-95% by weight. More preferred is the Mo content in the range of 65-95% by weight, most preferred is the Mo content in the range of 70-95% by weight. Surprisingly, there has been a very high rate of dissolution for reduced briquettes with a molybdenum content of 80-95% by weight. This result is due to the much larger specific surface area and is achieved despite the very high melting point of these alloys: 2,100-2,500 ° C.

By balancing the carbon additive, it is possible to regulate the carbon content of the reduced briquettes to less than 5% by weight, less than 2% by weight, less than 1% by weight, less than 0.5% by weight or less than 0.1% by weight. Low carbon briquettes can be used, for example, in the alloying of low carbon steels. However, in certain areas of use, for example in the production of steels with a high carbon content or cast iron, it may be desirable to have a carbon content in the range 1-5% by weight.

The iron content of the briquettes is preferably in the range 1-20% by weight, more preferably 2-10% by weight, most preferably 2-5% by weight. The iron content of the briquettes can be controlled by varying the relative proportions of the iron-containing powder in relation to the molybdenum oxide powder.

The reduced briquettes can be cost effective substitutes for MoO 3 powder or standard FeMo in alloying in smelting processes, with respect to price and / or exchange of the Mo additive in the smelter. Normally such an additive could be made, for example, in an electric baking oven and, for example, be a Mo additive in stainless steel, tool steel or high speed steel. Depending on the purity of the powder mixture, the briquettes may contain additional elements including oxides which are responsible for reducing. Other basic substances besides Mo, Fe, C and 0 can be allowed up to less than 15% by weight. Preferably, the total quantity of other elements of 0, C, Mo and Fe is less than 10% by weight, more preferably less than 7% by weight. The quantity of other major substances is mainly determined by the purity of the molybdenum trioxide, but can also come from impurities in the ferrous powder, the carbonaceous powder and from reactions with the substances in the ambient atmosphere during heating, reduction or cooling. and the carbonaceous powder, the total quantity of other elements in addition to 0, C, Mo and Fe, if desired, can be kept lower by 1% by weight. The basic elements of the group Si, Ca, Al and Mg are, if present in the briquettes, mainly bound as oxides. For example, in a steel malt, silicon bonded as silicon oxides may be easier to handle than silicon dissolved in the alloy lattice. The other elements may in some embodiments be limited to at least 1% by weight or to at least 2% by weight. Other elements include contaminants.

Preferably, in certain embodiments, the other elements are limited to, in weight percent: max 2 N, more preferred max 1 N, max 1 S, more preferred max 0.5 S, max 2 Al, more preferred max 1.5 Al, max 2 Mg , more lecture max 1 Mg, max 2 Na, more lecture max 1 Na, max 4 Ca, more Lecture max 2 Ca, max 6 Si, more lecture max 3 Si, max 1 K, more lecture max 0.5 K, max 1 Cu, more lecture max 0.5 Cu, max 1 Pb, more lecture max 0.1 Pb, max 1 W, more lecture max 0.1 W, max 1 V, more lecture max 0.1 V, and the remaining basic elements preferably harvests 0.5 var, more preferably harvests 0.1 var, most preferably harvests 0.05 var.

In some embodiments, the Si content is in the weight percent in the range of 0.5-3, the Ca content in the range of 0.3-2, the Al content in the range of 0.1-1, and / or the Mg content in the range of 0.1-1.

Preferably the elements in the group Si, Ca, Al and Mg, if present, are bound to at least 50% by weight as oxides in the briquettes, preferably to at least 90% by weight.

The nitrogen content depends mainly on the nitrogen level in the atmosphere during reduction and cooling of the briquettes. By regulating the atmosphere at these moments, the nitrogen content can be made lower by 0.5% by weight, preferably lower by 0.1% by weight and most preferably lower by 0.05% by weight.

The reduced briquettes have a geometric density in the range 1.0-4.0 g / cm 3, preferably 1.2-3.5 g / cm 3, more preferably 1.2-3.0 g / cm 3. 537 536 A lower density results in higher porosity, which is considered to give a shorter dissolution time for the briquettes. On the other hand, a higher density increases the quantity of Mo air by a given volume. The geometric density is measured in accordance with ASTM 962-08. 16

Claims (21)

1. CLAHVIS 17 A process for producing iron and molybdenum containing briquettes including thesteps of: mixing: an iron containing powder, a molybdenum oxide powder, a carbonaceous powder, a liquid, preferably water, optionally a binder and/or a lubricant and/or a slag former, and b) briquetting to provide a plurality of green briquettes.

2. A process according to claim 1 further including the step: <2) drying the green briquettes.

3. A process according to any one of claims 2, wherein the drying step includes at least one of the following: drying the green briquettes to a moisture content less than 5 % by weight,preferably less than 3 % by weight; drying the green briquettes at a temperature in the range of 50-250 °C, preferably80-200 °C, more preferably 100-150 °C.

4. A process according to any one of claims l -3 further including the step: d) reducing the green briquettes to provide a plurality of reduced briquettes.

5. A process according to claim 4 wherein the reduction step includes at least one of the following: reducing at a temperature in the range of 800-1500 °C, preferably 800-1350 °C,more preferably 1000-1200 °C; reducing during at least 20 minutes, more preferably at least 30 minutes.reducing in a fumace supplied with an inert or reducing gas, preferably suppliedwith a weakly reducing gas reducing at an Operating pressure in the range of 0.1-5 atm, preferably 08-2 atm, more preferably 1.05-1.2 atm. 10. 11. 12. 13. 18 A process according to any one of claims 1-5 , wherein the briquetting is performed at a briquetting pressure in the range of 80-1000 kg/cm2, preferably 100-500 kg/cm2. A process according to any one of claims 1-5, wherein the briquetting is performed at a briquetting pressure in the range of 1000-10000 kg/cm2, preferably 2000-5000 kg/cm2. A process according to any one of claims 4-6, wherein the method further includes thestep:e) cooling the reduced briquettes in a non-oxídising atmosphere to a temperature below 200 °C , more preferably below 150 °C, preferably in an inert atmosphere. A process according to any one of claims 1-7, wherein the molybdenum oxide powder contains 50-80 % by weight of Mo. A process according to any one of claims 1-8, wherein at least 90% by weight theparticles of the molybdenum oxide powder pass through a test sieve having norninalaperture sizes of 300 um and at least 50 % by weight of the particles of themolybdenum oxide powder pass through a test sieve having nominal aperture sizes of 125 um. A process according to any one of claims 1-9, wherein the iron containing powdercontains at least 80 % by weight of Fe, preferably at least 90 wt%, more preferably atleast 95 wt%, most preferably at least 99% by weight. A process according to any one of claims 1-20, wherein at least 90% by weight theparticles of the iron containing powder pass through a test sieve having norninalaperture sizes of 125 um and at least 50 % by weight of the particles of the iron containing powder pass through a test sieve having nominal aperture sizes of 45 um. A process according to any one of claims 1-11, wherein at least 90 % by weight of theparticles of the carbonaceous powder pass through a test sieve having norninal aperturesizes of 125 um and at least 50 % by weight of the particles of the carbonaceous powder pass through a test sieve having norninal aperture sizes of 45 um 14. 15. 1

6. 1

7. 1

8. 1

9. 20. 19 A process according to any one of claims 1-12, wherein the carbonaceous powder ischosen from the group consisting of: sub-bituminous coals, bituminous coals, anthracite, lignite, coke, petroleum coke, and bio-carbons in particular charcoal. A process according to any one of claims 1-14, wherein the carbonaceous powder is chosen from the group consisting of: soot, carbon black, and activated carbon. A process according to any one of claims 1-15 wherein adding in step a) dry matter comprising in weight %: 1-15 iron containing powder; 5-25 carbonaceous powder; Optionally 0.1-10 lubricant and/or binder and/or slag former; and balance 50-90 molybdenum oxide powder. A process according to claim 16, wherein the liquid of step a) is added in amount of 1-10 % by weight of the added dry matter. Iron and molybdenum containing green briquettes having a dry matter composition inweight-% of:1-15 iron containing powder;5-25 carbonaceous powder;Optionally0.1-10 lubricant and/or binder and/or slag former; and balance 50-90 molybdenum oxide powder. Green briquettes according to claim 18, wherein the briquettes have a geometric density in the range of 1.0-4.0 g/cma, preferably l.2-3.5 g/cm3, more preferably 1.2-3.0 g/cms. Reduced iron and molybdenum containing briquettes having a composition in weight %of: 1-20 Fe; less than 10 O; less than 10 C; less than 15 of other elements; and balance at least 40 Mo, preferably at least 50 Mo. 21. Reduced briquettes according to claím 20, wherein the briquettes have a geometricdensity in the range of 1.0-4.0 g/cm3, preferably 1.2-3.5 g/cm3, more preferably 1.2-3.0g/cm3.