KR20140108659A - Iron and molybdenum containing pellets - Google Patents

Abstract

Iron and molybdenum containing pellets and methods for producing the pellets are disclosed. The green pellets are produced by mixing iron-containing powder, molybdenum oxide powder, and carbonaceous powder. The green pellets can be reduced at temperatures ranging from 400 to 1500 < 0 > C. The pellets can be monochromated.

Description

[0001] IRON AND MOLYBDENUM CONTAINING PELLETS [0002]

The present invention relates to a process for producing iron- and molybdenum-containing pellets and pellets produced by said process.

Ferromolybdenum is an iron molybdenum alloy generally having a molybdenum content of 60 to 80% by weight.

In most commercial applications, molybdenum iron is produced from molybdenum trioxide (MoO ₃ ) by carbothermic reduction, aluminothermic reduction or silicothermic reduction. The latter two methods produce low carbon molybdenum iron, while the carbon thermal reduction method produces high carbon molybdenum iron. Low carbon molybdenum iron is more common than high carbon alloys. The molybdenum iron lumps produced by these methods typically have a density of about 9 g / cm < ^{3 &} gt ;. Dissolution of lumps into steel melt can be difficult due to the high melting point of the lumps, for example, commercial grade FeMo ₇₀ has a melting point of 1950 ° C and the temperature of the molten steel is quite low , The dissolution of molybdenum iron is mainly influenced by the diffusion method which slows the dissolution time of molybdenum iron. Another factor is the high price of raw materials in aluminum thermal reduction and silicon thermal reduction. Also, about 2% of Mo can be lost to slag in the process.

Object of the Invention

It is an object of the present invention to provide novel iron and molybdenum containing materials suitable for molybdenum addition in the melting industry, for example the steel, casting and superalloy industries, and a method for producing such materials in a relatively cost effective manner.

Another object is to provide novel iron and molybdenum containing materials having a relatively fast dissolution time in molten steel.

Another object is to provide novel iron and molybdenum containing materials having low carbon content and high Mo content and methods of producing such materials in a relatively cost effective manner.

Summary of the Invention

At least one of the above-mentioned objects includes:

a) mixing iron-containing powder, molybdenum oxide powder and carbon-based powder,

b) adding liquid and optionally a binder and / or slag former to the mixture and pelletizing to provide a plurality of green pellets;

and c) optionally drying the green pellets to reduce the water content to less than 10% by weight.

The water content is defined as the water present in the green pellet in addition to the water of crystallization. The moisture content can be confirmed by LOD (loss on drying) analysis according to ASTM D2216-10. By drying the green pellets to less than 10% moisture content, the risk of cracking due to rapid evaporation of the liquid when heated at high temperatures is minimized. Preferably, the green pellets are dried to have a water content of less than 5% by weight, more preferably less than 3% by weight.

Preferably the method comprises:

 d) heat treating the green pellet at a temperature in the range of 400 to 800 占 폚, preferably for at least 20 minutes, more preferably for at least 30 minutes;

e) pellets derived from step c) or d) are heated at a temperature in the range of 800 to 1500 DEG C, preferably 800 to 1350 DEG C, more preferably 1000 to 1200 DEG C, preferably at least 10 minutes, For at least 20 minutes, most preferably for at least 30 minutes.

Preferably, the process comprises: f) heating the pellets of step d) or e) in a non-oxidizing atmosphere (e.g. a reducing or inert atmosphere) to a temperature of 200 ° C or less, Lt; RTI ID = 0.0 > 150 C < / RTI > in an inert atmosphere.

The resulting pellets may additionally include:

g) crushing and / or grinding the pellets;

h) sieving the crushed and / or ground pellets;

i) hot briquetting between two counter-rotating rollers at a temperature in the range of from 250 to 1000 캜, preferably from 400 to 800 캜, more preferably between two counter-

j) agglomerating the pellets with pellet agglomerates comprising from 2 to 300 pellets.

The iron and molybdenum-containing green pellets produced by the proposed process preferably contain 1 to 25% by weight of Fe, 15 to 40% by weight of O, 5 to 25% by weight of C, less than 15% by weight of other elements, And the balance Mo building composition of at least 30% by weight. More preferably, the iron and molybdenum-containing green pellets comprise 1 to 25% by weight of Fe, 15 to 30% by weight of O, 5 to 25% by weight of C, less than 15% by weight of other elements, % Mo building composition.

The composition of the building refers to the composition of the dried sample, ie, the composition excluding moisture present in the green pellet.

When alloying the melt in industrial production, the non-reduced green pellets can be used as a substitute for conventionally prepared molybdenum iron alloys or even as a substitute for molybdenum oxide. Iron-and / or molybdenum-containing green pellets can be produced at a lower cost than standard grade molybdenum iron.

1.0 to 6.0 g / cm ^3, preferably 2.0 to 5.0 g / cm has a geometric density of the ^third range, 2 to 30% by weight of Fe, less than 30 weight% O, less than 20% by weight of C, Mo, Fe It is possible from step d) and / or e) to produce iron and molybdenum-containing pellets having less than 15% by weight of other elements excluding C and O, and the remainder having an Mo composition of at least 40% by weight. When alloying with molybdenum in a melting practice, the pellets can replace molybdenum iron alloys prepared by conventional methods. Iron- and / or molybdenum-containing pellets can be produced at a lower cost than standard grade molybdenum iron. As shown in the following examples, iron and molybdenum containing pellets dissolve faster than standard grade molybdenum iron. Depending on the reduction time, the amount of carbon relative to the amount of oxide that can be reduced and the reduction temperature, the oxygen content of the pellets can be partially or completely reduced.

Figure 1 shows the dissolution rate of the iron and molybdenum containing pellets of the present invention compared to the reference grade solid molybdenum iron.
Figure 2 is a general schematic of a process for producing iron and molybdenum-containing pellets according to the present invention.
Figure 3 shows the logarithmic differential intrusion of the pore diameter of the iron and molybdenum-containing pellets according to the present invention.
Figure 4 shows the cumulative intrusion for the pore diameter of the iron and molybdenum-containing pellets according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in more detail and will be described with reference to the drawings.

Figure 1 shows that the dissolution time of the inventive material is much shorter than the dissolution time of the reference grade.

Figure 2 shows a general scheme of a process for producing iron and molybdenum-containing pellets according to the present invention.

In the mixing station 3, a powder mixture is prepared by mixing iron-containing powder, carbon-based powder, and molybdenum oxide powder.

In general, iron powder is added in an amount of 1 to 10 wt%, but Fe can be added in an amount of 25 wt%. The iron powder is mainly used to strengthen the pellets (e.g., acts like a binder) but can be changed to control the amount of Fe and Mo required in the final product. The molybdenum oxide powder is generally added in an amount of 70 to 90% by weight.

Preferably, the amount of the carbon-based powder is selected so as to be able to reduce the oxygen content to 0 to 10 wt%, while maintaining the carbon content after complete reduction at less than 5 wt%. Preferably, the carbon-based powder is controlled such that most of the molybdenum oxide is reduced to Mo, preferably all of the molybdenum oxide is Mo, for example, MoO _x of x? 0.5. Therefore, most oxides remaining after reduction are oxides that are difficult to reduce to carbon. Examples of oxides that are difficult to reduce with carbon include Al ₂ O ₃ , SiO ₂ , MgO, and CaO. As described below, the green pellets produced from the powder mixture can be reduced in a reduction furnace (6). Otherwise, non-reduced green pellets can be used as alloying additives in the manufacture of iron and steel.

The powder may be mixed in a dry state, that is, without addition of liquid during mixing, but is preferably mixed in a wet state in which a liquid, preferably water, is added in the blending part (3). Preferably, 5 to 15% by weight of water is added during mixing. The addition of water during mixing minimizes the dusting problem.

Before being added to the blend part 3, the molybdenum oxide powder can be milled in a rod mill 1. Of course, other grinders, grinders or crushers can be used to break molybdenum oxide into smaller particles. Further, the iron-containing powder and / or the carbon-based powder may also be broken down into smaller particles by pulverization and / or grinding and / or crushing.

The pulverized and / or ground and / or ground pulverized molybdenum oxide particles may be filtered in the sieve 2 to provide the desired particle distribution. Of course, filtering can also be applied to iron-containing powders and / or carbon-based powders.

In one embodiment, the molybdenum oxide powder and the carbon-based powder are mixed and ground together, and then the iron-containing powder is added and mixed with the molybdenum oxide powder and the carbon-based powder. However, the mixing order can be combined.

The mixing in the compounding part 3 can be carried out batchwise or continuously.

Optionally, a binder and / or auxiliary agent may be added at the time of mixing. The optional binder may be an organic or inorganic binder. The binder may be, for example, a carbon-containing binder that partially replaces the carbon-based powder. Other binders may be, for example, bentonite and / or dextrin and / or sodium silicate and / or lime. The optional additives may be limestone, dolomite and / or olivine. The total amount of optional binder and / or optional conditioning agent may be from 1 to 10 wt%, more preferably less than 5 wt%, based on the dry weight of the mixture. The binders are optional since the iron-containing powder can provide sufficiently strong pellets (e.g., at least 200 N / pellet after drying).

The powder mixture thus prepared is delivered to the pelletizer (4) at the blending part (3). In the pelletizer 4, the powder mixture is pelletized to provide a plurality of green pellets. If the powder is dry blended in the blend part 3, liquid is supplied when pelletized. If the powder is wet-blended in the blend part 3, liquid is optionally additionally supplied when it is pelletized. The pelletizer 4 is preferably a disc pelletizer or rotary drum type pelletizer.

Throughout the mixing and pelletization, the amount of added liquid is about 5 to 25 wt.%, More preferably 10 to 20 wt.% Of the mixture, for example 10 wt.% During mixing and 5 wt.% During pelletization .

The pellets produced from the pelletizer (4) are referred to as green pellets in the present invention. Immediately after the pelletizer (4), the green pellets generally have a compressive strength of about 10 to 20 N / pellt. The shape of the green pellet is generally spherical, spheroidal or elliptical.

In order to reduce the moisture content, the green pellets are delivered to a drier 5, for example a rotary dryer. Of course, many different types of industrial dryers can be used. The water vapor is preferably removed by a gas steam or by a vacuum. The pellets are dried until the desired moisture content is reached. Preferably the green pellets are 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. Preferably, the green pellets are dried at a temperature ranging from 50 to 250 캜, more preferably from 80 to 200 캜, and most preferably from 100 to 150 캜. For an economically improved method, the drying time is preferably in the range of 10 to 120 minutes, more preferably 20 to 60 minutes. However, longer drying times are also possible. In addition, the green pellets can be dried without active heating, e.g., at ambient air temperatures. After drying, the green pellets have a water content of up to 10% by weight. Hereinafter referred to as dried green pellets.

Reducing the moisture content has several advantages. One advantage is that the risk of cracking in the reduction furnace (6) is minimized. Green pellets may crack due to rapid evaporation of the liquid remaining in the pellets when heated at elevated temperatures. In addition, after drying, the dried green pellets are surprisingly firm, and need not be compressed before, during or after reduction. In Example 1 below, the dried green pellets have a compressive strength of about 450 to 500 N / pellet. The iron-containing powder acts as a binding agent when mixed under wet conditions, and for this reason it does not need to have additional binders. The carbon-based powder also contributes to the strength of the pellets. Thus, adding the binder during mixing is an optional step (except for the iron-containing powder and the carbon-based powder in the term binder). The dried green pellets may have a compressive strength in the range of 200 to 1000 N / pellet, preferably a compressive strength of 300 to 800 N / pellet. This compressive strength is sufficient to effect the handling of pellets including reduction in rotary kilns. Stronger pellets may be produced, if desired, by the addition of a binder, such that the compressive strength exceeds 1000 N / pellet.

After dryer (5), the dried green pellets can be used as alloying additives in iron and steel making. The strength and shape of the green pellets facilitates their transport and reduces the handling of shredding losses. Unexpectedly, the dried green pellets used as alloying additives have not been found to cause any significant molybdenum loss.

The dried green pellets can be partially or fully reduced in a reduction furnace, such as a rotary kiln 6. The green pellets in a rotary kiln furnace (6) are heat treated in a furnace in the temperature range of 400 to 1500 ° C.

The dried green pellets are optionally heat-treated in step d) for a period of at least 20 minutes at a temperature in the range from 400 to 800 ° C, preferably below 700 ° C. Preferably, the optional heat treatment step d) is carried out in not more than 2 hours, preferably less than 1 hour. Molybdenum trioxide can be reduced to molybdenum dioxide by having a heat treatment step at a lower temperature. This step can be used as the main reduction step in producing the partially reduced pellets as a pre-reduction step prior to the reduction step e). The optional heat treatment step can be carried out in the same furnace as in the reduction step e) (see below). Otherwise it would be possible to transfer the partially reduced pellets to another furnace for the reduction step e).

Preferably, in step e), the pellets derived from step c) or d) are heated at a temperature in the range of 800 to 1500 DEG C, preferably 800 to 1350 DEG C, more preferably 1000 to 1200 DEG C, Min, at least 20 minutes, or at least 30 minutes. By monitoring the formation of CO / CO _2, the end of the reduction process can be identified. Preferably, the reduction time in step e) is at most 10 hours, preferably at most 2 hours, more preferably at 1 hour. Depending on the relationship between the reduction time, the reduction temperature, and the reducible oxides in the carbon and pellets; The reducing oxides of the pellets can be partially or fully reduced.

Unexpectedly, it has been found that the dried green pellets can be reduced at high temperatures without significant sublimation loss of MoO ₃ . The claimed process thus leads to a simplified process which results in an improved yield and a final product with a higher Mo content. That is, it is not necessary to carry out the pre-reduction step d) before step e), because the range of 400 to 800 ° C can pass quickly when the temperature rises to 800 to 1500 ° C.

During the reduction, CO and CO ₂ can be formed from the reaction of the carbon source and the reducing oxide in the pellet. In addition, the remaining water can evaporate. The reduction time can be optimized by measuring CO and CO ₂ formation; In particular, CO ₂ can be optimized by measuring CO, since CO formation is predominant until only the first few minutes of reduction are formed and then the carbon source is consumed or all the reducing oxides are reduced.

The reduction reaction is endothermic and requires heat. Preferably, the heat is generated by heating, meaning that it does not affect the atmosphere inside the furnace, more preferably the heat is generated by electrical heating.

Suitable types of furnaces for the optional heat treatment and reduction stages include, for example, rotary kilns, rotary hearth furnaces, shaft furnaces, grate kilns, travelling grate kilns, It is a tunnel furnace or batch furnaces. Other types of furnaces used for direct solid phase reduction of metal oxides can also be used.

In a preferred embodiment, the rotary kiln is used to reduce the pellets. In the rotary kiln furnace, the green pellet from step c) is poured into a rotary kiln that rotates slightly at an angle to the horizontal axis and spreads towards the outlet of the kiln at the inlet of the kiln, as the kiln rotates about its axis.

The atmosphere inside the blast furnace 6 is supplied with an inert or reducing gas, preferably a weak reducing gas, for example H ₂ / N ₂ (at 5:95 by volume) at one end of the furnace, (For example, CO, CO ₂ , and H ₂ O) and the gas supplied, and more preferably, at the outlet side 8 of the furnace 6, And the exhaust gas is supplied from the suction port side 7 of the blast furnace 6 so as to be regulated. That is, the inert or reducing gas is preferably supplied in a countercurrent flow.

Preferably, the furnace is operated at a pressure ranging from 0.1 to 5 atm, preferably at a pressure ranging from 0.8 to 2 atm, more preferably from 1.0 to 1.5, most preferably from 1.05 to 1.2 atm.

A (heating zone reserved) in the possible embodiment, the first portion of the kiln, the temperature zone of 400 to 800 ℃ range, in the green pellets 50 to 100 wt% MoO ₃ is reduced by the carbon-based powder is MoO ₂ And the second portion downstream of the first portion provides a temperature zone in the range of 800 to 1500 占 폚 wherein 50 to 100 wt% of the remaining molybdenum oxides are reduced to Mo by the remaining carbon-based powder.

In other embodiments, oxygen gas or air may be provided in the pre-heat zone to form carbon dioxide gas in reaction with the formed carbon monoxide to reduce the amount of external heat required. If air is used, the nitrogen uptake of the pellets can be increased. Oxygen can be used to minimize nitrogen uptake during the heating and reduction steps.

At the outlet 8 of the reduction furnace, the pellets are heated to a temperature of less than or equal to 200 DEG C in a non-oxidizing atmosphere (e. G., Reduced or inert) To cooling section 9 providing step f) of cooling to below 150 < 0 > C in an inert atmosphere. The atmosphere may be, for example, 95 vol-% N ₂ And 5 vol.% H ₂ may be the standby. If it is desired to have a very low degree of nitrogen in the pellets, the pellets may be cooled, for example, in a nitrogen-free atmosphere, such as an argon gas atmosphere.

The resulting pellets may additionally include:

g) crushing and / or grinding the pellets;

h) sieving the crushed and / or ground pellets;

i) hot briquetting between two counter-rotating rollers at a temperature in the range of from 250 to 1000 占 폚, preferably from 400 to 800 占 폚, more preferably;

j) agglomerating the pellets with pellet agglomerates of 2 to 300 pellets.

Molybdenum oxide powder

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

The molybdenum powder should contain 50 to 80% of Mo, remaining elements that are oxygen, and impurities. Pure grades of molybdenum oxide, more pure iron and molybdenum containing pellets can be made. However, the pure grade MoO ₃ is more expensive on the other hand.

In a preferred embodiment, industrial MoO ₃ is used. These powders are less expensive than the more pure grades of MoO ₃ and may contain oxides that are difficult to reduce to carbon in solid reduction. Examples of such oxides are, for example, Al ₂ O ₃ , SiO ₂ and MgO. Fortunately, these oxides can be easily removed from the slag phase when alloyed with molten steel and therefore acceptable in the product.

Preferably, at least 90% by weight of the molybdenum oxide powder particles pass through the test body having a nominal opening size of 300 [mu] m and at least 50% by weight of the molybdenum oxide powder particles pass through the test body having a nominal opening size of 125 [mu] m. More preferably, at least 90 wt% of the molybdenum oxide powder particles pass through the test body having a nominal opening size of 125 mu m and at least 50 wt% of the molybdenum oxide powder particles pass through the test body having a nominal opening size of 45 mu m . The nominal aperture size in the present invention is in accordance with ISO 565: 1990, incorporated herein by reference.

In one embodiment at least 90 wt.%, More preferably at least 99 wt.% Of molybdenum oxide powder particles pass through a specimen having a nominal opening size of 250 μm, more preferably 125 μm, most preferably 45 μm.

Iron-containing powder

The iron-containing powder is preferably an iron powder containing at least 80 wt% Fe, preferably at least 90 wt% Fe, more preferably at least 95 wt% Fe, most preferably at least 99 wt% Fe Do. The iron powder may be iron sponge powder and / or water jet iron powder and / or gas jet iron powder and / or iron dust and / or iron sludge powder. For example, filter dust X-RFS40 from Hoganas AB, Sweden is a suitable powder.

The iron powder may be partially or wholly replaced with iron oxide powder, for example, one selected from the group consisting of FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , FeO (OH, (Fe ₂ O ₃ ^* H ₂ O) Iron powder may be, for example, a mill scale, but preferably the iron-containing powder is at least 50 wt% of metallic iron, more preferably, , At least 80 wt% metal Fe, and most preferably at least 90 wt% metal Fe.

Preferably at least 90% by weight of the iron-containing powder particles pass through the test piece having a nominal opening size of 125 탆 and at least 50% by weight of the iron-containing powder particles pass through the test piece having a nominal opening size of 45 탆.

In one embodiment at least 90% by weight, more preferably at least 99% by weight of the iron-containing powder particles pass through a specimen having a nominal opening size of 125 [mu] m, more preferably 45 [mu] m. In one embodiment at least 90% by weight, more preferably 99% by weight, of the iron-containing powder particles pass through the test body having a nominal opening size of 20 [mu] m.

Carbon-based powder

The carbon-based powder is preferably selected from the group of carbon-containing powders processed from bio-carbon such as: bituminous coal, bituminous coal, lignite, anthracite, coke, petroleum coke and charcoal, or from such raw materials. The carbon-based powder may be, for example, soot, carbon black, or activated carbon. The carbon-based powder may also be a mixture of other carbon-based powders.

This factor is preferably taken into account in the selection of the carbon-based powder, since the yield as well as the yield of Mo depend on the reactivity of the carbon. High reactivity is preferred. In particular, it is preferable to have a carbon-based powder that is reactive at a lower temperature (preferably < 700 ° C). For example, German lignite (brown coal) is typically reactive at lower temperatures than petroleum coke, which is suitable because it has relatively high reactivity at low temperatures. In addition, charcoal, bituminous coal and bituminous coal can exhibit relatively high reactivity. Particularly suitable examples are soot, carbon black and activated carbon.

The amount of the carbon-based powder is preferably determined by analyzing the amount of the molybdenum oxide powder and, optionally, the amount of the oxide in the iron-containing powder. Preferably, the amount of the reducing oxide is determined. The oxygen content can be analyzed, for example, by LECO® TC400. It is also preferred that the maximum allowable carbon content in the pellets is also taken into account. Preferably, the amount is chosen such that it stoichiometrically matches or slightly exceeds the amount of reducing metal oxide in the molybdenum oxide powder and the iron-containing powder. However, the amount of carbon may also be less than stoichiometric.

The amount of carbon-based powder can be optimized by measuring the carbon and oxygen levels in the produced pellets (e.g., by producing pellets in laboratory furnaces and measuring carbon and oxygen levels). The amount of carbon-based powder can be optimized based on the measurements to achieve the desired level of carbon and oxygen in the produced pellets. Some oxides that may be present in the molybdenum oxide powder are difficult to reduce to carbon. All oxides with a high affinity for oxygen at the reduction maximum temperature will remain as oxides in the final product, thus not consuming carbon in the reduction process. Such oxides may be, for example, Si, Ca, Al and Mg oxides, and such oxides may be present, for example, when low levels of molybdenum trioxide, for example industrial molybdenum trioxide, are used. However, in many steel metallurgy applications, these oxides can be treated by removing them, for example, with molten steel slag, so that they can be acceptable to the pellets. If a lower amount of the above oxides and elements is desired, a less pure grade, for example, less or no such oxide, may be used for molybdenum trioxide.

Adjusting the amount of the carbon-based powder and matching it with the amount of the reducing oxide in the green pellet; Iron and molybdenum containing pellets having a carbon content (after reduction) of less than 1 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt%, most preferably less than 0.05 or 0.01 wt% . Such pellets can be used, for example, when alloying low carbon steel.

However, it is also possible to produce fully reduced pellets having a carbon content ranging from 1 to 10% by weight.

Preferably, at least 90 wt.%, More preferably at least 99 wt.% Of the carbon-based powder particles pass through the test body having a nominal opening size of 125 mu m and at least 50 wt.% Of the carbon- Passes through a specimen having a nominal opening size.

In one embodiment, at least 90 wt.%, More preferably at least 99 wt.% Of the carbon-based powder particles are passed through a specimen having a nominal opening size of 45 mu m and at least 50 wt.% Of the carbon- Passes through the specimen with the nominal opening size. In one embodiment, at least 90 wt%, more preferably at least 99 wt% of the carbon-based powder particles pass through the test body having a nominal opening size of 20 mu m.

Green containing iron and molybdenum Pellets

The iron and molybdenum-containing green pellets contain less than 15 weight percent of other elements, excluding 1 to 25 weight percent Fe, 15 to 40 weight percent O, 5 to 25 weight percent C, O, C, Mo, With the remainder being at least 30 wt% Mo building composition.

Iron is preferably in the range of 1.5 to 20 wt%, more preferably 2 to 15 wt%, and even more preferably 2 to 10 wt%.

The carbon content is preferably 7 to 20% by weight.

The oxygen content is preferably 15 to 30% by weight.

The molybdenum content is preferably 40 to 65 wt%.

Other elements are preferably at least 1 wt% and less than 10 wt%, more preferably at least 2 wt% and less than 7 wt%.

In subsequent reduction steps, the relative amounts of iron and molybdenum will increase in the pellet as the reduction proceeds. The same is true for other remaining elements.

The dried green pellets can reach a compressive strength of 200 to 1,000 N / pellet, preferably 300 to 800 N / pellet.

The green pellets can be cost-effectively replaced with MoO ₃ powder or standard FeMo, taking into account the cost and / or yield of Mo added to the melt during the performance of the molten alloy. Generally, this addition may be made, for example, of an electrical arc furnace (EAF), for example by adding Mo to stainless steels, tool steels or high speed steels.

The average diameter of the green pellets is preferably in the range of 3 to 35 mm, preferably in the range of 5 to 25 mm. Too small pellets can be difficult to handle, while too large pellets require more reduction time.

Green pellets shall have the geometric density originating from the 1.0 g / cm ^3, preferably at least 1.2 g / cm ^3. Density can also be restricted to be at least 1.5 g / cm ^3, or at least 2.0 g / cm ^3. The geometric density is preferably less than 4.0 g / cm &lt; ³ &gt;. The geometric density may also be limited to less than 3.5 g / cm ³ , or less than 3.2 g / cm ³ , or less than 3.0 g / cm ³ , or less than 2.9 g / cm ³ , or less than 2.8 g / cm ³ . The lower geometric density results in higher porosity, which is thought to have a shorter dissolution time of the pellets. The geometric (inclusion) density can be measured according to ASTM 962-08.

The shape of the green pellet is generally spherical, spheroidal or elliptical. When handled, this form reduces the risk of crushing compared to the shape of the compressed briquettes. Also, the fluidity is better than the fluidity of the briquettes.

Reduced iron and molybdenum content Pellets

The iron and molybdenum containing pellets which can be produced by the proposed process steps d) and / or e) comprise 2 to 30% by weight of Fe, less than 30% by weight of O, less than 20% by weight of C, O, C, Mo And less than 15 wt.% Of other elements excluding Fe, and the remainder at least 40 wt.% Mo, preferably at least 50 wt.% Mo composition.

Molybdenum trioxide in the pellets can be partially reduced, for example, 0.5 <x <3, preferably 1 ≤ x ≤ 2.6 the pellets containing MoO _x. When producing such pellets, the amount of carbon-based powder required is less than what is required to reduce all reducing oxides. Thus, such pellets can be made to be stoichiometric by selecting the relative amount of the carbon-based powder.

However, the partially reduced pellets may later be made to have carbon remaining in the pellets, for example, which can be activated to reduce the remaining reducing oxides when the pellets are added to the molten steel. Such pellets can be made by controlling the reduction temperature and duration, for example, by heat treating at 400 to 800 DEG C to partially reduce the pellets.

The partially reduced pellets are preferably reduced to contain less than 30 wt% O, more preferably less than 25 wt% O, generally about 10 to 20 wt%, and the remaining carbon content is less than 15 wt% And more preferably 5 to 15% by weight. The molybdenum content of the partially reduced pellets is preferably at least 40% by weight, more preferably at least 50% by weight, most preferably at least 60% by weight.

For various applications, however, it is preferred that the content of O is less than 10 wt%, more preferably less than 8 wt%, even more preferably less than 6 wt%, and most preferably less than 4 wt% It is preferred that only the content originates from unreduced molybdenum oxide, i. E., A pellet containing MoO _x of x &lt; = 0.5. Preferably, essentially all the molybdenum oxide is reduced to Mo, i. E., Where x is about zero. Here, the residual oxygen content mainly originates from oxides and iron-containing powders in the molybdenum oxide powder which are difficult to reduce, for example, Si, Ca, Al and Mg oxides. If desired, a more pure grade of molybdenum oxide powder, iron-containing powder, and carbon-based powder may be used to make the oxygen content of the pellets 2 wt% or less. However, since many of the oxides which are difficult to reduce can be handled in steel melt metallurgy (e. G., They are removed on slag), they can be tolerated in iron and molybdenum containing pellets. The lower limit for oxygen can be about 0 wt%, but generally the oxygen is at least 1 wt%, more usually at least 2 wt%.

The molybdenum content in the pellets can be controlled by varying the relative proportion of the molybdenum oxide powder to the iron-containing powder. It is preferred that the content of molybdenum is adjusted to be in the range of 60 to 95 wt.% For basically completely reduced pellets (i. E. MoO _x containing pellets with x? 0.5). More preferably, the content of Mo is in the range of 65 to 95 wt%, and the content of Mo is most preferably in the range of 70 to 95 wt%. Surprisingly, reduced pellets having a molybdenum content of 80 to 95 wt.% Have been found to have a very high dissolution rate. This result is due to the higher specific surface area of these alloys, despite their very high melting point, 2100 to 2500 ° C.

By adjusting the carbon addition, the carbon content of the reduced pellets is reduced to 5 wt. %, 2 wt. %, 0.5 wt. %, 0.1 wt. %, Or 0.05 wt. %. &Lt; / RTI &gt; Pellets with low carbon can be used, for example, in low carbon steel alloys. However, in some applications, for example, in high carbon steel or cast iron production, it may be desirable to have a carbon content in the range of 1 to 5 weight percent.

The iron content of the pellets is preferably in the range of 2 to 25% by weight, more preferably 3 to 20% by weight. The iron content may also be limited to 4 to 15% by weight or 5 to 10% by weight. The iron content in the pellets can be controlled by changing the relative proportion of the iron-containing powder to the molybdenum oxide powder.

The reduced pellets can be cost-effectively replaced with MoO ₃ powder or standard FeMo, taking into account the cost and / or yield of Mo added to the melt during the performance of the molten alloy. Generally, this addition may be made, for example, of an electrical arc furnace (EAF), for example by adding Mo to stainless steels, tool steels or high speed steels.

Depending on the purity of the powder mixture, the pellets may contain additional elements including oxides which are difficult to reduce. Mo, Fe, C and O can be allowed to be less than 15% by weight. Preferably, the total amount of the elements other than O, C, Mo and Fe is 10% by weight, more preferably less than 7% by weight. The amount of other elements can be controlled not only by the purity of the molybdenum trioxide but also from the iron-containing powder, the impurities in the carbon-based powder, and the reaction with the elements of the ambient atmosphere during heating, reduction or cooling. If desired, using high purity grades of molybdenum trioxide, iron-containing powders and carbon-based powders; The total amount of the elements other than O, C, Mo and Fe can be kept lower than 1 wt%. If present in the pellet, the elements of the Si, Ca, Al and Mg groups are mainly bound to the oxide. For example, in molten steel, silicon bonded with silicon oxide can be more easily handled than silicon dissolved in the lattice of the alloy. Other elements may be limited to at least 1 wt% or at least 2 wt% in some embodiments.

Preferably, in some embodiments, the other elements are:

N up to 2% by weight, more preferably N up to 1% by weight;

Up to 1% by weight of S, more preferably up to 0.5% by weight of S;

Al up to 2 wt%, more preferably Al up to 1.5 wt%;

Up to 2% by weight of Mg, more preferably up to 1% by weight of Mg;

Up to 2% by weight of Na, more preferably up to 1% by weight of Na;

Up to 4% by weight of Ca, more preferably up to 2% by weight of Ca;

Up to 6% by weight of Si, more preferably up to 3% by weight of Si;

K up to 1 wt.%, More preferably K up to 0.5 wt.%;

At most 1 wt% Cu, more preferably at most 0.5 wt% Cu;

Up to 1% by weight of Pb, more preferably up to 0.1% by weight of Pb;

W up to 1 wt%, more preferably W up to 0.1 wt%;

V up to 1 wt%, more preferably V up to 0.1 wt%;

And the remaining elements are preferably at most 0.5 wt.% Each, more preferably at most 0.1 wt.% Each, most preferably at most 0.05 wt.% Each.

In some embodiments, the Si content is in the range of 0.5 to 3 wt%, the Ca content is in the range of 0.3 to 2 wt%, the Al content is in the range of 0.1 to 1 wt%, and / or the Mg content is in the range of 0.1 to 1 wt% Range.

Preferably, at least 50 wt.%, Preferably at least 90 wt.%, If elements of the Si, Ca, Al and Mg groups bound to the oxide by the pellets are present.

The nitrogen content mainly depends on the nitrogen level in the atmosphere during the heating, reduction and cooling of the pellets. By adjusting the atmosphere in the above steps, the nitrogen content can be made lower than 0.5 wt%, preferably lower than 0.1 wt%, and most preferably lower than 0.05 wt%.

The average diameter of the pellets is preferably in the range of 3 to 30 mm, preferably in the range of 5 to 20 mm. Too small pellets can be difficult to handle, while too large pellets can delay the reduction time.

The pellets have a geometric density of 1.0 g / cm &lt; ³ &gt;, preferably 1.2 g / cm &lt; ^{3 &} gt ;. Density can also be restricted to be at least 1.5 g / cm ^3, or at least 2.0 g / cm ^3. The geometric density is preferably less than 4.0 g / cm &lt; ³ &gt;. The geometric density may also be limited to less than 3.5 g / cm ³ , or less than 3.2 g / cm ³ , or less than 3.0 g / cm ³ , or less than 2.9 g / cm ³ , or less than 2.8 g / cm ³ . Lower densities result in higher porosity, which is believed to have a shorter dissolution time of the pellets. Density is measured according to ASTM 962-08.

The apparent density of the pellets (as determined by the helium specific gravity measurement) is preferably in the range of 5 to 10 g / cm &lt; ³ &gt;. The apparent density can also be limited to a range of 6 to 8 g / cm &lt; ³ &gt;.

It is preferred that the bulk density of the pellets (determined by filling the pellets with a pellet having a volume of 1 liter and measuring the weight thereof) is in the range of 0.5 to 3 g / cm ³ , more preferably 1.0 to 2.0 g / cm ³ .

The open porosity (as determined by a mercury intrusion porosimeter at 4.45 psia) is preferably in the range of 0.1 to 0.6 cm ³ / g. The open porosity may also be limited to within the range of 0.2 to 0.45 cm &lt; ³ &gt; / g.

Preferably, the open pore diameter (identified by mercury penetration porosity analyzer at 4.45 psia) is in the range of 0.5 to 20 占 퐉. Also, the intermediate open pore diameter may be limited to a range of 2 to 10 mu m, or a range of 3 to 6 mu m.

Preferably 20 to 95%, more preferably at least 50%, most preferably at least 70% of the pore volume (determined by mercury penetration porosity analyzer at 4.45 psia) results from pores in the range of 1 to 10 [mu] m.

The open porosity (as determined by mercury intrusion porosity analyzer at 4.45 psia) is preferably in the range of 50 to 80 vol%.

The BET surface area is preferably in the range of 0.1 to 10 m ² / g. The BET value may also be limited to 0.4 to 4 m ² / g, or 0.6 to 2 m ² / g, or 0.8 to 1.5 m ² / g.

The pellets preferably have a compressive strength in the range of 200 to 1000 N / pellet. The compressive strength may also be limited to a range of 300 to 800 N / pellet.

The shape of the pellet is generally spherical, spheroid, or elliptical. When handled, this form generally reduces the risk of breakage compared to the shape of a compressed briquettes with sharp edges. Also, the fluidity is better than the fluidity of the briquettes. Also, the pellets can be produced at low cost because no single light treatment step is required.

In some applications it may be desirable to have a shape other than spherical, spheroid, or elliptical. For example, the pellets conveyed by the conveyor belt can be pierced from the belt depending on how the conveyor belt is installed.

Pellet agglomerates consisting of 2 to 300 pellets are less likely to fall off the conveyor belt.

The pellets may be agglomerated by a binder such as glue. Preferably, such agglomerates contain 2 to 20 pellets, more preferably 5 to 15 pellets.

It is also possible to form pellet aggregates by filling plastic bags with pellets, preferably by heat shrinking and / or vacuuming the plastic around the pellets. Preferably these aggregates contain 30 to 300 pellets, more preferably 50 to 200 pellets, most preferably 75 to 150 pellets.

Another way to avoid problems is to fill the coneiner with metal pellets. Preferably, the container has an internal volume in the range of 100 to 125000 cm &lt; ^{3 &} gt ;.

Of course, the green pellets can also be agglomerated or put into containers in the manner described above.

The pellets are added at a temperature in the range of 250 to 1000 DEG C, preferably in the range of 400 to 800 DEG C, and more preferably in the range of 60 to 200 kN per cm of active roller width, most preferably between two reversing rollers, As shown in FIG. Suitable hot-dip treatment machines are sold, for example, by Maschinenfabrik Koppern GmbH & In the hot monochromatic step, a binder may be optionally added. The volume of the briquettes is preferably between 15 and 200 cm &lt; ³ &gt;. Of course, the green pellets can also be hot-coked. The briquettes have geometric densities ranging from 3.0 to 8.0 g / cm ³ , preferably from 4.0 to 6.0 g / cm ³ .

Iron and molybdenum-containing powder

The pellets may also be ground with irregularly shaped pieces, for example, coarse iron and molybdenum containing powders, wherein 90 wt% of the powder particles have a diameter of at least 250 μm according to ISO 3310-1: 2000, preferably at least 500 [mu] m, more preferably at least 1 mm.

The pellets may be further comminuted and selectively filtered to provide a powder containing fine iron and molybdenum. Preferably at least 90% by weight, more preferably at least 99% by weight of the particles of fine size, here 250 [mu] m according to ISO 3310-1: 2000, more preferably 125 [ Lt; RTI ID = 0.0 &gt; um. &Lt; / RTI &gt; The fine powder may be provided as a core filler for cored wire, for example for injection alloys or welding applications. Such wires generally consist of a metal sheet comprising a metal powder and a core filler. The metal sheet in the injection alloy can be wrapped, for example, by wrapping paper. The diameter of the wire, the thickness of the metal sheet, the type of metal used in the metal sheet, and the particle size of the powder are suitably adjusted according to the particular application.

Preferably, the iron and molybdenum containing powder for the cored wire comprises: 2 to 25 wt.% Fe, less than 25 wt.% O, less than 10 wt.% C, less than 15 wt.% Other elements, Mo composition by weight. More preferably, the iron and molybdenum containing powder for the cored wire comprises:

3 to 20 wt.% Fe, preferably 4 to 15 wt.% Fe, more preferably 5 to 10 wt.% Fe;

Less than 10 wt% O, preferably less than 8 wt% O, more preferably less than 6 wt% O, most preferably less than 4 wt% O;

Less than 5 wt% C, preferably less than 2 wt% C, more preferably less than 0.5 wt% C, most preferably less than 0.05 wt% C;

Less than 10 wt% of other elements, preferably less than 7 wt% of other elements and Fe, most preferably less than 1 wt% of other elements, and

With the remainder having a Mo composition of at least 65% by weight.

Example 1

(Mo &gt; 57 wt.%, &Lt; 40 mu m) and 13 wt.% (Manufactured by Hoganas AB Co., % Carbon powder (&lt; 20 mu m, carbon black). Water was added to the mixture and green pellets were produced in a disc pelletizer. The pellets had a water content of about 10% by weight as determined by LOD according to ASTM D2216-10. Thereafter, the pellets were dried at room temperature at a moisture content of 2% by weight.

The green pellets were reduced in a batch of 1100 ° C under N ₂ 95 vol-% and H ₂ 5 vol-% atmosphere for 2 hours. The pellets were then cooled to a temperature of about 100 DEG C before being removed from the atmospheric exhaust and furnace. The result was a pellet having a weight of about 0.4 grams and a diameter of about 6 to 7 mm. The average geometric density of the pellets was determined to be 2.6 g / cm &lt; ³ &gt; as measured according to ASTM 962-08.

The pellet was pulverized into powder and the chemical composition of the powder was confirmed. The results are shown in Table 1.

The oxygen content of the pellets is mainly derived from oxides which are difficult to reduce, for example, Mg, Al, Si and Ca oxides. These oxides can be present in industrial grades of molybdenum trioxide and are difficult to reduce. Thus, by using a purer grade of molybdenum trioxide, the oxygen content can be made significantly lower. However, in many applications these oxides can be allowed to pellets because they are quickly separated into slag.

Example 2

Figure 1 shows the dissolution rates for the iron and molybdenum containing pellets of the present invention, i.e., the standard molybdenum iron standard reference grade compared to the novel molybdenum iron grade. Pellets of the same arrangement as in Example 1 are provided and for this reason have the composition of Table 1. The average geometric density of the pellets as described in Example 1 was found to be 2.6 g / cm &lt; ³ &gt;.

The reference material was 10 masses of standard molybdenum iron containing 70 wt% molybdenum, less than 2% impurities and the balance iron. The size of each lump was approximately 10x50 mm.

The goal of the experiment is to evaluate whether the iron- and molybdenum-containing pellets have a faster dissolution time than standard molybdenum iron.

The first and second molten steel were produced and their compositions were analyzed. The target component of the melt is Mo 5.0 wt. %, C 0.6 wt%, the remainder Fe, and the Mo content was originally 0 wt% in the two molten steel. Both of them were maintained at a temperature of about 1550 DEG C during the experiment. Mo was added to the first melt in the form of iron and molybdenum containing pellets as described in Example 1 and lumps of a reference grade were added to the second molten steel. The pellets and the reference grade were added in batches to the corresponding molten steel, respectively. The test specimens were taken from each of the molten steel every 30 seconds to measure the Mo- content therein. Ten experimental samples were taken from each melt, and Figure 1 shows how the Mo content of each melt varies over time. As shown, the Mo content of the molten steel alloyed with pellets is much faster than that of standard molybdenum steel alloys of the reference grade.

Example 3

(Mo &gt; 57 wt.%, &Lt; 40 mu m) and 13.5 wt.% (2.5 wt.% Of fine grain iron powder (<40 μm, Fe> 99 wt.%, X- RSF40 from Hoganas AB), 84 wt.% Industrial grade molybdenum oxide % Of carbon-based powder (<20 μm, carbon black). Water was added to the mixture and green pellets were produced in a disc pelletizer. After pelleting, the green pellets were dried at 90 DEG C for 2 hours to reduce the moisture to less than 2 wt%.

The dried green pellets were reduced in a rotary furnace at a temperature of 1120 DEG C for 0.5 hour. Weak reducing gas 95 vol-% N ₂ and 5 vol-% H ₂ atmosphere, was fed to the reverse flow during the reduction. The pellets were then cooled to a temperature of about 100 DEG C under a protective atmosphere. As a result, a pellet having a weight of about 1.9 grams and a diameter of about 12 mm was produced.

Both pellets were inspected in a mercury intrusion porosity analyzer and the pressure was 4.45 psia (instrument: Micromeritics AutoPore III 9410). The analysis was carried out in the pore size range of 330 μm ≥ Ø ≥ 0.003 μm. The results are shown in Table 2. Here, the total open pore volume is 0.32 cm ³ / g and the mean open pore diameter is 4 μm. The open porosity was confirmed to be 68 vol% and the pore area was found to be 0.7 m ² / g. The data show that the pellets have a microporous structure, which can improve the dissolution rate in molten steel. The geometric (inclusion) density was found to be 2.1 g / cm ³ . The skeletal (apparent) density was confirmed to be 6.56 g / cm ³ by intrusion porosity through a mercury penetration porosity analyzer. Also, the skeletal (apparent) density was 7.36 g / cm ³ by measuring the helium specific gravity (instrument: AccuPyc 1330, Micromeritics).

The BET surface area was found to be 0.98 m ² / g (instrument: Gemini 2360, Micromeritics).

In FIG. 3, logarithmic differential penetration is plotted versus the pore diameter of the pellet. As shown in the figure, most of the pores have a pore diameter of between 1 and 10 mu m forming a narrow band around the intermediate pore diameter of 4 mu m. In FIG. 4, the cumulative intrusion is plotted against the pore diameter. It is evident from the figures that more than 70% of the pore volume originates from pores in the range of 1 to 10 [mu] m.

The bulk density of the pellets was confirmed by filling the pellets in a 1 liter volume can and weighing them, resulting in a bulk density value of 1.5 g / cm ³ .

The size and shape of the pellets provide a relatively large macroscopic surface area for the plurality of pellets, i. E. The outer surface of the pellet. In addition, the pellets provide relatively large open porosity and pore structures that provide a relatively large internal microfacet. The combination of large microsurface area and large macroscopic surface area improves the high dissolution rate and minimizes the sublimation loss of Mo when added, for example, as an alloy additive to molten steel.

Example 4

The compressive strength of the green pellet from the mixture A of Example 3 was examined and compared with the compressive strength of the green pellet made of the mixture B. Mixture B was prepared by mixing 84 wt% of industrial molybdenum oxide (Mo> 57 wt.%, <40 μm) and 13.5 wt.% Of carbon-based powder (<20 μm, carbon black). That is, an important difference between mixtures A and B was that B did not contain iron powder. The powders were wet blended and then the wet blend was transferred to a disc pelletizer that produced the green pellets. The compressive strength was confirmed by increasing the load on the pellets until they were broken. One hour after removal from the pelletizer, the green pellets from mixture B had a compressive strength of 37 N / pellet, while the mixture A-derived green pellets had a compressive strength of 50 N / pellet.

After drying in a ventilation drier at 90 ° C for 2 hours, the average compressive strength of the dried green pellets from Mixture A was found to be 155 N / pellet while the average compressive strength of the dried green pellets from Mixture A was 530 N / pellet. This indicates that the iron addition significantly increased the compressive strength of the dried green pellets.

Claims (28)

a) mixing an iron-containing powder, a molybdenum oxide powder, and a carbon-based powder;
b) adding a liquid, preferably water, and optionally a binder and / or slag former to the mixture and pelletizing to provide a plurality of green pellets; And
c) optionally drying the green pellets to reduce the moisture content to less than 10% by weight. The method of claim 1,
d) heat treating the green pellet at a temperature in the range of 400 to 800 占 폚, preferably for at least 20 minutes; And
e) heating the pellets resulting from step c) or d) at a temperature in the range of 800 to 1500 DEG C, preferably 800 to 1350 DEG C, more preferably 1000 to 1200 DEG C, preferably for at least 10 minutes, At least 20 minutes, most preferably at least 30 minutes. Process according to claim 2, characterized in that the heat treatment step d) and / or the reduction step e) is carried out in a furnace supplied with an inert or reducing gas, preferably a weak reducing gas. 4. Process according to claim 3, characterized in that the heat treatment step d) and / or the reduction step e) is carried out at an operating pressure in the range of 0.1 to 5 atm, preferably 0.8 to 2 atm. 5. Process according to claim 4, characterized in that the heat treatment step d) and / or the reduction step e) is carried out at an operating pressure in the range of 1.05 to 1.2 atm. 6. The method of claim 5, wherein the inert or reducing gas is supplied in counter flow. 7. Process according to any one of the claims 1 to 6, characterized in that the green pellet comprises drying to a moisture content of less than 5% by weight, preferably less than 3% by weight. 8. A process according to any one of claims 7 to 7, characterized in that the green pellets are dried at a temperature ranging from 50 to 250 DEG C, preferably from 80 to 200 DEG C, more preferably from 100 to 150 DEG C. 9. A process according to any one of claims 2 to 8, characterized in that it comprises the following steps:
f) cooling the pellets in a non-oxidizing atmosphere at a temperature of 200 ° C or less, more preferably at a temperature of 150 ° C or less, preferably in an inert atmosphere;
g) crushing and / or grinding the pellets;
h) sieving the crushed and / or ground pellets;
i) hot briquetting between two counter-rotating rollers at a temperature in the range of from 250 to 1000 占 폚, preferably from 400 to 800 占 폚, more preferably; And
j) agglomerating the pellet with pellet agglomerates comprising 2 to 300 pellets. 10. A process according to any one of claims 1 to 9, characterized in that the molybdenum oxide powder contains 50 to 80% by weight of Mo. 11. A process according to any one of the preceding claims, wherein at least 90% by weight of molybdenum oxide powder particles are passed through a test body having a nominal aperture size of 300 [mu] m and at least 50% by weight of molybdenum oxide powder particles Is passed through a test body having a nominal opening size of 125 [mu] m. 12. A process as claimed in any of the preceding claims wherein the iron-containing powder contains at least 80 wt%, preferably at least 90 wt%, more preferably at least 95 wt%, most preferably at least 99 wt% Fe &Lt; / RTI &gt; 13. A process according to any one of claims 1 to 12, wherein at least 90% by weight of the iron-containing powder particles are passed through a test body having a nominal aperture size of 125 [mu] m and at least 50% Is passed through a test body having a nominal opening size of 45 [mu] m. 14. The method according to any one of claims 1 to 13, wherein at least 90% by weight of the carbon-based powder particles are passed through a test body having a nominal aperture size of 125 [mu] m and at least 50% Is passed through a test body having a nominal opening size of 45 [mu] m. The method of any one of claims 1 to 14, wherein the carbon-based powder is selected from the group consisting of sub-bituminous coals, bituminous coals, anthracite, lignite, coke, petroleum coke, and bio-carbons present in a particular charcoal. 16. The method according to any one of claims 1 to 15, wherein the carbon-based powder is selected from the group consisting of soot, carbon black and activated carbon. Have a geometric density of less than 4.0 g / cm &lt; ³ &gt;
1 to 25% by weight, preferably 1.5 to 20% by weight of Fe;
15 to 40% by weight, preferably 15 to 30% by weight of O;
5 to 25% by weight, preferably 7 to 20% by weight, of C;
Less than 15% by weight, preferably less than 10% by weight, of other elements, and
An iron and molybdenum-containing green pellet having a Mo composition of at least 30% by weight, preferably at least 40% by weight. 14. Green pellet according to claim 13, characterized in that it meets at least one of the following conditions:
- a moisture rate of less than 10% by weight, preferably less than 5% by weight;
Compression strength range 200 to 1000 N / pellet, preferably 300 to 800 N / pellet;
A geometric density of at least 1.2, preferably at least 1.5 g / cm &lt; ³ &gt;;
- geometric density 3.5 g / cm ^3, preferably less than 3.2 g / cm less than ^3; And
Diameter range 3 to 35 mm, preferably 5 to 25 mm. Have a geometric density of less than 4.0 g / cm &lt; ³ &gt;
2 to 30% by weight of Fe;
Less than 30% O;
Less than 20% C;
Less than 15% by weight of other elements; And
A reduced iron and molybdenum containing pellet having a Mo composition of at least 40% by weight, preferably at least 50% by weight. 20. The method of claim 19,
Characterized in that it contains from 2 to 25% by weight of Fe, preferably from 3 to 20% by weight of Fe, more preferably from 4 to 15% by weight of Fe, most preferably from 5 to 10% Pellets. 21. A process according to any one of claims 19 to 20,
By weight, less than 10% by weight of other elements, preferably less than 7% by weight of other elements. 22. A process according to any one of claims 19 to 21,
Characterized in that it contains at least 1% by weight of other elements, preferably at least 2% by weight, of other elements. 24. A process according to any one of claims 19 to 22,
Characterized in that it contains at least 60 wt.% Mo, preferably at least 65 wt.% Mo, more preferably at least 70 wt.% Mo. 24. A method according to any one of claims 19 to 23, wherein the pellet
Less than 10 wt.% O, preferably less than 8 wt.% O, more preferably less than 6 wt.% O, most preferably less than 4 wt.% O. 25. A method according to any one of claims 19 to 24,
By weight of C, less than 5% by weight of C, more preferably less than 0.5% by weight of C. 26. A pellet according to any one of claims 19 to 25,
Lt; RTI ID = 0.0 &gt; 95% &lt; / RTI &gt; by weight of Mo. 24. A method according to any one of claims 19 to 23, wherein the pellet
10 to 20% by weight of O, and 5 to 15% by weight of C, based on the total weight of the pellets. 28. The reduced pellet according to any one of claims 19 to 27, characterized in that it meets at least one of the following conditions:
Compression strength range 200 to 1000 N / pellet, preferably 300 to 800 N / pellet;
A geometric density of at least 1.2, preferably at least 1.5 g / cm &lt; ³ &gt;;
- geometric density 3.5 g / cm ^3, preferably less than 3.2 g / cm less than ^3;
Diameter range 3 to 30 mm, preferably 5 to 20 mm.

Images