TW201501839A - Iron and tungsten containing briquettes - Google Patents

Abstract

The invention relates to iron and tungsten containing briquettes and a process for producing the briquettes. A green briquette is produced from mixing an iron powder, a tungsten containing powder, and briquetting the mixture.

Description

Agglomerates containing iron and tungsten

This invention relates to a method of making agglomerates containing iron and tungsten. The invention also relates to agglomerates made by the method.

WO11053231 discloses a process for the manufacture of powders or powder agglomerates containing iron and tungsten. The powder containing tungsten carbide is mixed with iron oxide powder and/or powder containing tungsten oxide and optionally iron powder. The mixture is heated in a neutral or weak reducing atmosphere.

WO2008091210 discloses a powder comprising iron and tungsten comprising 30-60% by weight of W and the balance being iron. The powder was produced by mixing iron powder with WO ₃ powder. A bullet can be made from the powder.

It is an object of the present invention to provide novel iron and tungsten containing materials suitable for use in the fusion industry (e.g., steel), tungsten in casting and superalloy industries, and in a comparable cost effective manner.

At least one of the above objects is achieved, at least to some extent, by a process for the manufacture of agglomerates comprising iron and tungsten, the process comprising the steps of: a) providing a mixture comprising (wt%): 1-40 iron-containing powder 2-97 tungsten-containing powder containing at least one of tungsten oxide and tungsten carbide, optionally 1-25 carbon powder, 2-90 molybdenum powder b) added to the mixture: liquid, preferably water, One or more of the following may be selected as appropriate: binder, slagging agent, desulfurizing agent; c) briquetting to provide a plurality of green briquettes.

By this method, a green agglomerate containing iron and tungsten can be produced. When the melt is melted into an alloy in industrial production, the unreduced green compact can be used as a substitute for the conventionally fabricated iron-tungsten alloy and/or molybdenum-iron alloy. These green agglomerates can be manufactured at lower cost than standard grade iron alloys compared to standard grade ferroalloys. Its porous structure contributes to the rapid dissolution time in the melting of steel. The mass can be easily transported on the conveyor belt without the risk of slippage.

When the mixture is prepared, the total amount of water added is from about 1 to 10% by weight, more preferably from 2 to 5% by weight, based on the mixture.

Preferably, no binder or slag-forming agent is used. When mixed under wet conditions, the iron-containing powder strengthens the agglomerates, eliminating the need for a binder. Thereby the quality of the impurities can be reduced.

The method optionally includes the steps of: a) drying the green agglomerates.

By drying the green agglomerates, the risk of cracking caused by rapid vaporization of the liquid is minimized when heated at elevated temperatures.

The drying step optionally selected includes at least one of the following: - drying the green mass to a moisture content of less than 5% by weight, preferably less than 3% by weight; - drying the green body at a temperature in the range of 50-250 ° C, preferably 80-200 ° C, more preferably 100-150 ° C Agglomeration.

When the agglomerates are dried, there is still a temperature rise even if external heating is not used. It is believed that this is caused by the reaction of iron oxidation. The strength of the mass also increased. This makes it possible to provide a sufficiently strong agglomerate without the need to add a binder (ie, iron powder instead of the need for a binder). The dust problem is also minimized.

Many different types of industrial dryers can be used. The agglomerates can also be dried without active heating, such as at ambient air temperatures. In the dryer, the water vapor can be removed by evaporation of the gas or by vacuum. In order to improve process economy, the drying time in the dryer is preferably in the range of 10 to 120 minutes, more preferably 20 to 60 minutes. But longer drying times are of course also feasible.

The moisture content is defined as water present in the green agglomerate other than the water of crystallization. The moisture content can be determined by LOD (dry weight loss) analysis according to ASTM D2216-10. The dry matter composition refers to the composition of the dried sample, that is, any moisture present in the green mass is excluded.

The method preferably includes the step of: b) reducing the green agglomerates to provide a plurality of reduced agglomerates.

The reducing step preferably comprises at least one of the following: - reduction at a temperature in the range of 800-1500 ° C, preferably 1050-1400 ° C, more preferably 1100-1300 ° C, optimally 1150-1250 ° C; - at least Reduction in 20 minutes, more preferably in at least 30 minutes, - reduction in a furnace supplying inert or reducing gas, preferably a weak reducing gas, - 0.1-5 atm, preferably 0.8-2 atm, more preferably 1.05-1.2 Reduction is carried out under operating pressure in the atm range.

By monitoring the formation of CO/CO ₂ , it can be determined when the reduction process ends. The reduction time can be optimized by measuring the formation of CO and CO ₂ ; especially CO, since CO ₂ is formed mainly during the first few minutes of reduction, and then CO formation dominates until the carbon source is exhausted or all recoverable. The oxides have all been reduced. The reduction time is preferably up to 10 hours, preferably up to 2 hours, more preferably up to 1 hour. Depending on the reduction time, the reduction temperature and the relationship between carbon and the reducible oxides in the agglomerates; the reducible oxides of the agglomerates may be partially or completely reduced.

Preferably, the atmosphere in the furnace is controlled by supplying an inert or reducing gas at one end of the furnace, preferably a weak reducing gas and pumping at the opposite end (for example, a reaction gas (e.g., CO, CO ₂ and H ₂ O) and The supplied gas) is preferably supplied with an inert or reducing gas countercurrent on the outlet side of the furnace and evacuated at the inlet side of the furnace. That is, the inert or reducing gas is preferably supplied in a countercurrent manner. The inert or reducing gas can be, for example, any mixture of argon, N ₂ , H ₂ or H ₂ /N ₂ (e.g., 5:95 by volume).

The reduction furnace is preferably a continuous furnace, but may also be a batch furnace. In a continuous furnace, the agglomerates are transported from the inlet to the outlet during the reduction. Examples of furnaces are, for example, rotary kiln, rotary heart furnaces, shaft furnaces, grate kilns, travelling grate kilns, tunnel furnaces or batch furnaces. Other types of furnaces for solid state direct reduction of metal oxides can also be used. In a preferred embodiment, a belt furnace is used.

The reduction furnace is preferably operated at a pressure in the range of from 0.1 to 5 atm, preferably from 0.8 to 2 atm, more preferably from 1.0 to 1.5 atm, and most preferably from 1.05 to 1.2 atm.

Preferably, the atmosphere in the reduction furnace is controlled by supplying an inert or reducing gas at one end of the furnace, preferably a weak reducing gas and pumping at the opposite end (for example, a reaction gas (e.g., CO, CO ₂ and H ₂ O). And the supplied gas), it is more preferable to supply an inert or reducing gas countercurrent to the outlet side of the reduction furnace, and to evacuate at the inlet side of the reduction furnace. That is, the inert or reducing gas is preferably supplied in a countercurrent manner. The gas supplied may include argon, N ₂ , H ₂ , CO, CO ₂ or any mixture thereof. For example, H ₂ /N ₂ has a relationship such as 5:95, 20:80, 40:60, 80:20, and 95:5 by volume. In one particular example, the atmosphere comprising 20-60 vol% H ₂ and the remainder N _2. This atmosphere can reduce N ₂ absorption compared to, for example, H ₂ /N ₂ (5:95), and it can increase the density of the reduced aggregated particles. The atmosphere can also supply CO, for example from burning natural gas. Of course, other gas mixtures which are inert or reductive can be supplied to the furnace.

Preferably, the method further comprises the step of: c) cooling the reduced agglomerate to a temperature below 200 ° C, more preferably below 150 ° C in a non-oxidizing atmosphere (eg, a reducing or inert atmosphere), preferably in an inert atmosphere. temperature.

The atmosphere during cooling can be, for example, any mixture of argon, N ₂ , H ₂ or H ₂ /N ₂ (e.g., 5:95 by volume). Other ambiences are also available. If it is desired to have a very low nitrogen content in the agglomerates, the agglomerates can be cooled in a nitrogen-free atmosphere, such as an argon atmosphere.

In one embodiment, the compact is carried out at a compact pressure in the range of 80-1000 kg/cm ² , preferably 100-500 kg/cm ² .

In one specific example, the compact is carried out at a 1000-10000kg / cm ^2, preferably 2000-5000kg / cm ² of pressure within a range of the compact.

The briquetting machine is preferably a roller press. However, other types of briquetting machines can be used.

Prior to reduction, the green agglomerates are heat treated at lower temperatures as appropriate. The green compact is preferably heat treated at a temperature in the range of from 200 to 800 ° C, more preferably from 400 to 700 ° C. The heat treatment at a lower temperature as the case may be preferably carried out for 10 minutes to less than 2 hours, preferably less than 1 hour. By heat treatment at a lower temperature, the lubricant (if present) selected as appropriate can be burned off in a controlled manner. Additionally, molybdenum trioxide (if present) can be reduced to molybdenum dioxide. This can be used as a pre-reduction step prior to or prior to the reduction described in the previous paragraph. The heat treatment at 200-800 ° C can be carried out in the same furnace as the reduction. Heat treatment may be carried out as appropriate depending on the drying conditions as appropriate.

Lubricants and/or binders and/or slagging agents and/or desulfurizing agents may optionally be added during mixing. The binder selected as the case may be an organic or inorganic binder. The binder may be, for example, a carbonaceous binder that partially replaces the carbonaceous powder. Other binders may be, for example, bentonite and/or dextrin and/or sodium citrate and/or lime and/or gelatin. The slagging agent selected according to the situation may be limestone, dolomite and / or olivine. The total amount of lubricant and/or binder and/or slagging agent and/or desulfurizing agent may range from 0.1 to 10% by weight, more preferably less than 5% by weight, of the dry matter content of the green agglomerate. It can be in the range of from 1 to 10% by weight. The binder is optionally used because by adding water and iron, the green agglomerates become strong enough to be reduced in the reduction furnace without severe rupture. If a lubricant is added, it is preferably added in an amount of from 0.1 to 2%, for example from about 0.5 to 1% by weight, based on the dry matter content of the agglomerates. The lubricant can be, for example, zinc stearate. However, other lubricants used in powder metallurgy can be added.

Depending on the purity of the powder, the mixture agglomerates may contain other elements, including oxides that are difficult to reduce. The amount of these elements is mainly determined by the purity of the tungsten-containing powder and optionally the molybdenum-containing powder, but may also be derived from iron powder, impurities in the carbon powder, and elements from the surrounding atmosphere during heating, reduction or cooling. Reaction.

The entire process is an endothermic process and requires heating. To reduce the amount of external heating required, oxygen or air may be provided in the preheating zone to react with the formed carbon monoxide to form a carbon dioxide gas. If air is used, the nitrogen absorption of the agglomerates can be increased. If oxygen is used, the nitrogen uptake during the heating and reduction steps can be minimized.

Instead of drying the green mass prior to entering the reduction furnace, the furnace may have a drying zone operated at a temperature in the range of 80-200 ° C, preferably 100-150 ° C.

The reduction furnace may also include a pre-reduction zone located downstream of the drying zone (if used) and operating at a temperature in the range of 200-800 ° C, preferably 400-700 ° C.

The green and tungsten-containing green agglomerates have the following dry matter composition in weight percent: a) a mixture of 90-100, based on the weight percent of the mixture, comprising: 2-97 tungsten-containing powder containing tungsten oxide And at least one of tungsten carbide, optionally 0.1-25 carbon powder, 2-90 molybdenum powder, and the balance 1-40 iron powder; b) optionally used 10 Lubricants and / or binders and / or slagging agents and / or desulfurizers.

The reduced iron and tungsten agglomerates preferably comprise, by weight percent, W 3-97 Mo+W 50-97 O 10 C 10 Si 10 Co 10 other elements 5 and the rest is Fe 2-40.

When alloyed with tungsten and optionally tungsten/molybdenum in the practice of melting, the agglomerate can replace the iron alloy produced in a conventional manner. These green agglomerates can be manufactured at a lower cost than standard grade iron tungsten. The mass dissolves faster than standard grade iron tungsten. The oxygen content in the agglomerates may be partially or completely reduced depending on the reduction time, the relative carbon content associated with the amount of reducible oxides, and the reduction temperature. The mass can be easily transported on the conveyor belt without the risk of slippage.

By compacting prior to reduction, agglomerates having a higher porosity than the agglomerates formed from the reduced powder can be produced. In addition, agglomerates without binders and lubricants can be produced. The mixture provided in step a) of the mixture comprises (% by weight): 2-97 tungsten powder, optionally used 0.1-25 toner, 2-90 with molybdenum powder and the balance 1-40 iron powder.

The iron powder is preferably from 2 to 25% by weight, more preferably from 3 to 15% by weight. The tungsten-containing powder is preferably at least 20% by weight.

The tungsten-containing powder + molybdenum-containing powder preferably exceeds 50% by weight of the mixture, more preferably more than 70% by weight of the mixture.

In one embodiment, the mixture consists of (wt%): 1-40, preferably 3-15 iron-containing powder, and 75-99, preferably 85-97 tungsten-containing powder.

The tungsten-containing powder preferably includes tungsten oxide and tungsten carbide. The reducible oxide in the tungsten-containing powder and the iron-containing powder is preferably stoichiometrically matched with carbon in the tungsten carbide such that after reduction, the carbon content is less than 10% by weight, preferably less than 5% by weight, more preferably less than 1% by weight, optimally less than 0.5% by weight, and oxygen is less than 10% by weight, preferably less than 5% by weight, most preferably less than 3% by weight.

Thereby, agglomerates of iron and tungsten which are essentially composed of iron and tungsten and unavoidable impurities can be produced.

Agglomerates of iron and tungsten composed of iron and tungsten and unavoidable impurities may also be produced from a mixture in which tungsten carbide is partially or completely replaced by carbon powder, that is, carbon and tungsten in tungsten carbide and/or carbon powder. The reducible oxides in the powder and iron powder are stoichiometrically matched.

Iron-and-tungsten agglomerates composed of iron, tungsten and molybdenum and unavoidable impurities can be produced by adding a molybdenum-containing powder as the case may be used. Here, the carbon from the tungsten carbide and/or carbon powder is stoichiometrically matched to the molybdenum-containing powder, the tungsten-containing powder, and the reducible oxide in the iron powder. Here, the tungsten-containing powder is preferably a tungsten carbide powder comprising at least 70% by weight of WC, preferably at least 95% by weight of WC, or a tungsten oxide powder comprising at least 70% by weight of WO ₃ , preferably at least 95% by weight of WO ₃ , Or a mixture of such powders.

Preferably, the carbon is equilibrated with oxygen such that after reduction, the carbon content is less than 10% by weight, preferably less than 5% by weight, more preferably less than 1% by weight, most preferably less than 0.5% by weight, and less than 10% by weight of oxygen. Preferably less than 5% by weight, most preferably less than 3% by weight.

The relative amounts of molybdenum and tungsten can be varied by varying the relative amounts of tungsten-containing powder and molybdenum-containing powder while taking into account the carbon and oxygen balance.

In a preferred embodiment, the weight ratio (WC/WO ₃ ) between the tungsten carbide and the tungsten oxide is in the range of 0.5 to 5, preferably 1 to 4, more preferably 1.5 to 3. The best balance is about 2. Thereby, tungsten carbide can be matched with tungsten oxide without adding carbon powder.

In a specific example, the weight ratio (Mo/W) between molybdenum and tungsten is determined to be in the range of 0.25-4, preferably 0.5-2, more preferably 0.8-1.25.

Tungsten powder

The tungsten-containing powder is preferably one of the following: - a powder containing tungsten carbide, - a powder containing tungsten oxide, - a mixture of a powder containing tungsten carbide and a powder containing tungsten oxide.

Powder containing tungsten carbide

The powder containing tungsten carbide is a powder containing tungsten carbide contained in a metal matrix. The powder containing tungsten carbide is preferably obtained from tungsten sintered carbide fragments. The tungsten carbide-containing powder preferably contains from 1 to 10% by weight of carbon, the balance being tungsten and concomitant impurities. The powder containing tungsten carbide may also include an alloying element which forms a matrix (bonding material) of the sintered tungsten carbide material. The proportion of the carbide phase is usually between 70% and 97% of the total weight of the composite. Carbon is present in the powder particles in the form of tungsten carbide grains, and the average grain size is typically between 0.10 μm and 15 μm. Any powder particle can include several tungsten carbide grains, especially when the particle size is large. In addition, the tungsten carbide-containing powder may include powder particles that do not contain any tungsten carbide grains; however, most of the powder particles will include One or more tungsten carbide grains.

Some tungsten carbide powders may contain up to 15% by weight cobalt; typically from about 1 to 10% by weight Co. For example, tool materials in circuit board drills typically comprise fine-grained sintered tungsten carbide present in a cobalt matrix in an amount of 6% by weight of the tool material, while coarse-grained tungsten carbide materials are typically used A tool material for a mining bit, wherein the cemented carbide material has a cobalt content of about 10% by weight. These powders can be used if cobalt is allowed or is required in the agglomerates to be manufactured. If the opposite is true, the powder can be used after the cobalt is filtered off. For example, commercially available commercially available chips containing from 1 to 10% by weight of Co (typically from 3 to 8% by weight Co) may be hydrometallurgically leached to provide cobalt content. Reduced to less than 1% by weight Co, preferably less than 0.5% by weight Co, more preferably less than 0.2% by weight Co. The cobalt obtained by the leaching process can be recycled and can be used as a commercial product by itself.

Of course, a tungsten carbide powder having a low cobalt content or no cobalt can be used. That is, a powder containing less than 1% by weight of Co, more preferably less than 0.5% by weight of Co, even more preferably less than 0.2% by weight of Co.

The tungsten carbide powder preferably contains at least 90% by weight of WC, more preferably at least 95% by weight.

Preferably, at least 90% by weight, more preferably at least 99% by weight of the particles of the tungsten carbide-containing powder can pass through a test screen according to ISO 3310-1:2000, the screen having a nominal pore size of 250 μm, more preferably 125 μm. The best is 90 μm. Very fine powders can be suitably used, wherein at least 99% by weight passes through the 45 μm test screen.

Tungsten oxide-containing powder

The powder containing tungsten oxide may be a powder containing iron and tungsten oxide, more preferably iron tungstate in the form of tungsten iron ore. Preferred is a tungsten iron ore containing more than 60% WO ₃ , more preferably at least 70% WO ₃ . The tungsten iron ore is crushed and/or ground and/or ground into a powder such that at least 80% by weight of the particles, preferably at least 90%, pass through a test screen according to ISO 3310-1:2000, the nominal of which is nominal The pore size is 250 μm, more preferably 125 μm.

The tungsten oxide-containing powder may also be a pure tungsten oxide powder containing less than 5% by weight of other elements, preferably less than 1% by weight of other elements, in addition to W and O. By way of example, at least 95% by weight of WO ₃ (preferably at least 99% by weight) of powder is included.

Preferably at least 80% by weight of the particles, more preferably at least 90% by weight of the particles of the tungsten oxide powder pass through a test screen according to ISO 3310-1:2000, the screen having a nominal pore size of 250 μm, more preferably 125 μm, preferably It is 90 μm. Very fine powders can be suitably used, wherein at least 99% by weight passes through the 45 μm test screen.

The tungsten oxide-containing powder may also be a mixture of iron tungstate powder and pure tungsten oxide powder.

Other available grades of tungsten oxide powder can also be used.

Molybdenum powder

The molybdenum containing powder is preferably molybdenum oxide powder. The powder preferably consists of molybdenum dioxide and/or molybdenum trioxide powder.

The molybdenum oxide powder should contain 50 to 80% by weight of Mo, and the remaining elements are oxygen and impurities. The impurities are preferably less than 10% by weight, more preferably less than 5% by weight, most preferably less than 1% by weight.

Preferably at least 90% by weight, more preferably at least 99% by weight of the particles of the molybdenum oxide powder are passed through a test screen according to ISO 3310-1:2000, the screen having a nominal pore 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% by weight of metallic iron, preferably at least 90% by weight of metallic iron, more preferably at least 95% by weight of metallic iron, and most preferably at least 99% by weight of metallic iron. The iron powder may be sponge iron powder and/or water atomized iron powder and/or gas atomized iron powder and/or iron dust and/or iron sludge powder. For example, the dust filter X-RFS40 from Höganäs AB, Sweden is a suitable powder.

The iron powder may be partially or completely replaced by iron oxide powder, such as (but not limited to): from a group of FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , FeO(OH), (Fe ₂ O ₃ *H ₂ O) A powder consisting of one or more of them. The iron oxide powder may be, for example, rust. The iron-containing powder preferably contains at least 50% by weight of metallic iron, more preferably at least 80% by weight of metallic iron, and most preferably at least 90% by weight of metallic iron.

The iron-containing powder may also be feldspar FeWO ₄ . It may also be a mixture of one or more of FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , FeO(OH), (Fe ₂ O ₃ *H ₂ O), FeWO ₄ and Fe.

Preferably at least 90% by weight, more preferably at least 99% by weight of the iron-containing powder particles pass through a test screen according to ISO 3310-1:2000, the screen having a nominal pore size of 125 μm, more preferably 90 μm. Very fine powders can be suitably used, wherein at least 99% by weight passes through the 45 μm test screen.

Carbon powder as appropriate

The green mass preferably includes a carbon source. In a preferred embodiment, the carbon source is a tungsten carbide-containing powder wherein the carbon content is stoichiometrically matched to the oxide content of the green agglomerate. However, the carbon powder may also be used in combination with a powder containing tungsten carbide or as a carbon source in the form of a single carbon source.

The carbon powder is preferably selected from the group consisting of sub-bituminous coal, bituminous coal, lignite, anthracite, graphite, coke, petroleum coke, and bio-carbon (such as charcoal), or a carbonaceous powder obtained by processing such resources. The toner may be, for example, soot, carbon black, activated carbon. The toner can also be a mixture of different toners.

Regarding the choice of toner, it is preferable to consider the reactivity of carbon. Carbon black is preferably used. German lignite (brown coal), charcoal, bituminous coal and sub-bituminous coal are also highly reactive. Graphite is also suitable.

Preferably at least 90% by weight, more preferably at least 99% by weight of the carbon powder particles pass through a test screen according to ISO 3310-1:2000, the screen having a nominal pore size of 125 μm, more preferably 45 μm, most preferably 20 μm.

Preferably, the amount of carbon source (i.e., WC powder and/or carbon powder) is determined by analyzing the amount of tungsten-containing powder, iron powder, and optionally the reducible oxide in the molybdenum-containing powder. Preferably, the amount of carbon source is selected to stoichiometrically match or slightly exceed the amount of the reducible oxide in the tungsten-containing powder, iron powder, and optionally the amount of reducible oxide in the molybdenum-containing powder. However, the carbon source The amount can also be substoichiometric.

The amount of carbon source can be optimized by measuring the carbon content and the oxygen content (increasing or decreasing the carbon source to achieve the desired carbon and oxygen content) in the reduced agglomerates. Depending on the application of the agglomerates, oxides (such as Si, Ca, Al, and Mg) that are difficult to reduce by carbon can be allowed to reach at most certain levels. For example, in many steel metallurgical applications, such oxides can be treated, for example, by removing them in the slag of the steel melt. If lower amounts of such oxides and elements are desired, pure grade tungsten-containing powders, iron powders and, optionally, molybdenum-containing powders may be used, for example, containing lower amounts of such oxides or no such oxides. The level.

Green body containing iron and tungsten

The green mass comprises the mixture provided in step a). When the mixture is prepared, the total amount of water added is from about 1 to 10% by weight, more preferably from 2 to 5% by weight, based on the mixture. The green mass can be dried to reduce the moisture content to less than 5% by weight, or less than 3% by weight.

The green mass may optionally comprise up to 10% by weight of one or more organic or inorganic binders and/or slagging agents and/or desulfurizing agents and/or lubricants. In one embodiment, the green mass does not contain a lubricant, a binder, a slagging agent, and a desulfurizing agent.

The green mass is unexpectedly stabilized and thus the dried green agglomerate can be used to directly alloy the steel melt with tungsten and optionally tungsten and molybdenum, i.e., without pre-reduction of the green mass . The green mass can be a cost effective way of alloying tungsten and optionally tungsten and molybdenum. The green agglomerates may also be partially or completely reduced by heating the green agglomerates in a subsequent step.

Agglomerates containing iron and tungsten

Agglomerates containing iron and tungsten can be produced by the proposed method, which consists of the following (% by weight): W 3-97, preferably 30-95, Mo+W 50-97, preferably 70-95, O 10, preferably 5, better 3, C 10, preferably 5, better 1,Si 10, preferably 5, better 1,Co 10, preferably 5, better 1, other elements 5, preferably 1, and the rest is Fe 2-40, preferably 3-25, more preferably 5-20, and most preferably 5-15.

These blocks have a geometric density in the range of 2-6 g/cm ³ , preferably 4-5.5 g/cm ³ .

O and C can be present in an amount of 0.05% or higher. Si and Co can be present in trace amounts to both. It is preferably unintentionally added but can be present as an impurity. Other elements than W, Mo, Fe, O, C, Si, Co may be present in trace amounts to both. It is preferably unintentionally added but can be present as an impurity.

According to one example, agglomerates containing iron and tungsten consist of (% by weight): W 60-97, preferably 80-95, O 10, preferably 5, better 3, C 10, preferably 5, better 1,Si 10, preferably 5, better 1,Co 10, preferably 5, better 1, other elements 5, preferably 1, and the rest is Fe 2-40, preferably 3-25, more preferably 5-20, and most preferably 5-15.

These geometric density of the agglomerates ^3, in the preferred 3-7g 2-8g / cm / cm ^3, more preferably in the range of 4-6g / cm ^3. The geometric density can range from 4.5 to 5.5 g/cm ³ .

When alloyed with tungsten in the practice of melting, such agglomerates can replace the iron-tungsten alloy produced in a conventional manner. These agglomerates can be manufactured at lower cost than standard grade iron tungsten. In addition, the agglomerates dissolve faster than standard grade iron tungsten due to their porous structure.

According to another example, the agglomerates containing iron and tungsten consist of (wt%): W 20-80, preferably 30-65, more preferably 40-55, Mo 20-80, preferably 30-65, more preferably 40-55, Mo+W > 50, preferably > 70, O 10, preferably 5, better 3, C 10, preferably 5, better 1,Si 10, preferably 5, better 1,Co 10, preferably 5, better 1, other elements 5, preferably 1, and the rest is Fe 2-40, preferably 3-25, more preferably 5-20, and most preferably 5-15.

The weight ratio of molybdenum to tungsten (Mo/W) is preferably determined to be in the range of 0.25 to 4, preferably 0.5 to 2, more preferably 0.8 to 1.25.

Such agglomerates have a geometric density in the range of from 1 to 6 g/cm ³ , preferably from 2 to 5 g/cm ³ .

These agglomerates containing iron, tungsten and molybdenum are suitable for alloying with tungsten and molybdenum in the practice of melting. Agglomerates containing iron, tungsten and molybdenum can be produced at relatively low cost. In addition, the agglomerates dissolve more rapidly in the steel melt due to their porous structure.

The amount of other elements is mainly controlled by the purity of the tungsten-containing powder and optionally the molybdenum-containing powder. The purity of the iron-containing powder and optionally the toner may of course affect the amount of other elements.

The nitrogen content is mainly determined by the nitrogen content of the agglomerate during heating, reduction and cooling. By controlling the atmosphere in these steps, the nitrogen content can be less than 0.5% by weight, preferably less than 0.1% by weight and most preferably less than 0.05% by weight.

Example

A 1/3 WO ₃ powder by weight was mixed with 2/3 WC powder by weight. To the mixture was added 5% by weight of Fe powder. The amount of powder, particle size and purity are shown in Table 1. When the powder was mixed, 5 wt% of water was added.

The mixture is then fed into a briquetting machine. The green compact produced is subsequently dried to a moisture content of less than 3% by weight.

The green aggregates were reduced in a batch furnace at a temperature of 1200 ° C for a period of 2 hours in a 95% by volume N ₂ and 5 vol % H ₂ atmosphere. The mass is then cooled to a temperature of about 100 ° C, and then the atmosphere is evacuated and removed from the furnace. The average density of the reduced agglomerates was determined to be 5.9 g/cm ³ as measured according to ASTM 962-08.

Claims (9)

A method of producing agglomerates comprising iron and tungsten, the method comprising the steps of: a) providing a mixture comprising (wt%): 2 to 97 tungsten-containing powder comprising at least one of tungsten oxide and tungsten carbide, 0.1 to 25 toners, 2 to 90 molybdenum powder, 1 to 40 iron powder, b) to the mixture: liquid, preferably water, optionally using one or more of the following A lubricant, a binder, a slagging agent, a desulfurizing agent; c) a compact to provide a plurality of green agglomerates. The method of claim 1, wherein the mixture satisfies the following conditions: > 50 molybdenum-containing powder + tungsten-containing powder. The method of claim 1 or 2, wherein the method further comprises drying the green agglomerates at a temperature below 200 ° C, preferably below 150 ° C, until the moisture content of the agglomerates Less than 10% by weight, preferably less than 5% by weight. The method of any one of claims 1 to 3, wherein the method further comprises at 800-1500 ° C, preferably 1050-1400 ° C, more preferably 1100-1300 ° C, optimal 1150-1250 ° C range The green masses are reduced at the internal temperature. The method of claim 4, wherein the method comprises one or more of the following steps: d) cooling the reduced agglomerates below a non-oxidizing atmosphere, preferably in an inert atmosphere. 200 ° C, more preferably lower than 150 ° C temperature. A green body comprising iron and tungsten having the following dry matter composition in weight percent: a) a 90 to 100 mixture, based on the weight percent of the mixture, comprising: 2 to 97 tungsten powder, which contains At least one of tungsten oxide and tungsten carbide, optionally 0.1 to 25 carbon powder, 2 to 90 molybdenum powder, and 1 to 40 iron powder; b) optionally up to 10 binders and/or A slagging agent and/or a desulfurizing agent. A mass comprising iron and tungsten, in weight percent, consisting of W 3 to 97 Mo+W 50 to 97 O 10 C 10 Si 10 Co 10 other elements 5 and the rest are Fe 2 to 40. Iron and tungsten agglomerates as claimed in item 7 of the patent application, in weight percent, consisting of the following: W 60-97, preferably 80-95, O 10, preferably 5, better 3, C 10, preferably 5, better 1, Si 10, preferably 5, better 1,Co 10, preferably 5, better 1, other elements 5, preferably 1, and the rest is Fe 2-40, preferably 3-25, more preferably 5-20, and most preferably 5-15. The agglomerates containing iron and tungsten according to item 7 of the patent application are composed of the following components: W 20-80, preferably 30-65, more preferably 40-55, Mo 20-80, preferably. 30-65, better 40-55, Mo+W >50, preferably >70, O 10, preferably 5 , better 3, C 10, preferably 5, better 1Si 10, preferably 5, better 1,Co 10, preferably 5, better 1, other elements 5, preferably 1, and the rest is Fe 2-40, preferably 3-25, more preferably 5-20, and most preferably 5-15.