Method of production of powders of refractory metals
(57) Abstract:Usage: in the field of powder metallurgy for the production of powders of refractory metals, which can find application in the production of hard alloys, catalysts and bodies glow in the electronics industry. The inventive compounds of refractory metals in the form of acids or salts is subjected to thermal shock of cold. 2 C.p. f-crystals, 2 tab. The invention relates to the production of powders of refractory metals and can be used in enterprises: non-ferrous metallurgy in the production of high-quality hard alloys; chemical industry for preparation of catalysts; the electronics industry in the manufacture of bodies glow and so on.The end product of metallurgical and chemical processing of ores solid minerals and their concentrates are metal salts, for example, salts of tungstic acid, chlorides, fluorides, which play an essential role in the manufacture of oxides with a low content of impurities, respectively, and obtaining metals of high crystallographic perfection.A method of obtaining powder of refractory metals, including extraction, is orgie. M. Metallurgy, 1969.)
The disadvantage of this method is the difficulty of obtaining powder of high purity due to the low degree of extraction of mineral raw materials (for number of elements, it is difficult to be extracted from the minerals include, for example, beryllium, zirconium, vanadium) and the difficulty of separating pure compounds from concentrates.The known method of producing metal powder from a melt, comprising applying to the inside of the melt energy in the form of liquefied natural gas (ed. St. USSR N 117607, CL 5 B 22 F 9/08, publ.30.08.85, bull.N 32).However, this method is applicable only to obtain an amorphous powder.A method of obtaining powder by grinding solid material by mechanical impact on the material and coolant in the grinding zone. Moreover, for the intensification of the grinding process, first, for a certain period of time, perform only the mechanical stresses on the material, and then, simultaneously with the mechanical action, submit coolant (ed. St. USSR N 1551422, CL 5 B 02 19/18, publ.23.03.90, bull.N 11).The disadvantage of this method are significant energy costs.The closest proposed A acid (concentrated solutions of caustic soda or caustic potash), allocation in the form of crystals of parabolicamara ammonium, calcining it to obtain tungsten anhydride, followed by reduction to pure metal (Zelikman A. N. Nikitina L. S. Wolfram, M. Metallurgizdat, 1978).The disadvantage of this method is that when extracting valuable components of the ore remains in them an increased amount of impurities, which represent 0.06% of the total volume, which leads to increased structural heterogeneity in pure metals. In addition, the known method cannot obtain powdered metal components with a particle size within a narrow range (for example, for tungsten 3 20 µm) and its influence on physico-mechanical properties of finished products.The purpose of the invention improve the quality of powders of refractory metals by increasing the depth of the decomposition of raw materials due to cracking of the crystals at the grain boundaries of the impurity atoms.The aim is achieved in that in the method of production of powders of refractory metals, including grinding of the ore, removing the products of the compounds in the form of the acids or their salts, refining, calcining, and recovering the metal powder is injected operation thermal shock of cold. Pricol.Under the action of low temperatures in the crystal lattice defects occur, which allow to deform it and to make the split at the temperature of liquid helium, which aligns the grain of the metal powder. The occurrence of defects always causes a loss of strength of ties in a solid, which is equivalent to increasing the propensity of it to the isothermal decomposition. thermal shock, sufficient to restore defects in the material structure and even split large conglomerates may increase if pre-raw components to heat up to temperatures that do not cause redox processes from 25 to 400oC.Example 1. Obtained in a known manner from ore concentrates paraformat ammonium sprayed into liquid nitrogen and calcined in a furnace having three temperature zones (I 400oC, II 450oC, III 490oC), sieved and reduced to metallic tungsten. Cold treatment provides an excessive number of active centers, which allows to obtain the tungsten trioxide (WO3) high chemical activity and to improve the physicochemical and mechanical properties of metal powders.Example 2. Heated to 70o3. Heated to 150oC paraformat ammonium sprayed into liquid nitrogen and calcined to obtain WO3.Table 1 presents data on the change in purity WO3depending on the technology of production.Table 2 presents changes in particle size distribution of powders of tungsten at different processing modes parabolicamara ammonium.Cold treatment, as can be seen from the table.2, increases the depth of the decomposition of the original raw components and leads to a change in grain size fractions of metal powders.In addition, the grain size of the powder, as it is known (T. Millner Actg. Techn, Hung, 17, 1957, c.67-112, 289-30h), is a criterion tendency to recrystallization produced from this powder products. The latter makes it clear that the fine powder of tungsten is a "guarantee high durability products to recrystallization".Example 4. Paramolybdate ammonium extracted from ores known method, calcined at 450oC, is subjected to thermal shock of cold when the temperature of liquid nitrogen, the obtained molybdenum anhydride sift, restore in two stages (I 550oC, II 920oC) the metal powder is pressed and the experience a reduction of energy consumption on subsequent technological operations (welding, forging and wire drawing) due to the fineness of the structure of materials.Example 5. The ammonium perrhenate is subjected to blow cold when the temperature of liquid helium and restore in two stages in the environment of hydrogen at a temperature of 360 and 970oC to obtain rhenium powder, which is pressed and bake.The use of cryogenic cooling contributes to the refinement of the microstructure of the powder, the emancipation of impurity inclusions and improve the plasticity, which beneficially affects the process of rolling sheets to the size of the foil.Thus, low-temperature processing allows to prevent abnormal growth of grains and to obtain uniform fine-grain structure of the metal needed to improve the quality of products made of refractory metals. 1. Method of production of powders of refractory metals, including grinding of the ore, removing the products of compounds of refractory metals in the form of the acids or their salts, refining, calcining, and recovering the metal powder, characterized in that the source components in the form of acids or salts of refractory metals subjected to thermal shock of the cold.2. The method according to p. 1, characterized in that ishodny, not causing oxidative reactions.3. The method according to PP. 1 and 2, characterized in that thermal shock of cold carried out at any stage of the selection acids or salts of refractory metals.
FIELD: non-ferrous metallurgy, possibly production of highly purified powders of tantalum and niobium with large specific surface by metal thermal reduction.
SUBSTANCE: method is realized at using as corrosion protection means layer of halide of alkali metal formed on inner surface of vessel before creating in reaction vessel atmosphere of inert gas. Charge contains valve metal compound and halide of alkali metal. It is loaded into reaction vessel and restricted by protection layer of halide of alkali metal having melting temperature higher than that of charge by 50 - 400°C. Before loading charge, valve metal compound and alkali metal halide may be mixed one with other. Mass of protection layer of alkali metal halide Ml and charge mass Mc are selected in such a way that that to satisfy relation Ml = k Mc where k - empiric coefficient equal to 0.05 - 0.5. Gas atmosphere of reaction vessel contains argon, helium or their mixture. Fluorotantalate and(or) oxyfluorotantalate or fluoroniobate and(or) oxyfluoroniobate of potassium is used as valve metal compound. Sodium, potassium or their mixture is used as alkali metal. Chloride and(or) fluoride is used as alkali metal halide. Valve metal compound and alkali metal halide may contain alloying additives of phosphorus, sulfur, nitrogen at content of each additive in range 0.005 - 0.1% and 0.005 - 0.2% of mass valve metal compound respectively. Invention lowers by 1.3 - 2 times contamination of powder with metallic impurities penetrating from vessel material. Value of specific surface of powder is increased by 1.2 - 1.8 times, its charge is increased by 10 - 30 %, leakage current are reduced by 1.2 - 1.5 times.
EFFECT: improved quality of valve metal powder, enhanced efficiency of process due to using heat separated at process of reducing valve metal for melting protection layer.
9 cl, 1 tbl, 4 ex
FIELD: powder metallurgy, possibly production of finely dispersed powder of molybdenum, its composites with tungsten, namely for producing hard alloy materials on base of molybdenum and tungsten.
SUBSTANCE: method provides production of molybdenum and its composites with tungsten at temperature no more than 900°C and also production of materials in the form of finely dispersed powders. Method comprises steps of reducing compounds of molybdenum and tungsten (MoO3 and WO3) by metallic magnesium in medium of melt chlorides such NaCl, KCl or carbonates such as Na2CO3, K2CO3 or their binary mixtures such as NaCl - KCl, Na2CO3 - K2CO3, NaCl - Na2CO3, KCl - K2CO3 at temperature 770 -890°C. According to results of fineness analysis produced powder of molybdenum represents homogenous material having 80% of particles with fraction size 2.2 - 3 micrometers. Composition material depending upon Mo content includes particles with fraction size 5 - 15 micrometers.
EFFECT: enhanced efficiency of method.
1 tbl, 3 ex
FIELD: treatment of powdered, especially metal containing initial material introduced together with treating gas such as reducing gas for creating fluidized bed in fluidized bed chamber, for example in fluidized-bed reactor.
SUBSTANCE: treating gas at least after partial conversion in fluidized bed is removed out of fluidized bed and then outside fluidized bed it is partially recovered, preferably oxidized due to performing chemical, namely exothermal reaction with gaseous and(or) liquid oxidizer. Heat energy of such reaction at least partially is fed to fluidized-bed chamber, especially to fluidized bed or it is taken out of it. Cyclone is arranged over fluidized bed in fluidized-bed chamber. Powdered initial material is heated or cooled in zone of cyclone, namely near inlet opening of cyclone due to using treating gas at least partially recovered over fluidized bed in fluidized-bed chamber, possibly heated or cooled, and(or) due to using system for recovering treating gas.
EFFECT: possibility for decreasing caking on distributing collector of fluidized-bed reactor, lowered slagging in zone of fluidized bed.
10 cl, 1 dwg
FIELD: nonferrous metallurgy.
SUBSTANCE: invention relates to manufacturing zirconium powder for making pyrotechnic articles, in particular explosive and inflammable mixtures. By-layers prepared powered mixture of potassium fluorocirconate and alkali metal chloride, preferably sodium chloride, at ratio 1:(0.15-0.6) and sodium metal in amount exceeding its stoichiometrically required amount by 10-20%. Preparation involves grinding of potassium fluorocirconate and alkali metal chloride to fineness below 50 μm as well as preliminary recrystallization of potassium fluorocirconate. Charge is heated to temperature 450-600°C, at which reduction reaction starts and during this reaction reaction mixture heats to 700-800°C and reduction of potassium fluorocirconate takes place. Reaction products are cooled to 400-650°C and freed of sodium through vacuum distillation at residual pressure 1.3-13.3 Pa for 0.5-2.0 h, after which they are discharged from reaction vessel and ground. Zirconium powder is washed with water to remove fluoride and chloride salts and then dried. Zirconium powder contains 95-98% of fine fractions, including fraction below 10 μm in amount 45-55%.
EFFECT: enhanced fineness of prepared zirconium powder end assured fire safety of the process.
8 cl, 3 ex
SUBSTANCE: invention pertains to procurement of metallic device; in particular, parts for gas turbines of the flying constructions made from titanium alloys. To produce such metallic devices, the following range of procedures must be brought into action. Firstly, one or several non-metallic junction-predecessors should be made ready, each containing metallic composition element therein. These need to be chemically restored to procure a multitude of initial metallic particles, preferably those whose size varies between 0.0254 mm to approximately 13 mm, which do not have to be melted down. After having been fused at a later stage, they will solidify. The melted and solidified metal can be used either as a casting metal product or can be transferred into a partially finished product (billet) to be processed additionally until it is ultimately ready. The invention permits to substantially reduce the frequency of chemical faults in a metal product.
EFFECT: procurement of metal products by means of reconstruction of non-metal junction-predecessors and by fusion with a view to decrease the frequency of any chemical faults.
19 cl, 4 dwg
SUBSTANCE: method includes reduction of fluorine tantalite of potassium with liquid sodium in medium of melted saline bath of halogenides of alkali metals by means of alternate portioned dozing of sodium, and further - of fluorine tantalite of potassium. Fluorine tantalite of potassium is introduced into mixtures with part of the charge of halogenides of alkali metals, used for making of a saline bath. Amount of halogenides of alkali metals in the mixture introduced into melt with fluorine tantalite of potassium constitutes from 60 to 125% (wt) from weight of fluorine tantalite of potassium.
EFFECT: dimension in size of powder particles, reduction of duration of reduction process, decreasing of power consumption for melting of saline charge and forced cooling of reaction vessel.
1 tbl, 1 ex
SUBSTANCE: invention concerns rare-metal industry. Particularly it concerns receiving of metallic tantalum by metallothermic reduction of its salts. For receiving of metallic tantalum charge, containing mixture of double complex chloride salt of tantalum - KTaCl6 and potassium chloride - KCl in ratio 1:(0.2÷0.5) by mass are fed by portions or uninterruptedly in the form of powder or melt on melt mirror of metallic sodium, taken in excess 60-80% of stoichiometrically necessary amount. Reduction is implemented at temperature 550-650°C, with speed of charge feeding 15-20 g/cm2·hour of area melt mirror of metallic sodium melt. Received reduced reactionary mass is subject to vacuum- thermal processing at temperature 500-540°C and residual pressure, not exceeding equilibrium pressure of sodium steams at temperature of vacuum- thermal processing of unreacted sodium. After vacuum- thermal processing it is implemented hydro metallurgical treatment of reactionary mass.
EFFECT: exclusion of ecological pollution of environment.
4 cl, 2 tbl, 2 ex
SUBSTANCE: double complex chlorides of ittrium and potassium is reduced by lithium at temperature 450-720°C in inert atmosphere and high pressure. Received reacting mass is heated at a rate 3-5°C/min up to the temperature for 60-300°C higher the reduction temperature and then it is implemented vacuum separation at a temperature 750-780°C and evacuation 1·10-4 millimetres of mercury.
EFFECT: it is provided receiving of microcrystalline metallic powder of itrrium with minimal content of oxygen and gas-producing admixtures, described by high dispersity.
5 cl, 1 tbl, 1 dwg, 1 ex
SUBSTANCE: method includes heating of charge, containing oxygenous or oxygenous and oxygen-free composition of tantalum or niobium and halogenide of alkali metal with formation of melt. Into melt it is introduced alkali metal at blending and it is implemented reduction of tantalum or niobium at temperature 550-850°C. Additionally amount of oxygen in melt is regulated by means of changing of ratio of components of harge according to relation where n(O) - amount of oxygen, mol, k - empirically determined coefficient, k=60-350 mol, m1 and M1 - mass and molar mass of oxycompound of tantalum or niobium correspondingly in kg and kg/mol, m2 and M2 - mass and molar mass of oxygen-free composition of tantalum or niobium correspondingly in kg and kg/mol, m3 and M3 - mass and molar mass of alkali metal halogenide correspondingly in kg and kg/mol.
EFFECT: increased purity of powder, increasing of its specific surface area.
5 cl, 1 tbl, 7 ex
SUBSTANCE: invention refers to production of item out of alloy alloyed with alloying agent without melting. There is prepared a mixture of a non-metallic compound-precursor of basic metal and a non-metallic compound-precursor of an alloying element. Compounds-precursors are chemically reduced to metal alloy without melting. There is introduced one or more component-additive and metal alloy is compacted producing a packed metal item without melting. Also the component-additive is introduced during preparation of mixture or during chemical reduction, or upon chemical reduction. Additionally, an element, mixture of elements or a chemical compound are used as the component-additive. Notably, the component-additive is dissolved in a matrix or creates discrete phases in micro-structure of the alloy and is not reduced at the stage of chemical reduction.
EFFECT: facilitating production of items out of homogeneous alloy without melting its constituents causing oxidation; also composition of this alloy is impossible to produce by any other procedure.
9 cl, 3 dwg