121 results about "Ammonium paratungstate" patented technology

The invention discloses a preparation method of a high-strength tungsten alloy wire with the length exceeding 150 km for photovoltaic silicon wafer cutting, and belongs to the technical field of tungsten wire manufacturing. The preparation method of the high-strength tungsten alloy wire comprises the following steps that ammonium paratungstate and lanthanum oxide are added into water to obtain a mixed solution, and the mixed solution is dried, calcined and reduced to obtain mixed tungsten powder; pressing the mixed tungsten powder into a rod shape, and sintering to obtain a sintered tungsten rod; annealing the sintered tungsten rod to obtain a completely recrystallized rod, and performing rotary swaging to obtain a rotary swaged tungsten rod; drawing the rotary swaged tungsten rod to obtain a tungsten filament with the diameter of 0.37-0.41 mm, and annealing to obtain a tungsten filament A; drawing the tungsten filament A to obtain a tungsten filament with the diameter of 0.16-0.18 mm, and annealing to obtain a tungsten filament B; and drawing the tungsten filament B to obtain a tungsten filament with the diameter of 36-38 microns, namely the high-strength tungsten alloy wire. The invention discloses an annealing process in a tungsten alloy wire drawing process, which can effectively reduce the generation of defects such as cracks in a machining process.

The invention discloses abrasion-resistant concrete based on industrial waste residues and a preparation method of the abrasion-resistant concrete. The abrasion-resistant concrete is prepared from 1050 to 1200 parts by weight of coarse aggregate, 480 to 550 parts by weight of coarse sand, 135 to 210 parts by weight of tungsten slag, 300 to 360 parts by weight of Portland cement, 75 to 90 parts by weight of superfine tungsten slag powder, 1 to 1.5 parts by weight of high-performance water reducing agent and 140 to 160 parts by weight of water, the tungsten slag is obtained by drying industrial waste tungsten slag generated by producing ammonium paratungstate at 80 DEG C to constant weight, the superfine tungsten slag powder is obtained by grinding the tungsten slag, and the fineness of the superfine tungsten slag powder is 1%-5% of screen residue of a 45-micron screen; the coarse aggregate is formed by mixing small stones with the particle size of 5-20 mm and medium stones with the particle size of 20-40 mm. Through the combined action of the tungsten slag, the superfine tungsten slag powder and the Portland cement, the overall abrasion resistance of the concrete is improved, the problem of cyclic utilization of the tungsten slag industrial waste residues is solved, and meanwhile it is guaranteed that the workability of the concrete is not reduced.

The invention provides a rapid preparation method of tungsten trioxide, which specifically comprises the following steps: step 1, weighing crude tungstic acid, dissolving in ammonia water, heating and stirring to obtain an ammonium tungstate solution; step 2, slowly dropwise adding the ammonium tungstate solution in the step 1 into a poor solvent to obtain an ammonium paratungstate suspension, and step 3, filtering the ammonium paratungstate suspension in the step 2 to obtain an ammonium paratungstate filter cake, and leaching the ammonium paratungstate filter cake with the poor solvent; 4, the ammonium paratungstate filter cake in the step 3 is placed in a drying oven to be dried; and (5) roasting the ammonium paratungstate filter cake in the step (4) at high temperature to obtain a faint yellow irregular flaky tungsten trioxide product. According to the preparation method, a mixed solvent crystallization and high-temperature roasting two-step process is adopted, the solubility of ammonium tungstate in water is reduced by adding a poor solvent, so that an ammonium tungstate solution rapidly reaches a saturated state and is separated out, the crystallization process of ammonium paratungstate is accelerated, and the preparation speed and the crystallization rate of a tungsten trioxide product are high.

The invention discloses a regeneration method of a marine vanadium-titanium denitration catalyst. The regeneration method comprises the following steps: (1) immersing a deactivated catalyst into a diluent of a special cleaning agent for grease for cleaning; (2) carrying out spray cleaning on the catalyst cleaned in the step (1), wherein a spray cleaning solution is water; (3) carrying out acid chemical cleaning on the catalyst cleaned in the step (2) to remove alkali metal harmful substances such as sodium, potassium and the like attached to the catalyst; (4) washing the catalyst cleaned in the step (3) with water; (5) drying the catalyst cleaned in the step (4); (6) the catalyst dried in the step (5) is soaked in an active solution for active reimplantation, and the active solution mainly comprises ammonium paratungstate and ammonium molybdate and further comprises one of ammonium metavanadate and vanadyl oxalate; and (7) draining the catalyst subjected to activity reimplantation in the step (6), and putting the catalyst into a calcining furnace for activity activation. According to the method disclosed by the invention, more than 98% of pollutants such as grease, ash, alkali metal and sulfate can be removed, and the use temperature after regeneration is reduced by 20-60 DEG C compared with the original use temperature.

The invention discloses a treatment method of an ammonium paratungstate sieve head material. The treatment method comprises the following steps: S1, preparing a solution; step S2, dissolving; s3, filtering and washing; step S4, drying and screening; according to the process disclosed by the invention, the ammonium paratungstate sieve head material is adjusted and treated, the consumption of auxiliary materials is reduced, the energy consumption is low, and the open crystal appearance of the original ammonium paratungstate crystal is kept; compared with the original undersize ammonium paratungstate product, the ammonium paratungstate product recovered and treated by the method has the advantages that the impurity element content is lower, the total impurity content is 20-30ppm lower than that before treatment, and the product quality is integrally improved.

The invention discloses a preparation method of low-oxygen-index surface needle-shaped high-specific-surface blue tungsten, which comprises the following steps: by taking ammonium paratungstate as a raw material, putting the raw material into a mechanically-sealed rotary calcining furnace with the furnace tube inner diameter of 400mm, and calcining at the calcining temperature of 580-620 DEG C in a first zone, 600-660 DEG C in a second zone and 600-640 DEG C in a third zone for 1-3 hours; the feeding frequency is 13-19 Hz, the furnace rotation frequency is 25-35 Hz, the negative pressure in the furnace is-400 + / -200 mm water column, the nitrogen flow is 0-4 M < 3 > / h, the low-oxygen-index surface-needle-shaped high-specific-surface blue tungsten is prepared, the oxygen index is 2.90-2.94, the surface of the low-oxygen-index surface-needle-shaped high-specific-surface blue tungsten is full of fine needle-shaped morphology, the specific surface area reaches 10-14 m < 2 > / g, and the low-oxygen-index surface-needle-shaped high-specific-surface blue tungsten can be used for preparing the high-specific-surface blue tungsten. The method is suitable for producing high-quality fine, superfine and nano-particle tungsten powder, tungsten carbide powder and corresponding hard alloy products.

The invention provides submicron high-purity tungsten powder and a preparation method thereof, and relates to the field of tungsten powder preparation. Ammonium paratungstate and ammonia water are mixed to obtain a mixture, the mixture is subjected to ammonia dissolving treatment, and a first ammonium tungstate solution is obtained through filtering; carrying out first ion exchange on the first ammonium tungstate solution by adopting strong acid cation exchange resin to obtain a first ion-exchanged solution; carrying out second ion exchange on the solution subjected to the first ion exchange by adopting chelating resin to obtain a high-purity ammonium tungstate solution; the high-purity ammonium tungstate solution is subjected to vacuum spraying and freeze drying, and a submicron tungsten precursor is obtained; and carrying out hydrogen reduction reaction on the submicron tungsten precursor to obtain the submicron high-purity tungsten powder. Insoluble particles and metal cation impurities in the solution can be effectively removed, and the high-purity tungsten precursor solution is obtained; raw materials are easy to obtain, and operation is simple.

The invention belongs to the technical field of tungsten hydrometallurgy, and particularly relates to a method for improving the crystallization rate of ammonium paratungstate, which comprises the following steps: S1, obtaining an ammonium tungstate solution which comprises metatungstate ions; s2, adding a supersaturation degree regulator into the ammonium tungstate solution, wherein the supersaturation degree regulator comprises hydrogen peroxide and ammonia water; s3, heating the ammonium tungstate solution to a first temperature, and then adding superfine ammonium paratungstate; s4, the ammonium tungstate solution is heated to a second temperature, heat preservation and continuous stirring are conducted, and ammonium paratungstate crystals are obtained; by adjusting parameters such as temperature, pH value, solvent type and concentration, optimizing crystallization conditions with metatungstate ions and ammonium paratungstate at the same time, improving the crystallization rate, and by controlling the degree of supersaturation of the solution, the situation that the crystallization rate is affected due to non-uniform crystal growth caused by too high crystallization rate is avoided, and the quality of the product is improved. The supersaturation degree can be controlled by adjusting parameters such as solution concentration and temperature.

The invention belongs to the technical field of tungsten and tungsten products, and particularly relates to a doped tungsten oxide composite material and a preparation method and application thereof. The invention provides a method for preparing doped tungsten oxide by a chemical precipitation method, which comprises the following steps: dispersing two aqueous solutions in the form of tiny liquid drops in an atomization manner, and carrying out chemical reaction at the moment of contact and mixing, so that rare earth element cations are rapidly combined with hydroxyl anions in an alkaline environment; the preparation method comprises the following steps: adding ammonium paratungstate into an ammonium paratungstate precursor, quickly drying at high temperature, nucleating to obtain the doped ammonium paratungstate precursor, realizing uniform distribution of rare earth elements, and calcining at high temperature to obtain the doped tungsten oxide composite material with uniform particle size. The invention aims to provide a preparation method of a short-process doped composite material powder which can be efficiently industrialized and is uniform in nanoscale particle size.

The invention discloses a method for recycling process water in an APT (ammonium paratungstate) production process, and relates to the field of water recovery in an APT production process, and the method comprises the following steps: S1, recycling wastewater of an alkali extraction system; s2, evaporating strip liquor and recovering ammonia water; s3, chemical treatment of pure ammonium tungstate evaporation ammonia water; s4, ammonium molybdate evaporation ammonia water closed-loop utilization; and S5, recycling ammonia gas in a crystallization section. According to the method, the recovery rate of tungsten and molybdenum in the tail liquid is remarkably increased by optimizing the processes of wastewater reuse of the alkali extraction system, strip liquor evaporation, ammonia water recovery and the like; one part of the tail liquid is recycled in the pulping process, the other part of the tail liquid is subjected to evaporation treatment, zero emission of wastewater is achieved, evaporated condensate water can be recycled to be used for preparing a stripping agent, the utilization rate of water resources is further increased, the production cost is reduced, and meanwhile the environment-friendly requirement is met.

The invention belongs to the technical field of powder metallurgy, and particularly discloses a nanocrystal potassium-doped tungsten material and a preparation method thereof.The preparation method comprises the following steps that ammonium paratungstate is put into spray granulation equipment, then a dopant aqueous solution is added, mixing and drying are conducted, potassium-doped APT is obtained, pre-reduction is conducted through a converter, ammonium tungsten bronze is obtained, and the nanocrystal potassium-doped tungsten bronze is obtained; the method comprises the following steps: carrying out one-step reduction on ammonium tungsten bronze through a fifteen-tube furnace to prepare potassium-doped D powder, carrying out two-step reduction on the ammonium tungsten bronze through the fifteen-tube furnace to prepare potassium-doped B powder, then cleaning with hydrochloric acid and hydrofluoric acid, cleaning with water, filtering, dewatering, drying, crushing and sieving to obtain washed potassium-doped D powder and washed potassium-doped B powder, mixing the washed potassium-doped D powder and washed potassium-doped B powder to obtain mixed powder, and sintering the mixed powder to obtain the potassium-doped B powder. And carrying out isostatic pressing treatment to obtain a tungsten green body, and sintering the tungsten green body in a medium-frequency induction sintering furnace to obtain the tungsten ceramic. The nanocrystal potassium-doped tungsten material has the advantages of high strength, good plasticity, stable high-temperature performance and the like, and a product processed by the nanocrystal potassium-doped tungsten material is long in service life.

The application belongs to the technical field of metallurgy, and particularly relates to medium-granularity tungsten carbide powder and a preparation method and application thereof. The preparation method comprises the following steps: S1, obtaining high-purity ammonium paratungstate, and calcining the high-purity ammonium paratungstate to obtain tungsten oxide, wherein K in the high-purity ammonium paratungstate is less than or equal to 1 ppm, Na in the high-purity ammonium paratungstate is less than or equal to 1 ppm, and the specific surface area of the tungsten oxide is 0.3-1.0 m 2 / g; S2, first hydrogen reduction, second hydrogen reduction and third hydrogen reduction are performed on the tungsten oxide to obtain tungsten powder; S3, the tungsten powder is sieved and carbon is added to obtain a tungsten-carbon mixture, carbonization, crushing and sieving are performed on the tungsten-carbon mixture to obtain medium-granularity tungsten carbide powder. The application selects high-purity ammonium paratungstate with less than 1 ppm of impurity elements such as potassium and sodium as raw material, which can effectively reduce abnormal growth of tungsten powder particles caused by impurity elements in the reduction process, tungsten powder particles are developed completely by adopting three-stage hydrogen reduction, the powder activity is low, and the particle size increase is small in the subsequent carbonization process.

The application discloses a method for preparing high-purity superfine tungsten powder by series impurity removal and microwave calcination, and relates to the technical field of refractory metal powder metallurgy. The method uses 99% and below industrial-grade ammonium paratungstate as raw material, and sequentially performs pyrolysis, two-stage physical purification, ultrasonic synergic acidolysis deep purification, microwave uniform calcination and sectional reduction. Firstly, the ammonia solution-evaporation crystallization method and the chemical precipitation method are connected in series to realize deep impurity removal, and the chemical precipitation method is used to directly obtain a nano tungsten oxide precursor, so that the morphology of the tungsten powder is guaranteed for subsequent reduction; secondly, the microwave calcination process is introduced to realize fast and green and environment-friendly uniform heating, and the hard agglomeration of the precursor is significantly reduced; finally, the sectional reduction method is adopted to effectively block the CVT effect in the reduction process, and abnormal grain growth is avoided. The method solves the problems of incomplete purification, sintering agglomeration of the precursor during reduction and out-of-control reduction particle size in the prior art, and the prepared tungsten powder has high purity and small average particle size.

The invention belongs to the technical field of tungsten and tungsten products, and particularly relates to a preparation method and application of a rare earth oxide doped tungsten composite material. A tungsten salt solution and a rare earth metal salt solution are dispersed and distributed in a high-temperature environment in a tiny suspension form in an atomization manner and are mixed with each other. Then, at a high temperature, liquid drops formed by mixing are rapidly dried and are subjected to pyrolytic reaction to form tungsten oxide and nano rare earth oxide. In the subsequent reduction reaction, tungsten oxide is reduced into tungsten powder, and the rare earth oxide retains the original components and structure and is uniformly distributed. The invention provides the method capable of efficiently and industrially preparing the uniform rare earth doped tungsten powder in a short process, ammonium paratungstate does not need to be produced, the influence of the genetic effect of ammonium paratungstate is reduced, the process steps are reduced, and the energy utilization rate is increased; the rare earth and the tungsten element are uniformly mixed in a liquid-liquid mixing mode, the tungsten powder uniformly doped with the rare earth is obtained through high-temperature rapid oxidation, and no waste liquid is generated in the production process.

The utility model discloses a quick grinding device for ammonium paratungstate processing, which comprises a grinding cylinder, a grinding disc rotatably mounted in the grinding cylinder, a base welded on the outer side of the grinding cylinder and used for supporting, and a connecting column, a sliding structure is formed between the connecting column and a connecting plate which is fixed to the inner side wall of the upper end of the grinding cylinder and is of an annular structure, the screening box is arranged on the outer side of the lower end of the grinding cylinder in a sleeving mode, supporting blocks are fixedly connected to the front side and the rear side of the lower end of the grinding cylinder correspondingly, and a left-right sliding structure is formed between the screening box and the supporting blocks; the screen is mounted at the lower end of the screening box in a penetrating mode, and mounting mechanisms are arranged on the left side and the right side of the screen correspondingly. According to the rapid grinding device for ammonium paratungstate processing, ground raw materials can be screened, the size uniformity of the raw materials is improved, through the arrangement of a mounting mechanism, screened impurities can be conveniently cleaned, and the situation that a screen is blocked in the long-term use process is prevented.

The invention discloses a process for producing ammonium paratungstate by treating scheelite with sulfuric acid, and relates to the technical field of ammonium paratungstate production, the process comprises the following operation steps: S1, acid leaching decomposition: mixing scheelite powder with sulfuric acid by using mixing equipment, and reacting under normal pressure to dissolve tungsten in the form of phosphotungstic heteropolyacid to generate a tungsten-containing leachate; s2, purification and precipitation, wherein ammonium salt is added into the leachate to separate out ammonium phosphotungstate precipitate; s3, evaporative crystallization: concentrating and crystallizing the purified ammonium tungstate solution to obtain an ammonium paratungstate product; and S4, recovering by-products. According to the technology for producing ammonium paratungstate through sulfuric acid treatment of scheelite, the rotating pipe, the collecting box, the scraping strip and other structures are arranged, the pushing, scraping, cleaning and collecting effects are achieved at the same time, during mixing and stirring, the collecting box does not make continuous contact with the bottom of the mixing barrel, the scraping strip does not make continuous contact with the inner wall of the mixing barrel, abrasion is reduced, and the service life is prolonged. And the processing efficiency of the process for producing ammonium paratungstate by treating scheelite with sulfuric acid is improved.

The invention relates to the technical field of denitration catalyst regeneration, in particular to a preparation method of a regenerated denitration catalyst based on a reconstructed bulk phase carrier. The preparation method comprises the following steps: carrying out ultrasonic treatment on the waste catalyst by using an ethylenediamine tetraacetic acid-hydrofluoric acid mixed solution to realize targeted detoxification; carrying out hydrothermal reaction on the detoxified carrier, titanium sol, cerous nitrate and zirconium nitrate, and roasting with nitrogen to complete bulk phase reconstruction; carrying out microwave-assisted gradient loading on ammonium paratungstate and an ammonium metavanadate-oxalic acid solution on the reconstructed carrier to obtain a precursor; and roasting and activating the precursor in a gradient atmosphere to obtain the regenerated catalyst. The catalyst prepared by the invention has high denitration efficiency, excellent sulfur poisoning resistance stability, good circulation performance and long service life, can realize efficient regeneration of the waste vanadium-titanium-based denitration catalyst, is suitable for the field of industrial flue gas denitration, and has significant application value.

This invention provides nano-tungsten carbide and its preparation method. The preparation method includes: providing ammonium paratungstate; calcining the ammonium paratungstate to form purple tungsten; oxidizing the purple tungsten in pure oxygen to form yellow tungsten; ball milling the yellow tungsten with carbon, then isostatically pressing it into a block, followed by carbon reduction to obtain a tungsten-carbon mixed block; carbonizing the tungsten-carbon mixed block, and then crushing it to obtain nano-tungsten carbide powder. This invention can reduce the manufacturing cost of nano-tungsten carbide and is beneficial for preparing finer tungsten carbide powder.

The invention belongs to the related field of tungsten materials, and discloses nano ammonium paratungstate and a preparation method thereof. The morphology of the nano ammonium paratungstate is in a spherical shape or a sphere-like shape, and the particle size of the nano ammonium paratungstate is 20-100 nm. The nanoscale ammonium paratungstate product provided by the invention has high specific surface area and excellent catalytic activity and thermal stability.

The invention belongs to the technical field of recycling of rare and noble metal secondary resources, and discloses a method for preparing a tungsten compound and chloroplatinate from a waste catalyst and application of the method. The method comprises the following steps: (1) firing and crushing the waste catalyst, (2) reacting the waste catalyst with acid, (3) filtering and discarding filtrate, (4) reacting the precipitate with ammonia water, filtering to obtain an ammonium tungstate solution, and retaining filter residues; (5) concentrating the ammonium tungstate solution, crystallizing, separating and drying to obtain an ammonium paratungstate finished product; and (6) reacting the filter residues retained in the step (4) with aqua regia to prepare chloroplatinate. And (7) firing the ammonium paratungstate at a high temperature to obtain tungsten trioxide. According to the method, tungsten and platinum can be effectively separated from the carrier, and the recovery rate of rare and precious metals is increased.

The present application relates to the technical field of tungsten hydrometallurgy, in particular to an ion exchange automatic control system and method for ammonium paratungstate preparation, comprising: a stage control module for switching the process stage of an ion exchange column and generating stage switching instructions; a segmented determination module for determining the segmented determination result of the desorption liquid according to the tungsten elution rate in the desorption stage; a switching verification module for determining the impurity index according to the conductivity detection value of the outlet of the ion exchange column and verifying the segmented determination result based on the impurity index to generate a verification result; and a switching execution module for switching the desorption liquid generated by the ion exchange column in the desorption stage to the corresponding storage tank of the determined segment according to the segmented switching instructions generated in response to the verification result and the segmented determination result. The present application improves the tungsten resource recycling rate.

The utility model discloses a premixing structure for ammonium paratungstate processing. The premixing structure comprises a mixing box, the middle upper end of the mixing box is rotationally connected to a first mounting frame playing a bearing role, and the lower end of the interior of the mixing box is rotationally connected with a second connecting shaft; the lower end of the first mounting frame is in bolted connection with the upper end of the processing tank, a stirring structure and a feeding structure are arranged on the upper side of the first mounting frame, and the stirring structure comprises a gear ring, a gear, a first connecting shaft and a first motor; the feeding structure comprises an adjusting disc, an adjusting block, a connecting handle, a fourth connecting shaft, a third motor, a bearing plate, a storage tank, a discharging pipe and a control valve. A second motor is mounted at the rear end of the second connecting shaft, and a sealing plate is fixedly connected to the inner end of the second connecting shaft. According to the premixing structure for ammonium paratungstate processing, different raw materials can be conveniently fed, various raw materials can be conveniently and uniformly mixed together, and meanwhile, the mixed raw materials can be easily added into a processing tank.

The preparation method and application of the material for the dimethylamine gas sensor have the following advantages that ammonium paratungstate is used as a tungsten source, the tungsten oxide material with a (020) highly exposed surface crystal phase is prepared by regulating and controlling the usage amount and the adding sequence of polyvinyl alcohol (PVA), and the material has high selectivity to dimethylamine gas. The material does not need precious metal doping, and is low in manufacturing cost, environmentally friendly, simple in synthesis route and high in repeatability. The prepared sensor is rapid in response, low in detection line (1 ppm), high in sensitivity (74) when exposed to 50 ppm dimethylamine, and excellent in selectivity and repeatability. The excellent sensing capability can be attributed to a (020) highly exposed surface crystal phase and a unique hollow bowl-shaped tungsten oxide nano spherical shell structure formed by rich porous structures. The preparation method is simply realized through spray drying and the like, so that mass production can be realized. The technology has profound market application prospects and important significance in the fields of industrial production, environment monitoring, indoor air quality monitoring, safety protection and the like and in the aspect of food quality detection.

The invention discloses a method for green preparation of high-purity ammonium paratungstate from tungsten ore, and relates to the technical field of tungsten smelting, and the method comprises the working procedures of tungsten ore pretreatment, green ammoniacal decomposition, deep purification of ionic liquid, ultrasonic-assisted cooling crystallization, mother liquor recycling and ammonium paratungstate drying. Reacting with an ammonium carbonate-ammonia water mixed leaching agent, and breaking tungsten ore crystal lattices through a weakly alkaline system to dissolve out the tungsten element; the method comprises the following steps: extracting and purifying a crude ammonium tungstate solution by using a functionalized phosphate-based ionic liquid, and selectively removing impurities; cooling and crystallizing the purified solution under the regulation and control of an ultrasonic field, and inducing growth by combining with a nanocrystalline seed; the crystallization mother liquor is subjected to reduced pressure ammonia distillation, carbonization reaction and resin adsorption to realize recycling of ammonia, ammonium carbonate and residual tungsten; and finally, carrying out segmented drying to obtain a high-purity ammonium paratungstate product.

The invention belongs to the field of photocatalysts, and particularly relates to an H / WO3-x material and a preparation method and application thereof.The preparation method comprises the steps that ammonium paratungstate and urea are mixed and ground, the obtained mixture is heated, calcined, cooled and then ground, and WO3-x powder is obtained; dispersing the obtained WO3-x powder in deionized water, performing ultrasonic treatment, then adding a sodium borohydride solution, and performing stirring reaction; and washing a solid product obtained after the reaction with deionized water, carrying out suction filtration, and carrying out vacuum freeze drying to obtain the H / WO3-x material. The H / WO3-x material prepared by the invention shows excellent formaldehyde generation selectivity in photocatalytic methane oxidation reaction, the selectivity is close to 100%, and the generation of excessive oxidation products such as CO or CO2 can be effectively inhibited. The catalyst still keeps stable structure and high activity after being continuously recycled, and has good reusability.

The invention belongs to the technical field of metallurgy, and particularly relates to medium-particle tungsten carbide powder and a preparation method and application thereof.The preparation method comprises the following steps that S1, high-purity ammonium paratungstate is obtained, the high-purity ammonium paratungstate is calcined to obtain tungsten oxide, K in the high-purity ammonium paratungstate is smaller than or equal to 1 ppm, Na in the high-purity ammonium paratungstate is smaller than or equal to 1 ppm, N is smaller than or equal to 1 ppm, and N is smaller than or equal to 1 ppm; the specific surface area of the tungsten oxide is 0.3-1.0 m < 2 > / g; s2, the tungsten oxide is subjected to first hydrogen reduction, second hydrogen reduction and third hydrogen reduction, and tungsten powder is obtained; and S3, the tungsten powder is sieved, a tungsten-carbon mixture is obtained after carbon is added, the tungsten-carbon mixture is carbonized, crushed and sieved, and the medium-particle tungsten carbide powder is obtained. According to the method, high-purity ammonium paratungstate with the content of impurity elements such as potassium and sodium smaller than 1 ppm is selected as the raw material, abnormal growth of tungsten powder particles caused by the impurity elements in the reduction process can be effectively reduced, three-section hydrogen reduction is adopted, the tungsten powder particles are developed completely, the powder activity is low, and the particle size increase in the subsequent carbonization process is small.

The invention discloses a method for preparing a tungsten compound from artificial tungsten ore, which comprises the following steps: reacting sulfuric acid with the artificial tungsten ore to leach tungsten, and controlling the reaction conditions that the pH is 0.2-4.0, the temperature is 25-100 DEG C, the reaction time is 30 minutes to 6 hours, and the liquid-solid ratio is 1: 1-10: 1. And obtaining a metatungstate leaching solution after the reaction is completed, so that efficient leaching of tungsten is realized. And further performing purification and impurity removal on the solution to obtain a pure metatungstate solution. The pure metatungstate solution can be used for preparing different pure tungsten compound products such as solid metatungstate, phosphotungstic acid, ammonium phosphotungstate, tungsten oxide, ammonium metatungstate, ammonium paratungstate and tungstic acid. According to the technology, efficient leaching of tungsten under the mild condition can be achieved, high acid and high alkali are not needed in the whole process, and energy consumption and emission are greatly reduced; the obtained leachate is easy to purify to obtain a pure metatungstic acid solution, and the pure metatungstic acid solution can be directly used as a platform intermediate to flexibly prepare various tungsten chemicals.

The present invention belongs to the technical field of powder metallurgy, and specifically discloses a potassium-doped nanocrystalline tungsten material and a preparation method thereof, comprising the following steps: putting ammonium paratungstate into a spray granulation device, then adding an aqueous solution of a dopant, mixing, and drying to obtain potassium-doped APT; performing pre-reduction through a converter to obtain ammonium tungsten bronze; performing one-step reduction of the ammonium tungsten bronze through a fifteen-tube furnace to obtain potassium-doped D powder; performing two-step reduction of the ammonium tungsten bronze through a fifteen-tube furnace to obtain potassium-doped B powder; then cleaning with hydrochloric acid and hydrofluoric acid, followed by washing with water, removing water after filtration, drying, crushing and sieving to obtain washed potassium-doped D powder and washed potassium-doped B powder; mixing the two to obtain a mixed powder; then performing isostatic pressing treatment to obtain a tungsten green body; and sintering the tungsten green body in an intermediate frequency induction sintering furnace to obtain the product. The potassium-doped nanocrystalline tungsten material of the present invention has the advantages of high strength, good plasticity, stable high-temperature performance, etc., and the products processed therefrom have a long service life.

The invention belongs to the technical field of non-ferrous metal metallurgy, and particularly discloses a preparation method of coarse-particle high-purity ammonium paratungstate. The preparation method of the coarse-particle high-purity ammonium paratungstate comprises the following steps: heating low-purity ammonium paratungstate powder to obtain water-containing tungsten oxide; adding the water-containing tungsten oxide into ammonia water for dissolving, and heating to obtain an ammonium tungstate solution; the ammonium tungstate solution is subjected to two-stage evaporative crystallization treatment: in a nucleation stage, the evaporation temperature is 70-90 DEG C, and the stirring speed is 5.83-8.3 r / s; in the growth stage, the evaporation temperature is 80-100 DEG C, and the stirring speed is 4.17-6.67 r / s; a mixture of ammonium paratungstate crystals and mother liquor is obtained; separating the ammonium paratungstate crystal to obtain coarse-particle high-purity ammonium paratungstate; the purity of the low-purity ammonium paratungstate powder is 1t; 4N, average particle size lt; the particle size of the ammonium paratungstate powder is 30 microns. According to the method disclosed by the invention, the high-purity coarse particle ammonium paratungstate can be prepared through a simple process flow. The invention also provides a coarse-particle high-purity ammonium paratungstate product.

The application discloses an ultrafine ammonium paratungstate evaporation crystallization device and a crystallization method. The device comprises a shell, an evaporation barrel is arranged at the middle of the top end of the shell, a feeding pipe and a collecting pipe are arranged at the top end of the evaporation barrel, the other end of the collecting pipe is connected with the shell, the collecting pipe is arranged in a U shape, a heater is arranged at the bottom of the evaporation barrel, and a collecting assembly is arranged in the shell through the collecting pipe. The device has the beneficial effects that the collecting assembly, the flow guiding assembly, the drainage assembly and the screening assembly are arranged, the steam and the ammonia gas generated during evaporation can be utilized again, the ammonia gas and the steam can be filtered at the same time, the high energy of the high pressure of the ammonia gas can drive the screening assembly to screen the ammonium paratungstate crystals, and therefore, the device for separating the ammonia gas and the water vapor is not needed during the crystallization of the ammonium paratungstate, and the working efficiency is greatly improved.