Tungsten Oxide

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High-purity Ammonium Metatungstate 567

High-purity ammonium metatungstate may be prepared by a coupling process of neutralization-nanofiltration-crystallization. AMT solution is obtained by neutralization-nanofiltration, which can not only reduce cost as high concentration of AMT solution is obtained for the subsequent crystallization process, but also ensure to prepare high purity AMT as the impurity content is low. In the above figure, 1. High pressure pump; 2. Primary liquid tank; 3. Nanofiltration membrane device; 4. Valve; 5. Valve. The neutralization-nanofiltration-crystallization process consists of the following three steps:…

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Ammonium Metatungstate Microsphere 597

Ammonium metatungstate microsphere may be prepared by two different spray drying methods. Ammonium metatungstate (AMT) is usually used as one of the precursors of tungsten carbide (WC) catalysts. And the morphology and particle size distribution of WC microsphere are affected by the properties of precursor. In other words, AMT properties will have an important influence on morphology and particle size distribution of WC microsphere and have a finally effect on the catalytic activity of WC catalyst. Therefore, it is necessary…

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Ammonium Metatungstate Solution 372

Ammonium metatungstate solution is an aqueous solution of ammonium metatungstate (AMT), which may be prepared using ammonium tungstate solution as raw material by Bipolar Membrane Electrodialysis (BMED). AMT solution may be used as raw material for producing its downstream products by liquid phase process. AMT is extremely easily soluble in water, and its solubility in water increases with the increase of temperature. BMED is a new membrane separation technology, which has been widely applied in the preparation of acid, alkali,…

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Chromium Doped Ammonium Paratungstate 608

Chromium doped ammonium paratungstate may be produced by doping chromium (Cr) in evaporation crystallization process during the production of ammonium paratungstate. Adopting chromium acetate (CH3COO)3Cr (analytical reagent) and ammonium tungstate solution obtained by dissolving high-purity WO3 with ammonia water as raw materials to study the process of preparing APT powder by adding chromium acetate during crystallization. The result showed that: 1. Chromium mainly precipitated in the precipitation form of Cr(OH)3, which is prior to ammonium paratungstate, and the pH value…

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Arsenic Doped Ammonium Paratungstate 640

Arsenic doped ammonium paratungstate may be prepared by adopting simple arsenic, nitric acid solution and ammonium paratungstate (APT) as raw materials and forming in liquid phase, the preparing steps are as below: 1. Dissolve a certain amount of simple arsenic (As) in the nitric acid solution with a certain concentration until it completely dissolves; 2. Add APT powder into the nitric acid solution of simple arsenic, and control the content of arsenic in a certain value; 3. After completely mixing…

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Sodium Doped Ammonium Paratungstate 611

Sodium doped ammonium paratungstate may be used to prepare coarse grain size tungsten trioxide (WO3), and the content of sodium (Na) may affect the particle size of tungsten (W) powder prepared by WO3. APT with high sodium content may be calcined to produce high sodium content of WO3 powder – an upstream raw material for preparing coarse grain size tungsten powder, which is a raw material for tungsten carbide with coarse grain size. And tungsten carbide with coarse grain size…

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Coarse Ammonium Paratungstate 670

Coarse ammonium paratungstate has advantages of large apparent density and good fluidity, and its demand increases year by year as customers are requiring more and more strictly on the performance of subsequent products now. Preparation of Coarse Ammonium Paratungstate 1. Experimental solution and equipment: (1) Adopt (NH4)2WO4 solutions produced by classical process and ion exchange process as test material liquid; Part of the solution was prepared by diluting ammonia water. (2) A 1500L open type enamel reactor equipped with an…

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Super Grade Ammonium Paratungstate (APT-0) 770

Super grade ammonium paratungstate is ammonium paratungstate with grade of APT-0, which is divided by national standard. Generally, traditional process to prepare high-purity ammonium paratungstate is first to dissolve super grade ammonium paratungstate by ammonia-dissolving method, and then evaporation recrystallization. The high-purity APT produced by traditional process has the disadvantages as follows: The energy consumption is high and the comprehensive recovery rate of resources is low. Also, equipment and investment are increased when compared with new processing technology, so that…

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Grade 1 Ammonium Paratungstate (APT-1) 563

Grade 1 ammonium paratungstate is a national standard product of APT with grade of APT-1. The ammonium paratungstate may be obtained by the process of losing ammonia in ammonium tungstate solution. Its chemical equation is as follows: 12(NH4)2WO4→5(NH4)2O?12WO3?nH2O+(7-n)H2O+14NH3↑ Ammonium tungstate solution is not stable, so that water and ammonia escape when it is heated, and therefore ammonium paratungstate is continuously generated in solution. During this process, ammonium paratungstate changes from unsaturation to saturation to reach a stable state. Under the…

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APT Crystalline Mother Liquor 512

APT crystalline mother liquor’s main components are ammonium chloride, ammonium tungstate, a small amount of sulfur ions and sulfate ions. Tungsten and ammonia in mother liquor of APT crystal can be recovered by adopting one-step method, calcium hydroxide or calcium oxide as calcium source and caustic source. The one-step method has the advantages of simple process, easy availability of raw materials, and controllable cost. In a word, it provides a new way for resource utilization of APT crystalline mother liquor.…

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