Ammonium Metatungstate Solubility
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- Category: Ammonium Metatungstate
- Published on Thursday, 27 October 2016 09:36
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Ammonium metatungstate (AMT) is a white or yellowish crystalline powder, an important tungsten compound which can be used for producing tungsten oxide, tungsten powder and other products, or for the manufacture of all kinds of catalyst in petroleum chemical industry, the main raw material of tungsten based catalyst of oil refineries.
If there are no special instructions, the solubility of ammonium metatungstate refers to it in water; AMT has very good water soluble which is 303.99/100g at 20℃, and its aqueous solution is quite stable with acidity. With the improving of temperature, ammonium metatungstate solubility in water will raise until it reaches the highest solubility which is saturated state. Metatungstic acid and most of its metatungstate can well soluble in water, and the advantage of AMT is its very huge solubility in water, thus it can be directly used and to prepare high concentrated tungstate solution with no alkali metal ions.
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance fundamentally depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure and the pH of the solution. The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration, where adding more solute does not increase the concentration of the solution and begins to precipitate the excess amount of solute. The solubility of a substance is an entirely different property from the rate of solution, which is how fast it dissolves.
The factors that affect solubility are temperature, pressure ect.. Solubility is defined for specific phases. For example, the solubility of aragonite and calcite in water are expected to differ, even though they are both polymorphs of calcium carbonate and have the same chemical formula. The solubility of one substance in another is determined by the balance of intermolecular forces between the solvent and solute, and the entropy change that accompanies the solvation. Factors such as temperature and pressure will alter this balance, thus changing the solubility.
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Ammonium Metatungstate Price on Oct.26th, 2016
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- Category: Ammonium Metatungstate
- Published on Wednesday, 26 October 2016 18:11
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Ammonium metatungstate price with purity over 91.40% from Chinatungsten Online is 35.50 USD/KG, by Chinatungsten FOB Xiamen, Oct.26th, 2016.
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APT Liquid Phase Transformation Method Preparing AMT
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- Category: Ammonium Metatungstate
- Published on Tuesday, 25 October 2016 10:04
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Ammonium metatungstate (AMT) is an important tungsten compound, mainly used in the manufacture of tungsten oxide, tungsten and tungsten carbide powder and their downstream products ect., also it can be used as catalyst in fields of petroleum cracking, organic synthesis, nitration and so on; besides, with the rapid development of oil refining, petrochemical and other industries, the demand amount of ammonium metatungstate is growing fast. There are many preparation methods for ammonium metatungstate which can be divided into two catalogues of solid and liquid phase transformation method, such as thermal decomposition method, neutralization method, solvent extraction and ion exchange method, wherein the thermal decomposition method which is depending on raw material of ammonium paratungstate (APT) is the mainstream process for preparing AMT in industrial.
For manufacturing AMT with high solubility to meet the requirement of tungsten contained catalyst, an invention has pointed out a liquid phase transformation method to produce ammonium metatungstate which took ammonium paratungstate as raw material; and the result of experiment have shown that this method has the advantages of short process, little investment of equipment ect., furthermore, the product – AMT is highly dissolve in water with the stable quality. The preparation steps are shown as following:
1. Leaching the wet ammonium paratungstate: Mixing the material of wet ammonium paratungstate (which the water content is among 5~10%) and dilute nitric acid (HNO3) to prepare ammonium metatungstate solution, the chemical reaction is like bellow:
5(NH4)2•12WO3•5H2O+4HNO3=(NH4)6•H2W12O40•6H2O+4NH4NO3
2. Converting the dilute ammonium metatungstate solution to concentrated AMT solution: The dilute ammonium metatungstate solution is carried out standing for aging, filtering, heating for concentrating and again filtering for many times to finally get concentrated AMT solution;
3. Spraying and drying the concentrated AMT solution obtained in step 2 with an spray dry tower which will dry AMT feed liquid into powder quickly, thus to get product of AMT powder.
Compared to the traditional method, this kind of liquid phase transformation method requires no calcination step, so it is no need to use rotary kiln which will reduce the fixed investment; at the same time, product per ton will save 120KWH, while the recovery efficiency can be improved for 3%.
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2016.10.24-70WC30Cu Tungsten Carbide Copper Rod Price
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- Category: Tungsten Carbide Price
- Published on Monday, 24 October 2016 17:25
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As reported by Chinatungsten Online, the current price of 70%WC30%Cu tungsten carbide copper rod of Ø13mmx250mm is $45.50 per piece EXW Xiamen, China on OCT.24, 2016.
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2016.10.24-YG6x Tungsten Carbide Ball Price
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- Category: Tungsten Carbide Price
- Published on Monday, 24 October 2016 17:19
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As reported by Chinatungsten Online, the current price tungsten carbide ball for Ø0.7mm of YG6x is $0.00129 per piece EXW Xiamen, China on OCT.24, 2016.
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Ammonium Metatungstate Price on Oct.21st, 2016
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- Category: Ammonium Metatungstate
- Published on Friday, 21 October 2016 11:59
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Ammonium metatungstate price with purity over 91.40% from Chinatungsten Online is 35.50 USD/KG, by Chinatungsten FOB Xiamen, Oct.21st, 2016.
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Yellow Tungsten Oxide Price on Oct.21st, 2016
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- Category: Tungsten Oxide/Trioxide Price
- Published on Friday, 21 October 2016 11:42
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Yellow tungsten oxide price with purity over 99.90% from Chinatungsten Online is 35.50 USD/KG, by Chinatungsten FOB Xiamen, Oct.21st, 2016.
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Ammonium Metatungstate Decomposition Temperature
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- Category: Ammonium Metatungstate
- Published on Thursday, 20 October 2016 16:35
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Ammonium metatungstate decomposition temperature is the temperature of AMT coming out decomposition reaction; while in the actual production environment, ammonium metatungstate will have several different decomposition temperatures according to complete reaction or not. Decomposition temperature of a substance means the temperature at which the substance chemically decomposes, which the chemical decomposition caused by heat. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion.
Ammonium metatungstate will produce different products at different decomposition temperatures. When the heat treatment temperature is 200~300°C, AMT will be removed of all crystal water and most of the ammonium ions; then phase transformation will occur at 300-350°C to generate metastable tungsten oxide species; when the heat treatment temperature rise to 500~550°C, a small amount of ammonium and bound water is still not broken down; and when the temperature rises to 600°C and above, ammonium metatungstate will completely decomposed into tungsten trioxide (WO3); when the temperature raised to 700°C and held for 2 hours, mesoporous tungsten trioxide hollow balls will be obtained.
About ammonium metatungstate:
Ammonium metatungstate (AMT) is an important intermediate compound in tungsten wet smelting process, with the appearance of white or slightly yellow crystalline, the biggest solubility in all the tungsten compound, wherein the solubility will bigger than 300g WO3/100ml H2O at 25℃. The preparation methods of ammonium metatungstate are mainly Acid neutralization, Thermal separation, electrodialysis, solvent extraction and ion exchange method and the method depends on ammonium paratungstate (APT). AMT is the important raw material of tungsten compound (such as tungsten trioxide, blue tungsten oxide, tungsten hexachloride ect.); at the same time, it is usually used in industries of petroleum, chemical, ceramic, lubrication and so on; in addition, since the continually developing of electronics industry and the constantly mining of new material, AMT is also used in film substrate, capacitor and shielding ect. of semiconductor devices.
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2016.10.20-Tungsten Carbide Bar Price
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- Category: Tungsten Carbide Price
- Published on Thursday, 20 October 2016 13:56
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As reported by Chinatungsten Online, the current price of YG10x tungsten carbide bar for 100mmx9mmx4mm is $4.00 per piece EXW Xiamen, China on OCT.20, 2016.
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2016.10.20-Tungsten Copper Electrode Price
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- Category: Tungsten Copper Price
- Published on Thursday, 20 October 2016 13:52
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As reported by Chinatungsten Online, the current price of 70%W30%Cu tungsten copper electrode of is $62.20 per piece EXW Xiamen, China on OCT.20, 2016.
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