In this research, the possibility of mechanochemical decomposition of ammonium paratungstate (APT) has been studied, and compared with thermal decomposition method. For this purpose, APT powders were milled using a planetary ball mill up to 36 h and under air atmosphere. For thermal decomposition, APT powders were heated for 30 minutes at 300 and 450 °C in air atmosphere. X-ray diffraction (XRD), differential scanning calorimeter (DSC), and thermo gravimetric analyzer (TGA) were used to

Hydrogen produced in the cracking process of heated Ammonium paratungstate is used for the self-reduction of the cracked products. Studing the impacts on blue tungsten oxide's properties by the major reduction parameters,including temperature and rotary kiln speed without Ammonia or hydrogen.The application of this technology to environmental protection,energy conservation and production safety are focused.

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According to Arrhenius theory, using the method of nucleation period integral mean rate, the apparent activation energy of ammonium paratungstate(APT) crystal growth is calculated as 94.657kJ/mol. At the same time,the ralational expression between APT crystal growth rate constant and temperature is concluded as kn=8.46×1014exp(-94657/RT).The results show that the increasing rate of APT nucleation rate is bigger than that of APT crystal growth rate as temperature increasing and the granularity of crystal product is fine.

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At present, the tungsten alloy penetrators material technology development has made considerable progress, but there is a gap from the international advanced level, in some respects still significantly behind the Western countries. For this reason, in the future armor-piercing tungsten alloy developed, research should focus on the following aspects:
     
1) Armor-piercing shells performance is the most important performance indicators tungsten alloy, relatively little research in this respect, especially playing - study of the mechanism of action is still not deep enough plates, while also strengthening the adiabatic susceptibility tungsten alloys the study;
     
2) In order to improve air defense missiles and armor-piercing capability of the damage should be studied Bouncing brittle tungsten alloy material and wear-fired missile complex functional materials to carry out;
     
3) High Strength Composite tungsten penetrator is an important direction for future development of ultra-high-speed kinetic energy penetrators, and should be further strengthened by hypervelocity kinetic energy penetrator research body piercing tungsten composite beam material;
     
4) Although China is a tungsten-rich countries, but reserves are limited, should be strengthened missile waste recycling tungsten and tungsten alloy shavings and low consumption of raw technology research and development.
    
 5) Our coastline is very long, for the defense of coastal areas to prevent salt spray, water and humid environment for armor-piercing tungsten alloy with corrosion problems have been on the agenda for this should be targeted to carry out bomb tungsten alloy corrosion protection technology research.




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The name of the organization shall be the International Darts Federation, herein also called the IDF. It shall be a non-government non-profit organization incorporated as Association in the meaning of article 60 and following of the Swiss Civil Code; its resources are constituted by members' annual dues or charges, sponsorship income, gifts and donations and any other resource, such as income from competitions, tournaments and other events organized by the IDF; its resources shall be applied exclusively in furtherance of its beneficent purposes; and no part of its resources or earnings shall inure to the benefit of any private person.

The purpose of the international dart federation shall be to promote, foster, regulate and develop the sport of Darts throughout the world; to support the Olympic Movement, to be affiliated with the International Olympic Committee (IOC) as a recognized International Sports Federation (IF) in conformity with the requirements of the Olympic Charter and to contribute to the achievement of the goals set out in the Olympic Charter, to federate national Darts Sports associations in as many countries as possible; to establish standard rules of play for tournaments; to operate a referee training and qualification policy and supplement it as may be required; to support and encourage the highest sporting ethics amongst darts players to ensure that the spirit of fair play prevails; to devise methods and conduct competitions to award regional, international or world championship titles;to implement and monitor systems for ranking players in order to be able to organise tournaments with various categories of players; and to institute and operate appropriate anti-doping measures based on the World Anti-Doping Code.

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The invention is directed to a process for the continuous preparation of ammonium paratungstate hydrate by back reextraction of a tungsten-laden organic phase with an ammonia-containing aqueous solution in a mixer-settler apparatus. The reextraction is carried out at an NH₃:W molar ratio of from 0.83 to 1.30, and a volume feed ratio of the tungsten-laden organic phase to the ammonia-containing aqueous solution of from 5 to 25. The above crystalline is in high purity and in high yield. The production method can be carried out in a simple and energy-efficient manner.

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A method is disclosed for producing ammonium metatungstate from ammonium paratungstate. The method involves first roasting the ammonium paratungstate at from about 275° C. to about 300° C. for from about 10 hours to about 20 hours to remove some ammonia and some water. The roasted ammonium paratungstate is then added to dilute solution of an ammonium metatungstate which is at a pH of from about 3.6 to about 4.2, the rate of addition being such that a slurry is produced having a pH of from about 3.6 to about 4.2. The pH of the resulting slurry is then adjusted to stabilize it at from about 3.6 to about 4.2 followed by evaporation to form a relatively concentrated solution of ammonium metatungstate which is separated from any insolubles. Ammonium metatungstate is then crystallized from the relatively concentrated ammonium metatungstate solution.

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In order to solve the problem of determination of boron in ammonium paratungstate(APT), the authors began with the study on determination way by ICP AES. The matrix effect and spectral interference of tungsten on boron in ICP AES were studied. The effects of acidity, time of boiling and time of putting aside were investigated. Combining with matrix seperation and factor correction, a new simple,rapid and accurate method for determination of B in APT was developed. The recovery is higher than 95.8%; the relative standard deviation of determination of 0.000 x %～0.00 x %B in APT is lower than 3%. The accuracy and precision of the method are satisfactory.

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Coarse and spherical tungsten powders were prepared by wet hydrogen reduction.Ammonium tungstate solutions with the additives of Li,Na and K alkali metal salts were used as raw materials.The effects of the type and content of the alkali metal salts as well as reduction time on the microstructure,chemical composition,phase composition, and particle size of ammonium paratungstate(APT) and coarse tungsten powders were investigated by scanning electronic microscopy,energy dispersive

The bulk structural evolution during the decomposition of ammonium paratungstate (APT) under various oxidizing and reducing gases was elucidated by the complementary techniques, in situ XAS, in situ XRD, and TG/DSC, combined with mass spectrometry. In the temperature range from 300 to 650 K, the decomposition of APT proceeds nearly independently of the gas employed. At higher temperatures, an oxidizing gas results in the formation of crystalline triclinic WO3 as the majority phase at