Detail of "1311-93-9"

Reference

Study of the mechanochemical reactions of ammonium paratungstate undecahydrate

Study of the mechanochemical reactions of ammonium paratungstate undecahydrate. Petrovskaya, L. I.; Prodan, E. A.; Pavlyuchenko, M. 1311-93-9 and 12181-43-0 are also occured in this study. M. (Inst. Obshch. Neorg. Khim., Minsk, USSR). Vestsi Akad. Navuk B. SSR, Ser. Khim. Navuk, (5), 98-102 (Russian) 1976. CODEN: VBSKAK. DOCUMENT TYPE: Journal CA Section: 78 (Inorganic Chemicals and Reactions) With the use of dry grinding, the duration of vibratory milling or pulverization of 5(NH4)2O.12WO3.11H2O is 2-3 min. After this time at an invariable phase and chem. compn. of the samples, the av. size of the crystals are reduced to .apprx.5-.mu. diam. At longer milling times, the presence of 5(NH4)2O.12WO3.7H2O and 5(NH4)2O.12WO3.5H2O is detected by x-ray diffraction, the substance loses water of crystn. and is converted to an x-ray amorphous state. .

Kinetics of and an adsorption model for the dissolution of synthetic tungsten trioxide in aqueous ammonia

Kinetics of and an adsorption model for the dissolution of synthetic tungsten trioxide in aqueous ammonia. Van Put, J. W.; De Koning, P. M. (Dep. Raw Mater.In this study， 7664-41-7 and 1311-93-9 are also used. Technol., Delft Univ. Technol., Delft 2600 GA, Neth.). Hydrometallurgy, 28(3), 353-66 (English) 1992. CODEN: HYDRDA. ISSN: 0304-386X. DOCUMENT TYPE: Journal CA Section: 54 (Extractive Metallurgy) Ammonium paratungstate tetrahydrate dissolves slowly in aq. ammonia. The complete calcination into cryst. WO3, as a way to improve the dissoln. characteristics in aq. ammonia solns. was studied. Calcination expts. were carried out in air at 550°. The dissoln. rate of this calcine was investigated as a function of soln. temp., ammonia concn., particle size, and agitator speed. The dissoln. rate is controlled by chem. reaction and has an activation energy of 73±3 kJ/mol. A model based on the adsorption of ammonia ions at the particle surface adequately describes the asymptotic increase in dissoln. rate at higher ammonia concns. Complete calcination at 650 and 800° resulted in a decreased dissoln. rate. This behavior is attributed to a decreasing surface area of the calcine with increasing temp. Calcination at 450° resulted in a mixt. of hexagonal WO3 and phase which is isostructural with hexagonal ammonium tungsten bronze. This mixt. dissolves more slowly in aq. ammonia than does WO3. .