Tungsten is a high-yield resource in China. The scheelite (CaWO 4 ) is not leached with caustic as well as the wolframite because it does not decompose in the caustic solution, and is conventionally decomposed with hydrochloric acid. Institute of Process Engineering Kejia Jun et solubility product principle, proposed to add an appropriate amount of soluble phosphate at the caustic leaching, in order to precipitate calcium scheelite is insoluble compounds HAP Ca 5 (PO 4) 3 OH (kap = 1.6 × 10 -58 ), so that the scheelite is continuously dissolved and leached in the form of sodium tungstate. In order to confirm this possibility and the speculative mechanism, the alkali leaching kinetics of scheelite was studied. The disc samples were pressed with scheelite powder of 100% particle size <44 μm (-325 mesh), and the empirical leaching kinetic equation was obtained by the rotating disc method as follows: Where k is the apparent leaching rate constant. From the above formula, it can be seen that the apparent energy E α =42700 J∕mol, indicating that the leaching process is mainly controlled by surface chemical reactions. During the experiment, it was observed that solid suspension appeared in the liquid and the solid precipitate layer appeared on the surface of the disk sample, which is consistent with the conclusion that the leaching process derived from apparent activation energy is mainly controlled by surface chemical reaction. The results of X-ray diffraction and infrared spectroscopy of the solid suspension also confirmed the formation of calcium hydroxyphosphate in the leaching. It can be inferred that the caustic leaching of scheelite is carried out as follows: This is an example of understanding the reaction mechanism through kinetic studies. Aluminum Profiles For Middle East Compared with wooden and steel doors and windows, Aluminum Doors and Windows have obvious advantages in terms of strength, insulation, aesthetics and longevity. Aluminum profiles come in a variety of sizes and shapes and are very easy to install. If you need a durable and energy-efficient door and window solution, aluminum profiles would be the best choice. Aluminium Profile Price,Aluminium H Profile,Alu Profiles,Aluminium Extruded Sections,Aluminum alloy doors and windows Foshan Knilex Aluminum Co., Ltd. , https://www.aluprofilefactory.com
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