Ammonium Paratungstate to Prepare Ammonium Metatungstate

Ammonium paratungstate is an important material for preparing ammonium metatungstate by a thermal decomposition - resin exchange method. This method overcomes the problems of some traditional processes such as APT - tungstic acid method, APT - acidification - alcohol precipitation method, and APT thermal decomposition - alcoholization crystallization method, etc. It has the advantages of simple process, high single pass yield and excellent product quality.

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Preparation of Ammonium Metatungstate with Ammonium Paratungstate

Place 100g of ammonium paratungstate in an enamel tray or white steel tray, and put it in a drying oven with a constant temperature of 240 °C for 25-30 min. After taking out, it was slowly poured into 60ml of pure water at 95 °C while stirring. When most of the solids are dissolved, add about 5-8 g of L-shaped resin, at this time, the pH value is between 3.5-4.0. Stir at a constant temperature for 30 min. The obtained mixed liquid was passed through a stainless steel screen to remove resin and its impurities. The filtrate was placed for 12h and vacuum filtered to remove insoluble tungsten compounds and impurities. The prepared clear and transparent filtrate was heated and concentrated until a crystal film appeared on the liquid surface, then cooled and crystallized, and finally dried by airflow at 50-60 °C for 2 h to obtain ammonium metatungstate.

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