Tungsten Oxide

High purity quaternary ammonium paratungstate (APT) is a crystalline powder of ammonium paratungstate with a purity of 99.999% to 99.9999%. At present, the methods of producing high purity APT by controlling impurity content in industrial production are: re dissolution method, ion exchange method, ammonium tungstate method, electrolysis method, recrystallization method, etc.. But because of the different chemical properties of impurity elements, using only one method to achieve the purpose of removing all impurities, so the preparation of high purity APT often need two times of ion exchange, activated carbon adsorption and other means of further purification. It is found that the following three problems should be paid attention to during the purification of high purity ammonium paratungstate (APT). (1). The higher the crystallization rate, the higher the impurity content in APT crystallization. When the crystallization rate is more than 65%, the precipitation of impurities is accelera...

At present, in Chinese  ammonium paratungstate (APT) enterprises, the most commonly used crystallization method often requires a lot of ammonia, in the production of ammonium tungstate process there are two cases will escape ammonia. There are two cases will escape ammonia: One is the free ammonia in the ammonium tungstate solution, which quickly escapes in the early stages of the heating ammonium tungstate solution; the other is the reaction of ammonia, it is with the loss of the ammonia concentration in the solution and the precipitation of ammonium paratungstate, and constantly to escape. A mmonia l iquid is a high energy consumption products, the current market price is about 2400 RMB / ton. If the recycle rate of ammonia is 80%, the recycle value is considerable, and the recycle cost is low, it don’t need to increase in capacity, using the cooling cover to recycle,  only add a small amount of vacuum pump and water pump for electricity, thus ...