Chromium Doped Ammonium Paratungstate(APT)
Here are two inventions about chromium doped ammonium paratungstate.
The invention belongs to the technical field of tungsten smelting and production and in particular relates to a method for preparing uniformly chromium-doped APT (ammonium paratungstate). The method for preparing the uniformly chromium doped APT comprises the following steps: (1) dissolving WO3 with ammonia; (2) adding soluble chromic salt, heating, and carrying out evaporation crystallization; (3) after liquid in a crystallizing pan is completely boiled, stopping steam introduction while stirring continuously; (4) when crystal nucleuses appear in the crystallizing pan, regulating a rotating speed, and maintaining a steam pressure; (5) when density of a solution reaches 1.1g/cm-3, controlling a stirring speed, and maintaining the steam pressure; and (6) when the pH of the solution is 6.7-7.0, stopping heating, cooling and emptying. The method for preparing the uniformly chromium doped APT has the beneficial effects that APT powder with chromium uniformly distributed can be prepared, chromium is uniformly distributed at each APT crystal boundary, and molecular scale mixing is realized; and the prepared chromium doped APT can be used for effectively inhibiting abnormal growth of WC crystal grains in a liquid phase sintering process, so that properties of a hard alloy are greatly improved.
The invention belongs to the technical field of tungsten smelting production, and particularly relates to a method for deeply removing chromium from APT (Ammonium Paratungstate) crystallization mother liquor. The method for deeply removing the chromium from the APT crystallization mother liquor comprises the following steps: a, preparing 50% basic magnesium carbonate suspending liquid; b, regulating the pH value of a chromium-containing crystallization mother liquor; c, sealing a solution, heating in a water bath, stirring, heating, and reacting; and d, after the reaction is finished, filtering, detecting chromium content, recycling filter liquor to an existing tungsten smelting process, and effectively recovering tungsten. The method disclosed by the invention has the beneficial effects that basic magnesium carbonate is a novel reagent for deeply removing the chromium and can reduce the content of the chromium contained in the chromium-containing crystallization mother liquor to 1.5 mg.(L<-1>) without introducing other impurities, and the chromium removal ratio reaches as high as 99.9% and is superior to that of other chromium removing reagents, namely sodium hydroxide, ammonia water, magnesium chloride and the like. The method disclosed by the invention is one of critical technologies in a process for preparing uniformly chromium-doped APT powder and has great significance on realizing industrialization and preparing a high-end hard alloy.