Liquid Film Method Preparing Ammonium Paratungstate

Ammonium paratungstate (APT) prepared by liquid film method is taking crude sodium tungstate (Na₂WO₄) which is obtain from tungsten fine mud or tungsten concentrate dissolving in alkali, the N263 as extraction agent, the LMA-1 as emulsifier; then adjust the pH value to 8~9 to remove impurity of silicon, and then carry out l intermittent liquid film migration under the room temperature; the liquid membrane extraction can effectively separate P, As, Mo without the other impurity removal process, and also can directly generate ammonium paratungstate crystals in internal aqueous phase at one step. The results showed that the extraction rate of ammonium paratungstate can up to 99.85%, and the purity of APT can meet the standard of first grade; while if the process is improved, this will be a promising method to prepare APT.

Emulsion liquid membrane technology is the new separation technology developed in late late 1960s. In the year of 1987, Draxler and other scientists, Austria, have developed a new type of separation technology which successful recovered zinc from the viscose waste liquid, the liquid membrane separation technology has entered the practical application stage until then. The emulsion liquid membrane has the properties of selective specificity, large mass flux and good fluidity, which makes it suitable for continuous treatment of lead-containing industrial wastewater. The liquid membrane treatment of wastewater which contains lead not only purifies the water, but also enriches and recovers metal ions. At present, the liquid film method is mainly used for impurity removal and the optimization of wastewater treatment process.