Study On Separation Of Tungsten And Phosphorus And Separation Of Tungsten And Molybdenum In Acidic System

With the exploitation and utilization of high-quality tungsten ore resources,the development of low grade refractory mineral resources of tungsten has become an inevitable choice for sustainable development of tungsten industry.However,the scheelite has low grade.It has bring a serious problem of leaching,purification,transformation and emissions under the alkaline leaching.Therefore,the alkaline leaching technology system has getting more and more difficult to deal with the refractory tungsten ores.It has got attention again on the research in acid leaching system.As the two most common impurities,phosphorus and molybdenum were easily got into the liquid follow the acid leaching solution.Therefore,promoting the exploitation and utilization of low grade refractory tungsten ore resources in researching to the separation of tungsten and phosphorus and tungsten and molybdenum under the system of acidic conditions has been the vital significance.The tungsten element from high phosphorus containing tungsten acid solution was separated and extracted and the pure ammonium tungstate solution was obtained.Firstly,tungsten was extracted directly in acid medium by solvent extraction.99.8% tungsten in acidic high-phosphorus solution was extracted with Aliquat 336 in kerosene by one extraction stage under the conditions of O:A=1,pH=2,25 ?,t=2 min,20% v/v 2-Octanol and 10% v/v Aliquat 336.And then tungsten and phosphorus were preliminary separated through stripping process.Over 95% tungsten were recovered after five stripping stages under the optimum stripping conditions of 2.5M ammonium bicarbonate,8 min stripping time,O:A=1:1,pH=9 and 60 ?,but only about 1.2% phosphorus was recovered from feed liquor.Finally,a small amount of phosphorus left in strip liquor was deeply removed by magnesium salt precipitation method on the optimum conditions of pH=10.0,25 ?,reaction time 1 h and Mg/P molar ratio of 1:2 and the ammonium tungstate solution meeting the requirements of producing highquality APT can be obtained successfully.Compared to traditional phosphorus removal route,the process in this paper can help extract tungsten directly in acidic medium and decrease the quantity of phosphorus through extraction-stripping process,significantly reducing the consumption of alkali and magnesium salt and improving the separation efficiency of tungsten from acidic high-phosphorus solution.In order to solve the difficult problem of separating tungsten and molybdenum,the effect of separating tungsten and molybdenum using P204 and Cyanex301 under acidic conditions was investigated.The results showed that using Cyanex301 to separating tungsten and molybdenum was better than P204 under the same extraction conditions.91% molybdenum in acidic solution was extracted with Cyanex301 in kerosene by one extraction stage under the conditions of high tungsten and molybdenum rate(W:Mo=50:1),25 ?,pH=2,t=5 min,O:A=1 and 10% v/v Cyanex301,but only about 15% tungsten was extracted.The results of testing the extraction agent showed that the spectrum of P204 was no significant change before and after extraction,but Cyanex301 was varied significantly.The characteristic peak was appeared at 344 cm-1.This indicated that the presence of a sulfur element in Cyanex301 was promoted the selective extraction of molybdenum.