| The difficult problem of removing molybdenum from tungstate in the process of tungsten metallurgy has been studied in depth. Based on a lot of theoretical analysis and experimental investigation, a very effective and simple new technics of removing molybdenum from tungstate has been invented successfully. And we have put it into practice in the industrial production.The main content of this paper is:1) The behaviour of molybdenum sulfidation in tungsten solution has been investigated in detail.At first, the thermodynamic analysis of the molybdenum sulfidation was done, and the curves, which describe the distribution of MoOxS4.x2" according to the change of solution pH and sulfurizing reagent amount, has also been ploted. These work provided theoretic instruction for the practice of molybdenum sulfidation.Secondly, through the experimental investigation, the behaviour of molybdenum sulfidation was studied again, and the proper conditions of sulfurizing molybdenum in tungstate solution were put forward finally.2) Some existent technics of removing molybdenum from tungstate, such as ion-exchange technics by using of strong base anion ion-exchange resin or solvent extraction technics by using of quaternary ammonium salt, have a very great defect, that is desorption or back extraction of MoS42" is very difficult to complete . In order to overcome this defect, some new research was done in this paper.At first, the adsorption and desorption behaviour of MoS42" by using of alkalescent anion ion-exchange resin was studied, the experiment result shows that: D301 ion-exchange resin's (with tertiary amine radical) effect of absorbing MoS42" is better, but the effect of desorbing MoS42" with NaOH solution is not satisfying. On the contrary, although D312 ion-exchange resin's (with primary amine radical) effect of desorbing MoS42" with NaOH solution is better, it's effect of absorbing MoS42" is very bad. So by using of alkalescent anion ion-exchange resin can not overcome the defect that mentioned before.Secondly, the behaviour of extration and stripping of MoS42" in synergistic extraction technics (N263+P2o4+TBP+Coal oil) is studied, the experiment result shows that: With the increasing of P2o4 added into the extraction system, the extraction efficiency of MoS42" become small gradually, but the stripping efficiency of MoS42" increases gradually. Because the addition of P2o4 reduces the N263's capacity of extracting MoS42" greatly, this technics has no practical valule. So it is impossible to overcome the defect mentioned before by using synergistic extraction technics studied here.Finally, the method of revoming molybdenum from tungstate by using ion flotation technics was studied, the experiment result shows that: After the (NH4)2WO4 or Na2WO4 solution has been sulfurized, it is very effective of removing molybdenum from tungstate by using cetyl trimethyl ammonium bromide as ion flotation collector.Through this technics, the ammonium paratungstate(APT) in which the Mo/WO3 is under 20 X 10"6 can be produced. But how to reclaim the collector is very difficult in this technics.3) Based on the investigation of WO42" and MoS42"'s difference in microscopic property, the new reagent and technics for revoming molybdenum from tungstate have been invented, and it has been extended to revoming As, Sn and Sb from tungstate. The research work shows that:(T) The highest occupied molecular orbital energy HOMO of MoS42" is much higher than that of WO42"(the energy difference of them is 4.85eV), this indicates that the electrons are more liable to lose when the molecule react with the others, and it will shows the better coordinating ability; At the same time the result shows that, the highest occupied molecular orbit of MoS42~ is composed of Mo atom's orbits, but the highest occupied molecular orbit of WO42"is composed of W atom's orbits.Comparing MoS42" with the flotation collectors of sulphidic ore, we found that they are very similar to each other. So we regarded MoS42" as the flotation collectors o...
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