Research On The Pyrometallurgical Recovery Of Re From Different Forms Of W-Re Alloyed Scraps

Although rhenium(Re)is scarce and expensive,it is highly valued in aerospace,petrochemical and other fields because of its excellent properties such as high hardness,high strength and high heat resistance.With the increasing demand of Re,it is often difficult to extract Re from the limited minerals and recycling Re from containing-rhenium scraps is considered to be an important way to extract Re.On the other hand,W-Re alloy has excellent performance,and with the increase of its usage,more scraps will be produced.Therefore,it is of great economic value to develop efficient separation of W-Re alloyed scraps,especially to recover Re from it.This dissertation try to recover Re from different forms of W-Re alloyed scraps by pyrometallurgical method and carry out the reuse of recovered Re.(1)Because of the volatilization rate and collection rate of Re₂O₇ have obvious influence on the recovery rate of Re,a pyrometallurgical recovery device suitable for recovering Re from W-Re alloyed scraps was designed to solve the problem of low volatilization rate and collection rate of Re₂O₇.Using constructed device,Re was recovered from the W-5Re alloyed scraps by pyrometallurgical method.The results show that the Re₂O₇ can be completely volatilized and collected efficiently in air at 675?for 3 h and NH₄ReO₄ powder was obtained by leaching and evaporation crystallization of Re₂O₇ with ammonia water.The obtained NH₄ReO₄ powder was reduced in H₂ at550?for 90 min to produce Re powder with average particle size of 14.17?m and purity of 99.9634%.The total recovery of Re reaches 96.24%.(2)Research on recovery of Re from different raw W-5Re alloyed scraps by pyrometallurgical method was carried out.The oxidation process,the volatilization rate of Re₂O₇,the purity and recovery rate of Re powder were compared and analyzed.The results show that the form of W-5Re alloyed scraps has obvious influence on the recovery conditions needed and recovery rates.The oxidation temperature needed for the unalloyed powder,alloyed block and wire alloyed scraps is different,and the volatile rate of Re₂O₇ is different at different temperatures.The purity of recovered Re is higher than 99.9%,the recovery rate of Re is more than 91%,and the highest recovery rate was more than 96%.(3)The reuse research of NH₄ReO₄ and Re powder recovered from W-5Re alloyed scraps was carried out.Two kinds of W-5Re powder mixtures were prepared by mixing NH₄ReO₄ and Re powder with W powder,respectively.W-5Re alloy sintered specimens were prepared by pressing and sintering,and its properties were tested.And compared with the commercial W-5Re powder and the prepared sintered specimens.It is found that the recycling degree of NH₄ReO₄ and Re powder prepared by W-5Re alloyed scraps recycling is higher.W-5Re powder mixtures prepared by S-L method has uniform and fine particles with particle size between 100 nm and 200 nm.W-5Re alloy sintered specimens prepared by the W-5Re powder mixtures prepared by the S-L method after sintered at 1850?for 6 h has higher properties.The density and microhardness of the sintered specimens reaches 18.92 g/cm³ and 423.4 HV,respectively.The thermal conductivity at room temperature reaches 151.97 W/(m·K)and the resistivity at room temperature reaches 13.52??·cm.