Yuntian Metal Abstract: The application of hafnium metal in new materials is introduced, and the mechanism of hafnium in superalloys is emphatically expounded. The importance and methods of hafnium-containing superalloys are reviewed. The first methods of hafnium mainly include hafnium residues, reuse of hafnium-containing nickel-based superalloy returns, and hydrometallurgical methods to extract hafnium from waste.
The development trend of hafnium and related materials is prospected: the market demand for hafnium will increase with the development of superalloys;The extraction of hafnium from hafnium-containing waste is also the future development trend of the hafnium industryThe chemical metallurgy of materials will also be one of the ways to develop new materials.
Hafnium is a rare refractory metal that has no separate minerals and is always associated with zirconium in nature;Zirconium ore generally contains 1% 2% hafnium [1]. The key technology for the preparation of sponge hafnium used in the production is zirconium hafnium separation:
The first type of method is the separation of zirconium and hafnium by wet solvent extraction, which includes MIBK, N235, TBP, etc. [2];;The second method is the separation of zirconium and hafnium by pyrometallurgical distillation, which involves the use of chlorination or bromination [3].
In addition to the hafnium control rod in the field of nuclear power [7], the application of hafnium metal is also widely used in the non-nuclear field, and the application of hafnium in alloys can obviously improve the properties of alloys, such as the application of hafnium in superalloys [8], nitinol-based alloys [9], niobium-based alloys [10], rare earth permanent magnet materials [11], aluminum alloys [12], amorphous alloys [13], and copper alloys [14].The application direction of hafnium in new materials includes plasma-cut hafnium wire [15], optical coating [16], hafnium target for semiconductor memory devices [17], hafnium bomb [18], etc. Figure 2 shows the application of hafnium metal.
The waste superalloy contains 1% and 2% hafnium, and the superalloy waste is usually subjected to acid oxidation acid leaching or electrolysis by hydrochloric acid or sulfuric acid system, and about 20% of the 50% hafnium is transferred into the solution, and the remaining part remains in the slag. The hafnium of the superalloy acid solution was adsorbed by ion exchange quality, and then the hafnium adsorbed was dissolved with hydrochloric acid to obtain the hafnium solution, and finally the hafnium analysis was precipitated by alkali to obtain the hafnium enrichment. By using hydrofluoric acid and nitric acid to dissolve the hafnium waste, and then using ion exchange resin for adsorption, the final hafnium oxide purity is 99% and the hafnium yield can reach 90%.
It is pointed out that the composition of hafnium-containing scrap metals is complex, there are many elements, and the treatment process of scrap metals before hafnium enrichment is also different, and the separation and purification of hafnium scrap metals from hafnium-containing scrap metals and the preparation of hafnium are the future development trend of hafnium technology in ChinaIn this paper, MIBK was used as the extractant to extract and separate hafnium-containing alloy slag under hydrochloric acid systemExperiments show that the separation of hafnium and zirconium titanium is more difficult and chromium is easier.
Epilogue. 1) In this paper, the mechanism of hafnium metal in superalloys is described, and the reuse of returned materials and waste treatment of hafnium-containing superalloys are discussed.