Hafnium wire, made of hafnium metal. In nature, hafnium is often symbiotic with zirconium, and all zirconium containing minerals contain hafnium. Hafnium and zirconium are similar in quality, and hafnium are mainly found in zirconium quartzite. The amount of HfO2 in industrial zircons is 0.5-2%. The beryllium zircons in the secondary zirconium ore contain up to 15% HfO2. There is also a metamorphic zircon, which contains more than 5% HfO2. The latter two minerals have few reserves and are not yet used in industry. Hafnium is mainly recovered during the production of zirconium.
Hafnium smelting and zirconium are basically the same, generally divided into five steps. The first step is the decomposition of the ore, and there are three methods: the density zircon (Zr,Hf)Cl4. (2) alkaline fusion of zircon, zircon and NaOH at about 600 ℃ melting, more than 90% of O2 (Zr and Hf) into Na2 (Zr and Hf) O3, the SiO2 into Na2SiO3, water soluble removed. Na2(Zr,Hf)O3 can be used as the original solution for separating zirconium and hafnium after HNO3 is dissolved, but it is difficult for solvent extraction and separation because it contains SiO2 colloids. The K2(Zr,Hf)F6 solution was obtained by sintering K2SiF6. The solution can be separated from hafnium zirconium by fractional crystallization. The second step is the separation of zirconium and hafnium. Solvent extraction and separation methods of MIBK (methyl isobutyl ketone) system and hno3-tbp (tributyl phosphate) system can be used. The technology of multistage fractionation using the difference of HfCl4 and ZrCl4 melt vapor pressure at high pressure (above 20 atmospheres) has been studied for a long time, which can save the secondary chlorination process and reduce the cost. However, due to the corrosion problems of (Zr, Hf)Cl4 and HCl, it is not easy to find suitable fractionating column materials, but also reduces the quality of ZrCl4 and HfCl4, increasing the purification cost. The third step is the secondary chlorination of HfO2 to obtain the crude HfCl4 for reduction. The fourth step is purification and magnesium reduction of HfCl4. The process is the same as the purification and reduction of ZrCl4, and the semi-product is hafnium sponge. The fifth step is vacuum distillation of hafnium sponge, so as to remove MgCl2 and recycle the surplus magnesium, the final product is hafnium sponge metal. If the reducing agent is sodium instead of magnesium, the fifth step is water immersion.
The hafnium sponge should be carefully removed from the crucible to avoid spontaneous combustion. Large pieces of hafnium sponge should be broken into small pieces of a certain size in order to be pressed into a self-consuming electrode and then molten into ingots. Spontaneous combustion should also be prevented in case of breakage. The further purification of hafnium sponge was similar to that of titanium and zirconium by iodide pyrolysis. , a slightly different control conditions and zirconium sponge around the iodide can hafnium small pieces and keep the temperature of 600 ℃, and the hot wire in the center of the temperature is 1600 ℃, than preparing zirconium "crystallization" of 1300 ℃ is high. Hafnium processing and forming includes forging, extrusion, drawing tube and other steps, as well as zirconium processing methods.
