In recent years, HNO3 series TBP extraction and hcl-hno3 series TBP extraction have been used. The former ore differentiation by NaOH melting method brings a series of difficulties, including the three phase difficulties in extraction. The latter USES ZrCl4 as the material to avoid the above difficulties, but also has the disadvantage of strong corrosion of the solution. The obtained ZrO2 is chlorinated to obtain ZrCl4, which is called secondary chlorination in industry. ZrCl4 is purified by improvement, then coarse zirconium is prepared by metal thermal recovery (magnesium recovery or sodium recovery), vacuum distillation is performed to remove MgCl2 and recover the remaining magnesium (sodium recovery is washed with water). The process is similar to that of titanium, except that magnesium has to be pretreated and purified. The chemical reaction of magnesium recovery method is ZrCl4+2Mg→Zr+2MgCl2, and the recovery temperature is about 850℃. The vacuum distillation temperature is 950 ~ 1000℃. Zirconium itself has a suction effect, so the final vacuum is generally 10-5 torre.
The higher purity zirconium is produced by ZrI4 on hot wire, which is called crystal rod in industry. There are ZrI2 and ZrI3 participating effects in this process. Zirconium and zirconium alloy choose vacuum consumable electric arc remelting furnace smelting ingots, the most commonly used profile for the tube, forming method including casting, kneading, stretching, and titanium tube processing method is fundamentally the same.
Zirconium and zirconium alloys are primarily used in water-cooled atomic reactors. In an atomic reactor, a uranium rod cannot touch water directly. Because hot water corrodes the uranium rods, the rods make the water radioactive, which can harm human health. With zirconium as the uranium rod sheath, can meet the requirements of the following four aspects: (1) strong corrosion resistance, not with nuclear fuel and heat transfer medium (such as water) effect; (2) meet the strength, heat and corrosion resistance; (3) rarely absorb neutrons, ensuring that fission "chain reaction"; (4) simple processing forming.
Zirconium can also be used as an additive for special steel. Zirconium stainless steel and heat-resistant steel are important materials for making tanks, tanks, cannons and bulletproof plates. In addition to strengthening the strength and hardness of steel, zirconium can also improve the mechanical processing function of steel, hardening, weldability. It also breaks down the sulfur compounds in the steel and then refines the grain composition of the steel. The steel of zirconium is enhanced in oxidation resistance and corrosion resistance. Zirconia has a melting point of up to 2675℃. It has good chemical stability and is used as a high-grade refractory material.
