Niobium-titanium alloy is one of the main superconducting materials. There are a lot of debris and discarded copper - coated niobium-titanium wire in the process of niobium-titanium alloy. Decarbonization: For copper-clad Nb-Ti wires, decarbonization is performed by anodic oxidation first. In other words, the Copper coated Nb-Ti line is used as the anode, and copper is dissolved in the electrolyte of H2SO4-cusO4 on the anode in order to separate and recover niobium and titanium.
Chlorination: use niobium titanium waste composition: Nb52.20%, Ti46.00%, TA0.025%, Fe0.009%, Ni0.003%. The waste Nb-Ti alloy is cut into l0mm and chlorinated in a chlorination device, which includes a chlorination tower, a salt tower and a condensation tower. The material is heated to 250℃ and reacts with chlorine gas directly, that is, various metal chlorides are generated. The main chlorination reactions are as follows:
The metal chloride is collected in the condensation tower. At this point, the high boiling point chloride partially sinks to the bottom of the chlorination reactor and can be discharged periodically. Impurity iron and aluminum through the chloride outlet of the salt tower, the temperature is controlled at more than 300℃, preferably 300~500℃, so that iron and aluminum to generate difficult volatile complex salt, such as FeNaCl4 and AlNaCl4 are separated and removed.
Distillation: atmospheric distillation can be carried out at 240~250℃ to separate TiCl4, SiCl4 and other low boiling point chloride, and then heating up to 253℃, distillation of niobium pentachloride. High purity niobium pentachloride containing only tantalum was obtained.
Hydrogen reduction: Because the boiling point of niobium pentachloride and tantalum pentachloride is very close (242℃), only hydrogen reduction method is used to selectively reduce NbCl5, but TaCl5 is not reduced to separate niobium and tantalum. Hydrogen reduction temperature is 500~580℃, the gas-gas reduction reaction of niobium pentachloride can reduce NbCl5 to Nb3Cl8, and obtain high purity Nb3Cl8 without tantalum. This chloride is stable in the atmosphere and easy to handle. The reduction device consists of chloride evaporator, first reduction recovery tower, second reduction recovery tower and unreacted chloride collector. At 245℃, niobium octachloride was obtained in the first and second reduction stages.
