The first step of titanium material preparation is the process of melting titanium raw materials and adding materials to produce titanium and titanium alloy compact ingot billet.
In 1940, the Luxembourg scientist J. W. Kroll (Kroll) in the United States for the first time using vacuum non-consumable arc melting method to melt titanium sponge, obtained dense titanium ingot. In the late 1940s, the industrial-scale consumable furnace was first completed in the United States, which marked that the titanium smelting industry entered a stable development stage. Subsequently, the former Soviet Union, the United Kingdom, Japan in the mid-1950s, established their own titanium smelting industry. This is Titanium seamless Tube.
General titanium materials can be produced by two times of consumable melting, aviation and other important uses of some titanium alloys need to go through 3 times of melting, typical production process:
Sponge titanium smelting process:
① Magnesium thermal reduction method
The process of reducing titanium tetrachloride (TiCl4) with magnesium to produce titanium is one of the main methods of titanium production. The reduction operation was carried out in high temperature and inert gas atmosphere. The remaining magnesium and MgCl2 were separated by vacuum distillation to obtain spongy titanium.
Magnesium thermal reduction method in 1940 for Luxembourg scientist Klauer successful research, also known as Klauer process. In 1948 the DuPont company in the United States began using this method to produce commercial titanium sponge. The traditional magnesium thermal reduction method is to assemble the distillation equipment for vacuum separation after the reduction product is cooled at the end of the reduction operation. The semi-joint method was successfully adopted by the Soviet Union in the 1970s. In the early 1980s, Japan successfully adopted reduction - distillation combined process, referred to as combined process. The process features that after the completion of magnesium thermal reduction of TiCl4, the hot reduction product is directly transferred to vacuum distillation at high temperature to separate magnesium and MgCl2, which is a major technical progress since the industrialization of magnesium thermal reduction method. The technological process is as follows:
② Sodium (Na) reduction method
Hunter process, also known as Hunter process, is the first studied method used to produce titanium metal. Its flow chart is shown as follows:
The production process of titanium tetrachloride (TiCl4) by sodium reduction is exactly the same as that of magnesium thermal reduction. Under the protection of inert atmosphere, TiCl4 was reduced by Na to produce titanium sponge. Its main reaction is as follows:
TiCl4 + 2Na = TiCl2 + 2NaCl (1)
TiCl2 + 2Na = Ti + 2NaCl (2)
TiCl4 + 4Na = Ti + 4NaCl (3)
The obtained reduction product is washed and desalted with water, and finally the product is post-treated to obtain titanium sponge.
The sodium process can be divided into one - and two-stage processes according to the way the reduction process is carried out. In the reaction process, if the reduction reaction is completed in one time according to Formula (3), the process of preparing titanium sponge is called one-stage method. In the reaction process, if TiCl2 is prepared in the first step according to Formula (1), and then the second step continues to reduce TiCl2 to titanium sponge according to formula (2), the process is called two-stage. At present, both methods have been used in industrial production.