Titanium, as an important metal element, has not been widely exploited and used, although it was discovered in the early days. Until 1910, the American chemist Hunt through the sodium reduction of titanium tetrachloride method, at a high temperature of 700-800 ℃ for the first time produced a purity of up to 99.9% of the metal titanium, but the yield is extremely limited, less than 1 gram in total. This method is known as the "Hunt method", however, due to the expensive cost of the reducing agent sodium, it is only suitable for the preparation of titanium in small quantities, and cannot meet the needs of large-scale production.
In 1932, Kroll, an American scientist from Luxembourg, made a breakthrough. He used relatively cheap calcium to reduce titanium tetrachloride at a high temperature of more than 800 degrees Celsius, successfully realizing the commercial production of titanium. A few years later, Kroll further optimized the production process by replacing calcium with magnesium, which is easier to preserve, and this method has been used ever since and is known as the "Kroll method".
To 1948, the United States DuPont pioneered the use of magnesium reduction - vacuum distillation method for the production of titanium tonnage of the new process, which marks the official start of the industrial production of titanium. The process is mainly divided into three steps: first of all, through the chemical reaction of titanium dioxide into titanium tetrachloride; and then with the metal magnesium reduction of titanium tetrachloride to get titanium sponge; finally with the vacuum distillation method to remove impurities in the titanium sponge and excess magnesium, so as to obtain pure titanium. The titanium sponge coming out from the reactor is porous and similar in appearance to a sponge, hence the name.
Titanium sponge needs to be melted into liquid in an electric furnace before it can be cast into ingots. Because the entire reaction process needs to take place at high temperatures, titanium materials consume a lot of energy during production, which is one of the main reasons why they are so expensive.
Currently, the magnesium reduction-vacuum distillation method is commonly used in various countries around the world to produce titanium sponge due to the superior quality and higher production safety of titanium metal prepared by the Crowell method. From the discovery of the element titanium to the production of pure titanium, it took more than 100 years. Nowadays, titanium has gradually stepped into people's daily life, and because of its unique properties, it has been increasingly valued by people, and the field of application is also more and more extensive.
