Extractive metallurgy and recycling of titanium and its alloys

Titanium was discovered relatively recently. Indeed, it was only in 1790 that the Reverend William Gregor found the oxide of an unknown element in the black sands of the Cornish coast, exhibiting magnetic properties, but he did not identify the metal. It was the German chemist Klaproth who did, and named it "titanium" in 1795, in reference to the "Titans" of Greek mythology. These ores are found in Canada, the United States, Brazil, Norway, South Africa, India, China, Australia, the CIS...

Titanium has the symbol Ti in the periodic table of elements; its atomic mass is 47.5 and its atomic number is 22. It is the fourth most abundant metal in the earth's crust, accounting for 0.44% of its mass, compared with 8% for aluminum, 5% for iron and 2% for magnesium.

Obtaining the metal from the ore required a long process of fine-tuning. Indeed, the metallurgical extraction process is extremely delicate and environmentally damaging, due to the use of chlorine. The ductile metal, suitable for the manufacture of parts, was not obtained until 1910. This explains the late development of its industrial applications, which only began around 1950.

In terms of specific properties (property divided by density), titanium alloys rank ahead of aluminum alloys and steels; nevertheless, the cost price of parts is high. This explains why they are being used more and more in the aerospace and defense industries. Unalloyed titanium is highly resistant to corrosion and very flexible in form: this also explains its important applications in the chemical industry, seawater desalination plants, nuclear power plants, offshore oil production and civil engineering (ornamental plates, bridge pier protection, etc.).

The objectives of this article are to present a few elements of titanium metallurgy, then to focus on the manufacturing stages of semi-finished products by reviewing its extractive metallurgy, elaboration and first transformation.