The titanium is purified by high temperature vacuum distillation.
Van Arkel method is used for preparing ultra - pure metals by removing all the oxygen and nitrogen present in the form of impurity in titanium . In this method , crude titanium is heated in an evacuated vessel with iodine at 523K . The covalent titanium tetraiodide thus formed is separated .
Most titanium is now made by the Kroll process, in which titanium dioxide is reacted with chlorine to form titanium etrachloride, which is then reacted with magnesium to strip away the chlorine and leave behind the pure metal.
Titanium extraction
The process used to extract titanium is called the Kroll process and is named after William J. Kroll, who invented the method in the 1930s. It is slow and has at least two steps. First the titanium oxide ore is reacted with chlorine to make titanium chloride.
Due to titanium's affinity to other elements, it cannot be found naturally occurring and therefore requires complex and energy-intensive processes to refine it. This means that it is very expensive compared to other common materials.
Commercially Pure Titanium is represented by four distinct grades, specifically grade 1, grade 2, grade 3 and grade 4. Pure titanium ranges from grade 1, which has the highest corrosion resistance, formability and lowest strength, to grade 4, which offers the highest strength and moderate formability.
Hardness. Steel trumps titanium in a number of categories, including hardness. One of the reasons titanium is so difficult to process is because of its low Brinell number. Titanium alloys are prevalent in the industry because trace quantities of other metals balance titanium's poor material hardness.
The titanium is purified by high temperature vacuum distillation. The metal is in the form of a porous granule which is called sponge. This may be processed on site, or sold on to other companies for conversion to titanium products. Figure 6 Summary of the conversion of titanium ore into useful products.
The problem is that titanium forms a carbide, TiC, if it is heated with carbon, so you don't get the pure metal that you need. The presence of the carbide makes the metal very brittle. That means that you have to use an alternative reducing agent.
It can be shown that the dissolution of titanium in sulfuric, hydrochloric, hydrobromic and hydroiodic acids must proceed according to the reaction Ti° → Ti3+ 3e, exactly as when titanium dissolves in hydrofluoric acid.
Regardless of the final usage titanium must first be removed from its ore and turned into pure titanium. This is done by processing titanium oxide manufactured from either ilmenite or rutile though the Kroll process. The output is a titanium sponge which is purified, melted and alloyed with other metals.
Titanium readily reacts with oxygen at 1,200 °C (2,190 °F) in air, and at 610 °C (1,130 °F) in pure oxygen, forming titanium dioxide. Titanium is one of the few elements that burns in pure nitrogen gas, reacting at 800 °C (1,470 °F) to form titanium nitride, which causes embrittlement.
Titanium is expensive because the extraction process is slow, the chlorine and magnesium (or sodium) required are expensive, it costs a lot to heat the reactor and the process is labour intensive. Chlorine is also dangerous and difficult to handle.
Some titanium compounds undergo hydrolysis reactions in water, for example titanium chloride. Titanium only reacts with water after its protective titanium oxide surface layer is destroyed. It is therefore water insoluble. Titanium compounds generally are not very water soluble.
The Van Arkel method is a metallurgical method used to refine zirconium and titanium metal. The main impurity which is to be removed in this refining consists of oxygen and nitrogen. These impurities are removed by heating the zirconium or titanium metal in an evacuated vessel containing iodine.
Disadvantages of Titanium
It is not suited in high-temperature ranges, above 400 degrees Celsius, where it begins to lose its strength and nickel-based superalloys, are better equipped to handle the conditions.
These minerals resist weathering and are concentrated in placers and wind-blown sand deposits. Titanium is mined in Australia, Sierra Leone, South Africa, Russia and Japan. Ilmenite is a common mineral on the Moon. Any future settlements on the Moon would likely use titanium as a primary building material.
Titanium metal is coated with an oxide layer that usually renders it inactive. However once titanium starts to burn in air it burns with a spectacular white flame to form titanium dioxide, TiO2 and titanium nitride, TiN.
Seawater corrosion immunity: Titanium is immune to corrosive attack in all natural and harsh waters, including sea, polluted, brackish, fresh and high purity waters, to 600oF. Sulfides, sulfates, carbonates, and chlorides do not affect it.
The existing methods of removing the loose oxide layer and the α-phase oxygen-rich layer on titanium alloy surface mainly include mechanical cutting, pickling, laser ablation, high-pressure waterjet.
The major impurities in commercial titanium are iron, manganese, silicon, oxygen, nitrogen, carbon, and hydrogen.
Tungsten, which is Swedish for "heavy stone," is the strongest metal in the world. It was identified as a new element in 1781. It is commonly used to make bullets and missiles, metal evaporation work, manufacturing of paints, creating electron and Television tubes, and making glass to metal seals.
Titanium, however doesn't stand a chance against bullets fired from high-powered military grade firearms such as those used to penetrate tanks. Titanium can take single hits from high-caliber bullets, but it shatters and becomes penetrable with multiple hits from military-grade, armor piercing bullets.
Operational Temperature: Maintains strength and oxidation resistance up to ~300°C (572°F). Oxidation Resistance: Excellent due to the formation of a protective oxide layer. Titanium Alloys: Operational Temperature: Certain alloys (e.g., Grade 5) hold structural integrity up to ~400°C (752°F).