Cornwall, seen circled at left, is a unitary authority and ceremonial county of England within the United Kingdom. It is an English peninsula bordered to the north and west by the Celtic Sea, to the south by the English Channel. It is also bordered to the east by the county of Devon and the River Tamar. The county of Cornwall has a population of 536,000 and covers an area of 3,563 square kilometers.
Historically, tin mining has long been important to the Cornish economy, and increasingly so during the High Middle Ages (1001-100 AD). It then expanded greatly during the early 19th century when rich copper mines were also in production. In the mid-19th century, however, the tin and copper mines entered a period of decline; china clay extraction became more important and metal mining had virtually ended by the 1990s. Fishing and agriculture have historically also been important sectors of the Cornish economy. The area is noted for its wild moorlands, its long and varied coastline, its many place-names derived from the Cornish language, and its very mild climate. Extensive stretches of Cornwall’s coastline and Bodmin Moor are protected as an Area of Outstanding Natural Beauty. While Cornwall has a fascinating history, it is not our topic this week.
Our topic this week concerns, among others, William Gregor (1861-1817)(right), an English clergyman and mineralogist. While studying chemistry as an undergraduate at Cambridge University, he spent a good deal of time working investigating the minerals in Cornwall, charting areas in the county where one was more prevalent than another. As with most interesting discoveries, it was by accident that young Gregor found a sand that was magnetic and black in color, resembling gun powder in a stream near the parish of Mannacan. Now the sand is called ilmenite, and it is mostly comprised of a mixture of titanium and oxides of iron.
In analyzing the sand, Gregor found it was highly magnetic. Additionally, he realized it was a rather impure oxide of an unknown metal, which he described as “reddish brown calx.” He found that when dissolved in sulfuric acid, the calx turned yellow. When reduced with tin, zinc, or iron, the calx became purple. Thus, Gregor deduced that he was dealing with a new metal, which he named manaccanite to honor the parish of Mannacan. After his discovery, Gregor returned to his pastoral duties.
The oxide was independently rediscovered in 1795 by the German chemist Martin Heinrich Klaproth (left, 1743-1871). Klaproth found that some rutile from Hungary contained a new element, which he named Titanium after the Titans of Greek mythology. Later, after hearing about Gregor’s earlier discovery, Klaproth obtained a sample of manaccanite and confirmed that it contained titanium. Martin Klaproth was a trailblazing metallurgist, as he also discovered uranium (1789), zirconium (1789), and cerium (1803).
The pure elemental metal, however, did not exist until 1910 when Matthew A. Hunter (1878-1961), an employee of General Electric, invented a rather complex method of Titanium extraction. By heating TiCl4 to 800°C Hunter produced titanium for the first time in a method that became known as the Hunter Process. Through this process he discovered that titanium has a variety of desirable properties, which have subsequently made it the metal of choice in many industries, such as aerospace, architecture, sporting equipment, military hardware, medical implants, hearing aid components, and other applications where lightweight strength and ability to withstand temperature extremes are required.
While Hunter’s process was capable of extracting titanium, it was cumbersome and expensive. So, in 1932 it yielded to a more efficient process invented by a Luxembourg native, William Kroll. His process combined titanium tetrachloride with calcium to produce ductile titanium. By 1938, Kroll had produced 50 pounds of titanium using his process, later named the “Kroll Process”. (Click on the Boiler for an explanation of the Kroll Process.) With the rise of Nazi power through Europe, Kroll decided to take his metallurgic findings to the United States, ending up at the U.S. Bureau of Mines. In 1946, he showed that titanium could be produced commercially by reducing titanium tetrachloride with magnesium.
Titanium is the 9th most abundant element in the earth’s crust and is almost always found in igneous rocks. It occurs in rutile, ilmenite, sphene, and many iron ores and titanates. Titanium is also found in coal ash, plants, and in the human body as well as in the sun and in meteorites. Rocks from the Apollo 17 mission to the moon contained up to 12.1% TiO2. Rocks from earlier missions showed lower percentages of titanium dioxide. Titanium oxide bands are seen in spectra of M-type stars.
But, What does Titanium have to do with Hearing Devices?…
That’s a topic for next week’s HEARING INTERNATIONAL………….