ALUMINIUM FROM CLAY

Wairarapa Times-Age, 10 March 1942, Page 4

ALUMINIUM FROM CLAY

NEW EXTRACTION METHOD. RESEARCH BY CHEMISTS. Aluminium is obtained from alumina, and alumina is found nearly everywhere. Common clay is full of it. Yet bauxite is used because it is the richest source of alumina. Metallurgists are worried about the supply of bauxite, says a writer in the “New York Times.” Deposits within the United States probably aggregate no more than 13,000,000 tons, and 3,500,000 to 4,000,000 a year are required for war purposes. At this rate the American reserves will be exhausted in not more than three and a half years. Besides, it requires great amounts of electricity to recover the metal from bauxite, and the- Government is worried over a shortage of power.

Like other chemists Professor .Arthur W. Hixson (Columbia) has addressed himself to this problem. 'He worked in collaboration with Dr. Ivan J. Klein of the plastics division of the E. I. duPont de Nemours Company, and it looks as if the two had solved it. They have turned to clay and other alumina-containing “ores.” All these abundant sources are contaminated by silica and iron. The problem reduces itself to getting rid of the silica and iron cheaply and effectively. The Hixson-Klein process is purely chemical, requiring no electricity. The ores are first roasted at a temperature which makes them susceptible to attack by hydrochloric acid, which is pretty cheap. Roasting also destroys the organic matter and reduces the iron to the ferric state. This done, boiling hydrochloric acid is applied. Thus aluminium chloride in high concentration is obtained, with small amounts of ferric chloride, calcium chloride, sodium chloride, and possibly potassium chloride. Much of the watery solution is evaporated, whereupon the ferric chloride is separated with isopropyl ether, a cheap and abundant organic acid which is recovered and used again.

The aluminium chloride solution, now robbed of its iron, is heated to about 350 degrees C. At this temperature the aluminium chloride decomposes into aluminium oxide, hydrochloric acid, and water. The hydrochloric acid goes into the water and is recovered. Whereupon the watery aluminium oxide is heated to about 800 degrees C. to burn out the oxygen and leave aluminium vitually free from iron.

Chemists have known all along that acids could be used to extract aluminium from clays, but they did ndt solve the problem of recovering and regenerating the acid and separating the iron from the aluminium by acid, partly because acids can be used only with corrosion-resisting vessels. Here the development of plastic came to the rescue of Drs. Hixson and Klein. We now have dozens of acid-resist-ing synthetic plastics, ceramics, and forms of’ rubber, not to mention porce-

lains. Moreover, organic acids, like isopropyl ether, are available in large quantities because of the plastic industry. It follows that Drs. Hixson and Klein have cashed in most ingeniously on important industrial developments of the last twenty years.