654 



UNITED STATES MINERAL RESOURCES 



but above 800 °C it weakens considerably, and above 

 1,300°C it absoi'bs gases from the atmosphere and 

 becomes brittle. This latter characteristic makes it 

 necessary to utilize inert atmospheres or a vacuum 

 in high-temperature processing or fabrication op- 

 erations. Titanium metal has better corrosion re- 

 sistance than stainless steel to sea water and other 

 systems in which chloride ions are present. It is 

 heavier than aluminum alloys but is much stronger 

 and more chemically inert than aluminum. 



Titanium metal is widely used in the aerospace 

 industries and in the chemical industry (Miller, 

 1957; Stamper, 1970). In aircraft and spacecraft 

 structural components, where strength to weight 

 ratios are of great importance, the use of titanium 

 alloys has grown rapidly. In the aircraft engine 

 industry titanium alloys are used for parts requir- 

 ing strength at high temperatures. In the chemical 

 industry, where protection against corrosion is 

 necessary, tubing, valves, pumps, and other plant 

 components made of titanium alloys are widely 

 used. 



Titanium dioxides have properties of whiteness, 

 opacity, and chemical inertness that make them 

 especially suitable for use as pigments in paints and 

 other surface coatings and in plastics (Miller, 1957; 

 Stamper, 1970). Titanium dioxides have another 

 important use, as welding-rod coatings, where they 

 protect the surfaces of the weld from unwanted 

 reaction with the atmosphere during welding. Other 

 uses of titanium dioxides are in the manufacture of 

 mineral fibers, in ceramic components for electronic 

 equipment, in alloys, and in carbides. 



Because the uses of titanium have evolved so 

 recently, titanium and titaniferous materials are 

 substitutes replacing other more commonly utilized 

 materials. The production of titanium metal and 

 titanium compounds of high purity involves com- 

 plex and costly industrial processes, so these ma- 

 terials now are utilized as substitutes in the few 

 applications where advantages are gained in per- 

 formance or cost. 



Unprocessed titaniferous magnetite ores are used 

 in minor amounts as heavy aggregates because of 

 their density. 



The principal raw materials for the production 

 of titanium metal and titanium products are (1) 

 titanium ores, containing the minerals ilmenite 

 (FeTiOs), its alteration product leucoxene, and 

 rutile (TiOa) ; and (2) titanium slag made by smelt- 

 ing ilmenite ores (Lawthers, 1957). Ilmenite and 

 associated leucoxene are more abundant than rutile 

 and are produced in many countries, including the 

 United States (Lawthers and Mark, 1957; Lynd, 



1960). Rutile, however, is available in the United 

 States only in deposits that are economically mar- 

 ginal or submarginal, and the United States, at 

 present, is almost wholly dependent upon foreign 

 sources for this material. 



Two principal processes employed in converting 

 titanium raw materials to purified usable titanium 

 products are the chloride and sulfate processes 

 (Barksdale, 1966). Rutile is the raw material that 

 is preferred for the chloride process, which involves 

 the production of titanium tetrachloride, a highly 

 reactive liquid that must be handled under inert 

 conditions. The titanium tetrachloride is converted 

 to titanium dioxide of the rutile type or to titanium 

 metal. Ilmenite, leucoxene (ilmenite with a high 

 titanium content) , and titanium slag can also be 

 used in the chloride process. 



In the sulfate process, either ilmenite (Temple, 

 1966) or titanium slag is treated with sulfuric acid 

 to yield solutions from which iron sulfates produced 

 from iron in the ore are precipitated, and the 

 titanium remaining in the solution is then extracted 

 by precipitation. The titanium may be in two differ- 

 ent forms of titanium dioxide, anatase or rutile, 

 both suitable for use as pigments. 



Titanium metal is prepared commercially by the 

 Kroll method (Stamper, 1970), which involves the 

 reduction of titanium tetrachloride by metallic mag- 

 nesium in an inert atmosphere and the formation 

 of titanium sponge metal. Titanium sponge metal is 

 melted in a vacuum to prevent reaction with gases 

 in the atmosphere and is processed into titanium 

 ingots. 



The United States, as a leading industrial nation, 

 is a major producer and consumer of titanium 

 metal and welding rods ; and as an affluent society 

 it produces and utilizes great quantities of pig- 

 ments, as reported in U.S. Bureau of Mines "Miner- 

 als Yearbooks, 1950-70." It is one of the major con- 

 sumers of titanium raw materials as well as one of 

 the major producers of ilmenite. World and U.S. 

 production of ilmenite concentrates and Canadian 

 production of titanium slag in the last two decades 

 are shown in figure 72. 



Production of rutile in recent years has been lim- 

 ited to only a few countries. Information available 

 for rutile production in the world in recent years, 

 as reported in U.S. Bureau of Mines "Minerals Year- 

 book, 1970" and "Commodity Data Summaries, 

 1972," is shown in table 136. 



Closure of a mine in Sierra Leone in 1971 re- 

 duced world production of rutile by nearly 10 per- 

 cent, leaving Australia as the only major rutile- 

 producing country. 



