TITANIUM 



657 



In some places, titanium minerals are merely by- 

 products, and the exploitation of the deposits is de- 

 pendent upon market conditions for the other 

 minerals. 



The major byproducts and coproducts recovered 

 from titaniferous ores are iron-ore concentrates, 

 monazite, and zircon. Vanadium is obtained from 

 some titaniferous ores and is potentially recoverable 

 from many primary ilmenite deposits (Jones, 1965). 

 Potential coproducts from secondary deposits result- 

 ing from lateritic vi'eathering of the primary min- 

 erals are iron ores, aluminum ores, and nickel, 

 cobalt, and chromium concentrates. 



In deposits of rutile such as those near Evergreen, 

 Colo., topaz is a possible coproduct. 



Rutile has been recovered from deposits worked 

 for gold, diamonds, platinum, and tin. Other heavy 

 minerals which contain columbium, tantalum, ura- 

 nium, and rare earths are potential byproducts of 

 titanium. 



It is likely that future titanium mining and proc- 

 essing will involve increased recovery of coproduct 

 and byproduct materials. 



ENVIRONMENTAL PROBLEMS 



Environmental problems related to titanium pro- 

 duction are physical hazards, land despoilment, and 

 pollution, which are the same as those related to 

 other types of metal mining, processing, and fabri- 

 cation. Mining of primary deposits produces open- 

 cut pits and underground workings in which falling 

 rock, landslides, or land subsidence present direct 

 physical dangers. These dangers, however, can be 

 minimized by taking ordinary but at times costly 

 precautions. Land despoilment in the mining of 

 secondary deposits in particular can be a major 

 problem. Large areas along beaches and in terrace 

 deposits away from shorelines may be excavated. 

 These can be reclaimed by releveling in many 

 places, if the deposits are sufficiently valuable that 

 the costs of reclaiming the land can be covered by 

 the profits derived from mining. Some lands, how- 

 ever, have high surface values, particularly in in- 

 habited and recreational areas, and deposits in such 

 places may not be minable. Pollution by particulate 

 matter, such as sand and silt in streams and along 

 some shores, may be difficult or impossible to control 

 if some deposits are mined. Another major problem 

 is the disposal of large quantities of sulfates and 

 other chemicals that accumulate in waste products 

 that result from the chemical processing of titanium 

 ores. 



In present and future mining and processing of 

 titanium ores, the environmental problems require 



a great deal of consideration if the operations are 

 to be conducted profitably. In many places, deposits 

 may not be mined or mining may be curtailed be- 

 cause of conflicting environmental considerations. 



GEOLOGIC ENVIRONMENT 

 GEOCHEMISTRY 



Titanium is the ninth most abundant element, fol- 

 lowing oxygen, silicon, aluminum, iron, calcium, 

 magnesium, sodium, and potassium, which make up 

 more than 98 percent of the earth's crust. The re- 

 maining 84 elements are commonly considered to be 

 trace elements. 



Titanium is a lithophile element and has a strong 

 affinity for oxygen. It is in group IVA of the peri- 

 odic table, along with zirconium and hafnium. 

 Titanium, zirconium, and hafnium have approxi- 

 mately the same abundance ratio (Ti:Zr:Hf= 

 1,000:50:1) in igneous rocks, in silicate meteorites, 

 and in the solar atmosphere (Rankama and Ba- 

 hama, 1950). 



Because titanium is strongly lithophilic, it con- 

 centrates in stony matter of the "slag crust" of the 

 earth as well as in the stony matter of meteorites 

 (Goldschmidt, 1954, p. 409). Oceanic crust and con- 

 tinental crust contain about 8,100 ppm (parts per 

 million) and 5,300 ppm titanium, respectively (Lee 

 and Yao, 1970). It forms oxides and oxy-salts and 

 has no tendency to concentrate in metallic iron or 

 to form sulfides. Titanium tends to be incorporated 

 in ilmenite (FeTiOa) and sphene (CaTiSiOs). The 

 greatest abundance of titanium is in subsilicic rocks, 

 including mafic and alkalic rocks, or is associated 

 with anorthosites. The abundance of titanium in 

 different rock types in percent is (Vinogradov, 

 1962) : stony meteorites, 0.05; ultramafic rocks, 

 0.03 ; mafic rocks, 0.9 ; intermediate rocks, 0.8 ; felsic 

 rocks, 0.23 ; and sediments, 0.45. 



The behavior of titanium in magmatic crystalliza- 

 tion is complicated and depends on such factors as 

 the initial titanium content of the magma, the 

 chemical activities of iron, silicon, and aluminum, 

 the partial pressure of oxygen, and the temperature 

 of crystallization. Thus, in some magmas titanium 

 will enter silicate minerals at high temperatures 

 rather than form oxides (Verhoogen, 1962). 



Titanium commonly occurs in clinopyroxenes, 

 olivine, biotite, amphibole, and sphene. In crystal- 

 lizing magmas, Ti-Fe oxides will form in two ways : 

 (1) by direct precipitation of ilmenite or ilmenite- 

 hematite solid solution or ulvospinel-magnetite 

 solid solution; the earliest formed oxides will have 

 the highest Ti/Fe ratios; (2) by breakdown of 



