PIGMENTS AND FILLERS 



531 



ance; and because of rutile's high index of refrac- 

 tion, the rutile-type pigment has a very high opacity 

 or hiding power, making it valuable for paint or as 

 a paper coating. 



Titanium dioxide for pigment is the principal 

 product of titanium ores in the United States. Of 

 1.29 million tons of concentrates mined in 1970, 

 1.24 million tons or 96 percent was made into titan- 

 ium pigments. The paint and paper industries con- 

 sumed 76 percent of this and the remainder was 

 divided among rubber, floor covering, textiles, ink, 

 ceramics, and plastics manufacture and exports. 

 The value of titanium pigments shipped in 1969 

 was $333 million for 652,000 short tons (Noe, 1970) ; 

 data for 1970 are not available. Other aspects of 

 titanium and its resources are covered in the chap- 

 ter of this volume on titanium. 



CARBON BLACK 



Carbon black is a nearly pure micron-sized car- 

 bon produced from natural gas or liquid petroleum 

 by incomplete combustion or by thermal decomposi- 

 tion under carefully controlled conditions that de- 

 termine the particle size, structure, and physical 

 properties. Although carbon black is virtually a 

 black pigment, its main use is as a reinforcing agent 

 in tire rubber. As a pigment, it is used in ink and 

 paint. The plastics industry used only a small 

 amount of carbon black to color plastics until it 

 was discovered that a larger percentage greatly im- 

 proved the resistance of polyethylene to becoming 

 brittle from sunlight aging. Now as much as 50 

 percent carbon black is added to polyethylene cable 

 coverings for this purpose (Kelley and Harper, 

 1970, p. 66), another example of the overlapping 

 functions of pigments and fillers. 



A direct relation exists between the expanding 

 rubber industry and the growing consumption of 

 carbon black. Other uses of carbon black, especially 

 in inks and paints, do not show a similar increase 

 in growth. Production of carbon black in 1969 was 

 1.48 million short tons valued at $215 million. About 

 98,251 million cubic feet of natural gas and 524.4 

 million gallons of liquid hydrocarbons were con- 

 sumed in its production. A process having an effi- 

 ciency of 1-5 percent and using natural gas to pro- 

 duce "channel blacks" is giving way to much more 

 efficient processes as the price of natural gas climbs 

 (Kelley and Harper, 1970). Exports in 1969 were 

 98,100 tons of carbon black, which represented a 

 25.4 percent decrease from 1968 despite increased 

 foreign production of tires. Expansion of U.S.- 

 owned and foreign-owned carbon black companies 

 close to sources of foreign gas and oil accounts for 



this decrease in our exports (Kelley, 1969, p. 247). 

 Imports in 1969 were 3,000 tons of specialty carbon 

 blacks. 



OUTLOOK FOR PIGMENTS 



The demand for pigments is directly related to 

 the manufacture of paint, printing inks, and color- 

 ing matter for rubber and plastics. These products 

 are all voraciously consumed by a suburbia- and 

 automobile-oriented society such as that of the 

 United States. The demand for pigments will grow 

 as population and gross national product increase. 



The demand for natural mineral pigments, such 

 as iron oxide, however, is being supplanted by syn- 

 thetic pigments because consistency of the manu- 

 factured product is more easily controlled. This 

 trend toward the synthetic probably will continue 

 although the market for good natural pigments will 

 undoubtedly continue. Recovery on a large scale of 

 iron oxide pigments as a byproduct of treatment of 

 acid mine water is an intriguing possibility for the 

 future. 



Production of ZnO, TiOs, and carbon black is 

 increasing, and because these pigments are basic in 

 the manufacture of paints, rubber, and plastics their 

 demand will expand with the national groMdh. 



MINERAL FILLERS 



Mineral fillers are finely ground, generally inert 

 rock or mineral additives used for the purpose of 

 giving necessary or desirable physical properties to 

 a finished product. Almost any rock could be pul- 

 verized and serve some of the many functions of a 

 filler; however, several rocks and minerals satisfy 

 the rigid physical specifications of filler products 

 particularly well and are the backbone of mineral 

 filler consumption, which reached 7 million tons in 

 1969. The principal filler materials are kaolin, lime- 

 stone, diatomite, carbon black, talc, asbestos, mica, 

 barite, fuller's earth, pyrophyllite, and wollastonite. 

 Many of these have specific properties, such as the 

 fibrous particle shape of asbestos, that makes them 

 uniquely suited for certain uses. Others, however, 

 such as kaolin, talc, and pyrophyllite, can be substi- 

 tuted for each other for some purposes; their use 

 than also depends on availability, transportation, 

 and cost of mining and beneficiation. Because of 

 these additional factors and the ability of some filler 

 minerals to be substituted for others, attention 

 should be paid by geologists, working in districts 

 with convenient transportation to industrial parts 

 of the country, to the potential suitability of white- 

 grinding fairly soft, chemically inert rocks and 

 minerals for use as mineral fillers. 



