PIGMENTS AND FILLERS 



533 



combination for coating. In this combination, the 

 diatomite is a pigment extender (Cummins, 1960). 

 Chalk and Harris (1968) give a thorough discussion 

 of the uses of mineral fillers by the paper industry. 



PESTICIDES 



Mineral fillers are used as diluents and carriers 

 for insecticides and fungicides. Because the toxic 

 elements cannot be distributed efficiently or effec- 

 tively in the concentrated form, they must be diluted 

 in liquids or dusts to insure proper distribution and 

 a concentration that will not have deleterious effects 

 on the host, yet will destroy the harmful organisms. 

 The toxic chemicals are first mixed with a mineral 

 powder known as a carrier to make a concentrate 

 that is simple to store, ship, and handle prior to use 

 in the field. Mineral fillers suitable for carrier use, 

 like diatomite, fuller's earth, and some clays, are 

 highly absorptive. These must be dispersible in 

 liquids for sprays and must be inert and compatible 

 with the toxicant involved. Fineness and low abra- 

 siveness are important to avoid clogging and excess 

 wear of nozzles. 



This carrier-pesticide mixture usually is further 

 diluted for application from aircraft or ground 

 equipment. The filler used for this application is 

 known as a diluent. It must be of fine particle size 

 and have low abrasiveness but need not be highly 

 absorptive like the carrier. A good pesticide carrier 

 also acts as a grinding aid in preparation of some 

 pesticides, and as a conditioning agent for the 

 diluent, so that dust is free flowing but will stick 

 to the plant surface for maximum exposure to the 

 harmful organisms (Cummins, 1960). 



One interesting aspect of diluents and carriers is 

 that some mineral dusts cause very high mortality 

 rates on some insects and larvae when applied even 

 without the toxic chemicals. Apparently these min- 

 eral dusts clog the digestive and respiratory systems 

 (Huber Corp., 1955). 



OTHER USES 

 Much mineral filler is used as a carrier and diluent 

 for fertilizer, for most of the same reasons as in 

 pesticides. Fillers also have miscellaneous uses in 

 adhesives, joint cement, and many other products, 

 each of which demands specific physical properties 

 of the filler. 



FILLER MINERALS 



Cummins (1960, tables 1 and 2) listed 19 minerals 

 and mineral products, not including woUastonite, 

 that commonly are used for fillers in the United 

 States. Table 109 is an adaptation of his table 1 

 showing major uses for the principal filler minerals. 



Resources and the export-import relation for most 

 of these minerals are discussed in other chapters in 

 this volume and consequently are not discussed here. 

 Pumicite, rock dusts, slate, and vermiculite are in- 

 cluded by Cummins, but are excluded here because 

 they are minor fillers or because very few data are 

 available concerning their production and consump- 

 tion. Further information about vermiculite is in 

 the chapter on light-weight aggregates in this vol- 

 ume. Some fillers, such as rock dusts, are byproducts 

 of other milling or mining activities. 



Excluding carbon black, 55 percent of the total 

 tonnage of minerals or rocks consumed as fillers is 

 kaolin. Limestone ranks second with 23 percent and 

 of the remaining 22 percent, talc leads with 6 per- 

 cent of the consumption, and many minor fillers 

 make up the remaining 16 percent. 



The trends of domestic demand for seven major 

 fillers for the past 12 years are shown in figure 63. 

 Kaolin, fuller's earth, and talc show increasing 



1000 



900 



800 



700 



Z 600 



2 500 



t 400 



From Kollonitsch''^ 

 and others (1970a) 



BARITE (For paint and rubber only) 



Figure 6?. — Consumption trends of seven major mineral 

 fillers in the United States, 1957-69. 



