Grinding aids

Dispersing Agents and Grinding Aids There is no doubt that grinding aids are helpful under some conditions. For example, surfactants make it possible to ball-mill magnesium in kerosine to 0.5- Im size [Fochtman, Bitten, and Katz, Ind. Png. Chem. Prod. Res. Dev., 2, 212-216 (1963)]. Without surfactants the size attainable was 3 [Lm, and of course the rate of grinding was very slow at sizes below this. Also, the water in wet grinding may be considered to act as an additive. 

Additives can alter the rate of wet ball milling by changing the slurry viscosity or by altering the location of particles with respect to the balls. These effects are discussed under Tumbhng Mills. In conclusion, there is still no theoretical way to select the most effective additive. Empirical investigation, guided by the principles discussed earlier, is the only recourse. There are a number of commercially available grinding aids that may be tried. Also, a Idt of 450 surfactants that can be used for systematic trials (Model SU-450, Chem Service... 

Materials used as grinding aids include solids such as graphite, oleo-resinous liquid materials, volatile solids, and vapors. The complex effects of vapors have been extensively studied [Goette and Ziegler, Z. Ver. Dt.sch. Ing., 98, 373-376 (1956) and Locher and von Seebach,... 

Some further light may be shed on carbon floe structure by the electron micrographs of Figure 16 showing an appreciable decrease in floe size with increase in dispersant content (for the suspensions tumbled for 150 hours). One might conclude that the 0L0A-1200 was an efficient "grinding aid"... 

Grinding fluids or coolants are fluids employed in grinding to cool the work being ground, to act as a lubricant, and to act as a grinding aid. Soluble oil coolants in which petroleum oils are emulsified in water have been developed to impart some lubricity along with inst-pieventive properties. 

Table IX Examples of the Effect of Grinding Aids in Dry and Wet Grinding Systems (21).

The first three mechanisms of surfactant adsorption have been criticized mainly because crack propagation velocities in comminution devices are often much more than the rate of adsorption of the surfactants normally used as grinding aids (20). There is considerable evidence and concurrence of opinion on the prevention of agglomeration as the mechanism of grinding aid action (21). 

Many materials have been used as admixtures and the potential of many more has been examined. The literature, including the patent literature and other descriptions of proprietary materials, is voluminous a useful review published as long ago as 1980 includes over 600 references (M103). We shall only attempt to describe the effects of the most important classes of admixtures in general terms and to discuss the chemistry underlying those effects at a fundamental level. Grinding aids are similarly considered. 

Boc NaHCOs, HC02Na, nBu4NCI NaCl (grinding aid) ball mill (6 SS balls)... 

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