The Laboratory has studied the use of shell flours for use in plastics and plywood glues. Many of these flours are now in regular commercial use. Flours for these applications are prepared in various grades, all finer than 100-mesh. Use of these flours not only improves the properties of the final products but also reduces the cost of the products. Molded plastics prepared with fine flour from English walnut shells have exceptionally fine surface finish.
Insecticide Carriers
The insecticide field provides a good outlet for shell flours. Flour from walnut shells was the first of this type of material to be used for this purpose. Often the active ingredient in a finished insecticide is present in quantities of less than 1 percent. Custom grinders should plan to recover the flour as a co-product of their operations rather than attempting to grind to flour alone.
Explosives
Large amounts of shell grits and meal are used as diluents in the manufacture of dynamite. Material for this use ranges in size from No. 10 to No. 100, the requirements of the individual manufacturers falling within much narrower limits as to size.
Fur Cleaning
Furriers have found that various ground shell products are very effective agents for cleaning furs. Size requirements for this purpose are broad, the limits being dependent upon the cleaning equipment maintained by the furrier. The natural oils present in some shell products are considered advantageous for this application.
Sundry Applications
Stock bedding, poultry litters, fillers in feeds and fertilizers, mulches, charcoal, tannin and abrasives in hand soaps are some of the other products that are prepared from nut shells. The shell products cannot be used interchangeably but must be selected in accordance with their chemical and physical properties.
I hope that the foregoing brief discussion has conveyed to you the potential value that lies in the piles of shells accumulating at the cracking plants, and that these accumulations can be converted from expensive wastes to profitable products.