e plant, established
originally by the California Walnut Growers Association, was grinding
nut shells. This plant, following a number of operational difficulties
and administrative changes, now processes 40 tons or more of shells per
day and produces a wide variety of ground products including exceedingly
fine flours for use in plastics and plywood adhesives. It has been said
that this plant processes all of the English walnut and apricot pit
shells and 80 percent of the peach pit shells available in California.

The Laboratory has attempted to determine the amount of shells and pits
available commercially in different areas. Data of this nature has been
obtained for the larger cracking plants but there are many small
operations for which we lack this information. "Agricultural Statistics"
compiled and published annually by the U. S. Department of Agriculture
provide an excellent source of information regarding production and, in
many cases, the disposition of farm commodities. For example, the
production of pecans in 1951, presented by states, totaled more than
73,000 tons for the 10 states reported. However, no data were available
regarding marketings in-shell, or the quantities remaining on the farms
or in the orchards. Thus, the quantity of pecan shells actually
available for processing can be determined only through surveys of
cracking plants. Only limited information is available concerning black
walnut shells and this has been obtained through the cooperation of
shellers or crackers.

In some areas fruit pits, such as apricot and peach pits, accumulate at
canneries or freezing plants. Similarity in character of the pit shells
to those of the nuts permits their use in plants grinding nut shells.
Thus, the supply of raw material in any area may be augmented by
inclusion of fruit pit shells.

Collection of nut shells for grinding operations is a relatively simple
procedure, particularly where grinding is done at a cracking plant.
Where shells must be collected over large areas both rail and truck
transportation are used. If fruit pits are considered, provisions should
be made for removal of residual flesh or pulp before the pits leave the
canneries. In the cases where the pits have been cut during processing
of the fruits, the released kernels should be removed before shipping
the shells. Pit kernels are valuable for their oil content.

Shell Use During World War II

The production and maintenance schedules s