Keeping The Dust Down When Separating The Chaff From The Nuts

Researchers Derek Whitelock, Carlos Armijo and Ed Hughs at ARS’ Southwestern Cotton Ginning Research Laboratory in Mesilla Park, N.M., and Michael Buser in ARS’ Cotton Production and Processing Research Unit at Lubbock, Texas—working with Flory Industries engineers Seth Richmond and Mike Flora—are testing a prototype device that uses centrifugal force to trap soil and bits of leaves and sticks so the harvester emits cleaner air.

Mechanical shakers grab trees and shake out nuts—mainly walnuts, almonds and pecans. The nuts, plus unwanted leaves and twigs, fall to the ground and are swept into windrows. Pick-up machines then scoop up the windrows. Air flowing through the harvester separates the nuts from debris that also includes soil particles. The debris blows out into the air through a side exhaust as the nuts are conveyed into a cart pulled behind the harvester.

The prototype is trapping the debris and some dust, but it needs more work, primarily because of the difficulty presented by the 12,000-cubic-foot-a-minute airflow through the harvester and out the exhaust. Whitelock modeled the device after the large cyclone dust collectors attached to cotton gin exhausts.

But a tree nut harvester can't afford to have the huge cyclone that would normally handle that much airflow in cotton gin exhaust. Unlike a stationary cyclone attached to the outside exhaust of a cotton gin, the tree nut harvester has to be driven under the low tree canopies of many orchards.

The same harvester, with modifications, is used throughout the country to harvest various tree nuts, mainly almonds and walnuts in California and pecans in Georgia, Texas, New Mexico and Oklahoma.

This research is part of ARS' national program to develop agricultural technologies that minimize contamination of the air by dust particles from food and fiber production.