Besides improving product quality, removing stones from product flow protects equipment.

Smiths Detection Eagle Bulk 370 occupies its lofty height 20 feet above the plant floor and checks pistachios for metal, glass and rock contaminants. Source: Smiths Detection.

Setton Pistachio of Terra Bella Inc., located in Terra Bella, CA, is the second largest pistachio nut producer in the US. The Setton plant is located on 36 acres, with more than 150,000 sq.-ft. of processing capabilities including cold, dry and silo storage in excess of 60 million pounds.

In 2005, the producer launched a strategic initiative to improve quality by revamping foreign material detection in its process. Conventional technologies for detecting and removing metal contamination had limited success in finding other foreign materials. Metal detectors and magnets placed throughout the plant detected and removed metal particles, and color and hand sorters were used to identify and remove rocks. Unfortunately, due to similarities in size and shapes of rocks and pistachios, removing the stones proved difficult.

Setton’s management team researched inspection options that would remove even more foreign materials during inspection and further improve product quality, settling on three X-ray vendors.

According to Frank Aguilera, safety/quality assurance supervisor, “We considered two other X-ray vendors, but it was clear in talking with Smiths Detection that not only could [its equipment] handle the flow rates we needed to inspect all of our product, but the supplier’s knowledge and experience in X-ray in particular seemed above the competition.”

Setton Pistachio purchased Smiths Detection Eagle Bulk 370. The system was installed on an elevated mezzanine 20 feet above the plant floor, where it receives a steady stream of raw pistachios from the storage silos. The machine checks the bulk pistachios for foreign materials such as stones, glass and metal contaminants. Rejected product and contaminants are sent two-stories down a chute to a gravity table de-stoning device at ground level, which separates the rocks from the product so the good pistachios can be reclaimed.

While the gravity table can remove rocks, it is not capable of supporting the entire process product flow. Using the gravity table to sort only affected batches saves time and money.

Prior to using X-ray inspection, Setton used a variety of other methods to eliminate rocks. When rocks were not removed, they proceeded downstream, damaging sensitive processing equipment, such as the needle pickers. Needle pickers are large rotating drums that have thin needles inside to pick up only open shell pistachios and sort them from closed-shell nuts. When rocks come into this drum and tumble around, they break off the needle tips, resulting in higher maintenance costs and down time. Removing rocks before they reach the needle picker has been a key, unexpected benefit from the X-ray system.

The X-ray system provided other benefits. “We continue to use magnets and metal detectors spread throughout the plant,” says Aguilera. “But with the use of the X-ray machine, we were able to reduce our magnet cleaning schedule to once every three days instead of daily, saving considerable labor cost. The X-ray gives us a 30-lb. barrel once or twice a month to empty and saves time. It concentrates our inspection into a single point instead of multiple places around the plant that needed checking,” adds Aguilera.

For more information: Sherrie Moore, 865-379-1670 ext. 283,