Separation of shelled walnut particles using pneumatic method

Separation of shelled walnut particles was studied on two varieties of Persian walnut, Poost-Kaghazi and Poost-Sangi using pneumatic method. The moisture contents of the samples were determined. The particles were considered in three categories of shell, kernel and shell-kernel together. Each category was manually classified based on their size, in three portions of 1/8, 1/4, and 1/2, as well as the whole kernel and whole walnut. The terminal velocity of each group was determined. The shelled walnuts were sieved and classified in three groups of small, medium and large. The effects of separation time (5, 10 and 15 seconds), feeding value (50 to 80 gr) and air velocity on separation of the kernels and shells were studied for both varieties. The interaction effects were also studied for three walnut sizes (small, medium and large). The terminal velocity was the highest for the whole walnut and the whole kernel while it was lowest for 1/4 and 1/8 of the shell. The best separation was performed at air velocities of 9.20, 10.04 and 10.94 m/s with 98.2%, 98.9% and 98.2%, respectively.